Byte Magazine Volume 06 Number 04 - Future Computers

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APRIL 1981 Vol. 6,: No. 4
$2.50 in USA/$2.95 in Canada

A McGraw-Hill Publication

the small systems journal

FUTURE COMPUTERS I

masm

YOUR CHOICE-smart either way

• Over 140 software driven functions

• 82 x 24 or 82 x 20 screen format — software selectable

• High resolution 7x12 matrix characters - P-31 green phosphor

• Upper/lower case character set — plus graphics character set

• 56-key alphanumeric keyboard — plus 12-key cursor, numeric pad

• Internal editing functions - insert, delete, scroll, roll, slide, etc.

• Parallel printer I/O port

• 50 to 38,400 baud operation — programmable

• Cursor type, cursor position, print control characters, protected fields,
shift inversion, dual intensity and many other features

8212 — twelve-inch diagnonal screen or 8209 — nine-inch diagnonal screen

SOUTHWEST TECHNICAL PRODUCTS CORPORATION

219 W. RHAPSODY

SAN ANTONIO, TEXAS 78216 (512) 344-0241

Circle 360 on inquiry card.

INTELLIGENT 110

I/O INTERFACES

COLOR GRAPHICS

MULTI-PROCESSING

IT-MBYTE

EXTENSIVE

COLOR

FLOPPV DISK

HARD DISK

JOYSTICK

SOFTWARE

PRINTERS

MONITORS

DRIVES

DRIVE

CONSOLE

SUPPORT

What Cromemco computer card
capability can do for you

The above diagram shows in a func-
tional way one of the most complete
lines of computer cards in the industry.

Look it over carefully. It could be well
worth your while.

These are all cards that plug into our
S-100 bus microcomputers.

You can also assemble them into a
custom system in convenient Cromemco
card cages.

MULTI-PROCESSING AND
INTELLIGENT I/O

The range of capabilities and versatility
you can draw upon is enormous.

In processors, for example, you have a
choice of CPU's including our extremely
useful new I/O Processor. This can be
used as a satellite processor to do off-line
processing, multi-processing, and to form
intelligent I/O. It opens the door to a
whole new group of applications and
tasks. Ask us about it.

HIGH RESOLUTION
COLOR GRAPHICS

Again, you can have beautiful high-
resolution color graphics with our color
graphics interface. You can select from
over 4000 colors and have a picture with
a resolution at least equal to quality
broadcast-TV pictures.

Q

You have an unprecedented selection
of memory including our unusual 48K
and 16K two-port RAMs which allow
high-speed color graphics.

LOTS OF STORAGE

These days you often want lots of disk
storage. So you can select from our disk
controller card which will operate our 5"
and 8" floppy disk drives (up to 1.2
megabytes). Or select our WDI interface
to operate our 11-megabyte hard disk
drives.

POWERFUL SOFTWARE AND
PERIPHERAL SUPPORT

There's much more yet you can do
with our cards. And, of course, there's an
easy way to put them to work in our 8-,
12-, and 21 -slot card cages. Our PS8
power supply makes it simple to get the
system into operation.

Finally, Cromemco offers you the
strongest software support in the industry

Cromemco ™

incorporated

280 BERNARDO AVE., MOUNTAIN VIEW, CA 94040 • (415)964-7400

Tomorrow's computers today

Circle 1 on Inquiry card.

with languages like FORTRAN, C,
COBOL, ASSEMBLER, LISP, BASIC and
others. There is also a wide choice from
independent vendors.

To top it all off, you can draw from a
substantial array of peripherals: ter-
minals, printers, color monitors and disk
drives.

CONTACT YOUR CROMEMCO REP

There is even more capability than
we're able to describe here.

Contact your Cromemco rep now and
get this capability working for you.

CROMEMCO COMPUTER CARDS
PROCESSORS — 4 MHz Z-80 A CPU, single
card computer, I/O processor • MEMORY —
up to 64K including special 48K and 16K two-
port RAMS and our very well known
BYTESAVERS® with PROM programming
capability • HIGH RESOLUTION COLOR
GRAPHICS - our SDI offers up to 754 x 482
pixel resolution. • GENERAL PURPOSE
INTERFACES— QUADART four-channel serial
communications, TU-ART two-channel
parallel and two-channel serial, 8PIO 8-port
parallel, 4PIO 4-port isolated parallel, D+ 7A
7-channel D/A and A/D converter, printer inter-
face, floppy disk controller with RS-232 inter-
face and system, diagnostics, wire-wrap and
extender cards for your development work.

Management Information Display

Ultrasonic heart sector scan

High-resolution display with alphanumerics

Get the professional color

display that has
BASIC/FORTRAN simplicity

LOW-PRICED, TOO

Here's a color display that has
everything: professional-level resolution,
enormous color range, easy software,
NTSC conformance, and low price.

Basically, this new Cromemco Model
SDI* is a two-board interface that plugs
into any Cromemco computer.

The SDI then maps computer display
memory content onto a convenient color
monitor to give high-quality, high-
resolution displays (756 H x 482 V pixels).

When we say the SDI results in a high-
quality professional display, we mean you
can't get higher resolution than this
system offers in an NTSC-conforming
display.

The resolution surpasses that of a color
TV picture.

BASIC/FORTRAN programming

Besides its high resolution and low
price, the new SDI lets you control with
optional Cromemco software packages
that use simple BASIC- and FORTRAN-
like commands.

Pick any of 16 colors (from a
4096-color palette) with instructions like
DEFCLR (c, R, G, B). Or obtain a circle of
specified size, location, and color with
XCIRC (x, y, r, c).

t aW\

•U.S. Pat. No. 4121283

Model SDI High-Resolution Color
Graphics Interface

HIGH RESOLUTION

The SDI's high resolution gives a
professional-quality display that strictly
meets NTSC requirements. You get 756
pixels on every visible line of the NTSC
standard display of 482 image lines. Ver-
tical line spacing is 1 pixel.

To achieve the high-quality display, a
separate output signal is produced for
each of the three component colors (red,
green, blue). This yields a sharper image
than is possible using an NTSC-composite
video signal and color TV set. Full image
quality is readily realized with our high-
quality RGB Monitor or any conventional
red/green/blue monitor common in TV
work.

Model SDI plugs into Z-2H 11 -mega byte

hard disk computer or any Cromemco

computer

DISPLAY MEMORY

Along with the SDI we also offer an
optional fast and novel two-port memory
that gives independent high-speed access
to the computer memory. The two-port
memory stores one full display, permit-
ting fast computer operation even during
display.

CONTACT YOUR REP NOW

The Model SDI has been used in scien-
tific work, engineering, business, TV,
color graphics, and other areas. It's a
good example of how Cromemco keeps
computers in the field up to date, since it
turns any Cromemco computer into an
up-to-date color display computer.

The SDI has still more features that
you should be informed about. So contact
your Cromemco representative now and
see all that the SDI will do for you.

a Cromemco
incorporated
280 BERNARDO AVE., MOUNTAIN VIEW, CA 94043 • (415) 964-7400
Tomorrow's computers today

Circle 1 on inquiry card.

In The Queue

Volume 6, Number 4

April 1 98 1

Features

ZO Recurrence in Numerical Analysis by

James J Davidson / Recurrence can be used to
simplify the calculation of Bessel functions.

36 Build a Low-Cost Logic Analyzer by

Steve Ciarcia I Turn your computer into a powerful
diagnostic tool.

64 A-L BYTE Guide to The National Com-
puter Conference and Chicago / Up-to-date infor-
mation on the conference, the city, and much more.

66 Digital Minicassette Controller by

James Kahn / Use an intelligent peripheral controller
to lighten the load on your computer system.

102 Programming the Game of Go by

Jonathan K Millen / Even though Go is much
harder than chess, a microcomputer Go program can
produce surprisingly good play.

122 Build Your Own Turing Machine by

James Willis / Three different practical versions of
this theoretical tool produce the same output.

1 50 A Closer Look at the Tl Speak &

Spell by Peter Vernon / The author expands on
Michael Rigsby's September 1980 BYTE article.

2 1 8 An Introduction to Data Compres-
sion by Harold Corbin / Information can be
transmitted and stored using fewer data bits by ap-
propriate techniques.

Build an Intercomputer Data Link

by Mike Wingfield / Using this software, systems
based on the 6800 microprocessor can communicate
with other systems.

290 Three-Dimenslonal Computer

Graphics, Part 2 by Franklin C Crow / Soft-
ware to display solid objects without hidden
lines and surfaces.

348 PADDLES: Interfacing with Modular

Breadboards by Roger J Combs and Paul
Field / Designing and implementing breadboard cir-
cuits is greatly eased with the use of these standard-
ized modules.

Reviews

46 The MicroAce Computer by Delmar Searls
94 A Reformatter for CP/M and IBM Floppy

Disks by John Lehman

1 88 Three Versions of APL by Gregg Williams

Nucleus

6

10,

12

32,

98,

148

158
186
212
328
332
338
344
345
359
414
415
416

Editorial: Future Trends in Personal Computing

302 BYTE's Bugs

Letters

34 Programming Quickies: Apple Name-Address; A

Graphic Execution Display

304, 310, 314 Technical Forum: MicroShakespeare

Revisited or Kilobard; An ADM-3 Emulator for the

Hazeltine 1 500; Challenger Writes on Comprint; On

the Use of Fourier Transforms to Explore Biological

Rhythms

System Notes: A Relocatable Bootstrap for t+ie Tarbell

Disk Controller

Clubs and Newsletters

Cartoon

BYTELINES

Ask BYTE

Event Queue

Books Received

Software Received

BYTE's Bits

What's New?

Unclassified Ads

BOMB, BOMB Results

Reader Service

EITE

Page 36

Page 46

Page 186

Page 302

April 1981 © BYTE Publications Inc 3

m

Editor in Chief
Christopher Morgan

Managing Editor

Mark Haas

Technical Editors

Gregg Williams. Senior Editor;
Richard S Shuford; Curtis P Feigel;
Harold Nelson; Stan Miastkowski;
Kevin Cohan; Bruce Roberts;
Charles Freiberg. New Products Editor;
Steve Garcia. Mark Dahmke,
Consulting Editors;
Jon Swanson, Draftsman

Copy Editors

Richard Friedman, Chief; Faith Hanson;
Warren Williamson; Anthony J Lockwood;
Ann Graves

Assistants

Faith Ferry; Debe Wheeler;
Karen A Cilley

Production

Nancy Estle, Director; Christine Dixon,
Asst Director; Wai Chiu Li;
Jonathan M Graves; Deborah Porter;
Sherry McCarthy. Chief Typographer;
Debi Fredericks; Donna Sweeney;
Valerie Horn

Advertising

Thomas Harvey, Director; Marion Gagnon;
Barbara J Greene; Rob Hannings

Circulation

Gregory Spitzfaden, Manager;
Andrew Jackson, Asst Manager;
Agnes E Perry; Barbara Varnum;
Louise Menegus; Bill Watson;
Dealer Sales: Melanie Bertoni

Marketing

Jill E Callihan, Special Projects;
Laura Hanson

Controller's Office

Daniel Rodrigues, Controller; Mary E Fluhr,
Asst Controller; Karen Burgess; Jeanne Cilley

Traffic

N Scott Gagnon; Robert A Fiske

Receptionist

Jacqueline Earnshaw

Publishers

Virginia Londoner; Gordon R Williamson;
John E Hayes, Associate Publisher;
Cheryl A Hurd, Publisher's Assistant

Officers of McGraw-Hill Publications Com-
pany: Paul F McPherson, President; Executive
Vice Presidents: James E Boddorf, Gene W
Simpson; Group Vice President: Daniel A
McMillan; Senior Vice President-Editorial: Ralph
R Schulz; Vice Presidents: Kemp Anderson,
Business Systems Development; Robert B Doll,
Circulation; James E Hackett, Controller; Eric B
Herr, Planning and Development; H John
Sweger, Marketing.

Officers of the Corporation: Harold W
McGraw Jr. President, Chief Executive Officer
and Chairman of the Board; Robert F Landes,
Senior Vice President and Secretary; Ralph J
Webb, Treasurer.

In This Issue

"Future Computers" is our cover theme this month and the subject of the
editorial. Before you write to comment on our cover's "unusual" design
approach (created by artist Robert Tinney), keep in mind the proximity of April
1.

Elsewhere in this issue we describe Steve Ciarcia's latest project, a low-cost
logic analyzer, and tell how to build your own Turing machine. Other articles
include: a follow-up to our earlier review of the Sinclair computer, this time a
description of the MicroAce kit version; a reformatter for CP/M and IBM-
format floppy disks; a closer look at the Tl Speak & Spell; a fascinating review
of three different APL packages for the patient (but eager) APL fans in our
audience; details about data compression; all about intercomputer data links
and the game of Go; and the conclusion of an article from last month about
3-D computer graphics.

BYTE is published monthly by BYTE Publications Inc. 70 Main St, Peterborough NH 03458, phone |603)
924-928 1 , a wholly-owned subsidiary of McGraw-Hill. Inc. Address subscriptions, change of address. USPS Form
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Address all editorial correspondence to the editor at BYTE, POB 372, Hancock NH 03449. Unacceptable
manuscripts will be returned if accompanied by sufficient first class postage. Not responsible for lost manuscripts or
photos. Opinions expressed by the authors are not necessarily those of BYTE. Entire contents copyright © 1981
by BYTE Publications Inc. All rights reserved. Where necessary, permission is granted by the copyright owner for
libraries and others registered with the Copyright Clearance Center (CCC) to photocopy any article herein for the
base fee of S 1 .00 per copy of the article or item plus 25 cents per page. Payment should be sent directly to the
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NATIONAL ADVERTISING SALES REPRESENTATIVES:

NORTHEAST (617) 444-3946

Hajar Associates
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NORTHWEST (415J 964-0706

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lOOOEIwellCt, Suite 227
Palo Alto CA 94303

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MID ATLANTIC (212) 682-5844

Hajar Associates
52 1 Fifth Ave
New York NY 10017

SOUTHEAST (305) 886-7210

Hajar Associates
1220 Prairie Lane
Apopka FL 32703

April 1981 © BYTE Publications Inc

"... stands well above
other S-100 graphics dis-
plays in its price and per-
formance range."

BYTE, Product Review

. better monochromatic
. display .

ELECTRONIC DESIGN,
1981 Technology Forcast

MICROANGELO

HIGH RESOLUTION GRAPHICS SINGLE BOARD COMPUTER

512 x 480 resolution black and white and vivid color displays

RS-170 com-
posite or direct
drive output

Local or external
sync generation

4MhzZ80
microprocessor

60 hertz real-
time clock

8 level interrupt
tie-in

IEEE S100 bus
compatible

Screenware™ Pak I

A 4K byte operating system resident in PROM on
MicroAngelo™. Pak I emulates an 85 character
by 40 line graphics terminal and provides over
40 graphics commands. Provisions exist for user
defined character sets and directly callable user
extensions to Screenware™ Pak I.

Screenware™ Pak II

An optional software superset of Pak I which
adds circle generation, polygon flood, program-
mable split screen for separate graphics and ter-
minal I/O, relative coordinates, faster vector and
character plotting, a macro facility, full UCSD
Pascal compatibility, and more.

Light pen
interface

Time multi-
plexed refresh

4K resident

Screenware™

Pak I operating

system

32KRAM

isolated from

host address

space

High speed

communications

over parallel

bus ports

And now. . .COLOR"

The new MicroAngelo™ Palette board treats from
2 to 8 MicroAngelos as "bit planes" at a full
512 x 480 resolution. Up to 256 colors may be
chosen from 16.8 million through the program-
mable color lookup table. Overlays, bit plane
precedence, fade-in, fade-out, gray levels, blink-
ing bit plane, and a highly visual color editor are
standard.

Circle 2 on inquiry card.

SOON

8455-D Tyco Road • Vienna, Virginia 22180 • TWX: 710-831-9087 • (703) 827-0888

Circle 3 on inquiry card.

UCSD

PASCAL
FORTRAN

Portable

Develop on a Z-flOt,
runonLSI-1lt, T.I. 990,
6800 or vice versa

Efficient

Structured, readable
Speeds development X5
Easy maintenance

Powerful

Full standard Pascal

plus extensions

ANSI '77 Fortran Subset

Cost Effective

Complete system Including
Interpreter, screen editor,
utilities, filer, assembler,
and compiler,
with Pascal $400
with Fortran $450
with Both $600

APPLICATIONS

PFAS

(Pascal File Access System)
Keyed-ISAM in 6K user
memory $200

INTELLECT UL VI.2

A full range LISP interpreter
for UCSD p-systems $200

MEDOFFICE

Professional medical office
software for 1 to 5 doctors.
Call for pricing.

DATEBOOK

Appointment scheduling on
your micro $295

READY TO RUN ON
DEC PDP-11 for
TRS-80 MODEL 11 §

PCD

SYSTEMS

P. 0. Box 143
Penn Yan, NY 14527
315-536-3734

*TM Univ. of Calif.

JTMofZllog

JTM of Digital Equipment

STM of Tandy Corp.

Editorial

Future Trends in
Personal Computing

Chris Morgan, Editor in Chief

Future Com-
puters — what
will they be like?

Some exciting
developments have
been occurring in
the industry lately
that should give us
some clues. I at-
tended the Con-
sumer Electronics
Show in Las Vegas
this past January,
where Toshiba in-
troduced what
could be the most
significant product
of the year for the
personal-comput-
ing market: a pock-
et-size flat-screen
television set.
While no specific
mention was made
of its possible use
with a personal
computer, it takes
only a moment's
thought to see the
potential of this engineering marvel.

First introduced in japan some
months ago, the Toshiba television
has a 4.1 by 3.1 cm (l 3 / 5 by 1% inch)
LCD (liquid-crystal display) screen
housed in a case measuring 17.3 by
8.2 by 1.8 cm (6% by 3% by
7 /io inches)! It has only half the resolu-
tion of a standard CRT (cathode-ray
tube) display, but its small size masks
that fact effectively. Toshiba has also
solved the problem of liquid-crystal
"overhang," the slow-fade effect that
plagues LCDs in electronic games.
The response time of this particular
design is fast enough to handle the
1/30 of a second television-frame
refresh rate. Although the screen is
dimmer than a CRT display (the im-

Photo 1: Toshiba's new pocket-size
television prototype. A built-in zoom
feature is available that enlarges any
one of the four screen quadrants for
close-up viewing. Photo by Stan
Miastkowski.

age is formed from
reflected rather
than transmitted
light), it has accept-
able contrast and
sharpness. The
screen is fed by a
bank of shift regis-
ters; it would be an
easy task to display
computer graphics
and characters on
it.

The Toshiba flat-
screen unit is still
in the prototype
phase and will
probably not be
available for a year
or so, retailing for
approximately $600.
I predict that with-
in two years the
market will be
flooded with porta-
ble computers hav-
ing built-in screens
of every size and
shape.

Sony has introduced a new elec-
tronic "typewriter" that fits in a brief-
case and lets you enter, store, and
edit up to 200 pages of text using a
built-in microcassette recorder. Text
is displayed on a one-line liquid-
crystal display. Combine such a de-
vice with a flat-screen multiline video
display and you have a very attrac-
tive concept, indeed.

Another Sony breakthrough is a
new miniature floppy-disk system
(see photo 3, page 10). Each disk
measures 8.9 cm (3Vi inches) in
diameter and holds over 800,000
bytes 1 The disk resides in a rigid
housing for protection. Sony plans to
introduce the disk as part of a new,
miniature word-processing system.

Percom Mini-Disk Drive Systems for TRS-80* Computers . . .

Now! Add-On and Add-In Mini-Disk

Storage for your Model III.

New for the TRS-80* Model III

Patterned after our fast-selling TFD Model I drives. And
subjected to the same reliability controls. These new
TFD mini-disk systems for the Model III provide more
features than Tandy drives, yet cost far less.

• Flippy Capability: Both internal (add-in) and
external (add-on) drives permit recording on either
side of a diskette.

• Greater Storage Capacity: Available with either 40-
or 80-track drive mechanisms, Percom TFD mini-disk
systems store more. A 40-track drive stores up to 180
Kbytes — formatted — on one side of a 5-inch
diskette. An 80-track drive stores a whopping 364
Kbytes.

• 1.5 Mbyte On-line: The Percom drive controller
(included with the initial drive) handles up to four
drives. With four 80-track mini-disk drives you can
access over 1.5 million bytes of on-line file data.

Moreover, the initial drive may be either an
internal add-in drive or an external add-on drive. And
whichever configuration you get, the initial drive kit
comes complete with our advanced 4-drive
controller, interconnecting cables, power supplies,
installation hardware, a DOS and of course the drive
mechanism itself.

• First Drive Includes DOS: OS-80™, Percom's fast
extendable BASIC-language disk operating system, is
included on diskette when you purchase an initial
drive kit. Originally called MicroDOS, OS-80 was
favorably reviewed in the June 1980 issue of Creative
Computing magazine.

• Works with Model III TRSDOS: Besides being fully
hardware compatible, Percom's Model III 40-track
drive systems may be operated with Tandy's Model III
TRSDOS — without any modifications whatsoever.
And, TRSDOS may be easily upgraded with simple
software patches for operating 80-track drives.

Percom TFD add-on drives start at only $399. Model
III Drive kits start at only $749.95.

Quality Percom products are available at
authorized dealers. Call toll free 1-800-527-1592
for the address of your nearest dealer or to order
direct from Percom.

The industry leader in microcomputer peripherals,
Percom not only gives you better design, better
quality and first-rate service, but you pay less
to boot.

Still #1 for Model I

As if greater storage capacities, exceptional quality
control measures and lower prices aren't reasons
enough to make Percom your first choice for Model I
add-on drives, all Percom Model I drives are also rated
for double-density operation.

Add our innovative DOUBLER™ adapter to your
Model I Expansion Interface, and with Percom drive
systems you can enjoy the same double-density storage
capability as Model III owners.

The DOUBLER includes a TRSDOS*-like
double-density disk operating system called DBLDOS™

We also offer a double-density Model I version of
OS-80 as well as DOUBLEZAP programs for modifying
NEWDOS/80 and VTOS 4.0t for DOUBLER
compatibility.

Of course you don't have to upgrade your computer
for double-density operation to use Percom mini-disk
drive systems. In single-density operation, our TRS-80*
Model I compatible 40-track drives store 102 Kbytes of
formatted data on one side of a diskette, and our
80-track drives store 205 Kbytes. By comparison,
Tandy's standard drive for the Model I stores just 86
Kbytes.

And like our Model III drives, Model I add-on drives
are optionally available with "flippy" storage capability.

System Requirements:

Model III: 16-Kbyte system (min) and Model III BASIC.
The second internal drive may be installed after the first
internal drive kit is installed, and external drives #2, #3
and #4 may be added if either an internal or external
first-drive kit has been installed. External drives #3 and
#4 require an optional interconnecting cable.
Model I: 16-Kbyte system (min), Level II BASIC,
Expansion Interface, disk operating system and an
interconnecting cable. For double-density storage, a
Percom DOUBLER must be installed in the Expansion
Interface and DBLDOS (comes with the DOUBLER) or
other double-density DOS must be used. For
single-density operation, a Percom SEPARATOR™
adapter, installed in the Expansion Interface, will
virtually eliminate "CRC ERROR — TRACK LOCKED

OUT' read eiTOrS. Prices and specifications subject to change without notice.

PEfiGOM

PERCOM DATA COMPANY, INC.

211 N. KIRBY GARLAND. TEXAS 75042

C214) 272-3421

•Trademark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company.
™DOUBLER, DBLDOS. OS-80 and SEPARATOR are trademarks of Percom Data Company. Inc.
tTrademark of Virtual Technology Corporation.

Circle 4 on inquiry card.

BYTE April 1981

Editorial

Photo 2: The Osborne I per-
sonal computer. This new
64 K, Z80A machine has two
floppy-disk drives and fits
under an airline seat. Price:
$1795. Photo by Elliot Varner
Smith.

Although no official word has come from the company,
we have learned that it is developing a complete personal-
computer system. Fujitsu and Seiko are also developing
personal computers for the U.S. market.

New Trends in Portability: The Osborne I

This month Adam Osborne introduced a new personal
computer, called the Osborne I, at the West Coast Com-
puter Faire in San Francisco. Its features include: a Z80A
processor; 64 K bytes of dynamic programmable mem-
ory (60 K bytes are available to the programmer; the re-
maining 4 K bytes are used by the display screen); IEEE
and RS-232C interfaces; modem electronics; a 5-inch
video monitor with 24 rows of 50 characters, upper- and
lowercase, two display intensities, and underlining for all
characters; two 5-inch single-density, single-sided floppy-
disk drives; standard typewriter keyboard; 10-key nu-
meric pad; two pockets for storing floppy disks; and the
following software: the CP/M operating system,
CBASIC, WordStar, Mailmerge, and a CP/M-compati-
ble spread sheet program that resembles VisiCalc.

There are two particularly interesting points about this
computer: (1) it will cost $1795, and (2) it's portable! An
optional battery pack will be sold with the unit. Also op-
tional are a 9-inch monitor, an acoustic coupler, and
double-density, double-sided floppy-disk drives. The
$1795 price tag (which includes all the software) is re-
markably low. It remains to be seen if the company can
turn a profit at this price. I recently had an opportunity
to see the Osborne I in action. I was impressed with its
compactness: it will fit under an airplane seat. (Adam

PASCAL/Z ™- Q.E.D.

Ithaca Intersystems PASCAL/Z is the most powerful CP/M™
compatible Z-80™ Pascal compiler ever . . . and here's why:

PASCAL/Z generates true Z-80 native code - ROMable
and re-entrant — 5-1 OX faster than P-code interpreters;
permits separate compilation; supports Direct File Access
and variable length STRINGs; utilizes fast one-pass recursive
descent organization; the macro-assembler generates
relocatable object modules; and much, much more.

Complete package includes compiler, macro-assembler,
linker/loader and source for the full library on one disk; with
free copy of Jensen/Wirth book and complete documenta-
tion. Only $395.00.

IT'S DEMONSTRABLE!
Don't just take our word for it. Ask for a demonstration of
these features and more today at Computerland® and other
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Computerland is a registered trademark of Computerland Corporation.

CP/M and Z-80 are trademarks of Digital Research Corp. and Zilog, Inc. respectively.

PASCAL/Z and InterSystems are trademarks of Ithaca Intersystems Inc.

8 April 1981 © BYTE Publications Inc

Circle 5 on inquiry card.

Intersysten

Micros for bigger ideas.

The Intersystems
price-performance-reliability

story now has
three versions.

While everyone's been busy
trying to convince you that large
buses housed in strong metal
boxes will guarantee versatility
and ward off obsolescence, we've
been busy with something better.
Solving the real problem with the
first line of computer products
built from the ground up to con-
form to the new IEEE S-100 Bus
Standard. Offering you extra ver-
satility in 8-bit applications today.
And a full 16 bits tomorrow.

We call our new line Series
II. And even if you don't need the
full 24-bit address for up to 16
megabytes (!) of memory right
now, they're something to think
about. Because of all the perform-
ance, flexibility and economy

they offer. Whether you're looking
at one of our three mainframes, at
a new mainframe, expanding your
present one or upgrading your
system with an eye to the future.
(Series II boards are compatible
with most existing S-100 systems
and all IEEE S-100 Standard cards
as other manufacturers get around
to building them.)

Consider some of the fea-
tures: Reliable operation to 4MHz
and beyond. Full compatibility
with 8- and 16-bit CPUs, pe-
ripherals and other devices. Eight
levels of prioritized interrupts. Up
to 16 individually-addressable
DMA devices, with IEEE Standard
overlapped operation. User-selec-
table functions addressed by DIP-
switch or jumpers, eliminating sol-
dering. And that's just for openers.

The best part is that all this
heady stuff is available nowl In
our advanced processor — a full
IEEE Bus Master featuring Memory
Map addressing to a full mega-
byte. Our fast, flexible 16K Static
RAM and 64K Dynamic RAM
boards. An incredibly versatile and

Circle 6 on inquiry card.

economical 2-serial, 4-parallel
Multiple I/O board. Our 6-serial
I/O board. Our Double-Density
High-Speed Disk Controller. And
what is undoubtedly the most flex-
ible front panel in the business.
Everything you need for a com-
plete IEEE S-100 system. Available
separately, or all together in your
choice of DPS-1 mainframe styles.

Whatever your needs, why
dump your money into obsolete
products labelled "IEEE timing
compatible" or other words peo-
ple use to make up for a lack of
product. See the future now, at
your Intersystems dealer or call/
write for our new catalog. We'll
tell you all about Series II and the
new IEEE S-100 Bus we helped
pioneer. Because it doesn't make
sense to buy yesterday's products
when tomorrow's are already here.

Ithaca Intersystems Inc.,

1650 Hanshaw Road/RO. Box 91,

Ithaca, NY 14850

607-257-0190/TWX: 510 255 4346

\s^ Ithaca Intersystems Inc.

Micros for bigger ideas.

/

Editorial

Photo 3: Sony's new 3V2-inch floppy disk and drive. Each
double-sided floppy disk can hold up to 875 K bytes of informa-
tion, unformatted. The recording density is 1.47 times that of
the 5-inch disk.

Atiast-theDYNATYPER

TYPEWRITER INTERFACE!™

Turn your electric typewriter into a low cost,
high quality hard copy printer. 1 year warranty

DYNATYPER - Rochester Data's patented* Computer/Typewj
Interface is the industry standard for typewriter output.

o&l||Sta<
Scfcry w

S

2 minutes to initially install and 5 seconds to remove *Q|J(ace.
You do not have to modify your typewriter. All iJcrary war-
ranties and maintenance agreements on your typewriter will be
honored. tp*

Compatible with all power carriage return JApewriters having
standard U.S. keyboard. The Dynatyper j^Stks with Selectrics
(model 1) and most non-Selectrics (maps! 2). Please specify.
Typewriter conversion between modejapakes 2 minutes and the kit
(17 plungers) is available for a nornjoal fee.
The Dynatyper is compatible with ^(♦major word processing software.
(Scripsit, Pencil, Applewriterȣasywriter, Magic Window, Visi-calc
CCADBM, Supertext, WriWStTn)

Interfaces available for "WS-80, APPLE, PET/CBM, OSI, Northstar,
HP-85, H-89. WeigljjMnly 3 lbs. Extremely portable.
Delivery: StfHk towvo weeks. Price $499 for complete system.
F.O.B. Rj^hellfer, Domestic. VISA and Master Card accepted.
Ncky at 71 6-244-7804

Tlvfc'is a

Jailer;

Timing

a registered trademark of Rochester Data

3000 Winton Road South, Rochester, N.Y. 14623

incorporated

Osborne is currently seeking approval from the FAA to
operate the unit on board a plane.) One quibble: the
screen may be too small for some people's taste. Con-
sulting Editor Mark Dahmke is preparing a full test report
on this computer for an upcoming issue of BYTE.

Update

We have received numerous requests for more infor-
mation on the Microterminal described in the January
editorial. We cannot divulge any more information at
this time, but watch for a complete report coming soon.

Also in the works: full reports on the Commodore
VIC-20 color computer; the TRS-80 color computer hi-
res (high-resolution) graphics; a special issue on local net-
works; reviews of three LISP packages; the new spelling-
correction programs; Logo for the Apple II and TI 99/4;
and our annual August language issue, this year on
Smalltalk, one of the most exciting languages in the com-
puter field today. Watch our upcoming editorials for fur-
ther information about future computers. ■

The Carl Helmers Newsletter

Readers of recent issues of BYTE are probably aware that
Carl Helmers, former Editorial Director of BYTE, is now
working on projects outside of McGraw-Hill. One of Carl's
new undertakings is the Carl Helmers Personal Computer
Newsletter, which will cover the present state of personal
computing, future developments in hardware and software,
artificial intelligence, mass storage, and many other topics.
The newsletter will contain no advertising, cost $200 per
year, and will appear monthly. Carl is also considering a free
"personal computer industry conference call, " which would
be made available via a toll-free 800 number if interest
among subscribers is high enough. The setup would enable
up to twenty people to participate in a regularly scheduled
monthly "roundtable" discussion.

For more information about subscribing to the newsletter,
write to North American Technology Inc, Strand Building,
Suite 23, 174 Concord St, Peterborough, NH 03458, or call
603-924-6048. We wish Carl luck in his new venture... CM

BYTE's Bugs

Invisible
Software Review

Because of a last-minute
scheduling change, the prod-
uct review by BYTE editor
Gregg Williams, "The
muSIMP/muMATH-79 Sym-
bolic Math System" (Novem-
ber 1980 BYTE, page 324),
did not appear on the "In the
Queue" page for that issue.
We regret the omission.

10 April 1981 © BYTE Publications Inc

Circle 7 on inquiry card.

Getting the
Number Straight

In the February 1981
BYTE, on page 345 of the
"What's New?" section, the
telephone number given for
General Digital Corporation
was incorrect. The correct
number is (203) 289-7391. We
apologize for any difficulties
that may have arisen due to
the error. ■

Circle 8 on inquiry card. >

Make the Apple II* a powerful
IEEE-488 Controller in a snap.

Just plug the SSM A488 board into any Apple II* expansion slot for a low-cost,

full-featured instrumentation interface. SSM gives the Apple II the power and
versatility of a $9,000 IEEE-488 controller. At a fraction of the price.
Our board converts the Apple II into a truly sophisticated controller that
programs and controls up to 15 different instruments connected together
on the 488 bus.

We make programming easy. The 68488 chip, designed by Motorola, forms the
heart of our A488. We back this chip with powerful on-board firmware to
give you system control via simple string commands. The only software
you need is easy-to-program Applesoft* Basic. To develop special purpose
firmware, simply replace our PROM with a RAM. With the A488, bus com-
munications operate at top speed — without depending on software loops for
timing. And like the more expensive IEEE-488 controllers, this system interfaces
with more than 1200 instruments and peripherals.

Suitable for OEMs as well as end users. Whether you make test/measurement systems for re-
sale, or simply for yourself, the SSM/Apple combo gives you top performance. As it cuts
your costs. Call your local dealer or SSM today for complete details.

IEEE-488 bus cable

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Industrial grade circuit board

PROM firmware for powerful user interface
68488 IEEE-488 controller chip.

SSM's A488 board expands the Apple II to
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* Registered trademarks of Apple Computer Inc.

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San Jose, CA 95131
(408)946-7400 Telex: 171171
TWX: 910-338-2077

Letters

Computers and Trees:
The HHC Forest

I read Gregg Williams and Rick
Meyer's article about the Panasonic/
Quasar hand-held computers (January
1981 BYTE, page 34), and I could hardly
contain my excitement over the potential
use for these devices in my field: forest
measurements and statistics.

Forest inventory and survey work
typically involves many man-hours in the
forest collecting information on tree size,
species, sawtimber quality and value,
growth, etc. This information is normally
hand-written on tally sheets in the field,
and either hand-tabulated in an office or
key-encoded for statistical summary and
analysis by computer. Forest scientists
and practicing foresters are continually
looking for more economical methods of
obtaining resource information at the
level of precision required for complex
management planning and decision-
making.

The HHCs (hand-held computers) ap-
pear to have the capability of being used
in the field as data-entry devices, thereby
eliminating the need for subsequent key-

encoding of hand-written information.
With their alphanumeric capability, they
should be able to store and manipulate
descriptive text as well as numeric infor-
mation. With suitable applications pro-
grams, I would think they are also capable
of handling a fairly large repertoire of
forestry problems (eg: compiling tables
describing timber volumes by species, log
grade, and size class; estimating stumpage
values for timber sales, etc). For larger
data-processing requirements, they could
transmit their data, through the modem
attachment, to a host computer. In short,
I see in these devices a potential for great-
ly reducing the man-hours required for
routine data-entry and processing applica-
tions in forestery.

George L Martin Jr

Assistant Professor of Forest Biometry

Department of Forestry

College of Agricultural and Life Sciences

University of Wisconsin

1630 Linden Dr

Madison WI 53706

The advent of HHCs will be a boon to
many who must perform data entry and
sophisticated calculations in the field. Un-

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fortunately , neither the price nor the
availability date of the Panasonic/ Quasar
unit was announced at the CES (Con-
sumer Electronics Show), as I had origi-
nally hoped. As an educated guess, I
would place the price in the $400 to $650
range, with the units possibly being avail-
able as early as mid-1981.... GW

Oddest Programming
Language of Them All

In the December 1980 BYTE, Mr Daniel
Weise presented a version of a self-repro-
ducing program. (See "Thief -Reproduth-
ing Programth," page 16.) The following
version of the same fundamental algo-
rithm is written in my favorite program-
ming language — English:

Replace every occurrence of "x" in " x 'x'."
by "Replace every occurrence of 'x' in
'x "x".' by ".

Which executes as follows:

Unquote " x 'x'." to obtain the form x "x".

Replace "x" by the quoted substitute to
obtain x "Replace every occurrence of 'x'
in 'x "x". ' by ".

Replacing x by the unquoted substitute we
obtain Replace every occurrence of "x"
in " x 'x . " by "Replace every occurrence
of 'x in 'x "x". ' by ".

The operations quote and unquote
work as follows:

Quote text = "text*".
Unquote "text*" = text.

where text* is a faithful copy of text, ex-
cept for the replacement of each quote
mark, single or double, by its comple-
ment. This transformation is idempotent.
This is a time-honored syntactic device of
English.

I leave it to you, dear reader, to judge
the relative perspicuity of this English ver-
sion and the LISP version provided by Mr
Weise.

James P Corbett
24 Sheffield Lane
Florence MA 01060

Readers should note that they may not
be able to get this program to run on
every model of the human brain — which
is probably just as well, since once run-
ning, it would use up all available process-
ing time and memory space. . . . CPF

12 April 1981 © BYTE Publications Ire

Circle 9 on inquiry card.

Circle 10 on inquiry card.

Edison had over
1,800 patents in
his name, but
you can be just as inventive

with an Apple.

Apple is the company with the brightest ideas in
hardware and software and the best support — so you can
be as creative with a personal computer system as Edison
was with the incandescent bulb.

How Apple grows with you.

With Apple's reliable product family, the possibilities of
creating your own system are endless. Have expansion capa-
bilities of 4 or 8 accessory slots with your choice of system.

Expand memory to 64K bytes or 128K bytes. Add an
A to D conversion board. Plug into time sharing, news and
electronic mail services. Use an IEEE 488 bus to monitor
lab instruments. Add 4 or 6 disk drives — the 5 'A" 143K
bytes, high-speed, low-cost drive that's the most popular
on the market.

Apple speaks many languages.

Since more than 100 companies create software for
Apple, you'll have the most extensive library in the personal

computer world. Want to write your own programs?
Apple is fluent in BASIC, Pascal, FORTRAN, PILOT and
6502 assembly language.

There's even a series of utility programs called the
DOS Tool Kit that not only lets you design high-resolution
graphic displays, but lets you work wonders with
creative animation.

More illuminating experiences in store.

You won't want to miss all the Apple products being
introduced at your computer store all the time. Don't let
history pass you by. Visit your nearest
Apple dealer or call 800-538-9696.
In California, 800-662-9238. Or write:
Apple Computer, 10260 Bandley Drive,
Cupertino, CA 95014.

cippkz computer inc.

Letters

Vive la Guerre

I have a few comments on Bruce Car-
brey's article "A Pocket Computer? Sizing
up the HP-41C." (See the December 1980
BYTE, page 244.) The article was very in-
teresting, since I use both an HP-41C and
a TI-59 frequently. Mr Carbrey did a
comparison that I had planned but had
never done.

On page 246, he states that storing a
number in a register on a TI-59 requires
three lines. This applied to the earlier
SR-52, but only two lines are needed with
a TI-59. Two is better than three, but the

one-line approach of the HP-41C is better.
It makes editing a program without a
printer much easier, especially since you
don't have to remember key codes.

Mr Carbrey's benchmark test program
does not, however, use the TI-59's
strengths well. A major difference be-
tween the calculators is that both label
and absolute addressing exist on the
TI-59, while the HP-41C uses only labels.
Since the HP-41C program is compiled, it
is not penalized. Using absolute address-
ing in the TI-59 program cuts run time by
3 seconds and saves a step.

Listing 1 is a benchmark program that

YOU THINK YOU'VE SEEN WORD
PROCESSING SOFTWARE?

The

magic wand;

Word Processing

System offers you the best features of any system
in the micro market

FEATURES INCLUDE:

Full-screen text editor

Simple, control key operation
Edit programs as well as text

Assemble, compile or run programs

without modification
Files larger than memory

Files up to 256K
Library files

Merge part or all of one file with

another
Spool printing

Print a file while editing another
Easy page formatting

Simple commands set margins, page

length, etc.
Override commands at run-time

Give any command from the key-
board as well as in file
Variable pitch control

Change pitch in mid-line, even

mid-word
Up to 128 user-defined variables

String, numeric or dollar format
Form letter generation from external
data files

Compatible with both sequential and

fixed-record files
Conditional commands

Any command may be conditional
Print to disk and/or printer

Save all or part of output on disk
Switch from specialty printer to CP/M
list device

Print the same file on either specialty

or standard printer

Version 1.1 is now available

EASE OF OPERATION

With all its power, the MAGIC WAND is
remarkably easy to use. This is no acci-
dent. The command structure is designed
to be flexible and logical so that you can
perform basic functions with a minimum of
commands.

We have included in the manual a step-
by-step instructional program, for the per-
son who has never used a word-proces-
sor before. The trainee uses sample files
from the system disk and compares his
work to simulated screens and printouts.

In addition to the lessons, the manual
has a complete documentation of the
command structure, special notes for pro-
grammers, an introduction to CP/M for
non-programmers and a glossary. The
manual is typeset, rather than typewritten,
for greater legibility.

We have written the manual in non-
technical English, because we want you
to read it. We don't overload you with a
bunch of jargon that could confuse even a
PhD in Computer Sciences.

We send out newsletters so that users
of the MAGIC WAND can learn special
applications of the print commands. For
example, we might show you how to cre-
ate a mailing list or set up an index for
a file.

In short, we've done everything we can
to make things easy for you. Because the
best software in the world is just a bunch
of code if you can't use it.

For more information , call or write:

srciaW business ap^vcaXvoas, u\c.

3220 Louisiana • Suite 205 • Houston, Texas 77006 • 713-528-5158

CP'M is a registered irademarfc ol Digilai Research Core

uses the TI-59's parenthesis feature. This
seemed especially apt considering Hew-
lett-Packard's and Texas Instruments'
battle over Reverse Polish Notation vs
Algebraic Operating System. My pro-
gram is 10 steps shorter, uses 4 data
registers, and runs in 33 seconds. This im-
proved performance is achieved by reduc-
ing the number of relatively slow memory
arithmetic operations and utilizing the
TI-59's stack. (Also note that the correct
answer in Mr Carbrey's table 1, on page
254, is $17553.30, not $17533.30.)

Listing 1

000

76

LBL

001

11

A

002

58

FIX

003

02

02

004

42

STO

005

01

01

006

91

R/S

007

42

STO

008

02

02

009

91

R/S

010

42

STO

011

03

03

012

91

R/S

013

55

■j.

014

01

1

015

00

016

00

017

85

+

018

01

1

019

95

=

020

42

STO

021

04

04

022

45

Y*

023

43

RCL

024

02

02

025

94

+ /-

026

65

X

027

43

RCL

028

01

01

029

85

+

030

53

(

031

00

032

85

+

033

43

RCL

034

04

04

035

45

Y"

036

43

RCL

037

02

02

038

94

+ /-

039

97

DSZ

040

02

02

041

00

00

042

32

32

043

54

)

044

65

X

045

43

RCL

046

03

03

047

95

=

048

91

R/S

Much has been made of the HP-4lC's
plug-in accessories, but I wonder if they
are really a major design change. They
obviously follow TI's development of the
printer attachment and Solid State Soft-
ware. The HP printer has excellent print
quality and features, but it is very slow.
The Bar-Code reading "Warvd" is the only
significant advance in my opinion.

The capacities of the two calculators are
about equal in my experience. Most
users want both a printer and a card

14 April 1981 © BYTE Publications Inc

Circle 11 on inquiry card.

Circle 12 on inquiry card.

Easy on your Eyes

and your Budget

80 character display makes it ideal for word processing

and scientific applications.

America, Inc.

130 Martin Lane,Elk Grove Village, IL 60007

This high quality professional computer
monitor provides sharp, clear display of
up to 80 characters by 25 lines of text,
making it ideal for word processing as
well as standard business applications.

Lightweight industrial grade construc-
tion gives maximum portability with
reliable operation.

Letters

reader, so only two memory modules can
be added. Thus, a maximum of 830 pro-
gram lines is available without data
registers in practical applications, and this
limit is quickly reduced. Even allowing for
the HP-4lC's greater storage efficiency (I
find a 50% improvement over the TI-59),
the HP-41C is only marginally better.

The lack of a TI response to the HP-41C
threat mystifies me. Although users were
surveyed last spring, no new product has
appeared. The discounts being offered on
TI's "59" calculators clearly suggest that
something is coming soon, but it has been
a year since the HP-4lC's introduction.

Perhaps the pocket computers from Radio
Shack and Sharp threw a wrench into the
works. TI has always played a game of in-
creased capacity at lower cost in the pro-
grammable-calculator marketing wars. I
await TI's next entry with great anticipa-
tion. Users have profited immensely from
the battles between Hewlett-Packard and
Texas Instruments in this market. (Take
out your old calculator and try using it
now.) Vive la guerre!!!

G John Garner
319 Blue Haven Rd
Dollard des Ormeaux,

PQ, Canada

INTELLIGENT

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Patent Pending

Steve Ciarcia's article "Electromagnetic
Interference" (January 1981 BYTE, page
48) is a very good and long-overdue sum-
mary of the electronic noise-pollution
problem. Many radio engineers have been
fighting the battle against the plastic com-
puter box and the poorly designed digital
boards that dominate the industry. We
are ready for some stiff regulations
regarding fundamentals, such as simple
metallic shielding and grounding prac-
tices, so that the rest of the world can con-
tinue to use RF (radio-frequency) com-
munications.

One omission in Mr Ciarcia's article is
the reference to a state-of-the-art hand-
book or text for more comprehensive in-
formation on the subject. One of the best
comes from Bell Laboratories, in Henry W
Ott's book Noise Reduction Techniques in
Electronic Systems (New York: John
Wiley & Sons Inc, 1976).

R W Burhans
Ohio University
Avionics Engineering Center
Athens OH 45701

This omission was caught and rectified.
See "BYTE's Bits" March 1981 BYTE, page
314, for additional reading material. Also,
see J N Demas's review in the September
1980 BYTE, page 311. ...GW

Well-Rounded Machine

We at Hewlett-Packard were very
pleased to see Brain Hayes's excellent arti-
cle on the HP-41C calculator. (See "The
HP-41C: A Literate Calculator?", January
1981 BYTE, page 118.) He did make some
statements that deserve clarification,
however. In particular:

There is something absurd about the
world's fanciest calculator not being
able to give results accurate to more
than seven or eight decimal places.

The example he used was the (-JT)
computation, which is a good illustration
of a common misunderstanding about
computer arithmetic. When calculating
\fT, the 41C works internally with 13
digits and then rounds correctly to 10
digits. This helps to insure the accuracy of
the displayed result. But this result is still
not really -Jl, merely the best representa-
tion possible on this, or any other,
10-digit machine: 1.414213562.

At this point, the calculator does not
know where this number came from: it
could be a previous result, or it could
have been entered exactly as such through

16 April 1981 © BYTE Publications Inc

Circle 13 on inquiry card.

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BYTE April 1981 17

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WE HAVE NO READER INQUIRY NUMBER.
PLEASE WRITE OR CALL.

Letters

the keyboard. Squaring this number cor-
rectly and rounding again yields
1.999999999. Any 10-digit calculator that
does otherwise is either doing "funny
arithmetic," or else is not telling you
everything it knows. But the 41C has lived
up to its claim: each calculation was per-
formed correctly to 10 digits. Also, and at
least as important, the behavior of the cal-
culator is utterly predictable and repeat-
able.

A calculator is a tool, and, like any
tool, it has its limitations. These limita-
tions must be understood if the tool is to
be used properly. The point is this: there
exist sequences of calculations that will
generate errors of any magnitude on any
finite-precision arithmetic machine. Keep-
ing this in mind, the "world's fanciest cal-
culator," the HP-41C, is a tremendously
powerful tool indeed.

Steve Abell

Research and Development Engineer

Hewlett Packard Company

Corvallis Division

1000 NE Circle Blvd

Corvallis OR 97330

MIcroAce: More
Power to Sinclair

I disagree with John McCallum's state-
ment in 'The Sinclair Research ZX80" (see
the January 1981 BYTE, page 94) that by
building the kit version "you will not save
any money." My MicroAce cost a mere
$150 — a savings of 25 % over the price of
a ZX80. It was easy to build, although the
instructions were not nearly as elaborate
as Heathkit's.

The MicroAce has room for two more
programmable-memory integrated cir-
cuits than the ZX80. The increase to 2 K
bytes almost triples the possible program
length (portions of the first 1 K bytes are
used for "housekeeping"). This expanded
capacity gives you a much more usable
computer. Its unique design means that
you can store as much information as
other systems that use 3 K to 4 K bytes.

I couldn't afford $500 or more for a
computer, but, for about $175 (kit plus
memory chips), I have learned quite a bit
and gained much enjoyment while doing
so.

John R Mullen
8518 Terrang Ct
Rockford IL 61111

The MicroAce kit is reviewed by
Delmar Searls on page 46 of this issue.

Calling Z8000

The "BYTELINES" section of the
January 1981 BYTE (page 200) contained

an item saying that Microsoft proposed a
standard set of calling conventions speci-
fying parameter-passing and register
usage for the Z8000 microprocessor. It
was actually Zilog Inc, inventor of the
Z8000, that established the conventions.
Zilog announced the Z8000 standards at
last year's WESCON show in Anaheim,
California. The announcement contained
the statement that the conventions "have
thus far been adopted by Microsoft and
are under consideration by several other
companies."

Thank you, BYTE, for letting me set the
record straight by pointing out that Zilog
originated the Z8000 calling conventions
that were subsequently adopted by Micro-
soft.

Bruce Weiner

Product Marketing Manager

Zilog Inc

10460 Bubb Rd

Cupertino CA 95014

Why Didn't We Think....

-*\i ^

1 mtgml METUflN

I always look forward to the latest issue
of BYTE, as I am sure many others do. I
would like to pass along this suggestion to
my fellow readers who use an Apple II
computer. It is my solution to the well-
known "accidental RESET" problem that
plagues users of that machine.

Manauba Sakuta, MD
6324 Wilryan Ave
Edina MN 55435

December Adventure

BYTE's "Product Reviews" of games in
the December 1980 issue were absolutely
perfect. There are too many bad programs
on the market; being able to see a picture
of the display (along with a description of
how the game is played) is a big help.

I noticed that BYTE didn't continue this
policy in the January 1981 issue— I realize
that you can't have seven game reviews in
every issue, but it would be nice....

Thanks.

PAD from Livermore CAB

18 April 1981 © BYTE Publications Inc

Circle 16 on inquiry card.

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Recurrence in Numerical

Analysis

James J Davidson

c/o BYTE Publications

POB 372

Hancock NH 03449

Although Taylor's series are the most universally
useful method of computing higher mathematical func-
tions, they do have their drawbacks. In particular, many
functions have representations only in the form of alter-
nating series. This can cause great difficulty in maintain-
ing accuracy if large arguments are required. Often, so
many significant digits are lost in the process of computa-
tion that the results are, at best, useless. At worst, if you
do not suspect that gross inaccuracies are occurring, you
may make severe engineering mistakes.

If the various remedies such as argument scaling are in-
effectual in improving accuracy, the only recourse is to
seek alternate methods of computation. Of those alter-
natives, recurrence relations have the widest applicabili-
ty.

What's a Recurrence Relation?

Various functions have the mathematical property that
if you know two consecutive values, you can use those to
find a third. This process can be repeated to find a fourth
from the second and third, and so on. Of course, you
need to pick the right pair to start from, but if you do,
you can get to any value you want.

The simplest illustration of a recurrence relation is the
Fibonacci series. This is a series of special numbers
known in medieval times to Leonardo of Pisa, surnamed
Fibonacci (1175-1230). Fibonacci numbers are found in
botany and other natural sciences, as well as in certain
mathematical theories of aesthetics. They are interesting
in their own right, and there is at least one society
devoted to study of their mathematical properties.

The Fibonacci series proceeds in the following fashion:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, . . .

Each term is obtained by adding the two previous terms.
As a formula, the series can be expressed as:

a n *2 ~ H„+l + An

where the initial terms must be specified as and 1. Once
you get started, it is obvious that you can keep going in-
definitely using the same formula. It is not even necessary
to begin at the beginning. If you know the thirteenth and
fourteenth terms, for instance, you can find the fifteenth
by adding them together.

Programming this recurrence relation is not going to be
much of a chore. The important thing to keep in mind is
that three values must exist within the computer
simultaneously: the n and (n + 1) terms, and the sum of
these two, which is the value being calculated. Then,
after the value is found, it must be slid into the (n + 1)
position, with that one being slid into the n position. This
sliding process is the only tricky part because it must be
done in the proper order, and it is the heart of all recur-
rence programming.

Listing 1 shows how simple the job is. After initializa-
tion, the FOR... NEXT loop handles the calculation in 6
lines. The new term is calculated in line 160 and printed
in line 170. The sliding process is done in lines 180 and
190. Note that Al must be slid into A0 before A2 is slid
into Al; otherwise, Al will be lost. That, in principle, is
all there is to programming recurrence relations.

Forward and Backward Recurrence

Recurrence relations have a property that on first ac-
quaintance seems absolutely incredible: if you go in the
"right" direction, you increase the number of significant
digits in your answer with every new term. This means
that in certain cases you can start out with a completely
arbitrary guess and, if you go long enough, end up with
eight or nine significant digits in your final result! On the
other hand, if you go in the "wrong" direction, you lose
digits with each iteration and end up with garbage.

There is nothing at all mysterious about this property.
If you think about the Fibonacci series, you will realize

20 April 1981 © BYTE Publications Inc

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that that is exactly what happens there. Starting with two
numbers one digit long (0 and 1), you can build up after
thirty or forty terms to as many digits as your machine
will hold. For this case, we are going in the right direction
because the answers get progressively larger as we
calculate each new term.

In this case also, we are moving in the direction of in-
creasing index, n. This is called forward recurrence. If we
were to start out with a high-order pair of terms and
calculate down towards zero, that would be called

Listing 1: The Fibonacci numbers through recurrence. The
Fibonacci numbers are used here to demonstrate how easy it is
to program a recurrence relationship. All that is necessary is to
keep proper order in the calculation and the shifting of
variables.

0010 REM

0020 REM *** FIBONACCI NUMBERS

0030 REM *** BY RECURRENCE RELATION.

0040 REM

0100 INPUT "HOW MANY FIBONACCI NUMBERS",N

0110

A0 =

0120

PRINT A0

0130

Al = l

0140

PRINT Al

0150

FOR 1=1 TON

0160

A2 = A1 + A0

0170

PRINT A2

0180

A0 = A1

0190

A1=A2

0200

NEXT I

0210

END

Listing 2: A Taylor's series program for the Bessel functions.
Lines 160 thru 190 calculate the first term. (Line 160 should not
be necessary, but many BASlCs insist on executing a
FOR. ..NEXT loop at least once, regardless of index and target.)
This program is not recommended if the argument will ever ex-
ceed about five or ten, depending on your BASIC.

0010 REM

0020 REM *** BESSEL FUNCTIONS, FIRST KIND, INTEGER

ORDER

0030 REM **' BY TAYLOR'S SERIES.

0040 REM

0100 INPUT "ARGUMENT", X0

0110 INPUT "ORDER", N

0120 X = X0/2

0130 X2 = X*X

0140 S =

0150 T=l

0160 IF N = THEN 200

0170 FOR 1 = 1 TON

0180 T = X/I*T

0190 NEXT I

0200 FOR I = 1 TO 999

0210 S = S + T

0220 T=-X2/I/(N + I)*T

0230 IFSoS + TTHENNEXTI

0240 PRINTS

0250 END

Of the various mathematical func-
tions that can be calculated by
recurrence, the ones with the

greatest engineering utility are the
Bessel functions.

backward recurrence. For the Fibonacci series, backward
recurrence is "wrong" (because you lose significant digits)
and forward recurrence is "right" (because you gain
them), but for some other functions the reverse is true.

Putting it another way, if you lose digits going one
way, it is because (and only because) you are subtracting
nearly equal large numbers. Avoidance of that situation
is one of the cardinal principles of numerical calculation.
In this case, avoidance consists simply of going in the op-
posite direction, in which case you are adding the
numbers instead of subtracting them.

But how do you know which direction to go in? Very
simply, look in a mathematics handbook. If that fails,
and you have no knowledge of function behavior to
guide you, trial and error is a solution. Set the program
up for forward recurrence (which usually is easier) and
see whether the terms get larger or smaller. If they get
smaller, you guessed wrong. (Be sure that the decrease is
not just local. Unfortunately, global function behavior
must be known before you can be fully certain that you
are going the right way.)

Bessel Functions

Of the various mathematical functions that can be
calculated by recurrence, the ones with the greatest
engineering utility are the Bessel and the Bessel-related
functions. This is fortunate because many of these are
strictly alternating series with no hope of argument scal-
ing, and large arguments always seem to be the ones of
greatest interest.

The family of Bessel functions includes many varia-
tions. There are the first, second, and third kinds; in-
teger, fractional, and noninteger orders; and regular and
modified types. The related functions include Kelvin,
Airy, and Ricatti-Bessel. For now, though, we will be
concerned exclusively with regular Bessel functions of the
first kind, and of integer order. These arise as solutions of
Bessel's differential equation:

x*-pf- + x-&- + (x» - n 2 )y =
dx l dx

This equation appears in a wide variety of engineering
and scientific problems, such as heat transfer and mem-
brane vibrations. It also shows up indirectly in the
analysis of frequency-modulated signals. Any time cylin-
drical coordinates are used in analysis, Bessel's equation
is almost certain to be involved somewhere. As a conse-
quence of that fact, Bessel functions are also called (par-
ticularly in German) cylinder functions.

Let us see where the problem lies in computing these
functions by Taylor's series. The Taylor's expansion is:

lm = (t) VJ-r)*(-

i!(n + i)!

)

This is clearly a strictly alternating series, and the critical

22 April 1981 © BYTE Publications Ire

Circle 18 on inquiry card.

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Figure 1: The Bessel function of argument 10 and variable order v. When progamming a recurrence relation, information such as this
is needed to determine whether to use backward or forward recurrence. Since the function goes to zero for large orders (values of v),
we conclude that we need to use backward recurrence to achieve good accuracy. The Bessel function behaves similarly for other
arguments: as soon as the order (v) exceeds the argument (x), the function rapidly declines to zero.

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argument occurs at x = 2. But it is rare that one is satisfied
with values that small.

Listing 2 is the program for this series. Keep in mind
that the magnitude of the Bessel function can never ex-
ceed unity, and see where your machine starts to bomb.
If you have double precision, you may want to see how
much difference it makes. Recognize, too, that a range of
10 38 can be a real limitation. For x = 100, the largest term
nearly reaches 10 41 . Depending on your BASIC, a max-
imum argument of five to ten is recommended.

Bessel Recurrence Relation

Now to recurrence. The relation we will use is:

/„ +1 to = (2n/x)]Jx) - J„.i(x)

and the first thing we need to know is which direction to
go. This is a recurrence in order, not argument, so the
question is whether the function increases or decreases as
the order gets larger and the argument stays constant.
Figure 1 (from the National Bureau of Standards hand-
book) answers this clearly. At large positive arguments,
the function heads toward zero. This means that, when
we want to calculate J„(x) for a given n, we must calculate
higher-order values of J(x) and use the recurrence formula
to calculate down to order n.

The next problem is where to start. This is quite an in-
volved question, and, unfortunately, there are no
established answers.

Let us suppose we want to calculate / 8 (22). We have to
start someplace above eight, but where, and with what?
If we knew, for example, 7, 8 {22) by calculation, we would
probably just as easily know / 8 (22) by calculation and

24 April 1981 © BYTE Publications Inc

Circle 19 on inquiry card.

Circle 20 on inquiry card.

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m'a#, wf|L jyn

J ■

i

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C°

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<y

would not need to use recurrence. We will make an ar-
bitrary guess (using it and zero as the two numbers need-
ed to start recurrence) and let the virtues of "right" recur-
rence provide our significant digits.

However, while it is true that recurrence can provide
increased accuracy, this is true only relative to the initial
guess, which was arbitrary. This means the result we get
may be highly precise but completely inaccurate. What
we look for, then, is some way of normalizing, or ad-
justing, the result. Perhaps somewhere in the process, or
in the final answer, there is a clue to what the right output
should be. If so, that clue can be used to give us the cor-
rect value.

Normalizing Sum

The solution lies in one nice formula:

1 = ] (x) + 2h(x) + 2h(x) + 2h(x) + ....

If we simply double each even term as we calculate it and
add them all together, then subtract one zeroth term
(because it is not doubled in the formula), we should get
unity. If we do not (and we will not), divide the recur-
rence result by this sum and out comes a closer approx-
imation to the correct answer.

This does mean, however, that every calculation will
always have to proceed all the way to zero order. The
formula also tells us how far up we must start: at an order
high enough that its contribution to the sum will be
negligible.

The full process goes like this: you begin by choosing
an argument at random, then finding the highest order
that makes a difference in the total sum. If the total sum is
greater than 1.00, divide the beginning argument by this

number and repeat the process. The final result should be
a beginning argument and an order high enough so that
two conditions are true: first, that the next higher-ordeT
term does not contribute significantly to the sum; and
second, that the sum is approximately equal to 1.00.

You will find that the starting point depends both on
the argument and the order of the answer you desire.
Larger arguments always require higher starting points,
as do higher orders. But the relationship is not simple,
and no single equation will fit all points exactly. If the
equation must err (and it must), it is best that it do so on
the high side, although it should not be too far on the
high side.

If the starting point is too low, the normalizing sum is
inaccurate, degrading the answer. If it is too high, execu-
tion time becomes excessive and you run the risk of ex-
ceeding your machine's range. (The sum can grow very
quickly.) Note, however, that it is the normalizing sum,
not the recurrence calculation, that is the main source of
trouble. Recurrence starts with an arbitrary guess
anyway and goes in the "right" direction (backward), so
accuracy is not an issue here (with one important excep-
tion that will be explained later).

Programming all of this— except for the equation
derivation — really is not too difficult, but it is messy and
time-consuming. Fortunately, it has been gone through
by various mathematicians, and formulas do exist for
finding the starting order. The results listed will vary,
though, depending on the number of significant digits in
the particular machine they were developed for.

Table 1 gives the raw data rounded to the next higher
even integer of the starting order necessary for ten-place
accuracy. This information was compiled by Samuel G
Allen of New York on an SR-56 pocket calculator. From

i

1

5

10

15

20

25 30

35 40 45 50 55 60 65 70

75

30

35

30 95 100

36

38

5

D 56

64 70 76 86 88 94 98 1C

)4

1

116

122 128 134 138

15

22

24

30

36

I

17

24

28

32

36

;

20

26

30

36

38

38

25

30

36

38

42

44

5

D

30

36

40

42

44

46

5

2 56

35

40

44

46

48

48

5

4 58

6

4

40

46

48

50

54

56

5

3 60

6

4 7

n

45
50
55

54
58
62

54
58
64

56
60
64

58
62
66

60
64
68

6
6
7

2 64

3 68
D 72

6

7
7

8 7
7
4 7

7
4 7
8 8

6

8 8
8

6
6 8

3

60

66

68

70

72

74

7

3 78

8

8

8

2 8

6 9

: 9

4

65

70

72

72

76

78

8

D 82

8

4 8

4 8

6 8

8 9

2 9

4 9

8

70

74

76

78

80

82

8

\ 86

8

8 8

3 9

9

2 9

4 9

6 10

2 104

75

80

82

84

84

86

8

3 88

9

9

2 9

4 9

6 9

3 10

10

4 106

1'

80

86

86

88

90

90

9

I 94

9

6 9

3 9

8 10

10

2 10

4 10

6 108

112

116

85

92

92

92

94

96

9

3 98

10

10

2 10

4 10

S 10

3 10

6 10

8 112

116

118

122

90

96

96

98

100

100

10

Z 104

10

4 10

3 10

8 11

D 11

: 11

11

2 116

118

120

122 128

95

100

100

102

104

106

10

3 106

10

8 11

D 11

2 11

4 11

3 11

5 11

6 118

122

124

126 130 1C

14

100

104

104

106

108

110

11

D 11

2

11

2 11

4 11

6 11

3 12

D 12

12

12

2

1J

»6

11

>6

11

?8 1:

32 1C

!4 1:

S8

i

0.1

0.5

1

2

3

4

5

6

7

8

9

10

11

12

6

8

10

14

16

18

20

22

24

26

26

28

30

32

1

6

10

10

14

16

18

20

22

24

26

26

28

30

32

2

8

10

12

14

16

18

20

22

24

26

26

28

30

32

4

10

12

12

14

16

18

20

22

24

26

26

28

30

32

n

6

12

12

14

14

18

18

20

22

24

26

26

28

30

32

8

12

14

16

16

18

20

22

22

24

26

26

28

30

32

10

14

16

18

18

20

22

22

24

26

26

26

28

30

32

Table 1: Raw data used by 5 G Allen to derive his equation for the starting order of the recurrence relation.

26 April 1981 © BYTE Publicaeions Inc

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BYTE April 1981 27

Listing 3: Generating Bessel functions by recurrence. This one is
slower than Taylor's series for small arguments, but is vastly
more accurate for large ones. Within the accuracy range of a
machine, no limit has been found on maximum order or argu-
ment.

0010 REM
0020 REM **
ORDER
0030 REM *"
0040 REM

0100
0110

0120
0130

BESSEL FUNCTIONS, FIRST KIND, INTEGER
BY RECURRENCE RELATION.

INPUT "ARGUMENT", X0
INPUT "ORDER", N

X = X0

IF ABS(X)<1.E-

10THENX = 1.E-10

0140 Y = X

0150 IFN>XTHENY = N

0160 N9 = INT(Y + 3*SQR(X) + 9)

0170 J9 =

0180 J8=l.E-30

0190 S =

0200 FOR I = N9 TO STEP - 1

0210 J7 = 2*I/X*J8-J9

0220 79=78

0230 J8 = I7

0240 IF INT(I/2) = 1/2 THEN S = S + 2*J9

0250 IFI = NTHEN J = J9

0260 NEXT I

0270 S = S-J9

0280 J = I/S

0290 PRINT 7

0300 END

the data, he derived a fairly simple equation which errs
conservatively by about ten percent in the region N=4X.
The equation is as follows:

N9 = int(max(N,X) + 3-JJC + 9)
which is implemented in lines 140 thru 160 of listing 3.

Program Comments

If you have followed the discussion to this point, the
program in listing 3 should be straightforward. Lines 140
thru 160 calculate the starting order, and lines 170 thru
190 do the initialization. Note that the arbitrary guess for
J8 (]„(x)) is 1.0 X 10" 30 . It is chosen small (and can be
much smaller if your range goes to 10""), so that large
arguments can be accommodated without overflowing
the normalizing sum. J9 (J„+i(x)) is initialized to zero,
which reflects the assumption that the next higher term is
too small to be significant.

The recurrence loop (lines 200 thru 260) includes the
normalizing sum at line 240. Line 250 picks out the par-
ticular order you specified and stores it as variable J.

After exiting from the loop, line 270 subtracts a zero-
order term from the sum, and line 280 divides the chosen
value by S to normalize it properly.

One fact has not yet been mentioned: the recurrence
relation involves a division by x, so that x = causes an
error message. But this is a perfectly legitimate argument
at any order, so line 130 assigns a small value instead. It
cannot be too small, though, or overflow will occur
rapidly because of that division by x.

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Altering this program to give a complete array of
Bessel functions of various orders for a given argument is
easy. Simply define an array of dimension N + 1 and start
storing values when the variable I becomes equal to N. At
the end, each value must be divided by S.

You will find that execution time for this program is
quite long. For small x, the Taylor's series is much faster
and therefore may be preferred for arguments that are
guaranteed restricted. When in doubt, use the recurrence
method (listing 3).

Negative Orders

Note from figure 1 that the behavior at negative orders
is very different than that of positive orders. So, instead
of trying to adapt listing 3 to handle negative N, use the
absolute value of N for N and transform the output by
the relationship:

Ux) = (-1)" x L(x)

How Accurate Is It?

There is only one practical way to check accuracy on a
routine like this: compare the results against known
values in a published table. But that creates a problem
because available tables give out before the program
does. The massive compilation by the staff of the Har-
vard Computation Laboratory (Harvard: 1947) goes up
tox = 100andn = 135.

The most sensitive test, though, is to check in the
region of the zeros at various orders. The Bessel functions
look like damped sine or cosine waves, crossing zero at

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The most sensitive test is to check

In the region of the zeros of the

function.

intervals that look as though they might be periodic.
(However, they aren't and the exact locations of the zeros
is of considerable interest to mathematicians.) Obvious-
ly, if you put in an argument that is supposed to be at a
zero of the function, you expect to get a result of zero.
This is unlikely for two reasons:

• The locations of the zeros are transcendental numbers
and cannot be specified exactly. The theoretical result,
then, should not be exactly zero.

• Backward recurrence is "right" only when the function
increases as you proceed in that direction. But at a zero,
the function suddenly nosedives down (see figure 1).
Here, (2n/x) X J n (x) is supposed to equal J„*i(x), so their
difference is zero. This is subtraction of nearly equal large
numbers, which usually results in a small truncation er-
ror.

For the above reasons, all errors and inaccuracies ac-
cumulate at the zeros. In particular, truncation errors
show up flagrantly here. Not only does truncation cause
the output to be nonzero, it actually translates the ap-
parent location of the zero to a lower value. The trunca-
tion is not really bad (it usually affects only the last digit),
but those interested in the mathematical properties of
Bessel functions should be aware that this bias does exist.

With that background, we can state that the accuracy
of the program of listing 3 on a nine-digit truncating
BASIC is seven to eight decimal digits. Note that I said
decimal digits, not significant digits. As far as I can deter-
mine, the seventh digit after the decimal point is good to
within one count anyplace, including zeros. Away from
the zeros, the eighth digit appears good to within one
count. This includes any xornup to one hundred, based
on spot and systematic checks against the Harvard tables.

Using the Royal Society tables of zeros, further checks
can be made under worst-case conditions. For example,
the forty-eighth zero of order 19 occurs at

• = 178.846699. The actual output there is 7.6 X 1CT 8 ,
which will cause the seventh digit to be off by one count.
Worse errors may be possible, but this one is the largest I
found.

Other BASICs with fewer digits should have similar
properties: about a two-digit loss as long as the range is
not exceeded by the normalizing sum. For engineering
use, this should be entirely adequate. ■

References

1. Abramowitz, M and I A Stegun. Handbook of Mathematical Func-
tions with Formulas, Graphs, and Mathematical Tables. Washington:
National Bureau of Standards, 1964.

2. Harvard Computational Laboratory Staff. Tables of the Bessel
Functions of the First Kind. Cambridge: Harvard University Press, 12
volumes, 1947 and following years.

3. Olver, F W J (editor). Royal Society Mathematical Tables, Volume
7: Bessel Functions Part III, Zeros and Associated Values. New York:
Cambridge University Press, 1960.

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The required entries to add or change a name-address
record are the name, the street address, the city-state-zip,
and the telephone number. To list any one address, enter
the name. The name must be entered as last name first
with no commas. Option 5, "END", will always create a
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Listing 1: Name- Address— a program for the Apple II that will
store up to 100 entries, as shown here. More entries can be
stored by changing the DIM statements in lines 30 thru 90.

DIM NtClOO)
DIM A* < 100)

DIM B*t 100>
DIM LUC 100)
DIM RY. ( 1 00 >
DIM P*( 100)
DIM 8%C50) :

REM
REM
REM
REM

100
1 10
120
130

CHR*

LEFT LINK ARRAY
RIGHT LINK ARRAY
PHOME * ARRAY
STACK ARRAY

PRINT DtT"DPEN NAMAOR.

CALL - 93G: INPUT "IS

IF Y* ■ "N" THEN 200

PRINT D*T"READ NOMADR"

INPUT E

FOR | * 1 TO E

INPUT N*U>! INPUT A*< I )

INPUT B*( I ) : INPUT P*( 1 )

INPUT rw. r J )

next

PRINT

CALL

PRINT

PRINT

PRINT

PRINT

PRINT

PRINT

IF Ml

- 93G: print tab

"1 - ADD A NAME"

"2 - LIST A NAME"

"3 - LIST ALL NAMES"

"4 - CHANGE A NAME"

"5 - END"

I INPUT " ENTER YOUR SELECTION

' I DR Ml > 5 THEN 2G0

0.930. 1120. 1340

NAME/ADDRESS PROGRAM"

n*:ni

PRINT

410
420

430
440
450
460
470

500
510
520
530
540
550
5GO
570
5Bn
590
600
BIO
620
630

ON Ml GOSUB 320.72

GOTO 200

REM

REM (\DD A NAME SUBROUTINE

CALL - 936: PRINT TAB! 7)T"ADD NAME RECORD"

- E + IT REM FIRST EMPTY POSITION IN LIST

- I : REM START SEARCH AT ROOT
INPUT "ENTER NAME "TNI*

IF LEN (Nl*) < 1 THEN 350

INPUT "ENTER STREET ADDRESS "Tnt«

IF LEN (Alt) '. 1 THEN 370

INPUT "ENTER C ITY-STATE-2I P "IB1*

IF LEN (81*) < 1 THEN 330

INPUT "ENTER PHONE NUMBER "IPl*

REM IF NAME IS LARGER THAN I TH . SEARCH RIGHT BRANCH

IF Nl* > N«( I ) THEN S00

IF Nl* < > N«(I) THEN 4BO

PRINT "DUPLICATE NAME"

INPUT "ENTER C TO CONTINUE "IC*

RETURN

REM IF LEFT LINK NOT NULL. SEARCH LEFT BRANCH

IF LX(I) < > THEN I = LY.(I): GOTO 430

REM HANG NEW LEFT LINK ON PRIOR

Y. ( I ) - E

l*(E) - Nl*: REM FILL NEW RECORD

LX(E) ■
RXIE) ■
P*(E) = PI*

RETURN

REM IF RIGHT LINK NOT NULL. SEARCH RIGHT BRANCH

IF RY.(I) < > THEN I » RX(I>: GOTO 430

REM HANG NEW RIGHT LINK ON PRIOR

RX C I )
N*(E)

660 LXIEt
G70 RX(E)

Nl*

■

REM FILL

RECORD

6B0
690
700
710
720
730
740
750
7B0
770
760
790

Pli

P*(E)

RETURN

REM

REM LIST A NAME SUBROUTINE

CALL - 936: PRINT TAB( 7K"LIST A NAME/ADDRESS"

PRINT : INPUT "ENTER NAME TO LIST ";N1*

IF LEN (Nl*) < 1 THEN 720
I = 1

IF Nl* > N*( I ) THEN 870

IF Nl* < > H*fl) THEN B50

PRINT N* < I > : REM FOUND

PRINT A*(I>

PRINT BS1I)

PRINT P*(I)

PRINT : INPUT "KEY

RETURN

REM SEARCH LEFT

IF LY. II) < > THEN I

REM SEARCH RIGHT

IF RY. ( I) < > THEN I

REM

PRINT "NAME NOT FOUND"

RETURN

REM

TO CONTINUE

L7.( I > : GOTO 7B0

RY.( I I : GOTO 760

Listing 1 continued on page 34

32 April 1981 © BYTE Publications Inc

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with high performance through distributed
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Look for a single user CP/M® system that ex-
pands to multiuser configurations economically.

Look for independent 6 MHz Z80B-based User
Modules with 64Kof RAM memory, each module
with a port to the user terminal capable of handling
baud rates of up to 38K under program selection.
Look for high-speed block data transfers from user
modules to the Global Processor for disk storage.
That way, CP/M programs run independently for
each user. Fast. And each users's station acts just
like the fastest standalone system — no delays, no
waiting for other users.

Look for a Z80-based Global Processor for disk
and tape I/O that transfers data from disk to user
modules at the data transfer rate of the peripheral
device. And a controller that handles as many as 8

SMD disk drives for up to 528 megabytes of hard
disk storage, plus up to four 8" floppies, plus op-
tional streaming tape backup.

And look for a Z80-based General I/O Processor
that supports up to eight printers — with 64K bytes
of independent buffer memory.

That's part of how you tell if it's a White Com-
puter. There's a lot more. Here's a number and
address for more information.

CP/N is a registered trademark of Digital Reseach.

Z80, Z80A, Z80B are registered trademarks of Zilog Corporation.

White Computer Company A 1876 Industrial Way
Redwood City, California 94063 A 415 364 7570

High
Technology

We make our

competition

obsolete

with Information Master.™

Information Master™ is the sophisticate of
software packages, but it also speaks your
language. Its uncomplicated English-
speaking design makes it easy to learn.
No programming knowledge is necessary.
Put it in your Apple II*, and you're ready
to go.

High Technology's Information Master
organizes and prints everything from
mailing lists to stock market data. Specify
what records to store, type in the informa-
tion, and Information Master organizes,
calculates, stores and reports. Design your
own reports and labels. Information Master
is revolutionary in its adaptability and
comes with a simple step-by-step instruc-
tion manual. Its screen layouts are designed
to show you maximum information for
easy operation. Information Master is so
smart it stops mistakes that our competition
lets you make.

If your computer dealer doesn't have
Information Master, see one who does.

High Technology's perfect complement to
Information Master, Data Master, ,M allows
you to change your mind months later

without redoing
all the work
you've
already
done.
Ask
about
it!

Technology, Inc.

Software Products Division
P.O. Box B-1 4665
8001 N. Classen Blvd.
Oklahoma City, Okla. 731 13
405 840-9900

'Apple II is a trade name of
Apple Computer, Inc

Programming Quickies.

Listing 1 continued:

920
930
940 T *
950 SX(
3G0 IF
970 T =

EM LIST ALL NAMES SUBROUTINE

■ ULl ■ o:t ■ o: call - 93B

p: rem push stack

THEN P - L*/.<P>: GOTO 940

1

990

990

1000

1010

1020

1030

1040

1050

10GO

1070

1090

1090

IF T ' =0 THEN INPUT "ENTER C TD CONTINUE " :C»: RETURN : REM ALL NAME FOUND
' - SX<T>: REM POP 9TACK

PRINT N«<P>: REM PRINT NAME
PRINT A*(P>
PRINT B*(P>
PRINT P*(P)
PRINT
LI • LI + S
IF LI = 20 THEN LI = 0! INPUT "ENTER C TO CONTINUE "!C*
I

1 I 30
1140

1 150

' - RV.<P>: REM CHECK FOR RIGHT LINK

GOTO 940

REM

REM CHANGE AN ADDRESS

CALL - 93G: PRINT TAB< 7): "CHANGE A NAME/ ADDRESS"

INPUT "ENTER NAME TO CHANGE "INI*

IF LEN (Nl*) : 1 THEN 1120
I * 1

IF NI* '• N*l I ) THEN 1310

IF Nl* ■ > N«tl) THEN tZSO

PRINT "OLD ":A*<I>

input "new ":oi<n

IF LEN (0*<I>) < 1 THEN 1190

PRINT "OLD ";B*(I>

INPUT "NEW ":B*(I>

IF LEN (B*(IH < I THEN 1220

PRINT "OLD "fF*tI>

INPUT "NEW ";p*m

PRINT

RETURN

REM SEARCH LEFT

IF L7. (I 1 < > THEN I ■ I

REM SEARCH RIGHT

IF R'/.(I) ' •• THEN I *

GOTO 11 GO

REM

REM EOJ

PRINT D*T

1350
1 360
1370
1380
1390
1400
1410
112

PRI

it D»:

PRINT D«:

PRINT E

FOR I = 1

PRINT NT.(
NEXT

PRINT [>*:
END

DELETE NAMADR"
OPEN NAMADR"
'WRITE NAMADR"

PRINT n*( I 1

PRINT B*tl): PRINT P* ( I > : PRINT LRd)! PRINT R«(I]

A Graphic
Execution Display

R B Minton, 8617 E Stearn Lake Dr, Tucson AZ 85730

I wrote a program for my Ohio Scientific Superboard
to compute artificial satellite orbits and noted it ran
slower and slower as time and the number of orbits pro-
gressed.

It occurred to me that I could graphically display how
fast the program was executing and find out where it was
slowing down by adding some extra code. Every 20 lines
or so, I inserted K9 = K9 + l:GOSUB 2000, and then at
the end:

2000 S9 = 54244

2010 POKE S9 + K9, 48 + K9

2020 FORZ = lTO30:NEXTZ

2030 POKES9 + K9,32

2040 IFK9 = 9THENK9=0

2050 RETURN

This flashes the numbers 1 thru 9 from left to right on
the bottom row of the video screen every time the main
portion of the program loops. You can easily note the
delay between certain numbers; this helps to pinpoint
where the program is spending most of its time. The
troublesome area or line can be further narrowed down
by adding more GOSUBs, or by moving those from the
faster part to the slower part. (Be sure that there are nine
GOSUBs and that each is executed only once within the
loop.)

This method alerted me to a poorly written line of code
I would have otherwise never suspected. ■

34 April 1981 © BYTE Publications Inc

Circle 27 on inquiry card.

Circle 28 on inquiry card.

TRS-80* Model I Computer Owners . . .

Double-density storage,
It's really here!

Here at Percom. And your authorized Percom dealers.

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Although rated for double-density operation, all
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You can operate these drives in ordinary single-
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or any other single-density operating system.

Or, you can add a Percom DOUBLER™ to your
Tandy Expansion Interface and store data and
programs in either single- or double-density
format.

Under double-density operation, you can store
as much as 350 Kbytes of formatted data — de-
pending on the drive model — on one side of a
five-inch minidiskette. That's four times the
capacity of standard 35-track Model I mini-
disks, almost 100 Kbytes more than the capacity
of the eight-inch IBM 3740 format!

Available in 1-, 2- and 3-drive configurations in
all three model lines, Percom burned-in, fully-
tested drives start at only $399.

TFD-40™ Drives

TFD-40 Drives store 180 Kbytes (double-density) or
102 Kbytes (single-density) of formatted data on one
side of a 40-track minidiskette. Although economical-
ly priced, TFD-40 drives receive the same full Percom
quality control measures as TFD-100 and TFD-200
drives.

TFD-100™ Drives

TFD-100 drives are "flippy" drives. You store twice
the data per minidiskette by using both sides of the
disk. TFD-100 drives store 180 Kbytes (double-
density) or 102 Kbytes (single-density) per side.
Under double-density operation, you can store a 70-
page document on one minidiskette.

TFD-200™ Drives

TFD-200 drives store 350 Kbytes (double-density) or
197 Kbytes (single-density) on one side of a minidis-
kette. By comparison, 3740-formatted eight-inch
disks store only 256 Kbytes. Enormous on-line stor-
age capacity in a 5" drive, plus proven Percom
reliability. That's what you get in a TFD-200.

-■/siiiiwj'i.t.i"i''". .•••';. ■ ti.vh.

The DOUBLER™ — This proprietary
adapter for the TRS-80* Model I com-
puter packs approximately twice the
data on a disk track.

Depending on the type of drive, you
can store up to four times as much
data — 350 Kbytes — on one side of a
minidiskette as you can store using a
Tandy standard Model I computer drive.

Easy to install, the DOUBLER merely plugs into the disk
controller chip socket of your Expansion Interface. No rewir-
ing. No trace cutting.

And because the DOUBLER reads, writes and formats
either single- or double-density disks, you can continue to
run all of your single-density software, then switch to dou-
ble-density operation at any convenient time.

Included with the PC card adapter is a TRSDOS*-
compatible double-density disk operating system, called
DBLDOS™, plus a CONVERT utility that converts files and
programs from single- to double-density or double- to sing-
le-density format.

Each DOUBLER also includes an on-card high-
performance data separator circuit which ensures reliable
disk read operation.

The DOUBLER works with standard 35-, 40-, 77- and
80-track drives rated for double-density operation.

Note. Opening the Expansion Interface to install the
DOUBLER may void Tandy's limited 90-day warranty.

Free software patch with drive purchase. This software
patch, called PATCH PAK,'" upgrades TRSDOS* for single-
density operation with improved 40- and 77-track drives.

Quality Percom products are available at authorized dealers. Call toll free
1-800-527-1592 for the address of your nearest dealer or to order directly from
Percom. In Canada call 519-824-7041.

TM , , _ _ _ , Prices and specifications subject to change without notice.

IM trademark of Percom Data Company, Inc.

.nark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company.

PEFQCM

PERCOM DATA COMPANY. INC.

211 N. KIRBY • GARLAND TX • 75042

(214)272-3421

Ciarcia's Circuit Cellar

Build a Low-Cost Logic Analyzer

Steve Ciarcia

POB 582

Glastonbury CT 06033

The Digital Age has
spawned a variety of elec-
tronic troubleshooting
aids, including logic
probes, integrated-circuit
test clips, multi-trace os-
cilloscopes, and logic ana-
lyzers. All are useful, up
to a point, but it is impor-
tant to know when to use
a particular test instru-
ment and how much you
can depend on it.

If the logic states of
signal lines were the only
information needed, a
simple voltage measure-
ment would suffice in
digital troubleshooting.
But timing, rather than
absolute voltage level, is
the more important con-
sideration in digital sys-
tems. Most digital systems
operate by setting discrete
logic conditions on bus
lines and then strobing
that data through the sys-
tem at the occurrence of
edges of specific clock
pulses. A system operates
correctly only if all the
parallel states are set correctly at a
specific instant in time. The system
fails if any single logic state is in error
at any clock time during program ex-
ecution.

Photo 1: One frequently used test instrument is a direct-reading
state indicator. The sixteen indicators are transistor-driven in-
candescent lamps or LEDs (light-emitting diodes). The indicator
panel is attached to a "chip-clip" connector so that the logic
states on any TTL (transistor-transistor logic) or L5 (low-power
Schottky-diode-clamped) TTL dual in-line package can be read
while the circuit is energized. The display is most valid for static
conditions.

The first special digital instrument
was the logic probe. A schematic
diagram of a typical logic probe is
shown in figure 1. This device ac-
curately indicates the logic state on

LED (light-emitting diode)
indicators at any selected
point in a circuit. How-
ever, it is a static device
and will not follow rapid-
ly clocked digital logic
other than to indicate
general activity. Even
when the concept is ex-
panded to include four-
teen or sixteen separate in-
dicators on the probe (as
shown in photo 1), effec-
tive use still depends on
stopping the system clock
(or slowing it substantial-
ly) to examine static logic
states. Unfortunately,
stopping the clock changes
the dynamics of circuit
operation and may, in
many instances, mask the
true cause of problems.

More frequently, digi-
tal-logic errors are
dynamic and occur during
clock-state transitions.
The errors are often due to
timing problems asso-
ciated with the propaga-
tion of signals through the
circuit or with miscuing of
multiplexed components. Because the
logic state at clock transitions often

Copyright © 1981 by Steven A Garcia.
All rights reserved.

36 April 1981 © BYTE Publications Inc

determines either proper operation or
failure, a more suitable test instru-
ment would be one that provides the
operator with a view of all logic ac-
tivity coincident with the transition
of the clock.

To most people this sounds like a
job for a multi-trace oscilloscope with
its sweep triggered from the system
clock. An oscilloscope can in many
instances be of value, but unless it is
an expensive storage-tube scope, fast
system-clock rates can make viewing
difficult. Also, viewing two signals
with respect to each other in real time
is of little help when the error occurs
intermittently and involves more sig-
nals than can be viewed simul-
taneously.

What Is a Logic Analyzer?

One solution to the digital-
troubleshooting dilemma is called a
logic analyzer. This is an instrument
that displays a "truth table" of the ac-
tivity of the digital circuit being tested
under actual operating conditions.
After you have selected a key com-
bination of input signals, called a trig-
ger or sync word, and activated the
analyzer, it stores all signal-input
logic states for a specific number of

system-clock transitions. Depending
upon the sophistication of the par-
ticular unit, many commercial logic
analyzers can accommodate 32 or
more inputs and store up to 256 clock
cycles before and after the trigger
event.

A logic analyzer acts

like an electronic time

machine.

In effect, a logic analyzer acts like
an electronic time machine. When se-
quentially displayed in the order it
was acquired, the stored data can be
used to form state tables or timing
diagrams of the circuit's operation.

For example, a logic analyzer might
be used to troubleshoot a malfunc-
tioning microcomputer I/O (in-
put/output) port that keeps receiving
consistent but wrong data. You don't
know whether the error is caused by
the wrong data being sent to the out-
put register or by an incorrect address
signal strobing the register at the

wrong time (try troubleshooting this
kind of problem with just an
oscilloscope). You can find out by
connecting the logic analyzer to the
address and data buses of the micro-
computer.

Set the trigger-word switches to
produce a trigger pulse when the ad-
dress bus contains the I/O port ad-
dress. When the trigger pulse occurs,
you can examine the logic states on
the data bus with the analyzer to see
what value was being loaded into the
port register at the occurrence of the
trigger pulse, as well as those states
following the pulse. It is like having
an 8- to 32-channel oscilloscope with
the display frozen in time on a
specific clock cycle.

Commercial logic analyzers are
generally stand-alone instruments
with integral video-monitor or oscil-
loscope displays. They can present
stored data in a variety of ways. A
data-domain analyzer ordinarily
displays logic states as lists of Is and
Os. The listings are sequential and in
either binary, octal, or hexadecimal
format. This display method is par-
ticularly helpful when you are debug-
ging address-bus problems. In such
cases, data is most easily read as

INPUT

+ 5V

Number Type

IC1 74LS14

IC2 74121

+5V GND

14 7

14 7

Figure 1: A simple logic probe that uses two integrated circuits. When a logic-0 signal voltage is applied to the input, the "logic 0"
LED will light. When a logic-1 signal voltage is applied to the input, the "logic 1" LED indicator will light. If the input oscillates be-
tween the and 1 states, the "Pulse" LED indicator will also light.

April 1981 © BYTE Publications Inc 37

4-digit hexadecimal values.

For hardware troubleshooting, a
time-domain analyzer is preferred.
This unit presents the stored data in
timing-diagram format. The result
appears like the display of an 8- or
16-channel oscilloscope. The vertical
scale has a high-voltage value that
represents a logic 1 and a low-voltage
value that represents a logic 0. The

data signals are plotted with respect
to each other and can be displayed as
a function of actual time.

A third data format is the mapped
mode. Essentially, the display screen
is divided into an x, y coordinate
system, and data points are plotted as
dots on the screen. In some units, vec-
tors between dots connect successive
data points so that it is easier for an

^^L

\

\

Si

■•

i

%

^^^^^^^^

Photo 2: The prototype logic analyzer described in this article. The switches on the left
are for setting the trigger (sync) word.

Photo 3: Inside the box of photo 2 is the circuit of the analyzer as shown schematically
in figure 4. Seventeen integrated circuits are used.

operator to trace sequential activity
in the device under test. The process
of interpreting this kind of display is
essentially one of recognizing a
"good" pattern and identifying wild
vectors. Presumably, a properly
operating program will have a
repeatable pattern. Any discrepancies
will show up as an extra dot or "wild
vector."

The various types of logic-analyzer
display formats are shown in figure 2
on page 40.

Regardless of the display format,
all logic analyzers share a common
internal structure. Generally, they in-
corporate the subsystems outlined in
the block diagram of figure 3. All
logic analyzers have some form of in-
put conditioning, trigger-word selec-
tion and comparison, memory, and
display (LEDs, oscilloscope, or raster-
display tube, etc). The combination
of capabilities is usually a function of
price, which can range from $2500 to
$10,000.

A Low-Cost Logic Analyzer

Obviously, we cannot hope to con-
struct a logic analyzer that is
equivalent to an $8500 Hewlett-
Packard unit. However, we can
design a special logic analyzer as a
peripheral device of a personal com-
puter. By utilizing the display and
processing power of the computer,
we can greatly enhance the capa-
bilities of a relatively simple hard-
ware interface. Also, for those
readers interested in the concept but
not quite ready to grab their soldering
irons, I will outline a method that
demonstrates how to use your present
computer to perform logic-analyzer
functions totally in software. First,
the hardware approach.

Figure 4 is the schematic diagram of
a low-cost eight-input logic-analyzer
interface that requires only one and a
half parallel I/O ports (9 output and 6
input bits) for complete operation. It
is easily expandable to 16 or even 32
inputs.

All probe inputs and clock signals
are conditioned through Schmitt trig-
gers to reduce noise and false trigger-
ing. When the sync word, set on ex-
ternal switches (SWl through SW8),
appears on the input lines, the
analyzer automatically collects and
stores 16 sequential words repre-

38 April 1981 © BYTE Publications Inc

senting input status at the instant of
either an internal or external clock
signal (usually the system clock). It
can operate on either edge of the
clock pulse and store data at frequen-
cies as fast as 5 MHz. The prototype
interface is shown in photo 2.

Unlike commercial logic analyzers,
this unit has no integral CRT
(cathode-ray tube) display: it has
eight externally controlled LEDs. It
depends instead upon the computer
to display the list of stored data.
After the interface has taken sixteen
samples, it sends a Scan Complete
signal to the computer. A computer
program sets the Read/Write line to
the Read mode and sets a 4-bit ad-
dress to access the contents of the
16-word scratch-pad memory. As the
4-bit address is incremented, the ap-
propriate 8-bit output is placed on the
analyzer's data-output lines from the
scratch-pad memory and is stored by
the computer. In addition, as the
computer reads the scratch-pad
memory, the contents of each loca-
tion are displayed on eight LEDs. If
the addresses are changed slowly, or
are otherwise physically set, the 16
stored words can be viewed directly
without a special display program.

Once the data has been acquired by
the computer, a format-and-display
program lists the values on the com-
puter's display in binary, octal, or
hexadecimal format, simulating a
commercial analyzer display. To
gather an additional 16 words, the
computer program merely sets the
Read/Write line to the Write mode
and toggles the Sample Enable line.
The BASIC program in listing 1 on
page 43 exercises the interface and
displays the output shown in listing 2.

Inside the Interface

The analyzer hardware (shown in
photo 3) has an interface consisting of
seventeen integrated circuits. Input
signals are fed through IC1 and IC2,
which are hex Schmitt-trigger in-
verters. Photo 4 shows typical test
connections. These conditioned out-
puts are in turn buffered and gated
through to the memory section by
IC3, a type-74LS240 8-input bus
driver. The output of this driver is
compared to eight preset switches
through two 74L85 4-bit comparators
(IC7 and IC8). (Trigger-word initia-
tion is disabled by setting all switches
to the logic-1 state. Storage will com-

mence on the first clock pulse after
Sample Enable.) If the switch settings
and data input are equal, a pulse is
generated which stores the current in-
put data. The first word stored is
usually the sync word (assuming that
the trigger word and external clock-
pulse edge are synchronous).

On the trailing edge of the
WE (memory-write-enable) pulse, the
4-bit memory-address counter IC9 is
incremented. Data will be stored
again at the occurrence of the next
edge (positive or negative as selected)
of the clock pulse.

Text continued on page 42

Photo 4: The analyzer is intended for use while a circuit is in dynamic operation. Con-
nection to the circuit can be done with the "chip-clip" method shown in photo 1, or by
using separate test probes. The latter is more versatile. The circuit shown under test is
the Disk-80 expansion interface from last month's Circuit Cellar.

Photo 5: When the circuit of figure 5 (on page 42) is attached to the logic analyzer, a
data-domain display can be converted to a time-domain display. Essentially nothing
more than an eight-channel scope multiplexer, this circuit greatly expands the display
potential of the average oscilloscope, as the photo demonstrates.

April 1981 © BYTE Publications Inc 39

(2a)

(2b)

(2c)

(2d)

Figure 2: The data acquired by a logic analyzer can be displayed in various formats.
The different types are:

(2a) The ones and zeros logic-state display. In this format, binary words are plotted
against clock pulses in a matrix m bits wide by n clock pulses deep. This format is used
most often where word flow or data sequence is of prime concern.

(2b) Same as 2a except that the data is listed in hexadecimal notation. Hexadecimal
listings are most frequently used in logic analyzers specifically designed for
microprocessor troubleshooting, where thirty-two to forty inputs are not uncommon.

(2c) The timing-diagram display. In the timing format, data words are plotted
against time. This format is used most often for hardware troubleshooting to detect in-
correct timing between signals.

(2d) Vector-display analyzer. In the vector-display format, data words define points
on an x, y coordinate system. Usually, the data word is divided in half with a separate
D/A converter attached to each segment. One output goes to the display's x input and
the other goes to the y input.

INTERNAL
CLOCK

EXTERNAL
CLOCK

o-

o-

EIGHT

TTL-

LEVEL

INPUTS

o-
o-
o-

o-
o-

INPUT
CONDITIONERS

TRIGGER
WORD

SELECTION
SWITCHES

DISPLAY
I

MEMORY

COMPUTER

WORD

COMPARATOR

AND

TRIGGER

CIRCUITRY

c

SAMPLE
AND
READ
CONTROL

Figure 3: Basic block diagram of the simple logic analyzer. In this case, the block labeled "computer" refers to an externally attached
personal computer. In commercial units, the computer and display are integral components of the logic analyzer.

40 April 1981 © BYTE Publications Inc

Figure 4: Schematic diagram of an eight-input logic analyzer. One and a half parallel I/O ports are required for operation. Note
that the 74L85 integrated circuits used here have a different pinout specification from the 74LS85. User connections are on the left;
computer connections are on the right.

April 1981 © BYTE Publications Inc 41

Number

Type

+ 5V

GND

IC1

74LS14

14

7

IC2

74LS14

14

7

IC3

74LS240

20

10

IC4

7489

16

8

IC5

7489

16

8

IC6

74LS157

16

8

IC7

74L85

16

8

IC8

74L85

16

8

IC9

74LS93

5

10

IC10

74121

14

7

IC11

NE555

8

1

IC12

74121

14

7

IC13

74LS74

14

7

IC14

74LS02

14

7

IC15

74LS20

14

7

IC16

7416

14

7

IC17

7416

14

7

Table 1: Power connections

for in-

tegrated circuits of figure 4,

on page

41.

Text continued from page 39:

When sixteen samples have been
taken, the 4-bit memory address is
binary 1111. IC13 and IC14 detect
this condition and set the Scan Com-
plete line to a logic 0. This also
disables further storage until the in-
terface is reset with a Sample Enable
pulse to IC2.

Reading the contents is simply a
matter of setting the Read/Write line
to a logic and placing an ap-
propriate 4-bit address on the Read
Address input lines. When an address
is set on these lines, the data-output
lines of the analyzer will contain the
contents of that memory location.
The eight LEDs will also display that
value.

Creating a Time-Domain Display

As previously mentioned, the
display format available from this in-
terface is generally a listing of Is and
0s. This is quite useful under most
circumstances but not as appealing to
hardware buffs as a timing-diagram-
type output. Even if your computer
has graphics capability, writing a
program to simulate a multi-trace
oscilloscope display requires con-
siderable software expertise.

The logic-analyzer interface can be
converted to a time-domain display
with relatively little extra hardware
and only a single-line BASIC pro-
gram. Figure 5 is the schematic
diagram of the additional circuitry.
Essentially, it consists of a dual
4-input digital multiplexer and 2-bit
D/A (digital-to-analog) converter,
which offsets each of the four chan-
nels when displayed. In effect, it

U5 00 "3- CD CD r~- l~-

03 u-> ""*■ "" "O 7- i-

•q- •* ■* 2 2

i^ (^ i 1 —i

■9 *- cm m it cr> co
E O O O OOO

3

Figure 5: Eight-channel display multiplexer, which facilitates display of eight TTL in-
puts on a standard dual-trace oscilloscope. Its intended use is to convert the data-
domain output from the circuit of figure 4 into a time-domain display on an
oscilloscope.

42 April 1981 © BYTE Publications lnc

allows a dual-trace oscilloscope to
display eight channels simulta-
neously. Such a display appears in
photo 5.

Conversion from data-domain to
time-domain operation is not as dif-
ficult as it might seem. Consider the
operation of the analyzer for a mo-
ment. Once the 16-word buffer is full,
the data can be read out at any rate. If
we cycle the read addresses very
quickly, the outputs will form a
repetitive pattern which can be easily
viewed on an oscilloscope. The fast
cycling can be accomplished using a
4-bit counter and oscillator source at-
tached to the address-input lines or
by using a simple program statement
like:

100 FOR X = TO 255:OUT 16,X:
NEXT X: GOTO 100

Using a dual-trace oscilloscope,
you can view two signals, or, with
the circuit of figure 5, you can view
all eight data channels simulta-
neously. Since there is no system
clock to contend with and the pattern
repeats every sixteen steps, triggering
problems are reduced and the display
is stationary. All other interface
operations remain the same.

Adding a Vector-Display
Capability

If you are determined to hunt "wild
vectors," the same technique em-
ployed to provide a timing plot lends
itself to vector display. Using the
same methods to cycle the buffer data
on the output lines of the analyzer,
substitute D/A converters for the
multiplexer in figure 5. Typically,
two 4-bit D/A converters are needed.
One would be attached to the 4 high-
order bits and the other to the 4 low-
order bits. One D/A converter is at-
tached to the x-axis scope input and
the other to the y-axis input. When
the buffer is cycled, a unique vector
pattern will appear on the screen,
describing the 16 data words stored in
the analyzer's buffer. (A more infor-
mative discussion on this approach to
troubleshooting was one of my
previous articles, "A Penny Pinching
Address State Analyzer," February
1978 BYTE, page 6. It has been
reprinted in Ciarcia's Circuit Cellar,
Volume I, available from BYTE
Books.)

Listing 1: A BASIC program that exercises the computer/logic analyzer interface,
displaying output through the computer's normal output devices.

100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490

REM Logic Analyzer Program

REM

REM data in on port 16, scan complete on bit of port 17

REM read enable and sample enable are bits 6 and 7

REM of port 16

REM read address is bits thru 3 of port 16

REM memory locations 25000 to 25015 is set aside as the data

REM buffer

PRINT"LOGIC ANALYZER"

PRINT:PRINT"Enable New Sample or List Analyzer Buffer";

PRINT" (E or L)

INPUT A$

IF A$ ="E" THEN 250

IF A$ ="L" THEN 380

GOTO 190

REM Enable Logic Analyzer and take 16 readings

REM pulse sample enable line and set read/write line=0

OUT 16,255:OUT 16,0: OUT 16,255

REM

REM test scan complete line

IF INP(17) =255 THEN GOTO 300

REM when scan is completed store readings in table

FOR S=25000 TO 25015

N=S-25000

REM set read address and store analyzer output

OUT 16, N :A=INP(16) :POKE S,A

NEXT S

GOSUB 3 80

REM Ones and Zeros data-domain display routine

PRINT:PRINT

D3 D2 Dl DO"
:X=PEEK(S)

PRINT"D7 D6 D5 D4

FOR S=25000 TO 25015

FOR N=7 TO STEP -1

W=X AND 2"N

IF W>0 THEN PRINT"1

IF N=4 THEN PRINT"

NEXT N

PRINT" SAMPLE #";S-24999

NEXT S

GOTO 190

ELSE PRINT"0

READY

Listing 2: Sample output produced by the program of listing 1.

RUN

LOGIC ANALYZER

Enable New Sample or List Analyzer Buffer (E or L) ? E

D7

D6

D5

D4

D3

D2

Dl

DO

1

1

1

SAMPLE

#

1

1

1

1

1

1

SAMPLE

#

2

1

1

1

1

SAMPLE

#

3

1

1

SAMPLE

#

4

1

SAMPLE

#

5

1

1

1

1

1

1

SAMPLE

#

6

1

1

1

1

1

SAMPLE

#

7

1

SAMPLE

#

8

1

1

1

SAMPLE

#

9

1

1

1

1

1

SAMPLE

#

10

1

1

1

1

1

SAMPLE

#

11

1

1

SAMPLE

#

12

1

1

1

1

SAMPLE

#

13

1

SAMPLE

#

14

1

1

1

1

1

SAMPLE

#

15

1

1

1

1

1

SAMPLE

#

16

Enable New Sample or List Analyzer Buffer (E or L) ?

April 1981 © BYTE Publications Inc 43

c

BEGIN

J

SET STORAGE
BUFFER POINTERS
AND TRIGGER
WORD

SET SAMPLE-RATE
TIMER VALUE

INITIALIZE
PIA AND CLEAR
STORAGE BUFFER

READ PIA
PARALLEL
INPUT PORT

STORE
INPUT
WORD

INCREMENT

BUFFER

POINTER

Q

EXIT TO
DISPLAY PROGRAM

D

READ PIA
PARALLEL
INPUT PORT

Figure 6a: Flowchart of a software logic analyzer. Using a Motorola 6820 PIA
(Peripheral Interface Adapter), this sequence of operations is all that is required to
demonstrate logic-analyzer functions in software. This method is limited in speed of
operation by the execution time of the program.

v ANALYZER
/ INPUTS

<CH CLOCK
<^]GND

Figure 6b: Pinout chart of the Motorola 6820 PIA used by the algorithm of figure 6a.

Logic-Analyzer Functions Created
Through Software

While I generally prefer to
demonstrate hardware interfaces in
my articles, the functions of a logic
analyzer can easily be simulated in
software if data-acquisition speed
(under 20 kHz) is not critical. While it
may not be appropriate for testing
microcomputer bus signals, it should
work for slower applications.

Figure 6 is a flow diagram outlining
the specific steps involved in ac-
complishing this function. While any
existing parallel input port will suf-
fice, the Motorola 6820 PIA
(Peripheral Interface Adapter) shown
has a separate clock input, which
greatly facilitates proper timing.

In Conclusion

As digital hardware becomes more
complex, the instruments used in
troubleshooting and debugging these
circuits must themselves become
more sophisticated. This sophistica-
tion, however, need not always be
provided in the form of a commer-
cially produced test instrument.
Often the solution can be intelligent
application of existing equipment
with limited modifications.

The logic analyzer I have described
can be used for all types of trouble-
shooting and testing of digital cir-
cuits. However, its true flexibility is
revealed when the instrument cap-
tures the extremely fast data flowing
in a microcomputer and generates a
stationary timing diagram with the
results. Built from scratch, combined
with an oscilloscope, and exercised
by a computer, this interface costs
only a fraction of the price of com-
mercial analyzers, yet approximates
many of their features.

Next Month:

Build a remote-controlled motor-
ized moving platform. ■

Editor's Note: Steve often refers to
previous Circuit Cellar articles as
reference material for the articles he
presents each month. These articles are
available in reprint books from BYTE
Books, 70 Main St, Peterborough NH
03458. Ciarcia's Circuit Cellar covers ar-
ticles appeating in BYTE from September
1977 thru November 1978. Ciarcia's Cir-
cuit Cellar, Volume II presents articles
from December 1978 thru June 1980.

44 April 1981 © BYTE Publications Inc

Development Software

For Texas Instruments
TM990 Micro
Modules

v«

<0»

ei*

*<■*

Eyring Research Institute, Inc.,
authors of Tl's POWER BASIC®
and UNIVERSITY BASIC®, is
pleased to release development
software for use on the TM 990
microcomputer modules. PDOS/
EXPRES® is a powerful multi-user,
multi-tasking operating system
designed for development, scien-
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The PDOS/EXPRES® system in-
cludes:

• 8k byte PDOS multi-tasking
operating system

• Advanced EXPRESS BASIC
language interpreter

• Stand alone run module sup-
port

PDOS supports up to 16 con-
current user tasks with prioritized
round robin clock swapping. Up
to 32 contiguous or non-
contiguous files can be simultane-
ously open in sequential, random,
shared and read only access
modes. Large or small floppy
disks, bubble memory, hard disks

"After having worked with
PDOS and EXPRES for the past
three months I have found them to
be a powerful and versatile com-
bination. The true multi-user,
multi-tasking capability has made
it a pleasure to use in our labora
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are being used simultaneously for
controlling laboratory apparatus
taking and reducing data. . .We
are enthused by the product. . ."

Tom Ochs

Assistant Research Professor

Desert Research Institute

and extended memory capabilities
of up to 256k bytes are handled by
the operating system. Named files
on 256 directory levels are easily
accessible from EXPRES BASIC and
assembly language programs.
Disk files are time stamped with
date of creation and last update.
I/O drivers are a simple extension
to the PDOS file structure.

The EXPRES BASIC interpreter
uses advanced interpreting
techniques which approach
execution speeds of common
threaded code compilers while
maintaining the highly advantage-

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• Multi-line recursive functions
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• Variable names of unlimited
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• Reverse Polish pseudo-source
token storage

PDOS/EXPRES® is available for
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change without notice

Circle 29 on inquiry card.

BYTE April 1981 45

System Review

The Micro Ace Computer

Delmar Searls, 1825 S Johnstone, BartlesvUle OK 74003

About the Author

Delmar Searls is a professor of mathematics at BartlesvUle Wesleyan
College, BartlesvUle, Oklahoma. His interest in microcomputers is a
result of both professional and personal experience: he learned BASIC
programming by using a PET microcomputer on the job; at home, he
taught himself electronics, beginning with the basics, and continuing
through digital electronics and microprocessors. His interest in the
MicroAce was sparked by the remarkably low price.

The MicroAce is a small, Z80-based microcomputer in
kit form. When completed it measures 23.2 cm by 18.8
cm by 4.1 cm (9% inches deep, 7% inches wide, and 1%
inches high). It features an integer BASIC in ROM (read-
only memory), touch-sensitive keyboard input, cassette
I/O (input/output), and video output through an on-
board UHF modulator. The video display consists of 24
lines of 32 alphanumeric and graphics characters.

The kit comes in two forms, depending on the amount
of user-programmable memory purchased. For $149 (in-

Name

Memory

MicroAce (kit)

4096 bytes of ROM

1024 bytes of pro-

Manufacturer

grammable memory

MicroAce

1348 E Edinger

Mass Storage

Santa Ana CA 92705

Cassette tape recorder

(714) 547-2526

supplied by user

Price

Other Features

$149 (with 1 K bytes

Touch-sensitive

of programmable

keyboard, RF-

memory)

modulated output

(UHF channel 35),

Dimensions

display of 24 lines by

23.2 cm by 18.8 cm by

32 characters

4.1 cm (9y 8 inches by

7% inches by 1% in-

Documentation

ches)

Teach-yourself BASIC

manual (67 pages)

Processor

Z80, 8-bit

Audience

Anyone who wants an

System Clock

inexpensive microcom-

Frequency

puter

3.25 MHz

eluding shipping) you get a unit with 1 K bytes of pro-
grammable memory, expandable to a maximum of 2 K
bytes with the purchase of an upgrade kit for $29. You
can save $9 by buying the second version of the kit for
$169.

Depending on the sources available, you can save even
more by buying the 1 K-byte kit and purchasing the ex-
tra components from local or mail retailers. You would
need to buy three integrated-circuit sockets, two memory
circuits, a 74LS32 integrated circuit, and one capacitor.

If my experience is typical, you can expect to wait
about a month for your MicroAce to arrive if you mail
your order; less if you order by phone.

Construction

The advertisement for the MicroAce (as it appeared in
BYTE and in other magazines) states that you will receive
a "teach-yourself BASIC manual" and that "a hardware
manual is also included with every kit." This is not cor-
rect. There is no hardware manual supplied with the kit,
only the BASIC manual which includes a section entitled
"Construction," preceding the first chapter.

The assembly instructions are very general and, in my
opinion, not quite sufficient for those who have no ex-

Photo 1: The MicroAce kit as shipped. Starting at the bottom
and moving clockwise around the main circuit board are: the
discrete components, the integrated circuit sockets, the in-
tegrated circuits themselves, voltage regulator, power supply,
UHF modulator, antenna switch box, cable materials, and black
plastic case. The 8- by HVi-inch instruction manual gives an in-
dication of the size of this computer.

46 April 1981 © BYTE Publications Inc

perience in circuit-board kit construction. There are no
guidelines for proper soldering techniques and no step-
by-step instructions that are commonly found with kits
from the larger kit manufacturers.

Component values are written in a rather unusual
notation. For example, a resistance of 470 ohms is written
470R, 1000 ohms is written 1K0, 2200 ohms is written
2K2, 47,000 ohms is written 47K, and 1,000,000 ohms is
written 1M0.

There is a logical pattern to the notation, but it is dif-
ferent from that which is normally used. I suspect that the
notation is British, since the MicroAce is essentially the
kit version of the Sinclair ZX80, which is made in
England.

Another unusual practice is the frequent listing of
capacitance in nanofarads rather than picofarads. While
this notation may be unusual, it should not cause any real
problem as color codes and identifying marks are also
listed for the various components.

The smaller components are packaged in plastic bags,
while the larger items are packed loose (see photo 1).
There were no missing parts, and, in fact, I received three
extra resistors and one extra capacitor. There was a mo-
ment of concern when I discovered that the parts list
called for eleven diodes and only nine had been supplied.
A close inspection of the circuit board, however, revealed
that only nine were required.

The circuit board is double sided with holes soldered
through. Component locations are indicated by white
outlines and white identification labels on the component
side of the board (see photo 2). Component type and
value is determined by cross-referencing the identifica-
tion label (R2, C12, U8, etc) with the parts list.

The actual assembly is straightforward and very easy,
especially for those familiar with circuit-board projects.
The construction notes suggest that components be
soldered to the board in the following order: sockets for
the integrated circuits, discrete components, cable
sockets, voltage regulator, and the video modulator.

Next, the integrated circuits can be installed. Be sure to
follow the appropriate precautions when handling the
MOS (metal-oxide semiconductor) devices, which in-
clude the Z80, two programmable-memory chips, and
the ROM circuit. At this point the unit can be tested for
proper operation. The last stage in construction, follow-
ing successful testing, is the installation of the unit in its
case (see photo 3).

The 1 K-byte version of the kit does not provide the
sockets for three circuit locations. (These are supplied
with the upgrade kit.) I suggest that anyone building this
version use masking tape to identify these locations prior
to construction. Otherwise, it would be easy to install a
socket in one of these locations, only to come up short
later on. Once a socket is soldered in, it is practically im-
possible to remove.

There are no instructions given for the preparation of
the cables that will attach your television and cassette
recorder. You are provided with about 10 Vi feet of
shielded cable, two phono plugs, and four mini-jacks. As
simple as this task may appear, more instructions should

O O <V <=> "' Ml B

«*■■■■■■■■

<t» .<•; SAVE BUN CONI HEM If INPU' W»Nt

V* UM fOH GOTO POKE RAND l_E'

UTAH i.;li> ■./.'SUB Hi I NEXI

Photo 2: Component side of the main circuit board. Note that
component locations are clearly marked, and that the keyboard
is an integral part of the printed-circuit board.

■

IS

OEM

cts

GOfeUB

«£«

«*r

a* ak

Photo 3: Completed MicroAce with cables.

April 1981 © BYTE Publications Inc 47

ao PRINT

gOPR CO DISPLAY I

©O PRINT "« MICROftCE COMPUTttft'

©O PfiMENT notice: THAT ft ncu-

©O PRINT "PPOGPOM LINE IS

soil

HO PRINT "BOTF ITfflBBL

140U
ISO

iVO PRINT

NOT AND THEN TO

4.0 <>> c> HOME HUBOUT

■ ■■■■

NEW 10*0 SAVE RUN CONT HEM IF INK)' PRINT

LIST STOP DIM TOW SOTO POKE RAND LET

GLEAM l-LS aOSUB MET NEXT

OUOTP.TION MftRKa..fflB

Photo 5: Layout of the MicroAce keyboard. Note that each
BASIC keyword is associated with a specific key.

Photo 4: Sample program displayed on a standard color televi-
sion set. The current program line is 180, as indicated by the
reverse-video cursor.

have been given to aid the inexperienced builder.

The fastenings provided for attaching the circuit board
to the lower half of the case, and for fastening the upper
half of the case to the lower, are plastic devices referred
to as "rivets." In my opinion, these fasteners are inade-
quate. In fact, the rivet at one circuit-board location was
useless and kept popping out. To remedy the problem, I
used a fine round file to enlarge the holes in the plastic
case, and substituted small nuts and screws for the rivets.
Plastic washers were used to prevent the circuit board
from becoming marred.

The keyboard appears to be built up with two layers.
The bottom layer consists of the front one-third of the
circuit board, while the second layer is laid on top and
seems to be secured with some sort of adhesive. This is
done by the manufacturer, not the kit-builder.

On my unit, this overlay was positioned slightly too
far to the left, so that I had to press the right edge of the
key, rather than the middle, to get a response to the
keyboard entry. In addition, some keys require con-
siderably more pressure than others. These factors, plus
the fact that no audio or tactile feedback is given to in-
dicate a successful keyboard entry, make the keyboard a
little frustrating to use.

Program Entry

The output of the modulator is received on or near
channel 35 on a regular television set. I used an RCA
13-inch color set and had no trouble obtaining a good
display. With the controls set for normal reception of
commercial broadcasts, the display appears as white
characters on a gray background. If desired, white letters
on an almost black background can be obtained by ad-
justing the contrast and brightness controls (see photo 4).

On power-up, the display is blank with the exception
of a reverse-video "K" at the lower-left corner of the
screen. Whenever this reverse K appears, a nonshifted

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48 April 1981 © BYTE Publications Inc

Circle 30 on inquiry card.

Circle 31 on inquiry card.

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keyboard entry from the bottom three rows of keys (see
photo 5) will result in a BASIC keyword being printed on
the screen.

Keywords (and thus the use of a reverse K) are BASIC
commands which are stored in a single byte of memory
but are spelled out on the screen. For a list of these
keywords, as well as other BASIC commands and func-
tions, see table 1.

Nonshifted keyboard entries from the top row are
printed as numeric characters for the line numbers (which
must be between 1 and 9999, inclusive). As a line number
is entered, the reverse K will shift to the right, one space
at a time. As long as the reverse K is on the screen, any
shifted-key input (other than an editing command) will
result in a syntax error. Commands entered without a
preceding line number are executed immediately in the
"command mode."

After entering a line number, press the key corre-
sponding to the BASIC keyword with which your pro-
gram line is to begin. Every program line must start with
one of these keywords. For example, in some forms of
BASIC, the LET keyword is optional, and "10 LET A = 5"
can be written "10 A = 5". This is not possible with the
Micro Ace.

Following the entry of a keyword, the reverse K cursor
changes to a reverse L, signifying that you are in the letter
mode and that keyboard entries will be interpreted as
regular alphanumeric or graphics characters. As you type
in a program line, the system monitor checks for syntax
errors after each character is entered. A line contains a
syntax error if, in its present form, the line is incorrect or
incomplete. Suppose you wish to enter the following line:

SINGLE

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20 PRINT 'THE FINAL SUM IS "; A

The PRINT command is entered by pressing one key (the
letter O) because the machine is in its keyword mode at
the start of each new line. Immediately following the en-
try of the first set of quotation marks, a reverse-video S
(for syntax) appears to the right of the reverse-L program
cursor. This does not indicate that an error has been
made, but rather that the line is incomplete. As the literal

Keyword Commands

Keyboard

Comments

Abbreviation

CLEAR

Set all variables to zero

CLS

Clear the screen

CONT

Continue

DIM

Dimension (one-dimensional arrays)

FOR

GOSUB

GOTO

IF

INPUT

LET

LIST

LOAD

Cassette input

NEW

NEXT

POKE

PRINT

RAND

Randomize

REM

Remark

RET

Return

RUN

SAVE

Cassette output

STOP

String Functions

Function

Comments

CHR$(/V)

Return character or keyword string corre-

sponding to decimal code N.

CODE(S)

Return decimal code number of first

character in string S

STR$(/)

Convert the integer / into its corresponding

string representation.

TL$(S)

Delete the first character from string S.

Other Functions

Function

Comments

ABS(N)

Return absolute value of N.

PEEK(/V)

Return decimal value stored in memory at

address N.

USR(/V)

Start machine-language routine at address

N.

Return a random number between 1 and N

RND(W)

if N is positive.

Logical Functions

Function

Comments

AND

Check to see if two or more conditions are

met simultaneously.

OR

Check to see whether any one of two or

more conditions is met.

NOT

The opposite of a stated condition is tested.

(These logical functions have additional uses which cannot be

detailed here.)

Arithmetic Operations

+

Addition

—

Subtraction

*

Multiplication

/

Division

* *

Exponentiation (2**3 = 2*2*2 = 8)

Table 1: Commands and functions available in MicroAce in-

teger BASIC,

with comments at selected points. The manual

supplied with the kit provides a more detailed explanation.

50

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features: Z-80, 64K, CP/M 1 , dual double density 8"
floppies for 1MB on line storage, 82x24 CRT with
special features, IBM format keyboard with numeric
pad, NEC 55cps letter quality printer, S-100 bus.
Also, Millie is supported by a nationwide rep network
and one of the best service contracts in the business.
And Millie is price competitive with much smaller
computers. Why settle for less than the best? Call
or write today for flyers and manuals. You'll be glad
you did.

iCfODaSyS, IriC. 2811 Wilshire Blvd., Santa Monica, CA 9040:

(213)829-6781 TWX: 910-321-2378

n.g.TM, Digital R«B*atafi

■■■H

SYSTEM VARIABLES (40)
(eg: POINTERS)

PROGRAM

VARIABLES

END OF VARIABLES (2)

WORKING SPACE

DISPLAY FILE

SPARE

STACK

16384

AVAILABLE ON KEYBOARD AVAILABLE USING

AND USING CHRS CHR$ ONLY

Figure 1: Map of the programmable memory in the MicroAce
computer. Fixed boundary addresses are given in decimal; the
other boundaries are variable. Numbers in parentheses give the
size of a fixed block in decimal bytes.

string is entered, the reverse LS moves to the right as a
double cursor. When the second set of quotation marks is
entered, the reverse S disappears because the line now has
the correct syntax.

Consider a second example. You wish to enter the line:

125 LET 1 = 1 + 1

but inadvertently type:

125 LET 1 + 1 = 1

This line would not be accepted because it contains a syn-
tax error. The reverse S cursor would be located directly
after the + symbol.

Notice that in this case the reverse S does not follow
the reverse L cursor, but remains at the point where the
error occurred. In the case of multiple errors, the reverse
S will always be located at the first error contained in the
line. When this error is corrected, the reverse S moves to
the second error, and so on.

As indicated above, no line containing a syntax error
will be accepted into a program. This guarantees that
every line in your final program is complete and free of
syntax errors. It does not, of course, prevent errors of
logic. When a line is complete and correct, it can be
entered into a program by pressing the NEWLINE
key — the MicroAce equivalent of a RETURN key.

As a line is entered into a program it is placed into
memory in two places. First, it is placed into the program
storage area, which begins at decimal address 16424. (See
figure 1 for a simplified map of the programmable
memory.) It is also relocated in the display-file section of
memory so that it appears on the upper portion of the
screen.

E

H
E

a

H

H

Figure 2: Graphics symbols available with the MicroAce. Note
that the first ten symbols are addressable from the keyboard,
while the second ten are their reverse-video images, available
only through the use of the CHR$ function in BASIC.

Recall that on power-up the reverse K was at the lower
left and that line entry was done at the bottom of the
screen. As new lines are entered they appear in numerical
order. The most recently entered line is identified by a
line cursor (a reverse video > ).

A line entered with a number between those of two
previously entered lines is placed in the appropriate posi-
tion on the display, and the line cursor is moved to its
location. When the screen is full, the addition of new
lines causes the program listing to scroll up, always leav-
ing the most recently entered portion on the display.

This method of using programmable memory for both
program storage and display storage leads to problems.
In some systems, the video-display memory is dedicated,
meaning that an advertised 1 K bytes of programmable

52 April 1981 © BYTE Publications Inc

Circle 34 on inquiry card.

Most small system users think all micro-
computers are created equal. And they're
ight. If you want performance, convenience,
styling, high technology and reliability (and
vho doesn't?) your micro usually has a price
ag that looks more like a mini. It seems big
lerformance always means big bucks. But
rat so with the SuperBrain!

Standard SuperBrain features include: twin
double-density 5 1 / 4 " drives which boast nearly
350,000 bytes of disk storage - expandable
:o 10 megabytes. A full 64K of dynamic
RAM. A CP/M* Disk Operating System to
nsure compatibility to literally hundreds of
application packages presently available. And,
a 12" non-glare, 24 line by 80 column screen.

You'll also get a full ASCII keyboard with
an 18 key numeric pad and individual cursor
control keys. Twin RS232C serial ports for
fast and easy connection to a modem or
printer. Dual Z80 processors which operate
at 4 MHZ to insure lightning-fast program
execution. And the list goes on! Feature after
feature after feature.

Better yet, the SuperBrain boasts modular
design to make servicing a snap. A common
screwdriver is about the only service tool
you'll ever need. And with the money you'll
save on purchasing and maintaining the
SuperBrain, you could almost buy another one.
For under $3,500, it is truly one of the most
remarkable microcomputers available anywhere.

Whether your application is small
business, scientific, educational or just word
processing, the SuperBrain is certainly an
exciting solution to the small computer
problem. And since you can easily expand it,
you'll probably never outgrow it.

Call or write us today for a complimentary
copy of our "SuperBrain Buyer's Guide." We'll
show you how you can get big system per-
formance without having to spend big bucks.

r= INTE3TEC

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s systems.

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(803) 798-9100 TWX: 810-666-2115

■flegtsitred HWemark ot DtQiQI Research mc

TWI

n. intrtk: data sysems I sup^brain-

•■ " i i i i t, L

S

memory are used for program storage only, and that ad-
ditional memory is supplied for storing video data.

With the MicroAce, the programmable memory avail-
able to the user must perform both tasks. Thus, as pro-
gram length increases, the area for displaying the pro-
gram listing begins to shrink as less and less memory is
available for display storage. As a result, the program
line-entry "window" moves up from its bottom position
on the screen. The advantage of this system is that when
your line-entry window is near the top of the screen, you
know you are close to filling the available program
memory. The disadvantage is that shorter and shorter
segments of a program can be listed at any one time. As
you will see later, this dual use of memory causes similar
difficulties when running a program.

Another feature of the MicroAce is that there is no
limit (other than available memory) to the length of a
program line. Thus, a large section of text can be printed
using a single PRINT command. This can save time and
memory if properly used.

A disadvantage of the system is that multiple
statements on a single line are not allowed. For example:

230 LET A = 5: LET B = 9

would have to be written as:

230 LET A =5
235 LET B =9

In another example:

Leverage User
Environment Termed
'Unusually Friendly'

Advanced Human Engineering, Superior Documentation,
Detailed Tutorials and Ongoing Support Are Cited

Early reports from users of Leverage, the microcomputer-based infor-
mation management system recently introduced by Urban Software Cor-
poration, reveal a level of satisfaction rarely found among users of micro-
computer applications programs. Several factors have been cited to ex-
plain this highly favorable response, including:

• State of the art human engineering. Features like an extensive on-line
manual directly accessible by the program, graphic menu selection and
automatically programmed menus allow unparallelled ease of use.

• Several easy to follow tutorials demonstrate the capabilities of the
system and provide an ideal vehicle for mastering its operation.

• Clear, complete documentation includes a glossary, an index and
numerous tables and figures.

• Urban Software is firmly committed to the ongoing support of
Leverage. Many enhancements are planned, and a monthly newsletter
will provide application notes, manual updates, bug reports and new prod-
uct announcements.

Leverage Program $185

Manual Alone $ 15 (Credited to subsequent program purchase)

Leverage Newsletter ... $ 10/year (First year included with purchase)
For complete details on Leverage, call or write for a brochure.
Leverage is a trademark of Urban Software Corporation.

Urban Software Corporation

19 West 34th Street* New York, NY 10001 • (212)947-3811

200 INPUT A,B,C

would have to be written as:

200 INPUT A
205 INPUT B
210 INPUT C

Program Editing

As indicated earlier, new lines can be inserted
anywhere in a program by entering them in the normal
fashion. Entire lines can be deleted by entering the line
number and pressing NEWLINE. If the line that is cur-
rently displayed needs editing, the following procedure is
used: the up and down arrows (shifted 7 and shifted 6,
respectively) are used to locate the line cursor at the pro-
per line; then EDIT (shifted NEWLINE) is pressed to copy
the desired line in the program-entry window at the bot-
tom of the screen.

The left and right arrows (shifted 5 and shifted 8,
respectively) are used to position the program cursor
within the line. Deletions are made by placing the pro-
gram cursor to the right of the desired character or
keyword and pressing RUBOUT (shifted numeral 0).

Insertions are made by merely typing in the correct
character or keyword. The portion of the line to the right
of the insertion shifts to the right to accommodate the in-
serted text. You cannot over-type incorrect text; it must
be deleted using the RUBOUT command.

A line that is not presently on display can be edited in
one of two ways. The up or down arrows can be used to
scroll the program listing down or up on the display until
the desired line appears, or the LIST command can be
used instead.

Normally, a LIST command will list the program start-
ing with the line preceding the requested line. If, for ex-
ample, the lines are numbered by tens, then a LIST 120
will result in a listing that begins with line 110 and con-
tinues as far as space and display memory permit. In
either case, once the desired line is displayed on the
screen, it can be edited as described above.

MicroAce has one disconcerting feature that affects the
entering and editing of programs. The microprocessor
performs only one function or task at a time. Thus, it
either handles keyboard input or controls the video
display, and as a result, every key closure during pro-
gram entry and editing causes the display to roll. This
makes it difficult to use the editing arrows, as it is hard to
follow a moving cursor on a rolling display.

Running a Program

A program is executed by entering the RUN keyword
command followed by NEWLINE. During program ex-
ecution, the display remains blank until a STOP or IN-
PUT command is executed, a BREAK or an error occurs,
or the program completes its run. At that point, the
microprocessor is free to devote its attention to the video
display. This means that a PRINT command in a pro-
gram merely loads the data into the display memory for
future use. It will not appear on the display until active
execution of the program ceases. For this reason,
animated graphics are not possible.

As mentioned earlier, there are some problems related
to running programs, because the available program-

54 April 1981 © BYTE Publications toe

Circle 35 on inquiry card.

Circle 36 on inquiry card.

Sweeten Your Apple II* with the ES/F Mass Storage System

THESE FACTS SPEAK FOR THEMSELVES!

A Actual Size

Actual Thickness T

CASSETTE

ES/F

MINI-DISK

SPEED

(10K Load)

60 sec

5.5 sec

8.4 sec

CAPACITY

(K bytes)

100
(C-IO)

125
(75')

103

APPLE

DOS

RELIABILITY

(Designed for
digital data?)

NO

YES

YES

SYSTEM COST

(First unit W/l/F)

$60

$300

$600

SECOND UNIT

N/A

$150

$500

MEDIA COSTS

$3.00

$3.00

$5.00

OPERATING

SYSTEM

NONE

APPLE
SOS

APPLE
DOS

Let's face it. Cassette players were not
designed to store digital data and pro-
grams. That's why we designed a digital
storage system using a continuous tape
loop: the Exatron Stringy/ Floppy
(ES/F) and the Wafer. There's no ex-
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Once your Apple II* is sweetened with
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CALL OUR HOTLINE
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'Apple II is
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of Apple
Computer.

exatron

181 Commercial Street
Sunnyvale. CA 94086

SUPERBRAIN

ANDCOMPUSTAR

USERS'GROUP

Your users' group is here at last! We are Super* Star
International, an independent, world-wide users' group for
Intertec Data Systems' SUPERBRAIN™ and COMPUSTAR™
computers.

Our monthly magazine SUPER *STAR will fulfill all your
computing desires. When you join our group, you will enjoy
the latest: technical information, tips for beginners, special
business uses, equipment reviews, the Intertec story —
the people, ideas, and machines behind your computer. In
every issue you'll get a free program, industry news, and
software reviews.

Plus, we want your programs for our Software Supermarket,
where all members can buy programs at affordable prices.

We will investigate all the accessories you have always
wanted, test them, and offer them for sale at reduced prices.

With our group buying power we'll give you discounts on
commercial software. And that's not all. We'll find group
rates for car rentals, hotels, gifts, and more.

Super* Star International, with savings, service, and
efficiency — we're here to win your heart.

Yearly membership fee is $50.00 U.S., $58.00 Canada, $74.00 Europe
and So. America, $81.00 Australia.

Your fee may be tax deductible; consult your accountant.

Dealers are invited to contact us concerning a special dealer program.
Software houses, we are interested in your programs! Send checks with
your name and address, made out to:

SUPER *STAR INTERNATIONAL CORPORATION

3722 Chestnut Place

Denver, Colorado 80216

(303) 623-7973

Not affiliated with Intertec Data Systems.
'Superbrain and Compustar are the trademarks of Intertec Data Systems.

mable memory is used for both program and display
storage. Program memory is given priority, so if, for ex-
ample, a PRINT command giving some instructions con-
tains more characters than the available display memory
can accommodate, the displayed message terminates at
the point where display memory was filled, program ex-
ecution stops, and an error message appears at the lower-
left portion of the screen.

This clearly limits the amount of displayable text that
can be included in a program. In the worst possible situa-
tion, where the entire screen is filled, 768 bytes of
memory (32 X 24 =768) would be required for the
display alone. Only 256 bytes remain in which to store
system pointers, program lines, variables, and so on.

Furthermore, the display will not scroll during pro-
gram execution. If a PRINT command results in a line of
text beyond line 24, program execution ceases and a dif-
ferent error message is displayed. The PRINT and CLS
(clear screen) commands must be used judiciously in
order to avoid printing too many lines, on the one hand,
and clearing text before it can be read, on the other.

MicroAce Integer BASIC

Integer BASIC is limited in its computational capa-
bilities. All numbers used in computation must be in-
tegers in the range —32768 to 32767, inclusive. Results of
arithmetic operations are truncated (ie: all fractions are
dropped). Thus, 99 divided by 100 would come out 0,
because the division normally yields a quotient of 0.99.
But integer BASIC drops all fractions, leaving 0.

Only the fundamental operations of addition, subtrac-
tion, multiplication, division, and exponentiation (using
positive integral exponents) are implemented. This is true
not only for MicroAce integer BASIC, but for any form
of integer BASIC. The purpose of integer BASIC is to
provide the user with a high-level programming language
in as little memory as possible. This should be kept in
mind when evaluating the capabilities of an integer
BASIC.

While the features of MicroAce BASIC are given in
table 1, a few points should be emphasized. Note that
string manipulation, a feature not always included in in-
teger BASIC, is possible. Also, a USR function is pro-
vided which allows the user to run machine-language
programs. I have not yet experimented with this feature,
but should point out that the manual does not teach you
any machine-language programming. It merely suggests
that you write a monitor in BASIC to enter machine-
language programs, and use the USR function to run
them.

The use of keywords was discussed earlier. This greatly
simplifies program entry because entire commands are
entered with a single keystroke. Memory is conserved
because each keyword occupies only a single byte of
memory. Any keyword command can appear in an ex-
ecutable program line including LIST, LOAD, SAVE,
RUN, and NEW.

You have to be very careful with some of these com-
mands. Program execution terminates following a LIST.
The NEW command executed in a program, or in com-
mand mode (executed directly from the keyboard),
would wipe out everything in memory, including the pro-
gram itself. The LOAD and SAVE commands would be
of little value in a program since the cassette recorder

56 April 1981 © BYTE Publications Inc

Circle 37 on inquiry card.

Circle 38 on inquiry card.

THE SOLUTION STORE

Makes The Difference!

MicroAge Computer Stores sell solutions to your professional, business
and household-management problems, not just hardware. That's what
makes the MicroAge difference! From systems integration to easy-to-
understand application software, research and development to warranty
service and repair, systems consulting to training and installation. In all
these, we offer the latest, most innovative approaches. That's why we are
the forerunners . . . the pioneers in the microcomputer industry.

But don't just take our word for it. Visit the MicroAge Computer Store nearest
you and see the difference solutions make. We have differences you'll
experience with every time and money-saving idea. The difference that
will keep you satisfied now and for years to come!

/V1iera4ge.

ca/MPurer sTore

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Rochester, New York
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(817)284-3413

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Milwaukee, Wisconsin
(414)257-1100

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Coming soon to: Lincoln, Nebraska

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Indianapolis, Indiana

FOR FRANCHISE OPPORTUNITY INFORMATION CALL (602) 967-1421

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would have to be turned on at just the right moment in
order to complete the command execution.

The MicroAce BASIC provides an error message
whenever program execution ceases. The number of dif-
ferent messages is limited, but remember that all program
lines must have correct syntax before they are accepted
into a program. The error messages are given in the for-
mat c:nnn where c is an error code, and, in most cases,
nnn is the last program line executed. Here are some ex-
amples:

0:400 This could mean one of two things. Either the
program has come to a successful end at line 400,
or a BREAK was executed and line 400 would
have been the next line executed in the program.

5:40 This indicates that a PRINT command in line 40
attempted to print beyond the twenty-fourth line
on the display, which, as noted above, is not
possible.

4:40 This might indicate that a LET command was
used when there was no more memory available
for variables storage. (The error code indicates
there is not enough memory to perform the given
line.)

The system of error messages, together with the syntax
checking feature, make program debugging quite easy.
This is definitely one of the strong points of MicroAce
BASIC.

One negative aspect of the MicroAce BASIC is the in-
ability to halt program execution at an INPUT command.
When executing an INPUT command, the BREAK key is,
in effect, ignored. This is not that unusual as other com-
puters exhibit the same property. However, any key en-
try, including NEWLINE (and that is a bit unusual), that
is not a valid response to the INPUT command results in
the appearance of the reverse-video S syntax error cur-
sor, which means that the response will not be accepted.
It must be deleted using the RUBOUT command, and a
correct response must be entered before program execu-
tion resumes.

I entered a relatively simple game program which in-
volved locating a submarine within a three-dimensional
region. The player is allowed seven trials, and must input
three coordinates during each trial. Thus, a maximum of
twenty-one INPUT commands will be executed. Unless a
STOP command or an escape routine is included in the
program (or you disconnect the power), there is no ob-
vious way to terminate execution of the program until all
twenty-one INPUTs are responded to properly. This
could make debugging of highly interactive programs a
time-consuming process. By the way, even though this
program was quite short, the instructions for playing the
game could not be displayed without overflowing the
available display memory. Consequently, they had to be
omitted from the program.

Graphics

There are twenty graphics symbols available, as shown
in figure 2. Note that only ten are available from the
keyboard. The remaining ten are reverse- video graphics
available by using the CHR$ function.

In fact, any alphanumeric character, graphics symbol,
or keyword string can be printed using the CHR$ func-

58 April 1981 © BYTE Publications Inc

Circle 39 on inquiry card.

Circle 40 on inquiry card.

m — TV

] npan pan pnnni pnan ppi nmnni nnnnn pnnri pnnn p gnni pinna jbbm em mm mm ww i

NEVER UNDERSOLD!

That's right, if you can find a lower price in this magazine for any of the Items lilted In this ad, we will reduce our price
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Verbatim Dlfk.tl.i (box of 10)

5'/." MD525-01 soft.lOor 16 $26.50

5%" MD577-01 quad soft. 10 or 16 . .$33.00

8" FD34-1000soft $30.00

8" FD32-1000hard $30.00

8" FD34B000 double density soft . . . .$44.00
8" FD32-8OO0 double density hard . . $44.00

Prlntwheels (specify style]
Qume or Diablo $6.50

Lab*ll
3'/. "xlS/16" (5000 labels) $18.75

Other sizes and quantities CALL

Ribbons

Diablo Hy Type I $4.95

Diablo Hy Type II $5.25

Qume Sprint $3.50

Centronics Zip Pack $3.95

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Main Frame (Model

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Floppy Disk Controller (Model

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Z-80 CPU (Model 2810) $249

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Expando RAM $CALL

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tion. Most characters can be printed in reverse-video as
well. The BASIC manual provides a complete list of all
available characters and strings, along with their decimal
codes. The code is unique to MicroAce and thus not com-
patible with standard computer codes.

Since each character position on the 24 by 32 display is
divided into four parts by the graphics symbols, a resolu-
tion of 48 by 64 dots is possible. Remember though, that
an extensive graphics display greatly limits the amount of
memory available for program storage.

Cassette Input and Output

I had to try two tape recorders before I could suc-
cessfully load a program from tape. The first recorder I
tried lacked a tone control and could not load a program,
regardless of the volume setting. The second recorder had
a tone control and loaded properly with the control set at
maximum treble.

The proper volume level seems to vary from tape to
tape, even when they are made by the same company.
Before saving a program, the program name is recorded
on the tape by voice.

A cable is attached between the microphone output of
the computer and the microphone input of the recorder.
The recorder is placed in its record mode and the SAVE
command is entered followed by NEWLINE. The televi-
sion screen goes blank for about five seconds, followed
by a jumpy display of horizontal white lines. This in-
dicates that the data is being output to the recorder.
When the display returns to normal, the save is complete.

Loading a program involves a similar series of steps. In

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this case, however, you cannot be certain that the pro-
gram is being input until the screen resumes its normal
display, giving a listing of the tail end of the successfully
loaded program.

If, after a reasonable interval of time, the display does
not return to normal, the BREAK key may be used to
reset the computer. Occasionally, you may have to
disconnect the power momentarily to recover from an
unsuccessful load. Once the proper volume setting is
found, however, loading can be done quite reliably.

The Teach-Yourself Manual

The manual supplied with the MicroAce, entitled The
Teach-Yourself BASIC Manual, is shown in photo 1. The
title may be slightly misleading. It brings to mind a
tutorial text complete with exercises for the reader, but it
is not that kind of text. It merely introduces the BASIC
commands, one at a time, illustrating their proper use
and perhaps some typical applications.

At the same time, the processes of program entry, pro-
gram editing, and program execution are taught. Token
coverage is given to the art of programming, but in all
fairness it might be unreasonable to expect a more de-
tailed explanation. As an introduction to the use and syn-
tax of fundamental BASIC commands, the manual is
quite adequate.

While typing errors (or misprints) are inevitable, I do
think that special care should be given to printing sample
programs. One program in the manual has two lines
which read "GO TO 7000" when the program contains
no line numbered 7000. Those two lines should have read
"GO TO 1000". As written, the sample program would
not run successfully.

Other Considerations

I believe that any product's value is partially deter-
mined by the manufacturer's willingness to respond to
the consumer's request for aid or assistance. Nine weeks
prior to the writing of this review, I sent a letter to
MicroAce requesting answers to specific questions related
to the MicroAce and to future plans for upgrading and
expansion. That letter was never answered. This, to me,
indicates a lack of interest in serving the customer.

At the same time that the letter was sent to MicroAce,
a similar letter was sent to Sinclair Research Limited, the
company that markets the Sinclair ZX80. (The MicroAce
is essentially a kit version of Sinclair's machine and is
manufactured under a license from Sinclair Research
Limited.)

Sinclair's response to my letter left many questions
unanswered (especially in regard to future plans), but
they did say that the MicroAce operates in the same man-
ner as the ZX80. Consequently, the comments made in
this review concerning the operation of the MicroAce
would apply to the Sinclair ZX80 as well.

I was also told by Sinclair that while the unit operates
like the ZX80, it is not identical to it, and that peripherals
marketed for the ZX80 might not work with the Micro-
Ace. They did not elaborate, and, as noted above, Micro-
Ace had no comment at all.

Conclusions

The MicroAce kit is a very inexpensive introduction to
the world of microcomputers. Kit construction is easy

60 April 1981 © BYTE Publications Ire

Circle 41 on inquiry card.

Suddenly Radio Shack's New
TRS-80 Color Computer is

Even Better!

New Extended Color BASIC. Here's an advanced TRS-80
Color Computer that includes a 16K ROM Extended BASIC
with advanced graphics, eight brilliant colors, and sound, for
an unprecedented low price! You can draw fine lines, circles,
rectangles, boxes and more with easy-to-use one-line com-
mands. Four graphic modes with two color sets allow up to
49, 152 programmable screen points (pixels). There are 255
separate tones for music or sound effects. All this on a 16K
RAM machine (including video memory) loaded with the
dynamic features a serious programmer demands. You get
a 32x16 screen, multi-character variable names (two signifi-
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string arrays, floating point 9-digit accuracy, and even
machine language routines.

Priced at Only $599, the TRS-80 Extended Color BASIC
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you can add a pair of joysticks which add flexibility to games
and video displays. A built-in serial interface lets you attach
a printer or a modem. A tutorial Color BASIC instruction
manual is included, of course.

More Good News. Extended Color BASIC is also available as
an upgrade kit ($99) for the 4K Color Computer (16K RAM
required — $119). There's a modest installation charge for
each kit.

New TRS-80 VIDEOTEX Software (with the modem shown
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Only $29.95 Buys You VIDEOTEX Software including a free
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enough that beginners can tackle the project with con-
fidence, assuming that they learn correct soldering
techniques.

Proper soldering is so crucial to success that I would
advise those with no experience to purchase Heathkit's
soldering course. This course is part of Heathkit's con-
tinuing education program, and costs $15.95 plus ship-
ping. While I have not seen this particular course, I am
sure, based on my experience with their other products,
that it would be worthwhile. For further information,
write to Heath Company, Benton Harbor MI 49022.

MicroAce BASIC contains several nice features. The
use of keyword commands simplifies program entry and
reduces the amount of memory required for program
storage. Because line syntax is checked before the line is
entered into a program, fewer programming errors can
occur. This feature is especially useful for those just
learning how to use BASIC.

The machine's compact size and light weight make
storage and transportation very easy. The unit is simple

to attach to a home television set, and the cassette input
and output operations are reliable, once the proper set-
tings are found.

The largest drawback is the severely limited amount of
programmable memory. This disadvantage is most ap-
parent when you try to write any but the shortest pro-
grams utilizing a significant amount of video display. I
would strongly encourage any prospective buyer to pur-
chase the 2 K-byte version of the MicroAce. Another
drawback is that the screen is blank during active pro-
gram execution. This limits the types of possible graphic
displays, and can be somewhat annoying.

If you recognize the limitations of the machine and
don't expect too much, then I think you can buy the
MicroAce kit with confidence. It is most appropriate for
someone who wants an inexpensive unit as a teaching
tool in order to learn the fundamentals of BASIC pro-
gramming. It might also appeal to hobbyists who want to
"tinker around" with microcomputers but don't want to
risk their more expensive equipment. ■

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• Programmable function keys
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• Versatile screen attributes

• Self test

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• Buffered auxiliary port

• 14 X 10 character resolution

• Integral modem option

• Tillable screen

needs and make it your own. It has the flexibility and
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priced to make sense whether you need lO or 1 ,000.

The TeleVideo model 950 detachable keyboard CRT
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functions, even keyboard locations. And the (ISO's micro-
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Of course the 950 has premium TeleVideo perfor-
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Contact TeleVideo for a detailed brochure, or call to-
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Digital Minicassette Controller

James Kahn

2284 Ellena Dr

Santa Clara CA 95050

The microcomputer-system design-
er has had a difficult time finding
low -cost storage devices. Frequently,
the choices have been limited to either
standard Phillips audio cassettes or
floppy disks. Although these are
relatively inexpensive storage media,
the transport mechanisms, or drives,
are not. In addition to the transport,
a controller and data formatter is re-
quired to interface the transport to
the microcomputer system. The con-
troller may either be a dedicated LSI
(large-scale integration) device or be

Commonly used mass-
storage mechanisms
and associated con-
trollers are often quite
expensive.

built up discretely from SSI (small-
scale integration) logic consisting of
TTL (transistor-transistor logic) gates
and flip-flops.

Photo 1: The author's minicassette system includes an Intel iSBC 80/30 single-board
computer and a Braemar CM-600 Mini-Dek transport.

There is now another choice
besides the floppy disk and the
Phillips cassette: the digital mini-
cassette. Not only is the storage
medium inexpensive, so is the
transport (about $140, versus $400
for a floppy-disk drive). As a bonus,
the transport is extremely compact
(only 23 cubic inches) and requires lit-
tle power (1 watt). This makes it
suitable for a wide range of low-end
applications ranging from experimen-
tal systems to data logging for test in-
strumentation.

There is one problem with designs
using a minicassette: controlling it.
There are several choices for the
transport controller. One choice is to
design a controller of discrete SSI
logic. Although this choice will pro-
vide good performance, it requires a
handful of discrete components. The
SSI controller will use much circuit-
board space, compromising the ad-
vantage of a compact transport. A
better design would use a minimal
number of components and take ad-
vantage of current LSI technology.

One such controller-design solu-
tion is to use the Intel 8255A Pro-
grammable Peripheral Interface IC
(integrated circuit) to interface the
transport to a microcomputer system.
Although this design provides a sim-
ple solution to the problem, the pro-
cessor would be burdened with pro-
viding the low-level control needed
by the transport, in addition to sup-
porting its normal real-time I/O (in-
put/output) tasks. Examples of these
low-level tasks are transport start-up,
data formatting, and transport shut-
down.

There is, however, a better LSI
solution available: distribute the
system intelligence from the micro-

66 April 1981 © BYTE Publications Inc

The best news since CP/M ...
customizable full screen editing

As a serious computer user you spend much of
your time editing, whether it be for program development
or word processing. Make the best use of your time with
the help of VEDIT, an exceptionally fast and easy to use full
screen editor. VEDIT is a highly refined and proven editor
which is easy enough for novices to leam and use. Yet its
unequalled set of features also makes it the choice of
computer professionals. And because VEDIT is user
customizable, it adapts to your keyboard, hardware,
applications and preferences.

In VEDIT, the screen continuously displays the
region of the file being edited, a status line and cursor.
Changes are made by first moving the cursor to the text
you wish to change. You can then overtype, insert any
amount of new text or hit a function key. These changes
are immediately reflected on the screen and become the
changes to the file.

VEDIT has the features you need, including
searching, file handling, text move and macros, plus it has
many special features. Like an 'UNDO' key which undoes
the changes you mistakenly made to a screen line. And a
mode which allows a programmer to enter all text in lower
case and let VEDIT convert the labels, opcodes and
operands, but not the comments, to upper case. The
screen writing is almost instantaneous on a memory
mapped display or can use your CRT terminal's editing
capabilities. Disk access is very fast too, and VEDIT uses
less than 12K of memory. The extensive 70 page, clearly
written manual has sections for both the beginning and
experienced user.

Totally User Customizable

Included is a setup program which allows you to
easily customize many parameters in VEDIT, including

the keyboard layout for all cursor and function keys,
screen size (up to 70 lines, 200 columns), default tab
positions, scrolling methods and much more. This setup
program requires no programming knowledge or
'patches', but simply prompts you to press a key or enter a
parameter.

The CRT version supports all terminals by allowing
you to select during setup which terminal VEDIT will run
on. Features such as line insert and delete, reverse scroll
and reverse video are used on 'smart' terminals. Special
function keys on terminals such as the HI 9, Televideo
920C and IBM 3101, and keyboards producing 8 bit
codes or escape sequences are also supported.

New Features and Support

The new release includes disk write error recovery,
indent and undent keys for structured programming, and
the ability to insert a specified line range of another file at
the cursor position. Versions for MP/M and the Apple II R
SoftCard R are now also available.

Ordering

Specify the CRT version, your video board or
microcomputer, the 8080/Z80 or Z80 code version, and
disk format required.

Standard Package: Disk and manual $110

Manual: Price refunded with software purchase 15

VISA and MASTER CARD Welcomed.
Attractive Dealer Terms.

CP/M and MP/M are registered trademarks of Digital
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Computer, Inc. SoftCard is a trademark of Microsoft.

North Star • Heath H8/H89
TRS-80 Model II • MP/M

• SuperBrain • Apple II SoftCard • Sorcerer • TRS-80 Model I
• Most other CP/M R Systems with CRT or Memory Mapped Displays

CompuView Products Inc.

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Circle 45 on inquiry card.

BYTE April 1981 67

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processor to its peripheral devices by
using an intelligent peripheral con-
troller to carry the burden of low-
level peripheral interface re-
quirements. The processor now inter-
faces at a higher level, issuing the ap-
propriate command to the controller
and transferring the data to and from
the controller in response to its I/O
requests.

The controller provides a buffer
between the processor and the
transport. For example, the cassette
transport expects data in a serial for-
mat, while the microprocessor is
designed for handling data in either
8-bit words or 16-bit words. The con-
troller performs data conversion from
serial to parallel and buffers the data.
This buffering is necessary to com-
pensate for the I/O-service latency
caused by other time-critical tasks
handled by the microprocessor (ie:
the data is held until the computer
can devote itself to the controller). As
a direct result, the system's work load
is reduced, allowing it to utilize this
savings in time to support other
tasks, yielding a higher-performance
microprocessor system.

Applying this to the minicassette
design, we look through the available
literature for dedicated single-device
cassette controllers. Unfortunately,
there are no devices of this caliber for
minicassettes. There is, however,
another solution: use the Intel UPI-41
Universal Peripheral Interface (UPI)
integrated circuit. Two versions are
available; we can use one of them, the
8741A, and design software, custom-
izing it to control the minicassette
transport.

The 8741A, shown in figure 1, is a
complete, single-chip microcomputer
containing 1024 bytes of EPROM
(erasable programmable read-only
memory), 64 bytes of programmable
memory, 18 programmable I/O lines
(providing a direct interface to the
peripheral device), and a timer/event
counter with an 8-bit prescaler for
real-time I/O. In addition, it contains
a complete slave-microprocessor bus
interface, including both interrupt
and direct-memory-access capabili-
ties. A pin- and function-compatible
factory-mask ROM (ie: programmed
only at the factory) version of the
UPI-41, the 8041A, is also available.

The 8243 I/O-port expander com-
pletes the system and interfaces
directly to the I/O port of either of

68 April 1981 © BYTE Publications Inc

Circle 46 on inquiry card.

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STATUS

REGISTER

IB

I/O LINES

r

r

«

ERA

>

rEM

SYS -

BUS

PERIPh

L BUS

Figure 1: Internal block diagram of the 8741A/8041A Universal Peripheral Interface.
I/O lines can be programmed as inputs or outputs; 8041A control-program memory
must be factory programmed; 8741A memory is user-programmed.

the two slave microcomputers. Each
8243 provides 16 programmable,
bidirectional I/O lines.

Using the 8741A allows the design-
er to develop a custom peripheral in-
terface for particular I/O problems.
These devices have found applica-
tions in such diverse areas as
character-printer control, data en-
cryption, keyboard control, and in-
telligent displays. Developing an
8741 A design is straightforward. The

designer develops a control algorithm
using the UPI-41A cross assembler
and programs the on-board EPROM
of the 8741 A. Testing may be ac-
complished using either an ICE-41A
in-circuit emulator or the single-step
mode of the 8741 A.

The Hardware

The complete microcomputer
system is shown in photo 1, including
the CM-600 minicassette transport.

The microcomputer system for this
design consists of an Intel iSBC 80/30
single-board computer. It supports an
8085A microprocessor, 8 K bytes of
EPROM, and 16 K bytes of program-
mable memory. In addition to an
8255A parallel interface and an
8251 A serial interface, it contains a
Multibus system bus connector
allowing expansion beyond the
board's local resources. Incidentally,
there is an 8741A socket built into the
board as well.

Let us examine the microcomputer-
to-8741A hardware interface. The
computer sees the 8741A as three
registers in its I/O address space: the
data register, the command register,
and the status register. The decoding
of these registers is shown in figure 2.
Within the 8741A, both the data and
commands are written into the same
physical register, the Data Bus Buffer
Input register (DBBIN). The state of
the register-select input, Ao, deter-
mines whether a command or data
has been written (Ao = for data). All
output to the microprocessor is read
from the Data Bus Buffer Output
register (DBBOUT).

The status register is composed of 4
software-programmable bits and 4
reserved bits reflecting the state of the
8741A slave microcomputer (see
figure 3 on page 78). The Input Buffer
Full (IBF) bit and Output Buffer Full
(OBF) bit reflect the state of the
DBBIN and DBBOUT registers,
respectively. Flag (F ) and Flag 1 (Fi)
can be set and complemented via the

LET YOUR APPLE SEE THE WORLD!

The DS-65 Digisector® is a random access video digitizer
which converts a TV camera's output into digital infor-
mation the Apple can process. It features 256 X 256
resolution with up to 64 levels of grey scale.
Scanning sequences are user programmable.
On-board software in EPROM is provided for
displaying digitized images on the Hi-Res
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Use the DS-65 for: Precision Security Systems
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70 April 1981 © BYTE Publications Inc

Circle 47 on inquiry card.

The Perfect Fit

The Micromodem II data communications system
and the Apple II* computer. What better combination to
maximize the capabilities of your personal computer!

This popular direct connect modem can transmit
data between an Apple II and another Apple II, a
terminal, another microcomputer, minicomputer or
even a large time-sharing computer anywhere in North
America. The Micromodem II has unique automatic
dialing and answer capabilities which further increases
the communications possibilities between the Apple II
and another computer or terminal.

You can send and/or receive messages or data
when you are out of your office, home or out of town.
Your branch business locations can communicate with
each other regarding inventory and other matters over
the phone. Or you can communicate with friends
across the country. And you can access information
utilities like the SOURCE for various business and
personal applications.

The Micromodem II consists of two parts. One part
includes the printed circuit board which holds the
Micromodem II, ROM firmware and the serial interface.
The board plugs directly into the Apple II providing all
the functions of a serial interface card plus
programmable auto dialing and auto answer
capabilities. The on-board ROM firmware enables the
Micromodem II to operate in any of three modes to
perform different tasks-terminal mode, remote console
and program control mode.

The other part of the Micromodem lldatacomm
system is a Microcoupler which connects the
Micromodem board and Apple II to a telephone line.
The Microcoupler gets a dial tone, dials numbers,
answers the phone and hangs up when a transmission
is over. There are none of the losses or distortions
associated with acoustic couplers. The Microcoupler is
compatible with any North American standard
telephone lines and is FCC-approved for direct
connection in the U.S. It works with standard dial
phone service or Touch-tone service.

The Micromodem II is completely compatible with
Bell 103-type modems. Full and half-duplex operating
modes are available as well as speed selectable
transmission rates of 1 1 and 300 bps.

Why not increase your Apple ll's capabilities by
outfitting it with the sophisticated Micromodem II data
communications system? The Micromodem II is
available at retail computer stores nationwide. For the
store nearest you, call or write:

fflHayes

Circle 48 on inquiry card.

Hayes Microcomputer Products Inc.

5835 Peachtree Corners East, Norcross, Georgia 30092 (404) 449-8791

™ Micromodem II is a trademark of Hayes Microcomputer Products, Inc.

* Apple II is a registered trademark of Apple Computer Inc.

The Micromodem II can also be used with the Bell & Howell computer.

internal software. The remaining 4
bits are used to indicate the status of
the transport.

The TTL-compatible I/O lines of
the 8741A provide an uncomplicated
interface to the CM-600 Mini-Dek
minicassette transport (Mini-Dek is a
registered trademark of Braemar
Computer Devices Inc). The I/O lines
can be divided into three groups:
motor control, data control, and
cassette status. These I/O port lines
are shown in the 8741A interface
schematic in figure 4 on page 78. The
motor-group controls are go/stop,
fast/slow, and forward /reverse. The
data controls are read/write, data-in,
and data-out. The remaining group of
outputs reflects the CM-600's status:
clear leader, cassette present, file pro-
tected, and cassette side.

The Braemar CM-600 Mini-Dek
transport is representative of digital
minicassette transports. The
transport is compact, requiring only 3
by 3 by 2Vi inches for mounting. It
has a single read/write head and uses
only one drive motor. Operating
from a 5 V supply, it has modest
power-supply requirements, needing
only 200 mA during a read or write.

Tape speeds are 3 ips (inches per sec-
ond) during read/write, 5 ips for fast
forward, and 15 ips during rewind.
Calculating the data-transfer rate
based on the read/write speed and the
maximum recording density of 800
bpi (bits per inch) yields a maximum
data-transfer rate of 2400 bps (bits
per second). A more useful represen-
tation illustrating the significance of
this number is obtained by inverting
it. This yields the bit-cell period: 416
/as. This control requirement is easily
met by the 8741A, its timer having a
minimum resolution of 80 fis. If finer
resolution were required, software-
timing loops would have to be used.
The maximum resolution is limited to
the instruction-cycle time of the
8741 A, 2.5 /is, necessary for transfer
rates of 8000 bps.

Recording Format

Since the CM-600 does not provide
any data formatting, the 8741A must
perform this additional low-level
task. A multitude of encoding tech-
niques are available from which the
user may choose [ie: NRZ1 (Non-
return to Zero, change if 1), Phase,
GCR (Group Code Recording)]. For

Introducing. . .

MINI-FLEX

Designed Specifically

W^tt

Ah

The Newest
Member of The
Advance Access

Diskette
Protection Family

For Further Information

CALL TOLL FREE

800-323-3412

ADVANCE ACCESS GROUP

2200 S. Main St., Lombard, IL 60148 312-629-5800
"Manufacturers of Information Processing Supplies"

this application, a "self-clocking"
phase-encoding scheme similar to
that used in floppy disks was selected.
Phase encoding provides easy en-
coding and decoding of the serial
data, embedding the timing informa-
tion and data bits together in the
recorded bit cells on the tape. This is
an effective means of compensating
for speed variations of the drive.
Reading the data is accomplished by
using the clocking information of the
bit cell to synchronize the sampling of
the data bit coming from the
transport.

Figure 5 on page 78 illustrates this
encoding technique as applied to the
hexadecimal character 3A (all
characters referenced in this article
are hexadecimal). Notice that each bit
cell begins with a transition to a logic
level opposite the level of the preced-
ing bit-cell level. Decoding the data is
simply a matter of starting a timer on
this "clocking" transition of the cell,
waiting 3/4 of a bit-cell period, and
determining whether a mid-cell tran-
sition occurred. Cells with no mid-
cell transitions are 0s; cells with tran-
sitions are Is. Besides the encoding
Text continued on page 80

8741A

WR
RD
CS
A0

DATA
BUS

c

STATUS
REGISTER

\ DATA BUS
J INPUT REGISTE

DATA BUS
OUTPUT REGISTER

CS

RD

WR

A

REGISTER

1

DBBOUT

1

1

STATUS

1

DBBIN (DATA)

1

1

DBBIN (COMMAND)

1

X

X

X

NONE

72 April 1981 © BYTE Publications Inc

Circle 49 on inquiry card.

Figure 2: 8741A system-bus interface and
register decoding as seen by the host pro-
cessor.

Circle 50 on inquiry card. >

First compare quality.
Then compare cost.

Morrow Designs 9 10 megabyte
hard disk system: $3,695.

MORE MEMORY. LESS MONEY.

Compare Morrow Designs' DISCUS
M26™ hard disk systems
to any system available
for S-100 or Cromemco
machines. First, compare
features. Then, com-
pare cost per mega-
byte. The M26 works
out to under $200 a
megabyte. And the M10 is
about half the cost of com
peting systems.

COMPLETE SUBSYSTEMS.

Both the M10 (8"), and the M26
(14"), are delivered complete with
disk controller, cables, fan, power sup-
ply, cabinet and CP/M® operating
system. It's your choice: 10 Mb 8"
at $3,695 or 26 Mb 14" at $4,995.
That's single unit. Quantity prices are
available.

BUILD TO FOUR DRIVES.

104 Megabytes with the M26. 40+
megabytes with the M10. Formatted.
Additional drives: M26: $4,495.
M10: $3,195. Quantity discounts
available.

S-100, CROMEMCO
AND NORTH STAR?

The M26 and M10 are sealed-media
hard disk drives. Both S-100 controllers
incorporate intelligence to super-
vise all data transfers through four I/O
ports (command, 2 status and data).
Transfers between drives and control-
lers are transparent to the CPU. The
controller can also generate interrupts
at the completion of each command
. . . materially increasing system through-
put. Sectors are individually
write-protectable for multi
use environments. North
Star or Cromemco?
Call Micro Mike's,
Amarillo, TX,
(806) 372-3633
for the software
package that allows
theM26and MIOtorun
on North Star DOS. MICAH of

Morrow Designs'
26 megabyte
hard disk system:
$4,995.

Sausalito, CA, (415) 332-4443,
offers a CP/M expanded to full
Cromemco CDOS compatibility.

AND NOW, MULT-I/O.™

Mult-I/O is an I/O controller that allows
multi-terminal and multi-purpose
use of S-1 00 and Cromemco computers.
Three serial and two parallel output
ports. Real time clock. Fully program-
mable interrupt controller. Designed
with daisy-wheel printers in mind.
Price: $299 (kit), $349 assembled
and tested.

MAKE HARD COMPARISONS.

You'll find that Morrow Designs' hard
disk systems offer the best price/
performance ratios available for S-100,
Cromemco and North Star compu-
ters. See the M26 and M10 hard disk
subsystems at your computer dealer.
Or, write Morrow Designs. Need infor-
mation fast? Call us at (415) 524-2101.

Look to Morrow
for answers.

MORROW DESIGNS

•CP/M is a trademark of Digital Research Corp.
'Cromemco is a trademark of Cromemco, Inc.
North Star is a trademark of North Star Computers, Inc.

5221 Central Avenue
Richmond. CA 94804

PRINTERS

ANADEX DP-9500 W/2K DUFFER, 1375

ANADEX DP-9501 W/2K DUFFER 1450

DASE 2 800-D 599

C. ITOH STARWRITER 25 CP5 1750

C. ITOH STARWRITER 45 CP5 2450

A. CENTRONICS 707 625

EPSON MX-70 W/GRAPHICS 449

D. EPSON MX-80 132 col .620

PAPER TIGER IDS-445 W/DOT PLOT 749

C. PAPER TIGER IDS-460 W/DOT PLOT '. . 1 1 95

PAPER TIGER IDS-560 W/DOT PLOT 1495

D. QUME SPRINT 5/45 2550

SILENTYPE W/INTERFACE 549

b.

Tpriilii

j£i

SYSTEMS

A. APPLE II PLUS 1 6K 1 049

APPLE II PLUS 46K (APPLE Memory) 1 1 69

APPLE II STANDARD MODELS CALL

These are the newest models with FCC type
approval to prevent RF interference.

D. DISK II DRIVE & CONTROLLER 529

This model includes DOS 3.3 i6 sector

DISK II DRIVE ONLY (ADD-ON) 445

C. CHALLENGER 4P by OHIO SCIENTIFIC 699

C4PMF (MINI FLOPPY SYSTEM) 1 599

OP MODEL II 449

SARGON II (DISK OR CASSETTE) 35

FIG FORTH (DISK ONLY) 69

D. PMC-60 THE TRS-80 WORKALIKE' 629

16K LEVEL II W/PROGRAM RECORDER,
CALL OR WRITE FOR MORE INFORMATION

E. EXIDY SORCERER II CALL

AVAILABLE IN 16K, 32K & 48K MODELS

5-100 EXPANSION UNIT 375

WORD PROCESSING PAC 1 79

DEVELOPMENT PAC 89

F. ATARI 800 1 6K 799

ATARI 400 16K 499

810 DISK DRIVE 499

41 PROGRAM RECORDER 69

850 INTERFACE MODULE 175

VIDEO MONITORS

k. AMDEX/LEEDEX VIDEO-100 12" DGW 139

HITACHI 1 3" COLOR 389

i. NEC 12" P31 GREEN PHOSPHER CALL

PANACOLOR 1 0" COLOR 375

SANYO 9" D&W 179

:. SANYO 1 2" D&W 255

SANYO 1 2" P31 GREEN PHOSPHER 295

SANYO 1 3" COLOR 445

SHOPPING MAIL ORDER? CALL US TODAY!

We probably have what your' re looking for in stock ot an incredible price. Our company is an authorized dealer for sales and service for Apple Computer.
Atari and Ohio Scientific, if you receive a defective product from us we will repair or replace (at our option) any product in warranty, Our Service Center
will repair all Apple Computer products, in or out of warranty, whether it was purchased from us or another dealer, (call for more details)

PHONE ORDERS IN CALIFORNIA, ALASKA, HAWAII & FOREIGN (714)698-8086
SHIPPING INFORMATION OR DACKORDERS PLEASE CALL (71 4)696-0260

SERVICE CENTER AND FOR TECHNICAL INFORMATION (714)460-6502

74 BYTE April 1981

Circle 51 on Inquiry card.

Order Dept.

Open Every Day

9a.m. - 6 p.m.

P.5.T.

TOLL FREE ORDER LINE

600-854-6654

We honor these cords

AMERICAN] .

<•>

APPLE HARDWARE Y APPLE SOFTWARE

TOP FIVE SELLERS

LANGUAGE SYSTEM W/PASCAL. ... 425
SILENTYPE PRINTER W/INTERFACE. 549

HAYES MICROMODEM II 319

VIDEX VIDEOTERM 80 w/graphics. 335
Z-80 MICROSOFT CARD 299

APPLE COMPUTER INC.

DISK II DRIVE ONLY 445

INTEGER OR APPLESOFT II FIRMWARE CARD 155

GRAPHICS TABLET 649

PARALLEL PRINTER INTERFACE CARD 155

HI-SPEED SERIAL INTERFACE CARD 155

COMMUNICATIONS INTERFACE CARD 185

SMARTERM 80 COLUMN VIDEO CARD 335

MOUNTAIN COMPUTER INC.

MUSIC SYSTEM (16 Voices) 479

A/D + D/A INTERFACE 319

EXPANSION CHASSIS 555

INTROL/X-10 SYSTEM 249

CLOCK/CALENDAR CARD 239

SUPERTALKER SD-200 249

ROMPLU5 + CARD 135

ROMWRITER CARD 155

CALIFORNIA COMPUTER SYSTEMS

CLOCK/CALENDAR MODULE 1 09

GPID IEEE-488 CARD 259

ASYNCHRONOUS SERIAL INTERFACE CARD 1 29

CENTRONICS PARALLEL INTERFACE CARD 99

We carry all CCS hardware. Please call

MISC. APPLE HARDWARE

16K RAM UPGRADE (Apple, TRS-80. Exidy) 189

1 6K RAM CARD MICROSOFT 1 89

ACT NUMERIC KEYPAD (old or new kybrd) 115

ADT BAR CODE READER WAND 179

ALF 3 VOICE MUSIC CARD 229

ALF 9 VOICE MUSIC CARD 1 69

ALPHA SYNTAURI KEYBOARD SYSTEM 1 399

BIT 3 FULL VIEW 80 CARD 349

CAT NOVATION ACOUSTIC MODEM 1 69

CORVUS 1 0MB HARD DISK CALL

LAZER LOWER CASt PLUS 50

MICRO-SCI DISK DRIVES CALL

PAYMAR LOWER CASE (old or new Kybrd) 55

RADCOM AMATEUR RADIO INTERFACE CARD 189

SPEECHLINK 2000 HEURISTICS 229

SSM AIO SERIAL/PARALLEL CARD A&T 1 89

SUP-R-TERMINAL 80 COL. CARD 339

SVA 6 INCH FLOPPY DISK CONTROLLER 345

VERSAWRITER DIGITIZER PAD 229

VIDEX KEYBOARD ENHANCER 115

We stock much more than listed. Please call.

APPLE COMPUTER INC.

DOS TOOLKIT 65

APPLEPLOT 60

TAX PLANNER 99

APPLE WRITER 65

APPLE POST 45

DOW JONES PORTFOLIO EVALUATOR 45

DOW JONES NEWS G QUOTES REPORTER 85

APPLE FORTRAN 165

APPLE PILOT 129

DOS 3.3 UPGRADE 49

MUSIC THEORY 45

THE CASHIER Retail Mngmnt & Inv 1 99

THE CONTROLLER Gen. Bus. Sys 519

MISC APPLICATIONS PACKAGES

VISICALC 125

DESKTOP PLAN II 1 69

CCA DATA MANAGMENT DMS 85

EA5YWRITER WORD PROCESSOR 225

EA5YMOVER MAIL SYSTEM 225

EASYMAILER LETTER WRITER 225

ASCII EXPRESS 65

MICROSOFT FORTRAN 185

MICROSOFT COBOL 695

MICROSOFT BASIC COMPILER 375

SUPER TEXT II 139

PROGRAMMA APPLE PIE 119

THE LANDLORD Apt Mngmnt package 649

PEACHTREE BUSINESS SOFTWARE CALL

TAX PREPARER by HowardSoft 89

APPLEBUG ASSEM/DISASSM/EDITOR 75

3-D GRAPHICS By Bill Budge 53

SUPER FORTH 49

TOP TEN GAMES

APPLE GALAXIAN 23

FLIGHT SIMULATOR 34

THE WIZARD AND THE PRINCESS 32

COSMOS MISSION (SPACE INVADERS) 24

SARGON II CHESS 32

HI-RES FOOTBALL 39

COMPUTER QUARTERBACK 39

ADVENTURE BY MICROSOFT 27

PHANTOMS FIVE 39

REVERSAL (OTHELLO) 34

CALL OR WRITE

FOR A COMPLETE

SOFTWARE LIST

ORDERING INFORMATION, Phone Orders invited using VISA MASTERCARD AMERICAN EXPRESS DINERS CLUB CARTE BLANCHE or bonk wire transfer Credit
cords subject to service chorge 2% for VISA (j MC 5% for AE DC 6 CB Moil Orders may send credit card account number (include expiration date)
cashiers or certified check money order or personal check (ollow 10 days to dear) Pease include o telephone number with oil orders Foreign orders (excluding
Military PO s) odd 1 0% for shipping all funds must be m US dollars Shipping handling and insurance m U S odd 3% (minimum $4 00). California
residents add 6% sales tax We accept COD s under S500 OEMs Institutions Corporations please send for written quotation AH equipment is subject to
price change ond availability without notice All equipment is new and complete with manufacturer warranty (usually 90 days) We cannot guarantee
merchannbility of any produces We ship most orders withm 2 days

WE ARE A MEMDER OF THE DETTER BUSINESS BUREAU AND THE CHAMDER OF COMMERCE
SHOWROOM PRICES MAY DIFFER FROM MAIL ORDER PRICES.
PLEASE SEND ORDERS TO:
CONSUMER COMPUTERS MAIL ORDER 8014 PARKWAY DRIVE, GROS5MONT SHOPPING CENTER NORTH LA MESA CALIF. 92041

Circle 51 on inquiry card.

10 DAY FREE RETURN

NEC THE FIKST NAME IN LETTER
QUALITY PRINTERS.

CompuMart ofleis beautiful print
quality with NEC Spinwriter ter-
minals. Both KSR and RO versions
give unsurpassed hard copy out-
put CALL

CENTRONICS PRINTERS

The incredible Model 737. The
closest thing to letter quality print
tor under SLOOO.
737-1 (Parallel Interlace)— $899.

NEW FROM INTEGRAL DATA-
THE IDS 560 PRINTER. 132

column graphics printer.
$1,695

IDS 445. Priced lower
than the 440 and equipped
with a better print head. IDS
445 w/graphics $894. IDS 445
w/o graphics $795.

IDS 460 $1,295

The 460s features include Corre-
spondence quality printing, high
resolution graphics capability,
programmable print justification

Dysan Diskettes— Single side.

Single density, Hard or Soft Sector

$5. ea

Memoiex 3401's— 5 Vt discs

$3.25 with hub ring lor Apple

$3.50.

Memory Integrated Circuits—
Call tor qty. discounts when
ordering over 50 units.
Motorola 4116 (2CO Nanosecond
Plastic) $4.50 ea
Faircliild 2114 (Standard Power,
Plastic) $450 ea

Super Selling Terminals

We have the following Lear
Siegler Terminals in stock at
prices too low to print— Call for
quotes

ADM— 3A Indus-
tries favorite
dumb terminal
for some very
smart reasons.
ADM— 3A +
NEW from Lear
Siegler. CALL!
IT IS HEREI-It
is the new
Intermediate Terminal
from Lear Siegler. Call lor details.

Omni Printers
from Texas
Instruments

The 810-List $1895. SALE! $1795.
The 820 (Ro) Package-
Includes machine-mounted
paper tray and cable. A com-
pressed print option and device
forms control are standard fea-
tures $2,155.

The 820 (KSR) Package-
Includes full ASCII Keyboard plus
all of the features of the RO
$2395.

COMPUMART stocks the com-
plete line of MATROX PRODUCTS.
Call for specs

COMPUMART now offers the
ENTIRE DEC LSI-11 PRODUCT LINE.
Call tor prices 8t delivery.

NOVATION CAT 1 ™
ACOUSTIC MODEM

Answer Originate. 3CO Baud, Bell

108, Low Profile Design $179.00

NEW! D-CAT

Direct Coupler from Novation

$199.

We bare the following best-
selling Hazeltine terminals in
stock at prices much too low to
print

(1410. 1420, 1500, 1520, 1552)
Call COMPUMART Now for our
lowest prices ever.

HP-41C Calculator $239.00

Memory Modules. For storing
programs or up to 2.000 lines ol
program memory $29.95

"Extra Smart" Card Reader.
Records programs and data
back onto blank magcards. t
$199.00

The Printer. Upper and Lower
case. High resolution plot-
ting. Portable Thermal

operation $355.00

Application Modules

$29.95

NEW SUPER 41-C Systems with
Quad RAMS built-in (Maximum
memory onboard leaves slots
open for Application Pacs and
peripherals. The HP 41C C$325.00
HP 41C-C Plus Card Reader

$495.00
HP 41C-C Plus Card
Reader 8c Printer $845.00/
Quad RAMS for the 41-C <
(Equivalent to lour
Memory Modules^
all packed
into one)
$95.00

COMPUMARTs Microflex 65 Sys-
tem lor your AIM Includes
Adapter Buffer Module w/4-slot
module stack. 8K RAM module,
16K PROM/ROM module. Asyn-
chronous communications Inter-
face, and Power Supply $1,299
Call or write lor our complete
Microflex 65 brochure

NEW IN STOCK: The PMC-80. The

new computer that's software
compatible with the TRS-80.
Level II 16K at $645.

ACCESSORIES FOR PMC-80
EXP-lOO S-lOO Bus Expander
Disk Printer, RS232 I/O $410.

S-32K S-lOO Bus 32K RAM Board

tor EXP-lOO $295

CAB-40 Cable 12 " long ribbon
cable

lor EXP-lOO $25.

Visit our giant

ANN ARBOR
STORE

1250 North Main Street
Ann Arbor, Michigan

ROCKWELL AIM 65

Our AIM system includes 4K AM
with BASIC interpreter assembler,
Power Supply, Cassette recorder
8c Enclosure $799.

4K AIM-65 $499.

PL65 High Level Language $125.
Paper lor the AIM (roll) $2.50
Rockwell's 4-slot

Motherboard (sale) $175.

Fourth lor Rockwell AIM 65 $175.

SEND FOR OUR
FREE CATALOG

EXCLUSIVE from COMPUMART!
Special Oiler. Zenith Color
Video Monitor for $379!

NEW FROM SANYO-Four Great

Monitors at Low COMPUMART
Prices Sanyo's new line ol CRT
data display monitors are
designed tor the display ol
alphanumeric or graphic data.

9 " Sanyo Monitor $169.

12 " Sanyo Monitor $289.

12 " Sanyo Monitor with green

screen $299.

13 " Sanyo Color Display Monitor

$495.

HP-35— Hewlett-Packard's Per-
sonal Computer for Industry. This
extremely portable computer
features extended BASIC to solve
your problems quickly and effi-
ciently along with an advanced
graphics system to enhance
communication

HP-85 ACCESSORIES— We carry
HP. Peripherals (Disk Drives to
Graphics Plotters) Enhancements
(BASIC Training. General Statis-
tics. Financial Decision Math. Lin-
ear Programming $95 ea). HP-85
Accessories; (Enhancement
ROMs ROM drawer. Overhead
Transparency Kit).- Supplies (Plot-
ter Pens, Tape Cartridges), Inter-
face Modules (HP-IB Interface,
HP-IB Interconnect Cables, Serial
(RS-232C) Interlace Module).
We can get your every HP
peripheral made tor the HP-85.

VBICALC PLUS FOR HP-85 Every
thing you ever wanted from Visi-
calc plus plotting. $200.

HP83 VIRGO Has the same com-
puting power as the HP85 with-
out the added cost of tape drive
and printer, for use with disc
drives and optional printer/
plotter accessories.
CALL FOR COMPLETE DETAILS 8c
SPECS.

COMPUMART exclusive ATARI

SPECIALS— ATARI 8CO Personal

Computer System— Comes with

8CO operators Manual 16K Rany

Memory module, lOk ROM

Operating System Power,

Supply, TV

Switch

Box

$950.

PERIPHERALS

Atari 410 Program Recorder

$89.95

Atari 810 Disk Drive

(SlOO off with purchase) $699.95

NEW Dual Disk double density

$1499.95
825 Printer (Centronics 737)

S995.00
RS232 Interface w/Cable $249.95
NEW! Light Pens $74.95

NEW! Visicalc for Atari $199.00
Educators Take Note. Atari has
extended its 3 for 2 deal until 6-
30-8L Any educational institution
that buys two Atari 800s will
receive an Atari 400 computer
absolutely FREE. Call our sales
dept tor complete details.

TMPOKTANT ORDEBDJG INFORMATION All Orders must include 4%
shipping and handling. Mass. residents add 5% sales tax. Michigan
residents 4% tor sales tax Phones open trom 830 a.m. to 700 p.m..
Mon-Fri. 11:00 am. to 400 p.m. Sat P.O.'s accepted from Dun &
Biadstreet rated companies— shipment contingent upon receipt ol

signed purchase order. Sale prices valid tor month ol magazine
date only— all prices subject to change without notice. Our Ann
Arbor retail store is open 1LOO a.m. to 7,00 p.m. Tues-Fri, lOOO a.m.
lo 5,00 p.m. Saturdays.

apple n

We cany the most complete
inventory ol Apple computers,
peripherals, and software. CALL!
Our Best Selling Apple System.
Save over S250 on our most pop-
ular Apple System. System
includes a 48K Apple n. Apple
Disk. DOS3.3. & Controller, and a
Sup R. Mod RF Modulator.
List $2209.

COMPUMART Sale Price: $1895.

SOFTWARE FROM APPLE

Apple Plot The perfect graphic

complement for Visicalc. S70

Dow Jones News & Quotes $95

Adventure (Uses 48K) $35

DOS Tool Kit $75

Apple Fortran $200

Tax Planner $120

FROM PERSONAL software

Visicalc $149

Desk Top Plan $99
NEW FROM MUSE

The Voice $39.95

Super Text $150

Address Book $49.95

Miscellaneous Apple n
Accessories:

Easy Writer (80 col need a
Videx) $249

Easy Mover $49

Easy Mailer $69

NEW from Apple lor the Apple

DOS 3.3 Convert disks to 16 sector
format for 23% more storage and
faster access $60.

NEW lor the Apple n

From Microsoft

16K RAM Board

$195.00

FORTRAN

$175.00

COBOL

$750.00

Card Reader from Mountain

Hardware

$1,195.00

H-Res Dump for 460 Printer from

the Computer Station

$49.95

HARDWARE ACCESSORIES FOR
APPLE

Silentype Printer w/x face $635
Super Sound Generator (mono)
$159 (stereo) $259
Light Pen $249
X-IO Controller (plugs into pad-
dle port) $49
Mountain Computer— Expan-
sion accessories for your Apple
Introl-lO System $289
Super Talker $299
The Music System $545
ROM plus board w/Keyboard
filter $199
Clock Calendar $280
16 Channel A to D Converter
$35Q

Apple Expansion Chassis $650
ROM Writer $175

From VIDEX!— Video Term.

80 Cot x 24 line. 7x9 Matrix plug
in compatible board for the
Apple n. Price $325 without
graphics EPROM. With graphics
EPROM $350.

S.S.M Serial & Parallel Apple
Interface $225

ABTs Numeric Key Plan $UO
California Microcomputer
Keyboard $195

Apple m is in stock— CALL!

Commodore Strikes Back!

CompuMart carries the entire Commodore line ol computers,
peripherals, and accessories— call our sales force today for
complete prices and specs

The CompuMart/ Commodore
Word Processing System

Get crisp, letter quality output
and ease of operation that's
unsurpassed. This system
includes a Commodore 8032 32K
CPU. a 4040 Dual Disk, a C-Itoh
printer and X/face. and Word
Pro 4 Plus (all cables included).
Call (or details and low prices.
List S5685. COMPUMART $4995.

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List S3.985. CompuMart $3635

New accessories irom
Commodore lor Commodore
Visicalc $199
Word Pro 4 $299

Ozz the Information Wizard $395
Wordcralt 80 $395
Tax Preparation Planner $495
Dow Jones Portfolio Manage-
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Personal Tax Calculator $69
PASCAL Development Packaae
$295

Assembler Development
Fackage $99

Educators Take Note!! Commo-
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until 6-30-81.

Complete Word
Processing System
for Under $5,000!

COMPUMART has been serving the
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We stock, for immediate shipment, only
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And any product, except software, can
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' 65 BENT STREET, DEPT. 115, P.O. BOX 568
'CAMBRIDGE, MA 02139

Circle 52 on inquiry card.

The joy of music —

without years of practice!

ALF offers the very finest in music
hardware and software for the
Apple® II. You can enter your own
songs from sheet music and play
them back very easily — our de-
tailed manual shows you how, step
by step. And there's a growing
library of preprogrammed songs
available too — now over 115 songs
on 7 "albums", priced under $15
each. ALF's highly acclaimed music
software has many features found
on no other Apple music product —
and no customer has ever reported a
"bug" or error.

Whether you pick our exciting
9-voice MCI music card at just
$195, or our gourmet 3-voice MC16
card at $245, you'll get ALF's top-
quality hardware that's famous for
reliability and clean sound (we've
been designing computer-controlled
musical instruments since 1975).

So see your Apple dealer today, and
be sure to specify ALF music cards
for the best performance. When
you've seen ALF's total music
package, you'll know why some
music cards are more equal than
others!

Please mention this magazine when
requesting information from:

<3|\ A L F Products Inc.

^1/ 1448 Estes Denver, CO 80215 (303) 234-0871
Apple is a trademark of Apple Computer Inc.

EAR TRAINING

Four programs (pitch discrimination,
interval recognition, chord recognition,
and scale recognition) for the ALF MC16
music card (described above) are
available on disk (or cassette). Under
$50 for the set, see your local Apple
dealer.

For more information write:

ALF Products Inc.

1448 Estes Denver, CO 80215
(303) 234-0871

STATUS REGISTER

0BF - OUTPUT BUFFER FULL
■ IBF - INPUT BUFFER FULL
•F - FLAG (USER DEFINED)
• Fj - FLAG 1 (USER DEFINED)

- DRIVE ACTIVE
-FILE PROTECT
-CASSETTE PRESENT

- BUSY

Figure 3: Definitions of the status-register bits; Flag and Flag 1 may be controlled by
the user via the internal software.

+ 5V
A

C=_)

0BF

IBF

vcc

VDD

cs

RD
WR

A0

SS 3 •

TEST 1
p 20

'14

»-C RESET

Pl5

P 16

EA

V S S

7

MOTOR POWER
LOGIC POWER

DATA-OUT
DATA - IN

FORWARD/REVERSE

FAST /SLOW
READ/WRITE
CLEAR LEADER
FILE PROTECT
CASSETTE PRESENCE
POWER GND
SIGNAL GND
CHASSIS GND

Figure 4: The interface between the CM-600 Mini-Dek, the 8741A, and the host system.

r:\

-MID-CELL-

-CLOCKING TRANSITION

LOGIC LEVEL 1
LOGIC LEVEL

Figure 5: The hexadecimal character 3 A phase-encoded. This is the algorithm used with
the minicassette controller. It is not the logic level of a bit cell that determines its value,
but the presence or absence of a mid-cell transition.

78 April 1981 © BYTE Publications Ire

In this age of runaway inflation...

Look what $795* will buy

The ideal input device for the small
system user.

Ei 55

K£j «mo 2™-; **«

«'»-* C7UM ««-* m«
E'^l _\ 735-00 2n£i iltS

IS »!

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Available with stylus or optional cursor.

The HIP AD™ digitizer

Inexpensive input to your computer

The HIPAD™ digitizer can be used for both converting graphic information into
digital values and as a menu. Utilizing either the stylus or the optional cursor, the
operator can input graphic data into the computer by locating individual points on
the digtizers 11" x 11" (28cm x 28cm) active area. In the "stream mode" a contin-
uance of placements of coordinate pairs may be input.

Not a kit, the HIPAD™ comes complete with both RS-232C and parallel interfaces
and has its own built-in power source. The origin is completely relocatable so coor-
dinates may be positive or negative for a true reference value and oversized mater-
ial may be input by simply resetting the origin.

Accurate positional information, free form sketches,
even keyboard simulation

All can be entered using the multi-faceted HIPAD™ digitizer. Its capabilities and
low price make the UL listed HIPAD™ a natural selection over keyboard entry, inac-
curate joysticks, or expensive approximating light pens. It's perfect for inputting
isometric drawings, schematics, X-rays, architectural drawings, business graphs,
and many other forms of graphic information, as well as creating your own graphics.

Use it with Apple II™ , TRS-80 Level II ™ , PET ™ or other
popular computers

The HIPAD's™ built-in RS-232C and parallel 8 bit interfaces make it all
possible. (For Apple II order DT-11A, for TRS-80 or PET order DT-11).
Furthermore, you get English or metric scaling, data format (Binary/BCD/ASCII),
selectable baud rates, and resolution of either .005" or .01".

For complete information contact Houston Instrument, One Houston Square, Austin, Texas 78753.
(512)837-2820. For rush literature requests, outside Texas call toll free 1-800-531-5205. For technical
information ask for operator #5. In Europe contact Houston Instrument, Rochesterlaan 6, 8240 Gistel,
Belgium. Telephone 059/27-74-45.

Available with optional display.
'U.S. Suggested retail price

TM HIPAD is a trademark of Houston Instrument
TRS-80 is a trademark ot Tandy Corporation
APPLE is a trademark ol Apple Computer Inc.
PET is a trademark of Commodore Business Machines, Inc.

Circle 53 for literature

Circle 54 to have representative call

houston instrument

GRAPHICS DIVISION OF

BAUSCHSLOMB ▼

Text continued from page 12:
scheme, the data format is also up to
the user. The 8741A reads and writes
blocks of variable length with an 8-bit
checksum for error detection
automatically appended. An option is
to use the 8741A to check for errors
by generating a CRC (cyclic redun-
dancy check) code instead of a
checksum, as in the CRC-16 error
code used for floppy disks.

A block starts with a Sync
character (hexadecimal AA), fol-
lowed by the data (up to 64 K bytes),
which is in turn followed by the
checksum byte and trailing Sync

character. Blocks of data are
separated by an IRG (inter-record
gap). The IRG is such a length that
the transport can stop and start
within an IRG. The CM-600 drive
specification calls for a worst-case
start or stop time of 150 ms. A
450 ms IRG was selected for the
8741A to allow plenty of margin for
both controlling the transport (ie:
starting and stopping) and detecting
an IRG during the SKIP operation.

The 8741A Controller Software

The goal of the software design for
this application was to make the UPI-

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and are organized so that you can read
them straight through like a novel.
CP/M™ PRIMER, by Mitch Waite and
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No. 21791. $11.95.

PASCAL PRIMER A complete guide to the
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No. 21793. $16.95.

COMPUTER GRAPHICS PRIMER An easy-
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MICROCOMPUTER PRIMER (Second Edi-
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BASIC PROGRAMMING PRIMER A valuable
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Waite and Michael Pardee.
No. 21586. $10.95.

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Mail To: Howard W. Sams & Co., Inc.

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Saw 1 0% on Orders of S20 oi More! Quonlity —

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PASCAL Primer
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Microcomputer Primer
BASIC Programming Primer

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No. 21650 $12.95

No. 21653 $11.95

No. 21586 $10.95

Amount ol order $

Deduct 10% it order is $20 or more $

Add local sales lax where applicable $

Shipping & handling costs $2.00
Total amount of order $

Payment Enclosed Check

VISA MasterCard Interbank No. _

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CALL TOLL-FREE I -800-128-3696 for the name ol your

local Sams Book oullet or to order by phone.

Offer expires 7 '31 '81 AD08I

41A microcomputer into an in-
telligent cassette-control processor.
The host microprocessor (8085A,
8080A, 8088, etc) issues a high-level
command such as READ or WRITE
to the 8741A, which accepts the com-
mand and performs the requested
operation. Upon completion, it
returns a result code notifying the mi-
croprocessor of the outcome (eg:
Good-Completion, Sync Error, etc).
Table 1 on page 92 lists the high-level
command and result codes for the
functions performed by the
minicassette controller.

The internal 8741A software can be
roughly divided into the various com-
mand functions. At the top of the
hierarchy is the command recognizer.
Its job is to get a command from the

f WRITE J

GET CNTLSB/
CNTMSB

YES

Terror exit j

INITIALIZE
VARIABLES AND
START TIMER

START TRANSPORT

(error EXIT J

WRITE IRG AND
STOP TRANSPORT

C EX ' T )

Figure 6: Flowchart of the WRITE com-
mand sequence.

SEE THE COMPLETE SAMS LINE AT NCC. BOOTH #5209. Circle 55 on inquiry card.

New power at your fingertips.

Konan presents Hard Disk
Control, Tape Control, and
Serial I/O Boards for S-lOO
computers.

Konan, known throughout the industry for its
leading, innovative, guaranteed controllers
for S-lOO systems, does it again. Now, it offers
you more of the expanded capabilities you
want.

Take your pick to suit your needs. There's
the SMC-lOO™ storage module (SMD or CDC
9760 interface) hard disk controller. There's
the HARDTAPE™ subsystem which offers
Winchester hard disk control with tape
back up. Or maybe you could use Konan's
new KNX-500, software compatible with
the AM-500*, for lO megabyte fixed/
removable media hard disks. The "DAVID"
is Konan's new error-correcting intelligent
disk controller for 5 1/4" and 8" Winchester
hard disk drives. And the "ENHANCER" is an
intelligent reel-to-reel tape controller with
high speed printer port for spooling, offline
sorts, copies, etc. Watch for new controllers
coming soon!

Also, Konan introduces OCTOPORT™ and
OMNIPORT™-two new serial I/O boards.
OCTOPORT™, the 8-port board, offers a real
time clock and full interrupt control. And the
16 port OMNIPORT™ offers you an efficient,
economical board where more than 8 ports
are needed.

With these and other quality products,
Konan shows again that when it comes to
S-lOO systems, it is definitely in control. (And
all at attractive OEM. and dealer prices.)

Call Konan's toll-free order line :

800-528-4563.

Or write to: Konan Corporation
1448 North 27th Avenue

Phoenix, AZ 85009
TWX/TELEX 9109511552

'Alpha Micro AM-500 is a irademark of Alpha Micro Systems.

IN CONTROL. SMC-lOO, HARD TAPE, KNX-500. OCTOPORT, and OMNIPORT
are trademarks ot Konan Corporation.

Circle 125 on inquiry card.

Circle 56 on inquiry card.

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PROGRAMS MOST
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MASTERCARD/VISA

CHECK OR MONEY ORDER

ILL. RES. ADD SALES TAX

ACKERMAN

DIGITAL SYSTEMS, INC.

110 N. YORK RD., SUITE 208

ELMHURST, ILLINOIS 60126

(312) 530-8992

NO

COMPLEMENT
TAPE INPUT

YES

GET NEXT BIT
OF CHARACTER

F n =0

C Em )

< ^bit

\,_

NO

3 jr

YES

COMPLEMENT
BIT

'

/CHARACTERS.

YES

\WRITTEN yS

NO

GET NEXT
CHARACTER

'

GENERATE
CHECKSUM

( EX ' T )

Figure 7: Flowchart of the WRITE interrupt routine.

microprocessor and branch to the ap-
propriate command routine, ex-
ecuting until either the operation
specified by the command is complete
or aborted by the microcomputer or
CM-600. The command routine then
returns to the command recognizer to
await the next command. Since only
one command routine can be in ex-
ecution at any one time, the working
registers can change function based
upon which command is active.
These register names were assigned
according to their function to aid pro-
gram clarity. To understand the
operation of the controller, let us ex-
amine the flow of the various com-
mands in greater detail.

WRITE Command

When the WRITE command is
issued by the microprocessor, the
8741A expects a 16-bit unsigned
number specifying the number of
bytes to be written onto the tape to

follow immediately. The controller
requests only the desired number of
data bytes by keeping track of the
transfer count internally. All data
transfers to and from the computer
are double buffered. Before starting
the transport, the 8741A checks the
transport's status, verifying that the
cassette is present and writing to the
tape is not inhibited. If the drive is
not ready for the data transfer, an ap-
propriate error code will be returned;
otherwise, the transfer will com-
mence. The flowchart of this function
is diagrammed in figures 6 and 7.

The controller begins the block
transfer by writing a 450 ms IRG,
followed by the leading Sync
character, the data, the checksum
character, and the final Sync
character. The data is encoded with
the phase-encoding algorithm
described earlier before being written
onto the tape. The internal timer is
Text continued on page 86

82 April 1981 © BYTE Publications Inc

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Used by many companies, large and Modular Program Compilation:

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rFja^S 1 ilf^nn / MT Micro SYSTEMS \ 8080/Z80 - $250.00

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Assembler/Editor 45

Atari 400 Computer 439

Atari 820 Printer 429

Atari 810 Disk Drive 499

Atari 410 Program Recorder 69

Atari 16K RAM Module 149

Atari Basic ROM 45

Atari Visicalc 180

Basketball 30

Video Easel 30

Super Breakout 30

Music Composer 45

Computer Chess 30

Star Raiders 39

3D Tic-Tac-Toe 30

850 Interface 169

825 Printer 795

PRINTERS, MONITORS, DISCS

Anadex DP8000 850

Anadex DP8000AP 850

Color Monitor 375

Daisy Wheel Printer 1795

MPI 88T 595

NEC Spinwriter #5510 2595

Paper Tiger 445G w/Graphics 725

Paper Tiger 460 w/Graphics 1 195

Silentype w/interface Cd 540

Sanyo 9" B&W 169

Sanyo 15" B&W 259

NEC Green Screen 12" 239

Dysan disks (pkg. 10) 50

Memorex disks (pkg. 10) 40

Opus disks (pkg. 10) 35

Televideo 912C 699

Televideo 920C 749

Verbatim disks (pkg. 10) 30

LEEDEX VIDEO 100
1 2" Black & White $11 9

jfe MONTHLY jfc
^ SPECIALS ^

CENTRONICS 737
$737

cable extra

V/SA %

TO ORDER: Phone orders invited using Visa. Mastercard.
or bank wire transfers, Visa & MC credit card service charge
of >■'%. Mail orders may send charge card number (include
expiration date), cashiers check, money order, or personal
check (allow 10 business days for checks to clear). Please
include phone number. Include 3% (S5.00 minimum)
shipping, handling, and insurance in USA. Shipments

within Calif, add 6% sales Tax. Foreign orders include 1%
handling — shipped freight collect. Foreign orders over
S1000 allow 6 weeks extra and include S25 license fee.
All equipment is in factory cartons with the manufactures
warranty. Equipment is subject to price change and
availability. We ship the same day on most orders. No
C.O.D.s or P.O.s accepted. Retail store prices differ
from mail order prices.

(714) 579-0330 • MAIL TO: 1251 broadway, el cajon, ca. 92021

DISK with CONTROLLER
NEW DOS 3.3 $535
without . . . $446
Nearly Everything
for Apple

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IN STOCK

APPLE SOFTWARE

ALS Smarterm 324

Adventure by Microsoft 29

Apple Bowl "19

Apple Stellar Invaders 19

Assembler/Disassembler 69

Applebug Debugger 29

AppleGraph & Plot Sys 59

Applepost Mailing List Sys 44

Applesoft Cassette Demos 29

Applesoft Util. Prog. — Hayden 29

Applewriter Word Processor 65

Asteroids in Space 19

Autostart ROM Pkg 59

Battleship Commander 19

Bill Budges Space Game Album 39

Bill Budges 3-D Graphics/Tool 39

Bill Budges Trilogy of Games 29

Cashier Retail Mgmt. Sys 199

Checkbook Cassette 19

Contrib. Vols. 1-5 w/man 29

Controller Bus. Pkg 514

Cosmos Mission/Disk 25

CCA Data Mgmt. Sftwe 84

3-D Animation Pack 55

Desktop Plan Sftwe 79

DOS Tool Kit 65

DOS 3.3 Upgrade 49

Dow Jones Portfolio Evaluator 45

Fastgammon 23

Forth II by Softape 45

Fortran for Language Sys 159

Head-on 25

Integer Basic Cassette Demos 29

Lazer Systems Lower Case + Plus . . 59

Microsoft 16K Ramcard 179

PASCAL Language Sys 459

Sargon II Chess Game disk 34

Shell Games 29

Single Disk Copy Routines 35

Space Invader 25

Star Cruiser 24

Stellar Trek 23

Sub-Logic FS-1 Fit. Sim./disk 34

Tax Planner 99

The Correspondent 35

Tranquility Base 24

Visicalc by Personal Sftwe 119

Complete Peachtree Business
Package for Apple

AND MUCH MORE . . .

call 1-800-854-2833

PHONE ORDERS

MON. - SAT. 8 to 6 P.S.T.

Circle 57 on inquiry card.

APPLE COMPUTER
INTERFACE CARDS

HiSpeed Serial Int. Cd 155

Applesoft II Firmware Cd 149

Centronics Interface Cd 179

Apple Clock/Calendar Cd.

by Mtn. Comp 225

Comm. Cd. & DB25 Cable 179

Integer Basic Firmware Cd 149

Parallel Printer Cd 139

CCS Parallel Print Cd. 7720A 155

ROMPLUS w/keyboard filter 165

ROMPLUS (keyboard filter extra) ... 159
SSM AIO Serial/Parallel I/O

Assembled & Tested 189

Serial Interface Cd 139

CCS Asynchronous 7710A 139

ACCESSORIES

Apple Joystick 47

ABT Numer. Input Keyboard A or B 114

A/D D/A Board by Mtn. Comp 319

Arith. Processor 781 1 A or B 339

Clear Cover for Apple Computer 25

COPYROM by Mtn. Comp 51

Corvus 10MByte Disk w/pwr. supp. 4395

Dan Paymar L.C. Kit 1 or 2 59

Extender Board 27

GPIB by CCS model 7490A 259

Graphics Input Tablet 649

Hayes Micromodem' 319

Introl X-10 Remote Control Sys 239

Introl X-10 Controller Only 169

M&R Sup-R-Term 80 column board . 329

Microsoft Z-80 Soft Card 295

Novation Cat Modem 159

Programmable Timer CCS 7440A ... 159

Prototyping Hobby Card 22

ROMWRITER by Mtn. Comp 149

Speechlink 2000/64 Word Vocab. ... 215
SuperTalker Speech Synthesizer. . . . 239

Symtec Light Pen 214

Versa-Writer Digitizer

Drawing System 209

Videx Videoterm 319

START
TRANSPORT

(error EXIT J

WAIT FOR
CHANGE IN TAPE
OUTPUT DATA

START TIMER

STORE DATA
IN BUFFER

SKIP TO IRG

(ERROR EXIT )

YES

EMPTY BUFFER

(ERROR EXIT J

YES

( EXIT )

(error exit J

TRANSFER DATA
FROM BUFFER
TO DBBOUT

Figure 8: Flowchart of the READ command sequence.

Text continued from page 82:

used to signal both the initial cell
transition and the mid-cell transition,
generating an internal interrupt every
208 /is. Thus, a byte is written every
sixteen timer interrupts, or 3.3 ms. If
nothing unusual happens during the
operation, it returns a Good-
Completion result code (hexadecimal
00) to the host.

If an error occurs, the 8741A mini-
cassette controller provides error

wrap-up facilities, protecting the in-
formation on the tape from being cor-
rupted. For example, if the clear
leader of the tape is found during a
write operation, the transport is
halted immediately. Another error
results from the processor being late
in supplying data to the controller,
causing a data-underrun error and
aborting the data transfer. A 450 ms
IRG is then written onto the tape
before the transport is halted.

READ Command

The READ command provides er-
ror checking similar to the WRITE
command. Once the READ command
is issued by the microprocessor, the
controller checks for cassette presence
and starts the transport. The data
output from the transport is then ex-
amined and decoded continuously.
This function is shown in the
flowcharts of figures 8 and 9. The
first character must be a Sync, or the

86 April 1981 © BYTE Publications lnc

Introducing

quality print at matrix speed.

For only $1295!

Until now, word processing output
was a slow, expensive proposition. You
could pay thousands for a slow, letter-
quality character printer. Or give up
print quality for matrix speed and price.

But that was before Paper Tiger™ 460
offered you a better choice.

The new Paper Tiger 460 is the first
matrix printer with high-density dot
matrix characters plus high speed. At a
low price.

The secret? A unique nine-wire, stag-
gered matrix head provides overlap-
ping dots in both horizontal and
vertical planes. The result is
dense, high-quality characters
you'll be proud to show off.

What's more, Paper Tiger 460
gives you a combination of fea-
tures simply not available on any
other printer, at any price. Like
bi-directional, logic-seeking print-
ing at speeds in excess of 1 50
characters per second. Micro- ,

processor electronics, with built-in diag-
nostics and self-test. Proportional spacing.
Automatic text justification. DotPlot™ high

Integral Data Systems stands re£
performance printers ideally su
printer, the IDS 460, offers feat

Automatic proportional spacing
processing systems, plus the cap
resolution of 84 by 84 dots per

Paper Tiger 460 Print Sample

resolution graphics option. RS232 and paral-
lel interfaces. And more.

But its most important feature is high relia-
bility. Paper Tiger 460 is designed to be
tough and dependable. It has rugged,
stepper-motor head and paper drives.
A new rugged ballistic-type print head.

Circle 58 on inquiry card.

And its simple, chassis-mounted
cartridge ribbon lasts up to four times
longer than cassette or spool ribbons.
Paper Tiger 460 is the one printer
that gives your Apple, 1 TRS-80,*or
other small business computer both
data processing and word process-
ing output. At a price you can afford.
Get your paws on Paper
Tiger 460, and join the tens of
thousands of satisfied Integral
Data Systems users. For the
name of the Paper Tiger dealer
nearest you. Call us toll-free-.
800-258-1386. (In New Hamp-
shire, Alaska, and Hawaii, call
(603) 673-9100.) Or, write for
complete specifications. Integral
Data Systems Inc., Milford,
New Hampshire 03055.

•Suggested single-unit U.S. retail price.

t Apple is a trademark of Apple Computer Inc.

tTRS-80 is a trademark of Radio Shack, a division of Tandy Corp.

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• Fully compatible with all SuperBrain
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• Easy plug-in installation

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Complete two drive kit

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f RD INT J

STORE DATA
OUTPUT BIT
IN REGISTER

RELOAD AND
START TIMER

( EXIT )

Figure 9: Flowchart of the READ interrupt
routine.

controller will abort the read opera-
tion, return a Bad-First-Sync result
code (hexadecimal 42), and advance
to the next IRG of the tape. If the
Sync character is correct, succeeding
characters are read into an internal
30-character FIFO (first-in, first-out)
buffer, allowing the processor over 99
ms of service latency before a data-
overrun condition occurs. Whenever
the DBBOUT register is empty, data
is transferred to it from the FIFO buf-
fer. This continues until an IRG is en-
countered, at which point the
transport is stopped. The controller
then tests the last character. If it is a
Sync, the controller compares the ac-

f SKIP J

GET BLKCNT

YES

SELECT FORWARD

AND

START TRANSPORT

NO

SELECT REWIND

AND

START TRANSPORT

YES

SELECT
3 IPS
SPEED

NO /BLKCNT\ YES

>8
P

SELECT
5 IPS
SPEED

SKIP A BLOCK

DECREMENT
BLKCNT

NO

STOP TRANSPORT

Terror exit J

SKIP A BLOCK

DECREMENT
BLKCNT

STOP
TRANSPORT

( EX ' T )

STOP
TRANSPORT

C EXIT )

Figure 10: Flowchart of the SKIP command sequence.

88 April 1981 © BYTE Publications Inc

Meet the Tiger with,
a biaaer bite.

Introducing the remarkable 132-column
Paper Tiger™ 560. The first full-width matrix
printer to give you fully formed characters
for a low $1695.*

The new 560 features a staggered nine-
wire ballistic type print head that overlaps
dots in both horizontal and vertical planes.
It bi-directionally prints up to 150 dense, text
quality characters per second.

The 560 also features a reliable cartridge
ribbon that lasts up to four times as long

presents a breakthrough in matriK printim
ering the user excellent print quality wit;
ce of a matriK printer. Employing a uniq
red column" head manufactured by Integr
creates high quality printouts by overla

Paper Tiger 560 Print Sample

as spool and cassette ribbons, separate
heavy-duty stepper motors to drive the print
head and advance the paper, plus true
tractor feed.

And famous Paper Tiger performance
comes with every new 560. Like fixed or
proportionately spaced text, programmable
tabbing and business forms control, auto-
matic text justification, print formats to 220

columns, parallel and serial interfaces, self-
diagnostics, and more. All inside the most
compact printer of its kind.

Need more stripes? Dotplot ,™ our high-
resolution raster graphics package, is stan-
dard on every 560.

For data processing, word processing
and small business applications, this is your
Tiger. The business-sized Paper Tiger™ 560.

It's a Tiger you can count on.

Call TOLL FREE 800-258-1386 (In New
Hampshire, Alaska and Hawaii, call
603-673-9100.) Or write: Integral Data
Systems, Inc. , Milford, NH 03055.

Tiger 560

■Lw) jlntegral Data Systems, Inc.

Circle 59 on inquiry card.

*Suggested U.S. retail price.

SELECT REWIND
AND START
TRANSPORT

WAIT 50ms

STOP
TRANSPORT

C exit )

( EXIT )

Figure 11: Flowchart of the REWIND
command sequence.

cumulated internal checksum to the
block's checksum, the last character
of the block. If they match, a Good-
Completion result code (hexadecimal
00) is returned to the host. Otherwise,
the appropriate error-result code is
returned (ie: Bad Sync2 or Checksum
error). The READ command also
checks continuously for the End-of-
Tape (EOT) clear leader and returns
the appropriate error code if it is
found before the read operation is
complete.

SKIP Command

The SKIP command (see figure 10)
allows the host to skip up to 127
blocks forward or backward. Im-
mediately following the command
byte, the controller expects an 8-bit
signed-magnitude byte specifying the
number of blocks to skip. The most
significant bit of this byte selects the
direction of the skip (0 = forward,
l = reverse). SKIP provides two
search speeds in the forward direc-
tion. If the number of blocks to skip is
greater than 8, the controller uses fast
forward (5 ips) until it is within 8
blocks of the desired location, then

switches to the normal read speed of
3 ips to allow accurate placement of
the tape.

The reverse SKIP uses only the re-
wind speed (15 ips). Like the READ
and WRITE commands, SKIP also
checks for EOT and Beginning-of-
Tape (BOT) depending upon the
tape's direction, returning an error
code if either is encountered before
the specified number of blocks have
been skipped.

REWIND Command

The REWIND command routine,
figure 11, sets the transport to fast re-
wind of 15 ips and waits until the
clear-leader status input of the
transport is active for more than
50 ms. (There is a hole at each end of
the tape. It is guaranteed not to cause
the clear-leader input to be active for
more than 50 ms.) Once the clear
leader is found, the CM-600 is
stopped and a Good-Completion
result code is loaded into DBBOUT.

ABORT Command

The final command, ABORT, is
not a stand-alone command like the

From Ballet on Broadway

to Billiards m Dallas...

. . . people are finding unique ways to use the Powerful SciTronics REMOTE CONTROLLER

Whether it's the intricate fighting for a Broadway Ballet or the sim-
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are finding out SciTronics Remote Controller can meet their needs.

Here's Why:

Controls 256 BSR remote switches— not just 16
Hardware driven— requires minimum software
No ultrasonic link— prevents erratic operation
No BSR command module necessary

Real Time Clock gives Remote Controller an added dimension!

Real Time Clocks are now available to make your remote controller even more
powerful. The RTC feature allows for energy consumption scheduling, event
scheduling and much more. Your imagination is your only limitation when it comes
to the ways which this RC/RTC combination can be used.

Real Time Clocks feature:

Lithium battery back-up

Crystal controlled accuracy (.002%)

Clock generates interrupts (seconds, minutes, hours) for foreground/background operation

Complete software in BASIC to Set and Read clock

etc)

$159.
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S-100 CONTROLLER BOARD
S-100 REAL TIME CLOCK BOARD
ENCASED CONTROLLER

(TRS-80, Apple II etc.)
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APPLE II CLOCK BOARD

send check SciTronics Inc.

or money 523 s. Clewell St., P.O. BOX 5344

order,0: Bethlehem, PA 18015

(215) 868-7220
Please list system with which you plan to use
peripheral. Master Charge and Visa accepted.
PA residents add sales tax. COD's accepted.

90 April 1981 © BYTE Publications Inc

Circle 60 on inquiry card.

Big Savings for SS-50 Bus Computerists

Save
$140!

LFD-400'Mini-Disk System

$459.95

The choice of knowledgeable 680X computerists
since 1977 • Proven clock-data separation circuitry
and other superior design features • Reliable hard-
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formatted data on 40 tracks • Comes complete with
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each. Circle 363

REGULAR $599.95

SBC/^Single-Board Computer ^ '

$139.95

A computer or a fully compatible SS-
50 bus MPU card • Interchangeable
6802 or 6809 processor • Extendable
1-Kbyte ROM monitor • Parallel and
serial I/O ports — selectable, full-range bit rate
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On-card 1-Kbyte RAM • Provision for additional C~.,„

EPROM • On-card voltage regulator circuits circle 364 O <t V C

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6809 MPU Upgrade Adapter

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Upgrades 6800 MPU cards to 6809 pro-
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REGULAR $69.95

The ELECTRIC WINDOW

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Memory-mapped instant display updating •
Software-defined display formats • Expand-
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can be remapped • Video output can be composite
or separate sync-video • Voltage regulation circuitry
included on card. For an application review of the
ELECTRIC WINDOW; see Peter Stark's comments
on page 87 of the January 1981 issue of Kilobaud/
MICROCOMPUTING, circle 366

REGULAR $249.95

Save
$80!

Percom Price-Slashing,

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Fifth Anniversary Sale!

After five years of solid accomplishments, it's time to celebrate. So we've
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you can get Percom design and Percom quality at enormous savings. But
don't wait. Sale ends April 30th and quantities are limited to stock on hand.

Save $100.00 on fully assembled, tested and
burned-in RAM cards! Hurry, regular prices in
effect after April 30th.

These RAM cards feature 1-Mbyte extended addressing; buffered
data, address and control lines; and, on-card voltage regulation.
Cards are fully tested and burned-in. User manuals include 6800 &
6809 diagnostic memory test programs.

M24SS 24-Kbyte STATIC RAM CARD

$399.95 REGULAR $499.95

Save
$100!

Memory is organized as three independent
Kbyte blocks. Each block may be located at any
8-Kbyte boundary of a 64-Kbyie address space • Also

available in 8- and 16-Kbyte versions at regular prices. 8-Kbyte RAM expansion
kit includes extra RAM chip, plus sockets and other parts. Kit price is $139.95. •
Uses 2114L RAM chip, circle 367

M48DSS 16-Kbyte DYNAMIC RAM CARD

$399.95 REGULAR $499.95 Save

Expandable to 48 Kbytes • Memory is organized as three $1 00 !
independent 16-Kbyte blocks. Each block may be
located in any of the four 16-Kbyte zones of a 64-Kbyte address space •
Special "map-out" strapping can be used to depose any 8-Kbyte block
from upper 32-Kbyte memory • Uses type 4116 RAM chips • 16-Kbyte
RAM expansion kit includes extra RAM chip, plus sockets and other parts.
Kit price is $99.95. circle sea

Watch for the COLOi?AMA-50M

This soon-to-be-announced color VDG card for the SS-50 bus features
eleven colorful display formats in 2 to 8 colors, plus 2-color alpha-
numerics; full graphic resolutions from 64X64 pixels to 256X192
pixels; memory-mapped instant display control; low-cost modulator
option for TV interface; 1-Mbyte extended addressing; cassette I/O
option; and, operating software. Introductory price is only $219.95.

PERCOM DATA COMPANY, INC

211 M KIRBY GARLAND. TEXAS 75042
1214)272-3421

PRICES AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE.

PRICES DO NOT INCLUDE SHIPPING AND HANDLING.

COLORAMA-50. ELECTRIC WINDOW. LFD-400. PSYMON and SBC/9 are trademarks of Percom Data Company. Inc.

Nobody supports the SS-50 bus like Percom

Our field-proven software for 680X computers includes monitors,
operating systems, drivers, editors, assemblers, debuggers and high-
level languages like Super BASIC — our popular extended disk BASIC
interpreter.

Some of the other hardware products available include versatile proto-
typing cards in both 30- and 50-pin versions, extendable 50-pin
motherboards and 30-pin I/O card motherboards. Function cards,
prototyping cards and motherboards are optionally available with gold-
plated bus connectors. Also, most function cards are available in 86-
pin, EXORciser bus compatible versions.

Quality Percom products are available at Percom dealers nation-
wide. Call toll-free, 1-800-527-1592, for the address of
your nearest dealer, or to order direct from Percom.

EXORciser is a trademark of Motorola Corporation

others. Instead, the ABORT function
is part of each of the other com-
mands, allowing the microcomputer
to abort the current operation. If a
command is found in DBBIN register
during the operation of one of the

other commands, the command is
compared to the ABORT command
code. If it matches, the routine in ex-
ecution is terminated. The Abort-
Complete result code is then placed in
DBBOUT to acknowledge the abort.

Hexadecimal

Hexadecimal

Command

Representation

Result-Codes Returned

Representation

READ

01

Good-Completion
Buffer Overrun Error
Bad Synd Error
Bad Sync2 Error
Checksum Error
Command Error
End-of-Tape Error

00
41
42
43
44
45
46

REWIND

04

Good-Completion

00

SKIP

03

Good-Completion
End-of-Tape Error
Beginning-of-Tape Error

00

47
48

WRITE

02

Good-Completion
Buffer Underrun Error
Command Error
End-of-Tape Error

00
81
82
83

Table 1:

Commands

issued by

the host processor and possible

resultant codes

returned

l o it

when the EPROM

'n the 8741A is programmed with the software de-

scribed ir

this

article.

The aborted routine will, however,
exit gracefully. An aborted READ or
SKIP advances to the next IRG before
terminating. An aborted WRITE
command will record an IRG before
terminating execution. This protec-
tion helps insure the integrity of data
stored on the minicassette tape.

Conclusion

This application illustrates how the
8741A device can provide intelligent
peripheral interfaces between a com-
puter and a peripheral device such as
the CM-600 Mini-Dek transport. This
benefits the microprocessor system
by divorcing it from the close
management required by the periph-
eral. It interfaces to the 8741 A con-
troller producing a high-level I/O in-
terface. The 8741 A provides all the
low-level peripheral-control func-
tions. Another benefit of this task
modularity is that it allows the soft-
ware to be modified and upgraded
without affecting the computer
system software. In fact, the 8741A
software could be adapted to control
other cassette transports without af-
fecting the microprocessor. ■

Omikron's Mapper + NEWDOS/80
8 Drives for the TRS-80

NEWDOS/80 is Apparat's latest upgrade to
NEWDOS. Features include variable length
records, chaining, and drivers specifically con-
figured for Omikron's MAPPER II. $150.

MAPPER II adapts the TRS-80 to run both 5"
and 8" drives. With NEWDOS/80, storage is
increasedto300Kper8"drive.$99plus$50
per cable connector.

MAPPER I adapts the TRS-80 to run the vast
library of CP/M software as well as the TRS-80
software. All Lifeboat Software may be ordered
for the MAPPER I. All MAPPER I CP/M soft-
ware is compatible with the CP/M for the Model
II. With MAPPER II and 8" drives, the Model
I becomes disk compatible with the Model II.

Standard features include lower case support,
serial and parallel printer drivers, and an ad-
dressable cursor. MAPPER I is supplied with
complete utilities including a memory test, a
disk test, a copy program, and a proprietary
program for converting TRS-DOS files to CP/M
files. $199.

WORD PROCESSING- MAPPER I supports
professional word processors like the Magic
Wand and Word Star (see reviews in June 80
Kilobaud). Omikron's implementation includes
a blinking cursor, auto repeat, shift lock, de-
bouncing, and an input buffer that eliminates
missed characters. Magic Wand super discount
price $299.

FIEID PROVEN DESIGNS- After one year of
MAPPER production, Omikron has established
an impeccable reputation for reliability, integrity,
and user support. Omikron's customers include
the US Government, major corporations, uni-
versities, medical doctors, and professionals in
all fields.

SYSTEMS— Omikron sells complete systems
featuring Model II compatible Shugart disk
drives. Call for prices and delivery.

FOREIGN ORDERS must include full payment in
US funds plus $25 for air shipping and handling.

See review in July 80 BYTE By Jerry Pournelle.

*CP/M is a TM of Digital Research. TRS-80 is a TM of Tandy Corporation.

Circle 62 on inquiry card.

GOmPUTER WAREHOUSE

CALL TOLL FREE 1-800~528-1054

ATARI

Special 32K 800 System

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star raiders, joystick

800 (16K)

400

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825 Printer
850 Interface
410 Recorder
830 Modern
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Software From

MODEMS

Lexicon

LEX-II
Novation

CAT
D-CAT

SOFTWARE

Centa Systems

CBASIC
CP/M

VIDEO TERMINALS

Soroc
IQ 120
IQ135
IQ 140

Televideo

912 B $699

912 c $699

920 B $749

920 C $749

950 Call

Zenith -Z- 19 $789

PRINTERS

Centronics

737 Serial Call

737 Parallel Call

Citoh Call

Diablo Call

Epson

mx-80 Call

mx-7o Call

MPI-88G Call

NEC

5510 $2672

5520 $2955

Okidata

Microline 80 $420

Microline 82 $620

Microline 83 $923

Qume

5/45 RO $2684

5/45 KSR $3081

5/55 RO $2863

5/55 KSR $3144

Texas Instruments

810 Basic $1516

810 Loaded $1739

820 KSR Basic $1732

820 KSR Package $1916

COMPUTERS

Aitos Call

Dynabyte Call

Northstar

HRZ II-32K D (Assm) $2300

HRZ II-32K Q (Assm) $2665

Zenith

Z-89 48K $2210

DISKETTES

Memorex Call

BASF Call

Scotch

5'/4-0, 10, 16 Sector (Qty 100) $250
8"-0, 32 Sector (Qty 100) $260

Experienced Equipment

Centronics 779. . $450 Comprint 912
Teletype Model 40
(New) $2750

Hazeltine1510 .. $650
Hazeltine1420 .. $600
Centronics 730. . $375

$275
Atari 820 printer. $400

Soroc $500

Tl 810 Basic . . . $1200
Diablo, NEC, Qume

from $2100

Axiom 801 HS. . . $250

MONITORS

APF- 9" Monitor . .
Sanyo - 9" Monitor

$115
$165

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UJHIjCnUUjC (602)954 6109

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Personal checks will delay shipping two weeks Store Hours: Tues.- Friday 10-6 MST Saturday 10-5 MST

Prices reflect 3% cash discount. Product shipped in factory cartons with manufactures
warranty. Add 2%, a minimum of $5, for shipping and handling.

BYTE April 1981 93

Software Review

A Reformatter for
CP/M and IBM Floppy Disks

John A Lehman, 716 Hutchins #2, Ann Arbor MI 48013

In the "old" days of personal computing (ie: five years
ago), the transfer of programs or data between large and
small computers was not a major problem. You simply
turned on the paper-tape punch in your Teletype ASR33
terminal and listed the program on the source computer.
You then took the paper tape to the second computer, in-
serted it in the paper-tape reader, and read it in. This was
slow, noisy, and did not encourage transfer of long pro-
grams, which microprocessor-based computers didn't
have enough memory to run anyway.

The situation has changed quite a bit. Small computers
are no longer mere experimenter's toys, but serious tools
for science and business. Instead of being programmed
only in machine language or BASIC, they are now pro-
grammed in FORTRAN, Pascal, PL/I, COBOL, and
many other popular high-level languages. The fact that
small machines can now run the same programs as the

Memory Boards for ATARI™ 800 & 400 Computers

Assembled and Tested Ready to plug in

Completely Compatible One Year Warranty

No Modifications necessary

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16K with gold plated connector tabs 109.95

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Visa and Mastercard accepted Quality discounts available
Dealer inquiries invited

Anderson Peripherals, Inc.

P.O. Box 629

Richardson, Texas 75080

214-231-6866

TMATARI is trademark of Atari Corp.

larger ones has increased the demand for program trans-
fer between machines. For example, it is not uncommon
for me to take a 1000-line FORTRAN program from a
large timesharing system and run it (virtually unchanged)
on my CP/M system. However, a program of that size is
too large to dump to paper tape, even if any of the
systems I use still had a Teletype terminal with a paper-
tape reader.

This is where Microtech Exports' Reformatter for flop-
py disks comes in. IBM originally intended the floppy
disk to be a replacement for punched-card data entry.
The IBM 3740 Data-Entry System Basic Exchange Format
(BEF) is a fixed-field, uncomplicated standard for data
transfer between IBM equipment. Many machines that
use floppy disks do not use BEF for normal use, because it
is inefficient. However, almost all IBM equipment can
use it to transfer files. Reformatter allows the transfer of
data both ways between CP/M and BEF files.

Reformatter is a useful product for anyone who wants
to take programs developed on one system and run them
on another. For example, I have put a number of pub-
lished FORTRAN packages onto my CP/M system. Go-
ing the other way, to avoid being charged for develop-
ment time, I use my system to develop FORTRAN and
PL/I programs to run on larger systems.

Another group who will find Reformatter useful are
people with access to large computers that have peri-
pherals they would like to use on a smaller system. For
example, my CP/M system has neither 9-track magnetic
tape nor a high-speed line printer, but I have access to an
IBM Series /l system that does.

So much for the motivation for using the Reformatter
package. How does it work? Surprisingly well. It allows

Name

Reformatter

Format

8-inch floppy disk

Type

Translates between
CP/M and IBM Basic-
Exchange-Format floppy
disks.

Computer

Any CP/M system and
any IBM system. Re-
quires two 8-inch disk
drives.

Manufacturer

Microtech Exports
912 Cowper St
Palo Alto CA 94301
(415) 324-9114

Audience

Anyone with access to
both CP/M and IBM
systems.

Price

$195

94 April 1981 © BYTE Publications Inc

Circle 63 on inquiry card.

Circle 64 on inquiry card.

BUD

■u

dotasouth announces. • •

THE TOTAL PRINTER PACKAGE!

////

WW

T

9hoa

[

• •

With so many matrix printers on the market today, it may seem
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you to initialize Basic-Exchange-Format floppy disks, list
their directories, change the file definitions, dump, dis-
play, edit, or delete the files, and to transfer data to and
from CP/M files. Automatic character-set conversion
and proper handling of conversion between fixed- and
variable-record formats can be used or disabled. All of
these functions work well and rapidly. Reformatter can
transfer a file between CP/M and BEF twice as fast as an
IBM Series/1 can transfer that same file to hard disk. Its
file-manipulation facilities are also considerably more
flexible than are the IBM-supplied versions.

Reformatter is also easy to use. It is menu driven, and
entering a carriage return at any point backs you up one
level in the menu. In terms of ease of use, it ranks in the
top quarter of the CP/M software that I have used, and
in the top 1% of IBM software.

In fact, any problems I had using this package stemmed
from IBM's tendency to do things the hard way from the
user's standpoint. With any IBM software that I have
used, you are required to specify the size of a file at the

time you create it. On the other hand, CP/M can dynam-
ically expand a file; moreover, it uses variable-length
records, as opposed to IBM's fixed-length. The result is
that you must specify the size of the IBM file without
knowing the size of the CP/M file. There are a number of
ways around this. You can set up your IBM disks with
only one file per disk, which is not as wasteful as it
sounds, since a BEF disk holds about 50 K bytes of text or
programs (each line takes a full 128 bytes). The second
solution is to purposely create overlapping files, copy
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In summary, if you have access to an IBM or an IBM-
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Please allow 6-8 weeks for processing.

96 April 1981 © BYTE Publications Inc

1.1

1 m ■

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ill 1

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"And in conclusion,

111 only use

my exceptional powers

for the good of mankind."

"That's a vow all we Vector 3005s make. And it's not one
we make lightly.

"After all, being the only product on the market with
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you that kind of capacity.

"Our powers don't stop there, however. Each 3005 also
comes with a 32-bit error-correcting code — the first time
sophisticated IBM-style technology has been available
on a small business system. This lets us detect and correct
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disks due to dirt, wear, or damage.

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"Thank you all for coming today. And I hope we'll have
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VECTOR GRAPHIC INC.
COMPUTERS FOR THE ADVANCEMENT OF SOCIETY.

Circle 66 on inquiry card.

Technical Forum

MicroShakespeare Revisited

or Kilobard

Andrew Kalnik, 3201 Wamath Dr, Charlotte NC 28210

William Shakespeare would have made a first-rate
computer analyst. He had all the qualifications: superb
powers of observation, capacity to deal with complex
problems, imagination, and a fair ability to express
himself.

Looking at his writings, you can easily recognize the
vocabulary of a systems consultant making his pitch to
land an installation contract. Presented in a conference
room against a backdrop of easel charts, with gold-
stamped proposal binders on the broad walnut table,
some of his phrases would be right in place:

"...I'll teach you how to flow..."
(The Tempest, Act II, scene i)

"What is written shall be executed..."
(Titus Andronicus, Act V, scene ii)

"I will execute, and it shall go hard,

but I will better the instruction..."

(Merchant of Venice, Act III, scene i)

"...Our interpreter does it well..."
(All's Well That Ends Well, Act IV, scene iii)

From other lines, you can feel the sympathy the Pro-
grammer of Avon would give wretches like you and me
sentenced to a debugging session:

"O hateful error, melancholy's child

Why dost thou show to the apt thoughts of man
The things that are not? O, error, soon conceived

Thou never comest into a happy birth..."

(Julius Caesar, Act V, scene iii)

Here's another short quiz to test how well you can
match Master Will's golden words against the shiny
silicon jargon of our art. (Try your hand at the other quiz
in the April 1980 BYTE, page 104.) What we've done is to
make free translations from Shakespearean phrases into
terms familiar in computing.

Simply match the letter of the most pertinent modern
phrase against the quotations. No prizes, just the satisfac-
tion of puzzling out the answers. The answers and ratings
are on page 184. [Editor's note: Each of the items 1 thru
20 will match to one of the answers "a" thru "t, " so read
through all the answers before you try to make a match.
...GW]

1. (

2. (

3. ( )

4. (

5. ( )

( )

7. (

We'll evaluate

a. "And that

your purpose,

crashed the

and put on a

whole

form...

program!"

Troilus and

Cressida,

Act III, scene

iii

...an adder did

o. "We'll have

it...

the function

A Midsum-

graphed on

mer Night's

screen in a

Dream,

few seconds."

Ill/ii

That one error

:. "I wish I could

fills him with

check the reg-

faults.

ister flags."

Two

Gentlemen

of Verona,

V/iv

...shall run in a

d. "There isn't

new channel

much time to

fair and

convert the

evenly...

analog readings

I Henry IV,

between inter-

I/i

rupts."

...unpleasantest

2. "Put a scope on

words that ever

it to check

blotted paper...

those big

The Merchant

input spikes."

of Venice,

Ill/ii

...inferreth

: . "With the new

arguments of

I/O board, it

mighty

should just

strength...

perk right

Ill Henry VI,

along."

V/ii

...the minute of

g. "That frosts me

their plot is

— we're not get-

almost come...

ting any output

The Tempest,

from those

IV/i

ANDs."

98 April 1981 © BYTE Publications toe

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BYTE April 1981 99

Technical Forum.

8. ( ) This fierce

abridgement
hath to it cir-
cumstantial
branches.

Cymbeline,

V/v

9. ( ) Look, what thy

memory cannot
contain/ Com-
mit to these
waste blanks.
Sonnet Ixxvii

10. ( ) ...full char-

actered, lasting
memory...

Sonnet cxxii

11. ( ) ...the very

cipher of a
function...
Measure for
Measure,
Il/ii

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12. ( ) ...Would I were 1.

assured of my
condition...

King Lear,

IV/vii

13. ( ) ...Is it ended m.

then...?

Coriolanus,
IV/iii

14. ( ) ...The gates n.

made fast!
Brother, I like
not this.

Ill Henry VI,

IV/vii

15. ( ) O'erbearing o.

interruption...
King John,
Ill/iv

16. ( ) ...mark the high p.

noises...
King Lear,
Ill/vi

17. ( ) What should q.

that alpha-
betical position
portend?

Twelfth

Night,

II/v

18. ( ) Thou hast r.

caused printing
to be used...

Ill Henry VI,

IV/ii

19. ( ) What I can do s.

can do no hurt
to try...

All's Well

That Ends

Well,

Il/i

20. ( ) If it were done t.

when 'tis done,
then 'twere
well/ It were
done quickly...

Macbeth,

I/vii

See answers on page 184. ■

"If you have no
more memory
left, you store
everything on
a scratch disk."

"Let's work up
a high-level
flowchart."

"We can't be
any worse off.'

"It seems you
can call a
macro that in-
verts a 99 by 99
matrix."

"It's un-
maskable."

"That IF-THEN-
ELSE decision
sequence cut the
program down
by at least
40%."

"Are we at step
9999?"

"ROM with
complete ASCII
set."

"Can you tell
me what this
string is doing
in position
FFCA?"

100 April 1981 © BYTE Publications Inc

Circle 68 on inquiry card.

Software Professionals

At General Electric we're
using computers in ways
no one thought of before.

If you are looking for exciting technical chal-
lenges coupled with excellent growth oppor-
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requiring innovative design approaches. You

Entry level and Sr. positions available for

will be working in the following Data Proces-
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MVS Systems Programmers

Perform SYSGENs, maintain and tune
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Develop MVS enhancements, H/W-S/W
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Math Analysts

Perform modeling for simulation of complex
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Computer Systems Architects

Responsible for requirements analysis in the
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Perform data base design-administration and
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GE takes pride in being an equal opportunity employer, m/f

Programming the Game of Go

Jonathan K Millen

661 Main St
Concord MA 01742

Go is a board game. Like chess, it is
a game of pure skill; moreover, a con-
siderable body of literature has been
devoted to it. Go was invented in
China around 2000 BC. Since its in-
troduction into Japan around 700
AD, it has flourished there to the ex-
tent that the most accomplished
masters of the game are now
Japanese. However, the game has
spread world-wide. In the United
States, one can find Go clubs in the
vicinity of large cities and univer-
sities, and most large bookstores have
at least one substantial book on the
game.

Go is played on a 19 by 19 square
grid having black spots on nine in-
tersections, as illustrated in figure 1.
The traditional board, called a Go
Ban, is a wooden block about 17
inches square and several inches
thick, with four short feet. It stands
alone as a table at just the correct
height for players sitting on floor
cushions.

One player has a supply of black
stones; the other, white stones. The
stones are disks about the same size as
the grid spacing; they are approx-
imately three-eighths of an inch thick
in the middle and almost sharp
around the edge. The black stones
traditionally are made of slate, and
the white stones of clam shell.

Players move alternately, each

placing a stone on the point of in-
tersection of a pair of grid lines. The
object of the game is to enclose the
most area, measured by the number
of unoccupied points enclosed by
stones of a given color. A point is
enclosed by, say, black, if no path
along the grid from the point runs in-
to a white stone. Figure 2 shows some
enclosed areas. Note that the edge of
the board can form one boundary of
an area.

A player can increase his area by
capturing the opponent's stones.
Stones are captured a connected
group at a time. A set of stones forms
a connected group if there are paths
along the grid from any stone to any
other stone in the set, such that all
points on the path are occupied by
stones in the set. This criterion is easy
to visualize because the stones, being
as large as the grid spacing, actually
touch along paths of connection. The
phrase "connected group" also im-
plies that the stones in the group are
all of the same color, and that the
group is not merely a part of some
larger connected group.

A group of stones is captured when
it has no liberties. A liberty of a con-
nected group is an unoccupied point
adjacent (vertically or horizontally)
to a stone in the group. If a group has
just one liberty, the opponent may
capture it by placing one of his stones

on the liberty. The opponent then
picks up the captured stones and
keeps them as prisoners. At the end of
the game, a player's point count of
area is augmented by the number of
prisoners he has captured. Figure 3
shows a group having one liberty.

The game ends when both players
pass consecutively, because they both
see no further advantage in playing
more stones. Usually, when this hap-
pens, there are white stones within
areas enclosed by black, and vice ver-
sa. These stones have been given up
because the owner can predict that
they will be captured. They are
removed as prisoners at the end of the
game before counting the score.

The remaining rules are tech-
nicalities. Two that have a significant
effect on the game, concerning "ko"
and "suicide," will be mentioned later
on. The rest involve details of ending
the game and scoring, and are rarely
invoked.

A Go-Playing Program

A Go opponent, called Wally, was
programmed on a KIM-1 within its
approximately 1 K bytes of memory.
Wally's algorithm is based on essen-
tially two capabilities: finding the
liberties of a connected group, and
matching a few common patterns.
Moves take less than a second.

A 15 by 15 board was used because

102 April 1981 © BYTE Publications Inc

Circle 69 on inquiry card.

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■

Figure 1: The Go board. Players move alternately, placing stones on the points of in-
tersection of the lines, rather than in the spaces. The nine dots are handicap-stone loca-
tions. The line spacing is about 2.2 cm (seven-eighths of an inch).

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DIVISION OF MARK GORDON ASSOCIATES, INC.
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TRS-80 is a Tandy Corporation trademark. Use of above
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The Company cannot be liable for pictorial or
typographical Inaccuracies.

The above prices do not Include shipping.

Figure 2: Enclosed areas. Points marked x
are in areas enclosed by one player or the
other. The figure shows five black points
and eight white points.

Figure 3: A black group with exactly one
liberty, marked x. If it is white's turn, he
can capture the black group by placing a
stone at x and removing the black group
as his prisoners.

it was convenient for addressing
reasons to represent it internally
within a single 256-byte page, using
one byte per point. Although there
would be room for a 16 by 16 board,
a Go board ought to have a center
point. Rows and columns were num-
bered from 1 to F (in hexadecimal) so
that the coordinates of a move could
be entered on the KIM keyboard.

When a move is entered, Wally
responds with the coordinates of his
move on the KIM display, and the
complete board is also output on a
video terminal. The display of a game
in progress is shown in photo 1.

Once the board representation and
the input and output routines were set
up, the first major component of the

104 April 1981 © BYTE Publications Inc

Circle 70 on Inquiry card.

Circle 71 on inquiry card.

Multi-User

UniFLEX is the first full capability multi-user
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Designed for the 6809 and 68000, it offers its
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After a user 'logs-in' with his user name and
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run at will. One user may run the text editor
while another runs BASIC and still another runs
the C compiler. Each user operates in his own
system environment, unaware of other user
activity. The total number of users is only
restricted by the resources and efficiency of the
hardware in use.

The design of UniFLEX, with its hierarchical file
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Included in this list is a Text Processing System
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FLEX

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UniFLEX is a true multi-tasking operating system.
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program to be written was the routine
that walks through a connected group
of stones, marking the members of
the group, and both marking and
counting its liberties. Called
COUNT, this routine is a variety of
the maze-search algorithm. It was
programmed recursively in machine
language.

What COUNT does for each board
location it looks at is based on the
"invariant assertion" that any point it
looks at is one of the following:

• a stone in the connected group

• a liberty of the connected group

• a stone of the other color adjacent
to the connected group

If it is looking at a stone in the
group, it checks to see whether that
stone has previously been marked. If
not, it marks the stone and calls itself
to repeat the same process, starting
with each of the four locations north,
east, south, and west of the present
stone.

Marking a stone or point, of
course, means to set a particular bit in
the byte corresponding to that point
in the board representation. Other
bits encode whether the point is

■J

2

1 234!«;i)IICDEf
• - ♦ - II Q . . .

3
4
S
6
7
8

'. • • • . • t • t •

. ......

I.M.

9

A
1
C
D

E
F

•••• . e

o •••#0.

Photo 1: A game in progress. Wally (the
computer) is playing black, represented
by the solid-looking crosshatches (§). The
author is playing white, represented by
Os. The computer uses a 15 by 15 board;
the points of play are indicated by
periods. In this game, black was given a
nine-stone handicap.

occupied and, if so, by what color
stone.

If COUNT is looking at an unoc-
cupied point, it marks the point as a
liberty and increments the count of
liberties, unless the point has already
been marked and counted.

If COUNT is looking at a stone of
the other color, it does nothing, and

just returns.

If a stone is on the edge, or first
line, of the board, then one (or, in a
corner, two) of its neighbors will be
off the board. If COUNT is called for
an off-board location, it returns im-
mediately.

Note that, if COUNT starts on a
stone and operates as described
above, the recursive calls to COUNT
will carry the center of attention all
over the group and onto all neighbor-
ing points. The invariant assertion is
satisfied because COUNT progresses
one step each time only from stones
in the group, as sketched in figure 4.

The algorithm for COUNT is
specified concisely in listing 1 using a
kind of "structured English." The rest
of the Go-playing program will be
specified similarly, as a collection of
modules like COUNT.

Recursion is not difficult to imple-
ment; COUNT just calls itself with
the usual jump-to-subroutine instruc-
tion for each of the neighboring
points. The current board location is
in a register; it is saved on the KIM
stack before it is replaced by the loca-
tion of each neighboring point, and
then restored upon return from each
call. The size of the connected group

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106 April 1981 © BYTE Publications Inc

Circle 72 on inquiry card.

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Circle 73 on inquiry card.

BYTE April 1981 107

is limited by the size of the stack; one
byte of board location plus two bytes
of return address are pushed for each
call, and the calls are nested as the
algorithm "walks" around the group.
A 100-byte stack can handle a
33-stone group. A group of that size
would occur, if at all, only near the
end of the game, when Wally's play
deteriorates for other reasons
anyway.

Main Loop

After COUNT was coded, a
reasonable overall structure for a pro-
gram to use it followed quickly. The
main loop is specified in listing 2. The
"consequences" of counting a group
of stones include removing it from the
board (zero out the board locations)
if it has no liberties; other conse-
quences have to do with suggesting
tentative moves for Wally. Wally
always plays black, in accordance
with the Go tradition of giving the
black stones to the weaker player.

The pattern-matching facility was
not implemented immediately. In
fact, the first version of the program
chose black moves randomly, trying
again if it hit upon an occupied point.

At least the capturing of black groups
could be tested, and, for the most
part, it was playing legal Go.

Tactics and Priorities

The next step in the design of the
program was the decision that Wally
would make contact moves, adjacent
to white stones. In this way, the pro-
gram would appear to be attempting
to capture white groups, and would
eventually fill up the liberties of each
white group and capture it, if no
defensive action were taken.

At the same time, it was clear that
Wally also should take some defen-
sive moves to avoid capture. This
brought up the question of priorities:
when is a black group threatened
enough so that Wally should stop
attacking white and make a defensive
move instead? The answer had to be
based on the number of liberties re-
maining in the black and white
groups. It was decided that threats
would be ignored until a black group
had been reduced down to one or two
liberties. Otherwise, Wally attacks
whichever white group has the least
number of liberties, because that
group promises the best chance of be-

ing captured.

This strategy was implemented by
associating a number of liberties with
each suggested black move — namely,
the number of liberties remaining for
the group contacted by the stone.
When a move is suggested, such as
some liberty of a white group being

Figure 4: How the procedure COUNT
works. When tracing a black group,
COUNT begins on a stone in the group
and calls itself recursively to look at the
four neighboring locations. If a neighbor
is a black stone, the process is repeated
until all stones in the connected group
have been found. All unoccupied points
adjacent to stones in the groups (ie: liber-
ties) are also found and counted.

ft

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**When ordering state your Name, Address and Disk Type and Format
e.g. North Star Horizon 5V*" Single Density, and whether you
are using North Star, TRS-80, Apple or PET, etc.

EIRON COMPUTERS are distributors of North Star, NEC and Epson Products.

108 April 1981 © BYTE Publications Inc

Circle 74 on Inquiry card.

WHYCIS COBOL

LETS YOUR

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Now, you can use a microcomputer for
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CIS COBOL is Micro Focus' Compact,
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Or choose the
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The Standard CIS COBOL compiler
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A super- set of the Compact compiler,
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The same CIS COBOL
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• Its interactive features enable main-
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Forms

The FORMS utility lets you build a
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it automatically generates COBOL
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program.

Forms -2

A superset of FORMS, it eliminates the
need to write simple data entry and
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can be automatically generated from
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Environment

CIS COBOL products run on the 8080
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They are distributed in a variety of disk
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CIS COBOL was developed
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Distributor terms also available from
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Computer ModeL
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Rostronics and Johnson-Laird Inc. i Intellec is a trademark of Intel Corp. *CP/M is a trademark of Digital Research Inc.

BYTE April 1981 109

Listing 1: Structured English specification
of COUNT module to find and count the
liberties of a connected group containing a
stone at point "x" of color "color."
COUNT calls itself recursively, saving x
on the push-down stack during each call.

COUNT(x, color):

IF x is not off the edge
THEN

IF there is a stone at x AND
it is the given color AND
it is not marked
THEN

mark it

CALL COUNT(NORTH(x), color)
CALL COUNT(EAST(x), color)
CALL COUNT(SOUTH(x), color)
CALL COUNT(WEST(x), color)
ELSE IF there is no stone at x
THEN

mark the point as a liberty
increment the liberty count
END
END

counted, a best (move, liberties) pair
is updated if the new move is adjacent
to a group of a smaller or equal
number of liberties. Since black
groups are counted after the phase in
which white groups are counted, a
move by black in contact with a black
group with one or two liberties is
automatically preferred to a move
adjacent to a white group with the
same number of liberties. An excep-
tion was put in later: when Wally
finds a chance to capture a white
group on the next move, he always
takes it, even if some black group also
has only one liberty. There is some
doubt whether this exception was
wise, however.

Ko and Illegal Moves

There are two situations in which a

move on an unoccupied point is
illegal. A move that leaves one's own
group with no liberties is illegal.
Figure 5a shows a move by black that
would be illegal because the resulting
black group would have no liberties.
A move resulting in the capture of an
opponent's group, as in figure 5b, is
permissible because removing the
captured group creates at least one
liberty.

The second type of illegal move
arises from a ko, illustrated in figure
6a. If white captures the central black
stone on his next move, the position
will look as in figure 6b. Now black
can capture the white stone and
reproduce the original position in
figure 6a. This could go on forever.
To prevent such infinite repetition,
the Rule of Ko was introduced: no

Listing 2: Module specification for the main loop of the Go-
playing program and two of its called modules.

MAIN:

place black handicap stones

LOOP
display the board
get white's move from keyboard
CALL WEFFECT for the effect of white's move
CALL BEFFECT to obtain a tentative black move
CALL PATS to check for a pattern match
place black stone

END

WEFFECT:

FOR each point x with a black stone DO
CALL COUNT(x,black)
IF the group has no liberties
THEN remove its stones
ELSE IF the group has at least one liberty

THEN

choose a liberty not on edge line

IF the group has 1 or 2 liberties

THEN CALL EVAL for the chosen liberty

END
END

BEFFECT:

FOR each point x with a white stone DO
CALL COUNT(x,white)
IF the group has exactly 1 liberty
THEN

designate it as the black move
remove the white stones
EXIT
ELSE IF the group has 2 or more liberties
THEN

choose a liberty

CALL EVAL for the chosen liberty
END
END

rn

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110 April 1981 © BYTE Publications lnc

Circle 75 on inquiry card.

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drawing system for TRS-80. Has two font
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size drawings. Comes complete with
predefined symbols for standard logic, linear
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112 April 1981 © BYTE Publications Inc

(a)

Figure 5: Illegal moves. The point marked
x in 5a is illegal for black because it would
result in a black group with no liberties.
The point marked x in 5b is permissible,
however, because it captures the two
white stones, leaving the inner black
group with two liberties.

player may move so as to reproduce
the board position existing just prior
to his opponent's last move. A move
must be made elsewhere to change the
board position before the ko capture
is allowed.

Lookahead

Kos are common and often critical
in master games, but at Wally's level
it was simpler to leave out the Rule of
Ko. However, it is essential to avoid
suicidal or totally wasted moves
which fill in the last liberty of a
group, or leave it only one liberty, so
that the group will be captured
anyway. Hence a limited lookahead
capability was adopted. The last step
in evaluating a suggested black move
is to put the stone down tentatively
and count the liberties of the resulting
black group. This is done by calling
COUNT. The move is rejected if the
resulting group does not have at least
two liberties.

The complete move evaluation
module, EVAL, is shown in listing 3.
The module LOOKAHEAD saves the
current (move, liberties) pair before
COUNT is called with the tentative
black stone in place.

Pattern Matching

Wally's most intelligent-looking
moves are pattern matches. There are
common configurations of stones
which suggest an obvious next move
to a good player. Wally has a table of

Figure 6: Ko. In 6a, white can capture the
black stone, resulting in 6b. It is illegal for
black to restore 6a immediately by recap-
turing the white stone; he must wait a
turn.

patterns of this sort; these patterns
are illustrated in figure 7. Each pat-
tern includes one white stone and two
black stones, with a third black move
indicated. Patterns 7a thru 7e repre-
sent responses to threatened connec-
tions. Patterns 7f and 7g create good
"shape."

In Go, as in other spheres, there is
truth to the motto, "In unity there is
strength." The first step in capturing a
group of stones is to cut it off from
any other large groups nearby. Two
weak groups, when connected into a
single large group, often have a much
better chance of survival. That is why
defensive moves like figures 7a thru
7e are important.

Good shape in Go is a local posi-
tional strength. It is characterized by
diamond-shaped configurations, or
box-like shapes with at least two solid
walls. These patterns enclose an area
in an easily defended way, and serve
as a basis for expansion. Moves like
those in figures 7f and 7g are ag-
gressive moves that take area while
expanding against the opponent's
outposts.

The program looks at each white
stone, trying to find two black stones
near it in the same relative positions
as in one of the patterns. The table
entry for a pattern contains the ver-
tical and horizontal displacements of
the two black stones relative to the
white stone, and that of the suggested
black move. If the two black stones

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are found and the point for the black
move is unoccupied, the black move
is returned for evaluation.

Each pattern must be considered in
all possible orientations around the

Listing 3: Module specifications for move
evaluation, lookahead, and pattern
matching.

E VAL(move , liberties) :

GLOBAL (best-move, best-liberties)
IF liberties < best-liberties AND

LOOKAHEAD(move) a 2
THEN

best-move = move
best-liberties = liberties
END

LOOKAHEAD(move):
place black stone at move
CALL COUNT(move,black)
remove black stone
RETURN count of liberties

PATS:

FOR each white stone DO
IF there is a pattern in the table
centered on that white stone
THEN

get suggested black move y
CALL EVAL(y,2)
EXIT
END
END

white stone. Three-stone patterns
have either four or eight orientations,
depending on their lateral symmetry.
The program trades table space
against program space by performing
180° rotations automatically. Thus,
two or four table entries representing
different orientations of each pattern
are needed to account for all
possibilities.

Pattern matches are checked last,
because they almost always take
priority over moves arising from the
earlier phase of counting the liberties
of groups. Pattern-match moves are
associated with an artificial figure of
two liberties to set their priority.
Thus, if Wally can capture a white
group, or avoid the capture of a black
group having one liberty, he will do
so despite any pattern matches. The
priorities of the patterns are deter-
mined by the order in which they are
checked, since the first match found is
returned.

Ghost Stones

The edge of the Go board is
strategically important because it
helps to wall off areas. An attempt by
white, for example, to invade be-

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tween a black stone and the edge of
the board should be defended against.
The first five patterns in figure 7
already defend against threatened
connections; why not use them to pro-
tect the connection between a stone
and the edge of the board? Imagine
that there is an additional row of
black "ghost" stones all around the
board. As figure 8 shows, a white
move near the edge can then invoke a
pattern. This idea was implemented
in the pattern match by allowing off-
board positions to count as black
stones tested for in each pattern.

Edge Moves

One of the most startling im-
provements in Wally's performance
resulted from a simple observation in
the first few games. Groups on the
edge of the board, when attacked,
often extended fruitlessly along the
edge, as in figure 9. A prohibition
against edge moves, except to capture
or on a pattern match, was added.
Wally's play began at that moment to
take on the character of an opponent
to be reckoned with.

Handicaps

Go has a handicap system that
allows an expert to play an even and
interesting game with a novice. Black
is given a head start of two to nine
stones on designated points — the ones
marked with black spots on the board
(see figure 1). The handicap stones
are placed symmetrically like die
spots, except that a handicap of three
stones is placed on three corners. Ad-
ditional handicap points, for a total
of up to seventeen stones, were added
for Wally's benefit, since it was not
expected that he would be a strong
player. Each additional handicap
stone accounts for roughly 10 points
difference in score.

The handicap stones help to make
up for Wally's lack of overall
strategy. The handicap points are
good points to occupy early in the
game, so a large handicap solves
much of the strategy problem.

Eyes and Life

Wally has a blind spot that costs
him dearly against experienced
players: he does not understand that
any group, no matter how large, will
be captured unless it has two "eyes,"
or sufficient space to make them. An
eye is an unoccupied point or con-
nected group of points. A group
enclosing two eyes is immune from

114 April 1981 © BYTE Publications lnc

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BYTE April 1981 115

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ATARI is a trademark of ATARI, Inc.

116 BYTE April 1981

cost of the world.

Access to all the
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BYTE April 1981 117

4& 4&$t^

(a)

(b)

(c)

: <ft$ = = t^$ =

<v;

w

Figure 7: Patterns. In each of these seven configurations, the black move marked x is
suggested when the white stone and the two other black stones are already present.
These patterns are applied in all orientations.

capture, because a group cannot be
captured unless it can be brought
down to only one liberty. A group
with two eyes will always have at
least two liberties. The opponent can-
not fill either eye because such a
move would fill all the liberties of his
invading stone, and hence is illegal.
Figure 10 illustrates this.

Wally does surprisingly well
despite a fundamental ignorance of
the facts of life. Captures and pattern-

matching moves tend to create eyes
more or less automatically.

Play Experience and
Improvements

Wally plays like a beginner;
however, he does play better than
people just introduced to the game.
Experienced players are surprised by
the reasonableness and apparent skill
of some of Wally's moves but are
quick to discover that he does not

know about forming two eyes.

Along the present lines, there is no
room for significantly improving
Wally within the 1 K-byte memory
that my K1M-1 has. With a memory
(d) extension, the first improvement that

springs to mind for the future is a full-
sized board. The Rule of Ko is not
hard to implement and should be in-
cluded. Many more patterns ought to
be added, and the pattern-matching
mechanism could be more general.

Wally should be taught something
about ladders, if only to avoid them.
A ladder, illustrated in figure 11, is a
sequence of moves that ends in
disaster for one side or the other,
depending on conditions several
moves ahead.

The most challenging problem for a
Go-playing program is how to
recognize when a group does or does
not have the potential to form two
eyes.

Looking ahead down the move tree
as a general approach, as is done in
chess-playing programs, has two
obstacles: the sheer number of pos-
sible moves at each turn, and the need
to first develop a way to evaluate the
board configuration. The best can-
didate for an evaluation function is

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118 April 1981 © BYTE Publications Inc

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?' Y H

Figure 8: Ghost stones. The black move at
x is suggested by the pattern in figure 7d
because there is an imaginary black stone
at point Y, off the edge of the board, for
purposes of pattern matching.

Figure 9: Running along the edge. Before
the program was modified, black would
move at x, white could respond just above
x, and the process would be repeated until
the black "worm" reached the edge of the
board and was captured. Edge moves are
now prohibited except for captures and
pattern matches.

Figure 10: A safe group with two eyes.
White cannot capture black because both
eyes, marked x, would have to be filled.
But white can make only one move at a
time, and a move in either point is illegal.

Figure 11: A ladder. White threatens to
capture black by moving at 1. When black
attempts to escape at 2, white moves at 3,
and so on. The black stones form a stair-
case that eventually reaches the edge of
the board and is captured by white 9. If
there were a black stone at 6, however,
black would escape, and white would be
left in a vulnerable position.

an estimate of the area controlled by
each player. When an area is only
loosely surrounded, however, or an
invasion is in progress, it is very dif-
ficult to determine the ownership of
many points. A possible approach is
the perceptual-grouping heuristic
method developed by Zobrist
(reference 3). Move tree searching is
probably the only way to find the
best move in confined tactical situ-
ations, like those that appear in Go
problem books.

Another improvement suggested
by chess programs is to include some
of the countless known corner open-
ings, or "joseki." Joseki are useful
anywhere in the board, and should be
implemented as an extension of the
pattern matching.

After a move that leaves an
opponent's group with only one liber-
ty, one is supposed to say "atari" to
warn him that his group is about to
be captured. Wally says nothing, and
I have lost large groups by failing to
notice an impending capture. "Atari"
goes in next.B

References

1. Ryder, J. "Heuristic Analysis of Large
Trees as Generated in the Game of Go."
Stanford University: Ph D Thesis, 1971.

2. Wilcox, B. "Computer Go." American Go
Journal, 1979.

3. Zobrist, A. "A Model of Visual Organization
for the Game of Go." AFIPS Spring Joint
Computer Conference, 1969, pages 103 thru
112.

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Build Your Own Turing Machine

James E Willis

Lawrence Berkeley Lab

1 Cyclotron Rd

Building 4

Berkeley CA 94720

In 1936, Alan M Turing gave the
following description of a computing
machine:

The machine is supplied with a
"tape" (the analog of paper) run-
ning through it, and divided into
sections (called "squares"), each
capable of bearing a "symbol." At
any one moment there is only one
square, say the rth, bearing the
symbol G(r) which is "in the
machine." We may call this square
the "scanned square." The
"scanned symbol" is the only one
of which the machine is, so to
speak, "directly aware." However,
by altering its m-configuration, the
machine can effectively remember
some of the symbols which it has
"seen" (scanned) previously. The
possible behavior of the machine
at any moment is determined by
the m-configuration g(n) and the
scanned symbol G(r). This pair
g(n), G(r) will be called the "con-
figuration." Thus, the configura-
tion determines the possible
behavior of the machine. In some
configurations in which the
scanned square is blank (ie: bears
no symbol) the machine writes

down a new symbol on the square;
in other configurations, it erases
the scanned symbol. The machine
may also change the square which
is being scanned, but only by shift-
ing it one space to right or left.

A Turing Machine

consists of three parts:

a tape, a program, and

a device.

Turing's description has become the
definition of computability. That is,
if a Turing Machine can work the
problem, then the problem is said to
be computable. If no Turing Machine
can eventually find an answer to the
problem, then the problem is not
computable. John von Neumann and
others have tried to establish a rela-
tionship between a Turing Machine
and human neural networks. (See
Michael Arbib's book, listed in the
references at the end of this article.)
An overview of these concepts along
with some history of the problem is
given in an article by Jeremy Bern-
stein (reference 2). An example of a

hardwired version may be found in
Jonathan K Millen's article (reference
3).

As with other problems involving
computing machines, the first step is
to carefully define the problem or
task. Once a careful definition has
been given that defines and limits the
scope of the project, we may then at-
tempt a solution. The solution may
take on many forms depending on the
intended use of the project.

In this article, I will describe a finite
(theoretical) Turing Machine (TM)
and the implementation of a Practical
Turing Machine (PTM) in hardware,
in a program for the 6800 micro-
processor, and in a FORTRAN pro-
gram. These implementations are
equivalent in that they accept the
same input and, for that input, pro-
duce the same output.

Turing Machines — a Definition

A Turing Machine consists of three
parts: a tape, a program, and a
device. The tape consists of an in-
finite array of Is and 0s. The device
writes on the tape and moves the tape
according to the program. (See figure
la.)

Text continued on page 128

122 April 1981 © BYTE Publications Inc

Circle 84 on Inquiry card.

Configurability. . .

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Cook" a Public Servi

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Apple World

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The program made lamous on national T.V.!
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• Translates on 3 axes
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_^^W • 21 different commands
"^•^ • Rotate object 1 .4° to 360"
r increments at machine speeds

^ FOR 48K APPLE II OR PLUS WITH
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W Stock Options 24.95

Finance 12.95

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r Baseball 9.95

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Super Gomoku 9.95

124 BYTE April 1981

Relational Query System For Management

By Ken German & Toby Zweifach

DATABASES: You've Heard The Hype Before...
The Truth IS... REQUEST DELIVERS!

DATABASE MAINTENANCE —

• Uses sophisticated screen formatting & data
entry, like on IBM 3270's!

• Generates it's own screens automatically!

• Handles records up to 4K in length, using
multiple screen "Pages"!

• Automatic data compression for increased
disk capacity

• Uses Superkram (See below) access method
for incredibly fast access, LESS THAN .2
SECOND FOR A RECORD!

• Automatic index creation/maintenance

• Automatic maintenance capabilities

• "Goof-Proof" error handling

• Input can come from VISICALC 1 " or
SOURCE'"

DATABASE SELECTION—

• Uses screen masks to form query

• Provides extensive search capabilities

• Search arguments can include
arithmetic/boolean functions, multi-field
comparisons

• Queries can generate input for automatic
database maintenance

• Queries can be stored in "Query Library" and
executed from menu on demand

• Any number of fields can be queried
concurrently

• Query output can be routed to disk, CRT
report formatter, VISICALC™ or SOURCE'"

ONLY $225

DATABASE REPORTING—

• Automatic headlines

• Automatic field editing

• Report fields can be calculated, sub-totaled &
cross-footed in any manner desired.

• Optional counter breaks may be set

• Automatic grand totals

• Automatic statistics

REQUIREMENTS

Superkram (see below) and: Commodore Pet
32K (40 or 80 col.) and 2040/4040/8050 disk OR
Apple II 48K with Applesoft or language system
and 2 disk drives or CORVUS.

SUPERKRAM

Now With Multi-Key

Capabilities

For Apple & Pet

by Ken Germann

Since KRAM™ was introduced in 1 979 it has fast become known as the quickest
and most powerful access method for serious Apple and Pet users. Now, after
hundreds of requests we have added MULTI-KEY, MULTI-INDEX, functions,
as well as increasing processing speed.

IBM/370 users have VSAM (Virtual Storage Access Method) to
provide fast, flexible keyed-access lo their data. Now SUPER KRAM
(Keyed Random Access Method), from United Software of America,
gives Apple and Pel users the same flexibility, substantially
increasing the processing power of the Apple and Pet.

Until SUPER KRAM the only "random access" capability in the
Apple and Pet consisted of a crude form of "relative record"
processing. While this is usable for very simple applications, it falls
lar short of the needs of today's business and analytical
applications. Using SUPER KRAM records may be processed by
any one of multiple "Key" values, which may consist of any kind of
data: numbers, letters, special characters, etc. Even Apples's long-
awaited DOS 3.3 doesn't have anything like this!!

KRAM™ 2.0 Regular Features

• Written in 6502 machine code
Basic compatible

• Create/Open a dataset

• Put record by key

■ Add & delete records by key

• Get any record by Full/Partial key

• Access by any key in as little as 2 sec

■ Supports multiple disks

• Read next or previous record

• Dynamic space allocation

• Dynamic space reclamation

• Dynamic index compression

• Files never need reorganization

• Compatible with language systems

th Corvusdisk)

KRAM™ 2.0 Only $99.95
SUPER KRAM™ Only $175

ATTENTION-EXISTING KRAM USERS.

Send $15 with original disk and ROM to United Software for improved version ol Kram.

SUPER KRAM'S™ Added Features

• MULTIKEY SUPPORT — Allowing simultaneous access to a
KRAM file by more than one key field.

• HI -SPEED READ — This feature allows increased I/O speed up to
60% faster during processing of SUPER KRAM read next, read
previous, put and delete requests.

• IMPROVED INDEX ARCHITECTURE - Allowing faster index
searchers and more efficient disk space utilization.

• INTEGRATED BASIC COMMANDS — Allowing SUPER KRAM'"
commands to be coded in-line with Basic, providing easier usage
of KRAM than ever before.

• USER-SPECIFIABLE BUFFER POOL - Allowing the user to
specify how many KRAM files are allowed open at one time; will
support any number of KRAM files.

• LOGICAL RECORDS (KEYS MAY BE NON-UNIQUE) — Records
added to the KRAM files are immediately accessible by any of the
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• KRAM 2.0 files are totally compatible with SUPER KRAM

a UNITED
^r= SOFTWARE
OF
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750 3RD Avenue,

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(212) 682-0347 Telex 640055

Look for the RED-WHITE-BLUE
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moneyorder, plus $3.00 shipping to:

DEALER INQUIRIES INVITED

REQUEST & KRAM are trade marks ot United Software of America

(la)

STM.

R =

R'l

COMMENTS

NUMBER

W

ADR

w

D

ADR

1

1

1

2

CHECK FIRST BIT

1

3

1

1

4

CHECK SECOND BIT

2

4

1

1

3

3

1

5

1

1

5

WRITE A 1

4

5

1

5

WRITE A

5

6

1

6

LOOP TO 6

(HALT)

6

1

5

1

1

5

LOOP TO 5

c

PROGRAM

REGISTER
R

DEVICE

<L

001

i

TAPE

Waiting On Delivery
ofADECLA120?

Avoid the hassle by upgrading your LA36 for 1200
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The Datasouth DS120 gives your DECwriter® II the high speed
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( START J

(lb)

YES

YES

WRITE
ZERO

YES

WRITE
ONE

( STOP J

Figure 1: Model of a Turing Machine and
an example. Figure la presents a symbolic
representation of a Turing Machine divid-
ed into three principal components: a
program, a tape, and a mechanism or
device for executing the program. The
current instruction being executed is
pointed to by the Turing program counter
(TPC), the register R holds the contents of
current tape position. The index I points
to the character that is currently under the
tape head. The program given in figure la
reads 2 bits from the tape and writes a
third bit to give the three characters odd
parity (an odd number of Is among
them). The program has an initial state
given by statement and a final or halting
state given by the infinite loop of
statements 5 and 6. The flowchart in
figure lb shows the logic of this program,
with the numbers beside each box being
the statement number associated with that
position within the flowchart.

126 April 1981 © BYTE Publications Inc

Circle 85 on inquiry card.

grragggg

•ifcJ

(' ' "I

• •* i • • ■ 1 1 • • . i t i i « ,

•■

" '

1

• •-

t:l«.

*

c->_- -^_-

Turn your Apple into the world's
most versatile personal computer.

The SoftCard™ Solution. SoftCard
turns your Apple into two computers.
A Z-80 and a 6502. By adding a Z-80
microprocessor and CP/M to your
Apple, SoftCard turns your Apple into
a CP/M based machine. That means
you can access the single largest body
of microcomputer software in exist-
ence. Two computers in one. And, the
advantages of both.

Plug and go. The SoftCard system
starts with a Z-80 based circuit card.
Just plug it into any slot (except 0) of
your Apple. No modifications required.
SoftCard supports most of your Apple
peripherals, and, in 6502-mode, your
Apple is still your Apple.

CP/M for your Apple. You get CP/M
on disk with the SoftCard package. It's
a powerful and simple-to-use operating
system. It supports more software
than any other microcomputer operat-
ing system. And that's the key to the
versatility of the SoftCard/Apple.

Circle 86 on inquiry card.

BASIC included. A powerful tool,
BASIC-80 is included in the SoftCard
package. Running under CP/M, ANSI
Standard BASIC-80 is the most
powerful microcomputer BASIC
available. It includes extensive disk I/O
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variables, 16-digit precision, exten-
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tions, high and low-res Apple graphics,
PRINT USING, CHAIN and COM-
MON, plus many additional com-
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More languages. With SoftCard and
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Complete information? It's at your
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and include a dealer list. Write us. Call
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number below.

SoftCard is a trademark of Microsoft. Apple II and
Apple II Plus are registered trademarks of Apple
Computer. Z-80 is a registered trademark of Zilog.
Inc. CP/M is a registered trademark of Digital
Research, Inc.

/HCflQSOfT

V CONSUMER^ PRODUCTS^

Microsoft Consumer Products, 400 108th Ave. N.E.,
Bellevue, WA 98004. (206) 454-1315

Text continued from page 122:

The device first reads position / of
the tape through the tape head, then
places the value it finds into its
register, R. If R contains a zero, the
device executes the left side of pro-
gram statement number Turing Pro-
gram Counter (TPC). If R contains a
1, the device executes the right side of
program statement number Turing
Program Counter.

Each side of each program state-
ment contains a value for the
variables W, D, and ADR. The sym-
bol W indicates what is to be written
on the tape. The symbol D indicates
the direction to move the tape head: if
D = 0, the tape head is moved one
space to the left; if D = l, the tape
head is moved one space to the right.
The symbol ADR is the address of the
next program statement to be ex-
ecuted. Briefly, the device reads the
tape, writes on the tape, moves the
tape head, and transfers control to
another program statement. The pro-
gram presented in figure lb is a parity
checker — that is, the machine reads
two binary digits and writes a third to

give the total 3 bits an odd number of
Is — that is, odd parity.

[It should be noted that the
previously mentioned notation for a
Turning Machine is not the one usual-
ly encountered in classrooms and
textbooks. A more formal definition
defines a Turning Machine with the
program expressed as a set of 5-tuples
of the .following form:

(current state, character being
read, character to write over cur-
rent character, next state, direction
to move tape)

where the particular 5-tuple to be ap-
plied is the one that is given by the
current state and the character being
read. It can be seen that each line of
the notation used in this article can be
rewritten as two 5-tuples of the above
form; therefore, the two notations are
equivalent .... GW]

The operation of a Turing Machine
may be represented by a flowchart, as
in figure 2. Suppose that the variables
W, D, and ADR are contained in

D(R,TPC) = 1 ? I-

I I

f START J

1

.

READ TAPE INTO
REGISTER R
R = TAPE (1 )

WRITE CHARACTER

TO TAPE

TAPE(I ) = W(R,TPC)

_/'direc

""N. = Rl

TION\YE

s

GHT v?

NO

MOVE TAPE
HEAD LEFT
1 = 1-1

MOVE TAPE
HEAD RIGHT
1= 1 + 1

'

\

GET ADDRESS OF
NEXT INSTRUCTION
TPC = ADR { R ,TPC)

Figure 2: Flowchart for the Turing Machine algorithm. In this algorithm, written
primarily for a hardwired or assembly-language implementation, the only allowable
characters that can be written are and 1. The only allowable movements for the tape
head are left and right. The algorithm does not end as such, but a final or halting state
can be implemented by the addition of two program lines that unconditionally loop to
each other, denoting the end of the algorithm. This is done in the example of figure la.

three arrays, each two-dimensional:
W(R,TPC), D(R,TPC) and ADR
(R,TPC). The first subscript corre-
sponds to the value contained in reg-
ister R, while the second subscript re-
fers to the program statement num-
ber. (In the example of figure 1,
W(l,3) = 0, D(l,3) = l, and
ADR(1,3)=3.) The variable I refers
to the position of the tape. Hence, the
tape is represented by a one-dimen-
sional array, TAPE(Z). The variable
TPC represents the Turing program
counter — that is, the line of the Tur-
ing program being referenced. These
variables, along with the description,
of the operation of a Turing Machine,
are utilized in the flowchart of figure
2.

So far, no restrictions have been
placed on the values of TPC or the
tape index /. Turing assumed that the
program and tape were indefinitely
large. In a practical Turing machine,
the variable TPC takes on values up
to and including the maximum
number of program statements. The
tape index / may take on values up to
and including the number of spaces
on the tape. It is usual to assume that
when the value of / exceeds the length
of the tape, it returns to the first posi-
tion on the tape, so that the tape then
becomes finite and connected to form
a loop. We call such a restricted
machine a practical Turing Machine
(PTM). With these restrictions it is
possible to construct a PTM from
discrete digital components.

A Hardware Version

A hardwired version of a PTM
utilizing integrated circuits can be
readily constructed as described in
the Millen article (see reference 3).
In the present implementation,
the program is stored in a 128 by
8-bit programmable memory circuit.
(See figure 3.) The variables are
the same as those used in the flow-
chart. The temporary register holds
the value of ADR(R,TPC). Register
TPC points to a program statement.
Register R selects the left or right side
of the program statement. The value
of I is held in a 12-bit binary up-down
counter. The tape is represented by
4096 bits of programmable memory.
The boxes labeled "address selector"
operate like double-throw switches
and facilitate loading and execution
of programs. A maximum of sixty-
four program statements may be

Text continued on page 136

128 April 1981 © BYTE Publications Ire

Circle 87 on inquiry card.

-

r • *' - -

<**

.

a

. - . ..

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01

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Unretouched CAT 400 display. 242x256k 16 bits per pixel 128K byte imaae buffer Partial picture shown here to highlight detail quality Imao
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DIS

IC25

555

TRG
THR

OUT
RST

3

1

4

. 2

IC22
7400

^E^^

OCK IN

O.OOljiF

m

14 12 6 1 2 8

K CK CK PR C

IC23
7476

15 9

16 4

11

+ 5V

■IK

RESET

C CK CK J

IC24
7476

14 12

11

10

_0_

SINGLE CLOCK 1 RESET CLOCK 2 CLOCK 2 CLOCK 3 CLOCK 4

STEP

Figure 3: Schematic diagram for the hardwired Practical Turing Machine. The device is designed to be built on three small circuit
cards, figures 3a thru 3c. In figure 3a, the clock board, IC23 and IC24 produce a four-phase clock used by the other boards.

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130 April 1981 © BYTE Publications Inc

Circle 88 on inquiry card.

Circle 89 on Inquiry card.

A s 175 Program

That Makes your
Microcomputer

Worth Its Weight
In Gold.

•tfiE

The Denver

Software Company has
developed, with the
assistance of a Big Eight
accounting firm, a financial package for
microcomputers which accommodates
the needs of both the very small-
businessman and the household budget
manager, and costs far less than you
would imagine.

The FINANCIAL PARTNER™ contains all
essential accounting functions, and yet is
easy to use. It also has built-in flexibility:
Programming expertise and valuable time
are not needed to get the FINANCIAL
PARTNER™ ready to use. And most
important, this is a complete package,
containing the programs, language,
operating system, and supplies.
The beauty of the FINANCIAL
PARTNER™ is that you don't have to be a
professional bookkeeper or accountant to
use it. Controller Jim Vogt says, "It is one

of the

simplest accounting systems I have ever
worked with, and it has a great ability to
produce timely and accurate financial
statements for small business or home
use." All the necessary "how-to" is
detailed in a well-written, step-by-step
reference manual.

The FINANCIAL PARTNER™, which
operates from menu selections, collects
and organizes information for all of the
standard categories: Assets, liabilities
(including accounts payable), normal
living expenses, deductible expenses
(including all six deductions for personal
Federal Income Tax returns), earned
income (for both the wage earner and the

self-employed),
and other income
and expenses.
The provided chart of accounts
is tailored for most users, but it can
easily be modified by adding new
accounts or changing descriptions. The
FINANCIAL PARTNER™ generates
standard financial reports — including a
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The FINANCIAL PARTNER™ is available
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The FINANCIAL PARTNER™ is available from your
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MANUFACTURERS OF MICROCOMPUTER SOFTWARE

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Dealer inquiries welcome. 303 321-4551.

a. co

imii

*- s *

a: o-

Figure 3b: 77ie processor card. 1C1 is the Turing program memory; the lines coming into AO thru A6 of IC1 are the Turing Program
Counter (TPC). IC7 stores the R (direction) bit, and IC9, IC10, and ICll store the Turing program address at which the program will
start execution. The left/right switch designates which half of the Turing program word is written (switch open = left half) when the
RUN /PROGRAM bit is set to PROGRAM.

132 April 1981 © BYTE Publications Inc

HAVE WE

GO! A PROGRAM

FOR YOU IN 111

Attend the biggest public computer shows in the country.
Each show has 100,000 square feet of display space fea-
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electronic typewriters, peripheral equipment, supplies and com-
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All the major names are there including; IBM, Wang, DEC,
Xerox, Burroughs, Data General, Qantel, Nixdorf, NEC, Radio
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entertain, enthrall and educate kids, spouses and peo-
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Don't miss the Coming Of The New Computers-
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dren under 12 when accompanied by an adult.

Ticket Information

Send $5 per person with the name of the show
you will attend to National Computer Shows,
824 Boylston Street, Chestnut Hill. Mass. 02167.
Tel. 617 739 2000. Tickets can also be purchased
at the show.

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Circle 90 on inquiry card.

BYTE April 1981 133

(3c)

THREE UP/DOWN
COUNTERS

FOUR IK BY 1 BIT
PROGRAMMABLE MEMORIES

DIRECTION

CLOCK 3

Figure 3c: The memory card. 1C12, IC13, and IC14 store the
pointer I to the Practical Turing Machine tape, while IC15 thru
IC18 store the tape itself.

6 t

TAPE TAPE CLOCK 2

BIT BIT

WRITE READ

Bring the computer to your senses

The Soundchaser' computer music system transforms
the Apple II" into an expandable, professional quality,
polyphonic keyboard synthesizer and sequencer, Sound-
chaser's music modules include a 4 octave keyboard
housed in an attractively finished wood cabinet com-
plete with polyphonic interface card, connector and
control software. The synthesizer voice card provides

3 analog/digital hybrid, studio quality programmable
synthesizers. Each synthesizer consists of a wide range,
waveform select oscillator, digitally controlled 24 dB/
octave, low pass resonant filter, user definable LFO. fully
programmable envelope generators, and a digitally
controlled amplifier. System software includes a 4 chan-
nel sequencer which supports up to 12 synthesizers!

Explore Soundchaser's musical horizons.
Play the sounds at your fingertips.

Keyboard: $650.00.

3 Synthesizer voice card: S350.00.

Write or call for details.

Dealer inquiries invited.

(415) 747-0614

TV^WSSPORT
^-^DGSIGNS

Soundchaser is a trademark of Passport Designs. Inc.
Apple is a registered trademark of Apple Computer, Inc.

Marketing:
Box 21061,
Minneapolis. MN 55421

Headauarters:

Box 4/8,

La Honda, CA 94020

134 April 1981 © BYTE Publications Inc

Circle 91 on inquiry card.

Circle 92 on inquiry card.

MULTIUSER

tmmtfn

ON S- lOO BUS
DESIGNED TO
SATISFY A WIDE
VARIETY OF
APPLICATIONS.

STANDARD

INCLUDE: CP [VI 2.2
OPERATING SYSTEM, 64K
EXPANDABLE, BANKSE-
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AND 3 PARALLEL PORTS,
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Circle 93 on inquiry card.

NNhatdo/ouwant

your computer and

video player to do

thattheycan'tdonow?

DA.

□ B.

DC.

Display videotape segments
then automatically switch to
computer text.

Display multiple-choice options
at each stage of the presenta-
tion, then, depending on the
choice made, replay any portion
of text and/or video, or move on
to new material.

Show any portion of the com-
puter text and/or videotape
(randomly accessed) depend-
ing on the pace and/or choices
of the user.

□ D.

ALL OF THE ABOVE
do it all on one screen.

and

If you checked D, contact us for more
information on Cavri Interactive Video.
We offer a reasonably priced, sophisti-
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screen — with no modification. In-
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Plus frame-accurate stops and
switches with no accumulated error.

Write or call today and join the many
companies, large and small, that are
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and testing with the new technology
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Training, of course, is only one appli-
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"TM — Apple Computer Co.
136 April 1981 © BYTE Publications Inc

(3d)

PIN 18 ,.i— v,
OF IC1 A5 I— >

PIN 19 ..r—v,
OF IC1 A4 I — ->

PIN20 r— -^

OF IC1 A31_^>

TIL209

TYPICAL 330J1

FOR 7 TYPICAL

J» FOR 7

PIN 21
OF IC1

«o

PIN22 ..r-^
OF IC1 A ll_>

PIN 23 |

OF IC1 *0l_>

IC27
7404

o'f N ,C 8 7 E^>0i @^

+ 5V

MOST SIGNIFICANT BIT (MSB)

TURING

)PR0GRAM

COUNTER

LEAST SIGNIFICANT BIT(LSB)

REGISTER R

Figure 3d: This simple front panel for the PTM displays the address being pointed to by
the Turing Program Counter and the value in the R register.

Text continued from page 128:

stored in 128 8-bit locations.
Programs are stored by:

Number

Type

+ 5 V

GND

IC1

MCM6810

24

1

IC2

7475

5

12

IC3

7475

5

12

IC4

7475

5

12

IC5

74157

16

8

IC6

74157

16

8

IC7

7400

14

7

IC8

7400

14

7

IC9

7476

5

13

IC10

7476

5

13

IC11

7476

5

13

IC12

74191

16

8

IC13

74191

16

8

IC14

74191

16

8

IC15

2102

9

10

IC16

2102

9

10

IC17

2102

9

10

IC18

2102

9

10

IC19

7400

14

7

IC20

7400

14

7

IC21

7400

14

7

IC22

7400

14

7

IC23

7476

5

13

IC24

7476

5

13

IC25

555

8

1

IC26

7404

14

7

IC27

7404

14

7

Table 1:

Power-wiring

table for figures

3a, 3b,

and 3c.

• single-stepping the programming
counter to the desired statement
number,

• selecting the proper side of the
statement with the L/R switch,

• loading the values for W, D, and
ADR via the programming switches,
and

• depressing the "write" button.

This sequence is repeated until all of
the program has been entered.
Execution is initiated by:

• single-stepping the starting location
of the Turing program into register
TPC, and

• switching to RUN mode.

Timing signals are provided by a
4-phase clock through the inputs
labeled clock 1 thru clock 4.

This representation offers a
relatively fast execution time of about
2 fis per cycle. Changes in the length
of the tape or in the maximum
number of program statements are
extremely difficult to make. Output is
limited only by the imagination and

This

Single

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Multiprocessing Software

Our Distributed Processing Oper-
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means of the user. In my prototype, a
row of light-emitting diodes (LEDs)
displays the contents of register R and
register TPC (see figure 5). Com-
ponents for this hardwired represen-
tation of a PTM cost about $80.

An Assembly-Language Version

Another implementation of a Prac-
tical Turing Machine is with a micro-
processor. The code given in listing 1
is designed to run with only 512 bytes
of memory and a Motorola 6800
microprocessor. The main program,
as written, uses monitor routines
available on the Heathkit ET-3400
Trainer. The tape index / is
represented by the contents of loca-
tions 12 and II. The variable II points
to an 8-bit word in the tape array.
The 3 least significant bits of the con-
tents of the location 12 point to a bit
within that word. A maximum of
thirty-two program statements may
be stored in 64 bytes of memory.

Subroutine RUN is divided into
five parts:

•statements 0000 thru 0016 (hexa-
decimal) load R with the value of
TAPE (/)

STM#

R

=

R = l

0080

00A0

1

0081

0OA1

2

0082

00A2

3

0083

00A3

•

•

•

•

•

•

•

•

•

31

009F

00BF

WD — ADR —
7 6 5 4 3 2 10

Bit locations

Figure 4: Memory map of assembly-
language implementation of a Practical
Turing Machine. Memory locations hexa-
decimal 0080 thru 00BF are used to store
a program of up to thirty-two steps, with
2 bytes being used to store each statement
line. The character to be written, W, is in
bit 7 of a given byte. The direction of tape
head movement, D, is in bit 6. The state-
ment number of the next statement to be
executed is stored in bits 4 thru of the
byte. Bit 5 is unused.

•statements 0017 thru 001C (hexa-
decimal) establish an offset for find-
ing the proper half of a Turing pro-
gram statement
•statements 001D thru 002F (hexa-

decimal) print W(R,TPC) on the
TAPE

• statements 0030 thru 0044 (hexa-
decimal) increment or decrement /

• statements 0045 thru 0049 (hexa-
decimal) restore TPC to the next pro-
gram statement number

The main program provides output
through the ET-3400 monitor
routines and LED displays.

Details of storage of the Turing
program appear in figure 4. Each side
of each program statement is stored
in a separate memory location. The
value of W occupies the most signifi-
cant bit and the value of D occupies
the next most significant bit. The
value of ADR is stored in the 5 least
significant bits of a Turing program
statement location.

Program statements are entered
directly into memory locations using
monitor routines available on the
trainer.

Execution is initiated by:

entering the starting location of the
irine nroeram into the location

Turing
TPC,

program into the location

Text continued on page 146

Why Do Professionals Prefer

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Software from Cybernetics?

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Plus existing CBASIC2 packages:
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Inquire for details

Trademarks of: 'Ryan-McFarland Corp.. 'Compiler Systems. Inc.. 'Digital Research. 'Bell
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And system software packages:
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CBASIC2 Compiler BASIC
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us-

15-

8041 Newman Ave., Suite 208
Huntington Beach, CA 92647
(714) 848-1922

138 April 1981 © BYTE Publications Inc

Circle 95 on Inquiry card.

ALL

NEW

GUIDES

from OSBORNE/McGraw-Hill

The Apple II User's Guide by Lon Poole, Martin McNiff, and Steven Cook #46-2, $15. □

This Guide is the key to unlocking the full power of your Apple II or Apple II plus computer. The Apple II User's Guide brings together in
one place a wealth of information for Apple computer users. It will tell you more about your Apple than any other single source. This book
will save you both time and effort. No longer will you have to search endlessly for useful information. It's all here, in the Apple II User's Guide,
thoughtfully organized and easy to use. Topics include:

"Applesoft and Integer BASIC pro-
gramming - especially how lo
make the best use of Apple's
sound, color and graphics capabi-
lities. The book presents a
thorough description of every
BASIC statement, command and
function.

'Advanced programming - special

sections describe High Resolution
graphics techniques and other ad-
vanced applications.

"Hardware features - the disk drive
and printer are covered in sepa-
rate chapters.

"Machine level programming - al-
though not a machine language
programming guide, this book
covers the Machine Language
Monitor in detail.

"Apple is a trademark of the Apple Computer Corporation.

PET/CBM Personal Computer Guide Second Edition by Adam Osborne and Carroll Donahue #55-1. $15. □

The PET/CBM Personal Computer Guide is a step-by-step guide that assumes no prior knowledge of computers. If you can read En-
glish, you can use this book. This revised second edition provides even more useful material than the popular first edition. It covers the
most recent CBM products: the CBM 8000 and 4000 series computers, the 2040 and 8050 disk drives, and programmable printers. Adam
Osborne co-authored this new edition. He has re-writien it to be a step-by -step BASIC tutorial. So if you don't know BASIC, don't worry. This
book will teach you both BASIC and CBM BASIC. If you're thinking about buying any personal computer, this book will show you what the
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Personal Computer Guide covers everything you'll need to be master of your PET.

"PET and CBM are both trademarks of Commodore Business Machines.

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CP/M User's Guide by Thorn Hogan «44-6$i2 99D

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CP/M graphically explain each operator command and computer response. CP/M's Assembly Language Utilities
are described for the non-technical reader who wants maximum use of CP/M's capabilities. The book also
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well as the technical aspects of CP/M's internal structure which will permit you to make simple modifications. A full
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The Business System Buyer's Guide by Adam Osborne #47-0 $7.95 □

When you enter the marketplace of small business computers you face a bewilder-
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Make check payable to: {f\ OSBORNE/McGraw-HIII

630 Bancroft Way, Berkeley, CA 94710 Dept. B14 Phone Orders:(415) 548-2805

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Listing 1: Listing for implementation of the Practical Turing Machine in 6800 machine code. The program uses routines from the
Heathkit ET-3400 microprocessor trainer at hexadecimal locations 0058 and 005B.

MICRO-TURING
PRACTICAL TURING MACHINE SIMULATOR FOR USE WITH A 6800 MPU
AND AT LEAST 512 BYTES OF RAM. THE MAIN PROGRAM USES MONITOR
ROUTINES AVAILABLE ON HEATHKIT "S MODEL ET-3400 MICROPROCESSOR
TRAINER. WRITTEN BY JIM WILLIS PHYSICS DEPT. UNC CHAPEL HILL.
CHAPEL HILL , NC . 27514.

MICRO-TURING

COMMENTS

" READ TAPE

" SET UP TAPE MASK FROM (12)

A=00000001

B = I2

B=00000111 .AND. B

IF (B=0) GO TO NEXT

A=2*A

B=B-1

GO TO FIRST

R=B(=0)

" LOAD R WITH TAPE (12,11)

X=I1

IF ( (A.AND.TAPE(Il) ) .EQ.O) Z=1,ELSE Z=0

IF (Z=l) GO TO ENDR

B=B + 1

R=B(=1)

" LOAD B WITH TURING PROGRAM STM(R,TPC)

B=TPC

B=B+$20

TPC=B

X=TPC

B=TURING PROGRAM STM(R,TPC)

X=I1

" WRITE ON TAPE

IF( (B. AND. 10000000) .EQ.O) Z=1,ELSE Z=0

IF (Z=l) GO TO WZERO

A=A.OR.TAPE(Il)

GO TO ENDW

A=.NOT.A

A=A.AND.TAPE(I1)

TAPE(I1)=A

" MOVE TAPE POINTER

X=$004A

IF( (B. AND. 01000000) .EQ.O) Z=1,ELSE Z=0

IF (Z=l) GO TO DEC1

" INCREMENT (12, II)

11=11+1

IF(I1.NE.-128) GO TO ENDR

12=12+1

GO TO ENDD

" DECREMENT (12,11)

11=11-1

IF(I1.NE.127) GO TO ENDD

12=12-1

" TPC=ADR(R,TPC)

B=B. AND. 00011111

TPC=B

RETURN

MEM.

LOC.

OP.

CODE

LABEL

MNEMOMIC

0000

86

01

RUN

LDA

A # $01

0002

D6

4A

LDA

B 12

0004

C4

07

AND

B # $07

0006

27

04

FIRST

BEQ

NEXT

0008

48

ASL

A

0009

5A

DEC

B

00 0A

20

FA

BRA

FIRST

oooc

D7

4F

NEXT

STA

B R

000E

DE

4B

LDX

11

0010

A 5

00

BIT

A $00, X

0012

27

09

BEQ

ENDR

0014

5C

INC

B

0015

D7

4F

STA

B R

0017

D6

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LDA

B TPC

0019

CB

20

ADD

B # $20

001B

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B TPC

001D

DE

4D

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LDX

TPC

001F

E6

80

LDA

B $80, X

0021

DE

4B

LDX

11

0023

C5

80

BIT

B # $80

0025

27

04

BEQ

WZERO

0027

AA

00

ORA

A $00, X

0029

20

03

BRA

ENDW

002B

43

WZERO

COM

A

002C

A4

00

AND

A $00, X

002E

A7

00

ENDW

STA

A $00, X

0030

CE

00 4A

LDX

# $004A

0033

C5

40

BIT

B # $40

0035

27

08

BEQ

DEC1

0037

6C

02

INC

$02, X

0039

28

0A

BVC

ENDD

003B

6C

00

INC

$00, X

003D

20

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BRA

ENDD

003F

6A

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DEC

$02, X

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ENDD

0043

6A

00

DEC

$00, X

0045

C4

IF

ENDD

AND

B # $1F

0047

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04

STA

B $04, X

0049

39

RTS

004A XX

12

(12)

004B 01

$01

004C XX

11

(ID

004D 00

$00

" VARIABLES

12

II

Listing 1 continued on page 142

140 April 1981 © BYTE Publications Ire

Circle 101 on inquiry card.

The largest selection
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Write for our catalog with
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DIGITAL MICROSYSTEMS FDC3
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M ITS/ALTAI R
MOSTEKMDX
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TRS-80 MODELI
TRS-80 MODEL II
TRS-80 MODEL III
ZENITH Z89
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IBM/CPM

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Program names and computer names are
generally trademarks or service marks ol the
author or manufacturing company.

All software products have specific re-
quirements for hardware and additional as-
sociated software (e.g. operating system or
language).

All products are subject to terms-and condi-
tions of sale.

Copyright <c; 1981 Lifeboat Associates. No
portion ol this advertisement may be repro-
duced without prior permission.

Ordering Information

COMPUTERS SUPPORTED WITH MEDIA FORMAT ORDERING CODES.

ADDS Multivisicin

AVL Eagle

Altair8800

Alios

Apple CP/M 13 Sector

Apple CP/M 16 Sector

BASF Syslem 7100

Blackhawk Micropolis

Mod II

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COS Versatile 4

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CSSN Backup

Cromemco System 3

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Delta Systems

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RT Digital Microsystems A1

RB DurangoF-85 RL

B1 Oynabyle DB8/2 R1

A1 Dynabyte DB8/4 A1

R6 Exidy Sorcerer * Lifeboat

RR CP/M 02

RD Heath H8 + H17/H27 disk . P4
Heath H89 * Lileboal CP/M P4

02 Heath H89 • Magnolia

Q3 CP/M P7

01 Helios II B2

02 ICOM 2411 Micro Floppy . . . R3

02 ICOM 3712 A1

T1 ICOM 3812 A1

A1 ICOM 4511 5440 Cartridge

R6 CP/M D1

A1 ICOM 4511 5440 Cartridge

RD CP/M D2

RA

IMS 5000
IMS 8000
IMSAI VDP-40 R4

IMSAI VDP-42 R4

IMSAI VDP-44 R5

IMSAI VDP-80 . . A1

ISC Intecolor

8063/8360/8963 A1

Intertec Superbrain DOS 0.1 R7
Intertec Superbrain DOS 5 RJ
Intertec Superbrain DOS 3 x RK
Intertec Superbrain 00 RS

Kontron PSI-80 RF

MITS 3200-3202 81

MSD5.25in RC

MecaDelta-15 25in P6

Micromation A!

Micropolis Mod I 01

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(212) 860-0300 Telex: 640693

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Micropolis Mod II

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Moslek

North Star Single Density

North Star Double Density P2

North Star Quad Density P3

Nylac Micropolis Mod II

Nylac Single Density

Ohio Scientific C3

Onyx C8001

PettecPCC2000
Processor Technology

Helios II

Quay 500

Quay 520

RAIR Single Density
RAIR Double Density

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TRS-80 Model II
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Vector MZ

Vector System B

Vista V-805 25 in. Single

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Vista V200 5 25 in. Double

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Zenith Z89 + Heath CP/M P7
Zenith A89 + Lileboal CP/M P4
Zenith Z89 + Magnolia

CP/M P7

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SOFTWARE

In Germany, x

Intersoft GmbH, Schlossgartenweg 5,

D-8045 Ismaning Telephone 089/966-444 Telex: 5213643 isof

In Switzerland,

Lifeboat Associates GmbH, Aegeristr. 35, CH6340 Baar,

Telefon: 042/31 2931, Telex: 865265 MICO CH

Listing 1 continued:

004E XX
004F XX

TPC
R

0054 8D AA
0056 96 4F
0058 BD FC QC
005B BD FE 3C
005E 01 01 01
0061 20 F0

MAIN

(TPC)
(R)

BSR RUN

LDA A # R

JSR REDIS

J3R OUTHEX

NOP

BRA MAIN

TPC
R

" MAIN

BRANCH TO SUBROUTINE RUN

A=R

" SET UP DISPLAY ADDRESS

" DISPLAY CONTENTS OF A

" SPACE FOR ANOTHER JSR

GO TO MAIN

" END MAIN

0030

00

(0,0)

0081

81

(0,1)

00A0

81

(1.0)

00A1

00

(1,1)

0100

XX

THRU

XX

01FF

XX

" LOCATIONS $0080 THRU $00BF

" RESERVED FOR TURING PROGRAM

" STATEMENTS

" (1,0)=(R,TPC)

" TAPE

" TAPE

" TAPE

XX= LOCATION FILLED JUST PRIOR TO
EXECUTION

Listing 2: Listing for implementation of the Practical Turing Machine in FORTRAN.

:l.00 " TURING

110 " UNIVERSAL TURING MACHINE SIMULATOR. JIM WILLIS > PHYSICS DEPARTMENT

120 " UNIVERSITY OF NORTH CAROLINA » CHAPEL. HILL NORTH CAROLINA,

130 " DESIGNED TO RUN ON UNCCC'S VERSION OF IBM'S 360/370 CALL -OS

140 " TURING

ISO DIMENSION 17' APE < 128 )

160 INTEGER *2 W(2r64) nB<2»64> >ABR<2i>64) i-TAPE<128) t TPC > WI yDI » ADR 1 1 T

170 DATA Y/'YV

180 1000 WRITE (3 » 100)

190 100 FORMAT ( ' HOW MANY SPACES IN THE TAPE? 128 MAX. ' )

200 READ<1*#) MTAPE

2 1 I F ( H T A P E , G T , 1 28) MIA P E ~ 1 2 8

220 1001 WRITE (3v 102)

230 1 2 F R M A T < ' I N P U T T U R I N P R R A M , W » D » A D R 1 W 1 1 D 1 1 A D R 1 . W « 2 1" E N D ' )

240 NSTM'-O

250 1 NDEX-NSTM-fl

260 WRITE (3»103)NSTM

270 103 FORMAT (' STM.NO. '*I2)

280 READ ( 1 t # ) W ( 1 » NDEX ) v D ( 1 , NDEX ) t ADR ( 1 . NDEX )»U(2» NDEX ) >HH2> NDEX ) r ADR < 2 » NDEX )

290 I F ( N S T M , E 0.64)0 T 2

3 I! F ( W ( 1 r H D E X ) . G T ♦ 1 ) (3 T 2

310 NSTM^NSTM-fl

320 GOTO 1

330 2 WRITE<3»104)

340 104 FORM AT (' NO. WO DO ADRO Wl Dl ADR1 ')

350 DO 3 I~1»NSTM

360 N-I-l

370 WRITE<3»105)N»W<1»2 ) »D<1»I) »A0R(1»I) nW(2»I ) tBi2> I ) t ADR < 2 » I )

380 105 FORMAT'-' ' »4I4 r ' \ ' v3I4)

390 3 CONTINUE

400 WRITE (3 1-106)

4 1 1 6 F R M A T ( ' I N P U T F I R S T T U R I N G P R G R AM STM . NO,')

420 READ ( l.J * ) TPC Listing 2 continued on page 144

142 April 1981 © BYTE Publications Inc

Circle 97 on inquiry card.

SYBEX BREAKS THE

LANGUAGE BARRIER

NTRODUl WM v .

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620 pp., 200 illustr., 2nd Edition, Ref. C280, $14.95

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by Richard Mateosian

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WHAT'S

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And Will Turn

MICROSOFT'S

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The first and most complete
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We accept VISA and MASTERCARD

Ft/l-80 Is o trademark of Digital Research
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S-BASIC Is a trademark of Topaz Programming
PASCAL/MT* Is a trademark of MTMIcro Systems

Listing 2 continued:

430

440 107

450
460

4 70 .1:1.9
480

490 120

5

5 1

5 2
530 '
540 '
550 '
560
570
580
590
600
6.10
620

6 3
64

6 50
660
670
680
690
700
710
720
730

7 40
750
760
770 '
780 '
790 '
800

S 1

820

830

840

850

860

870

880

890

900

9 1

920

930

940

950

960

970

980

990

1000

1010

1020

1030

1040

121

1 8

»00

201

202

7 7

03

.09
1 1

144 April 1981 © BYTE Publications tac

WRITE (3 I- 107)

FORMAT C HOW MANY TIMES THROUGH THE TAPE?')

READCI. vUOMIT
WRITE (3.1 19)

F R M A T ( ' I N P U T C H A R A C T E R F R Z E R ♦ ' )
READ ( 1> 120) J. ZERO

FORMAT ( A 1 )
WRITE ( 3 v 121)

F R M A T ( -' I N P U T C H A R A C T E R F R N E . "' )
READCU 120) I ONE

INITIALIZE TAPE TO ZERO

HO 4 j>l vMTAPE
TAPE(I)=0

CONTINUE
KIT«0

TAPE LIST ROUTINE

KT APE** 1

KIT»KIT+i
DO 32 N»l yMTAPE
I T APE CN)~I ZERO
IF (TAPE (N) .EQ*0)G0T0 32
ITAPE(NXi:0NE

CONTINUE

W R I T E ( 3 >• 1 1 3 ) ( I T A P E ( I ) » I » 1 , M T A P E )

FORMAT (128A1)
IF (KIT, ECU MIT) GO TO 99

RUN

CONTINUE
TPOTPC+1
T -TAPE CRT APE) + 1

D:i>Dnvrpo

TAPE(KTAPE)~W<T»TPC)

IF <D I* E0M )G0TG 201

KTAPE-KTAPE-1

IF ( KTAPE J...T.1 ) KTAPE-MI APE

GOTO 202

KTAPE=KTAPE+1
I F ( K T A P E . B T . MT A P E ) K T A P E = 1

TPC = ADR<T'vTPC)
!i: F < K T A P E . E Q« M ')" A P E ) G T 9
GOTO 200

WRITE (3 i-l OS)

FORMAT < ' WANT TO CHANGE THE TAPE LENGTI
READ (1, 109) ANSWER
I F ( A N S W E R , E Q ♦ Y ) GO T 1

FORMAT (AD
WRITE (3v 110)

F R M A T ( ' WANT T R E P R G R AM?')
READCI. * 109) ANSWER
I F ( A N S W E R . E Q , Y ) G T 1 1
GOTO 2
END

Circle 99 on inquiry card. >

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clock „ JLIUUUULnJLILILIl

CLOCK 4

CLOCK 3

CLOCK 2

CLOCK 1

CLOCK
SIGNAL

J~l

J~~L

1_

TIME-

Figure 5: Timing diagram for the four-phase clock. The signals shown here are
generated by IC23 and 1C24 in figure 3a. Note that within the schematic of figure 3c, the
inverted counterparts of clock 2 and clock 3 are also used.

Text continued from page 138:
• entering the DO-0054 command in-
to the trainer (this begins program ex-
ecution at hexadecimal location
0054).

The value of R is displayed con-
tinuously on the leftmost LED of the
trainer.

The microprocessor representation
of the PTM is easier to implement
than the hardwired version. Changes
in the length of the tape or the max-
imum number of program statements
are relatively easy to make, but the
microprocessor is very slow com-
pared with the hardwired version.
Subroutine RUN requires about
150 /is per cycle as compared with
2 lis for the hardwired version.

A FORTRAN Version

One of the most useful and com-
prehendable representations of a
PTM is one written as a high-level
language program. Listing 2 is a
source listing for an interactive FOR-
TRAN program that can be used to
simulate a PTM. The run section of
this program follows the flowchart in
figure 2.

The program is stored in three ar-
rays dimensioned W(2,64), D(2,64),
and ADR(2,64). The maximum
length of the tape is 128 characters. A
shift is made in the subscripts to allow
R=0 and TPC=0. Output characters
for the tape are chosen by the user
rather than being restricted to and
1. Program statements are entered as
six-component vectors and can be
readily changed. The most important
variables are available interactively
to the user.

Summary

We have implemented the Practical
Turing Machine in three forms — as a
hardwired circuit, a 6800 machine
code program, and a FORTRAN pro-
gram. We have found that the hard-
wire version is the fastest but the
most difficult to run or modify, and
that the FORTRAN version is the
easiest to modify but the slowest in
execution. The microprocessor ver-
sion is a compromise in both speed
and utility. ■

Acknowledgments

/ would like to thank Tom Ainsworth for his
help in the design of the hardwired version, Dr
W ] Thompson for his guidance during the pro-
ject, and Alice Glenn for her help in the
preparation of the manuscript. The research
for this article was supported in part by the
United States Department of Energy.

References

1. Arbib, M. Brains, Machines, and
Mathematics. New York, McGraw-Hill
Book Company, 1964.

2. Bernstein, J. "When the Computer Pro-
creates." New York Times Magazine,
February 15 1976.

3. Millen, J K. "A Universal Turing Machine."
December 1976 BYTE, pages 114 thru
119.

4. Minsky, M L. Computation: Finite and In-
finite Machines. Englewood Cliffs NJ:
Prentice-Hall, 1967.

5. Munnecke, Thomas. "Designing a Univer-
sal Turing Machine: a Software
Approach." December 1979 BYTE, pages
26 thru 30.

6. Turing, A M. "On Computability with an
Application to the Entscheidungproblem."
Proceedings of the London Mathematical
Society, Volume 42, 1936, pages 230 thru
265.

146 April 1981 © BYTE Publication! Inc

Circle 100 on Inquiry card.

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stepped ahead with a mini-computer

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System Notes

A Relocatable Bootstrap
for the Tarbell Disk Controller

Hector M Smith

9852 Dandelion Ave

Fountain Valley CA 92708

Some Z80 microprocessors do not work properly with
the Tarbell disk -controller ROM (read-only memory).
For example, Ithaca Intersystems recommends that the
bootstrap program be relocated to high memory and that
a power-on jump to it should be executed. You can make
the program independent of memory location by using
the Z80 relative-jump instruction.

Listing 1 is a relocatable version of the Tarbell
bootstrap loader. Relative jumps are included at hexa-
decimal locations 0010 and 0016. A test bit instruction is
located at hexadecimal 000E.

The original 8080 code is shown in listing 2. In the

code, at hexadecimal locations 000E and 000F, ORA
resets the sign flag if the MSB (most significant bit) of
INTRQ is 0. If this is the case, JP jumps to RDONE.

Because the Z80 does not have a relative jump instruc-
tion activated by a positive test, BIT 7, A is used to check
if bit 7 (INTRQ) is 0. If it is, a jump relative to RDONE is
executed. At hexadecimal location 0016, a jump relative
to RLOOP and NOP was substituted for the original
jump.

The modified bootstrap (listing 1) can be located
anywhere in memory. A jump to it will boot the CP/M
operating system. ■

Listing 1: A Z80 relocatable bootstrap program for the Tarbell disk controller. The mnemonics are TDL Assembler.

ADDR MACH

LABEL

ASY

LANGUAGE COMMENTS

CODE

0000 DB FC

BOOT:

IN

WAIT

WAIT FOR HOME.

0002 AF

XRA

A

COMPLETE.

0003 6F

MOV

L,A

SETL = 0.

0004 67

MOV

H,A

H&L = 0.

0005 3C

INR

A

SET A = 1 .

0006 D3 FA

OUT

SECT

SECTOR = 1.

0008 3E 8C

MVI

A.8CH

READ SECTOR.

O00A D3 F8

OUT

DCOM

O00C D2 FC

RLOOP:

IN

WAIT

WAIT FOR DRQ OR INTRQ

000E CB 7F

BIT

7, A

TEST BIT 7

0010 28 07

JRZ

RDONE

DONE IF INTRQ

0012 DB FB

IN

DDATA

READ A BYTE OF DATA.

0014 77

MOV

M,A

PUT INTO MEMORY.

0015 23

INX

H

INCREMENT POINTER

0016 18 F4

JMPR

RLOOP

DO IT AGAIN

0018 00

NOP

FILLS EMPTY SPACE

0019 DB F8

RDONE:

IN

DSTAT

READ DISK STATUS.

001B B7

ORA

A

SET FLAGS.

001C CA 7D 00

JZ

07DH

IF ZERO, GO TO SBOOT.

001F 76

HLT

DISK ERROR, SO HALT.

WAIT

=

OFCH

SECT

=

OFAH

DCOM

=

OF8H

DDATA

=

OFHB

DSTAT

=

OF8H

sting 2: Original

8080 code before

modification

for the Z80 microprocesso

000E

B7

OR

A A

000F

F2 19 00

IP

RDONE

0016

C3 0C 00

JM

P RLOOP

148 April 1981 © BYTE Publications Inc

Circle 102 on inquiry card.

Lifelines*

The serious publication
for the serious
software user.

March 1981 Vol. 1 Issue #10

From the Software Evaluation Group:
A Review of the Configurable Busi-
ness System

Osborne/McGraw-Hill's General
Ledger, a Tutorial by One of Its
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BASIC Comparisons: An Introduction
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Details on Volume 48 from The CP/M
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Some Biting Comments on the Indus-
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■^Ms^n l^M^^ft

A Closer Look at the
TI Speak & Spell

Congratulations to Michael Rigsby
on his article "Dissecting the TI Speak
& Spell" (September 1980 BYTE, page
76). He is not alone in desiring an
economical voice-output device for
his computer, and the Speak & Spell
is an excellent choice. Economy is one
reason, and the circuitry of this
device has features that make it
potentially one of the most flexible
and comprehensive speech syn-
thesizers available.

The problem is how to interface the
Speak & Spell to a computer. Mr
Rigsby 's approach is the first step, but
it allows only a spelling computer,
not a talking one. In order to achieve
more, it is necessary to know
something about the workings of the
device. This information is difficult to
obtain. Texas Instruments has not
been very informative, although con-
sidering the investment it has in
speech technology this is perhaps
understandable. Thus, the Speak &
Spell is an irresistible challenge to the
experimenter.

Mr. Rigsby has, however, made
one fundamentally incorrect assump-
tion: the TI Speak & Spell is most
definitely not based on the SN76477N
complex-sound generator, nor does it
store words, or even phrases, as in-
dividual pulses in memory. As I will
show, it uses an entirely different
technique.

The Heart of the Unit

The TMC0281NL is a proprietary
Texas Instruments integrated circuit
that is virtually an entire digital signal
processor, with timing and decoding
circuits, a 10-pole digital lattice filter,
and a D/A (digital-to-analog) con-

Peter Vernon

31 Georgina St

Newtown NSW 2042

Australia

verter. All of this is contained on a
tiny piece of silicon just 44 mils
square. This is the heart of the speech
synthesizer.

Also on the board is the controller,
the TMC0271NL, which is a member
of the TMS-1000 microprocessor
family. The TMC0271 shares the
same basic architecture as the
TMS-1000 used in TI's calculators,
but it has been modified to enhance
its BCD (binary-coded decimal)
arithmetic capabilities. It also has an
expanded instruction set and an out-
put multiplexer to reduce the number
of pinouts required in its role as a
controller for the speech synthesizer
IC (integrated circuit).

The Speak & Spell is an

irresistible challenge to

the experimenter.

As Mr Rigsby guessed, the other
two integrated circuits on the board
are high-density ROMs (read-only
memories). The TMC0350 family are
128 K-bit ROMs, organized as 16 K
by 8 bits. They incorporate an inter-
nal 18-bit address counter/register
and two 8-bit output buffers, with the
four high-order bits of the address
driving a l-of-16 device-select
decoder and the other 14 bits address-
ing the ROM array directly.

Linear Predictive Coding

The circuitry is only part of the
story. The real secret of the Speak &
Spell and other Texas Instruments
speech-synthesis devices is a tech-

nique called LPC {linear predictive
coding). This technique makes it
possible to encode a complex speech
waveform with relatively little data.
A speech signal is highly redundant,
made up of a few basic waveforms
that are repeated to produce speech
sounds. Essentially, LPC eliminates
the redundancy inherent in the speech
signal and retains only the data re-
quired to drive the speech syn-
thesizer.

The TMC0281 can be thought of as
an electronic model of the human
vocal tract. The data input is a
description of the filter parameters
necessary to model the vocal tract as
its characteristics change over time.
Codes for twelve synthesis par-
ameters are stored in the ROMs.
These parameters are ten filter co-
efficients, and pitch and energy infor-
mation.

The filter parameters are derived
from samples of actual speech and are
encoded by a complex mathematical
algorithm that makes it possible to
predict a speech waveform based on
information derived from previous
waveforms. Because of the finite-time
response of the human vocal tract,
only a fixed number of speech sounds
can follow a particular vocalization.

To produce speech, the controller
specifies the starting point of a string
of data stored in the ROMs. The
ROM output provides the pitch,
amplitude, and filter parameters from
which the synthesizer constructs the
speech waveform.

The input to the filter is either a
periodic or random sequence of
pulses. A random sequence of pulses
is used to recreate unvoiced sounds,

150 April 1981 © BYTE Publications Inc

Circle 103 on inquiry card.

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such as "[" or "s," while a periodic se-
quence creates voiced sounds such as
"a." The pitch information either
varies the frequency of the periodic
pulses or, if all the bits are zero,
selects random noise as the input to
the lattice filter. An amplification fac-
tor is also input to the synthesizer and
adjusts the amplitude of the excita-
tion source to produce sounds of
varying intensity.

The lattice filter of the synthesizer
has ten stages. Each stage carries out
two multiplications and two addi-
tions on its two digital inputs before
passing the results backward and for-
ward to its neighbors. The operations
of the ten stages are carried out se-
quentially, as are the operations
within each stage. Through careful
consideration of timing and the use of
a pipeline approach, only one adder
and one multiplier are needed to
carry out the mathematical opera-
tions. Each separate arithmetic opera-
tion requires only 6 fis.

Figure 1 is a block diagram of the
basic elements of the TMC0281. The
multistage lattice filter uses the
parameters K x thru K„ to digitally
filter the amplified excitation signal,
and passes its output to a D/A con-
verter connected to the speaker.

The coefficients of the filter are up-
dated approximately every 20 ms.
However, because of the redundan-
cies in speech patterns, a complete set
of parameters is not always required.
Sections of the data stream may be
replaced by a single "repeat" bit, cut-
ting the data required to control the
filter from a maximum of 49 bits to a
minimum of 4, thus conserving
memory space.

During speech the TMC0281 ac-
cesses the ROMs directly until it
receives an end-of-phrase command
and returns control to the TMC0271
controller. Five lines are used to
transfer data and commands within
the system. One of these lines is the
processor data clock, which deter-
mines when the data on the other four
lines is valid. These are the five lines
mentioned by Mr Rigsby.

Timing

Timing for the synthesizer is based
on a 50 Hz frame rate — so a new
speech segment is read from the ROM
every 20 ms. The speech patterns cod-
ed in the ROM are sampled at a rate
of 10 kHz, which corresponds to the
maximum bandwidth of speech — 5

152 April 1981 © BYTE Publications Inc

Circle 104 on inquiry card.

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The first Key Tronic capacitive
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BYTE April 1981 153

Circle 106 on Inquiry card.

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:;

WHITE
1 ■ ■ ' . ■ ' ■■•■!

NOISE

PERIODIC
I I I I
PULSES

UNVOICED

VOICED*

PITCH

AMPLITUDE

LATTICE
FILTER

VOCAL
TRACT
MODEL

SPEAKER

D/A
CONVERTER

-<

FILTER

COEFFICIENTS

<Kl-K n >

Figure 1: Block diagram of the heart of the TI Speak & Spell— the Texas Instruments
TMC0281NL integrated circuit. The TMC0281NL is a proprietary circuit that is virtual-
ly an entire digital signal processor and can be thought of as an electronic model of the
human vocal tract. It includes timing and decoding circuits, a 10-pole digital lattice
filter, and a D/A converter. Speech synthesis takes place through a process called LPC
(linear predictive coding), which makes it possible to encode a complex waveform with
relatively little data. Either pseudo-random noise (for unvoiced sounds) or periodic
pulses (for voiced sounds) are amplified and fed to the lattice filter, which models the
vocal tract in accordance with coefficients stored in two external 16 K by 8-bit ROMs
(read-only memories). A maximum of 49 bits is needed to specify each sound pattern,
which is updated every 20 ms. This results in an overall data rate of 2400 bps (bits per
second). The TMC0281NL is controlled by a TI TMC0271 microprocessor, a specialized
member of the TMS-1000 microprocessor family.

kHz. (The maximum bandwidth for
telephone-quality speech is 3.5 to 4.5
kHz.) An 800 kHz oscillator is divid-
ed by four to produce the major
system clock. This four-phase clock
controls the transfer of data within
the system. The individual bit pat-
terns in each 20 ms frame are clocked
into the synthesizer at a rate cor-
responding to the sample frequency
of 10 kHz. It is this clock which pro-
duces the 0.1 ms pulses measured by
Mr Rigsby.

A maximum of 49 bits is needed to
specify the sound pattern that will be
produced every 20 ms. This is an
overall data rate of about 2400 bps
(bits per second). One hundred
seconds of speech time thus requires
the storage of 240,000 bits of infor-
mation, which corresponds well with
the 256,000 bits of storage provided
by the two TMC0351 ROMs.

Capabilities and Challenge

Because the Speak & Spell
reconstructs speech sounds from a
constant-excitation signal filtered
under digital control, it is potentially
capable of reproducing any sound at
all. The challenge for the ex-
perimenter is to determine what in-
formation needs to be input to create
a particular sound. Trial and error
seems to be the only approach. With

much work it would be possible to
determine which combinations of
data are needed to produce each
phoneme of the English language.
(All words are made up of combina-
tions of particular sound units called
phonemes. About 42 phonemes are
used in the English language.) These
phoneme patterns could be stored in
memory and arranged to produce any
word. At 49 bits per phoneme and 42
phonemes, only 2058 bits are re-
quired. The problem is, of course, to
find the right bits.

Perhaps the best place to start
would be the connector provided for
the attachment of expansion
modules. The module-select key on
the keyboard of the Speak & Spell is
used to signal the controller that an
expansion module is in place and that
it should instruct the synthesizer to
access this module rather than the
ROMs on the main circuit board. By
using this signal it is possible to force
the synthesizer to accept data that is
input on the module connector. The
system clock can be used to govern
the rate of this data input. Experi-
menting with this approach produces
a weird and wonderful series of
sounds. At present, my computer (an
Exidy Sorcerer) can only grunt and
squeak, but after all, that's how we
all started IB

154 April 1981 © BYTE Publications Inc

,0 $r

SSS ANSI 'ee STANDARD

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WITH

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TOGETHER AT LAST

SSS FORTRAN & RATFOR are the critic's choice!

The SSS FORTRAN compiler is fast, efficient, and complete (full 1966 ANSI
standard with extensions). The RATFOR compiler compiles into FORTRAN allowing
the user to write structured code while retaining the benefits of FORTRAN.
Together they form an incredible team!

SSS FORTRAN Specifics

SSS FORTRAN makes full FORTRAN IV available to microcomputers. SSS
FORTRAN meets and exceeds the ANS1 1966 FORTRAN standard. The compiler
supports many advanced features not found in less complete implementations,
including: complex arithmetic, character variables, and functions. SSS FORTRAN
will compile up to 600 lines per minute! Recursive subroutines with static
variables are supported. ROMable ".COM" files may be generated.

FEATURES

Code generation: ROMable ".COM" files or intermediate code files (saves disk
space). External routines may be called.

Data types: Byte, integer, real, double precision, complex, logical, charac-

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Operations: All standard operations plus string comparisons, assignments,

and .XOR.

Constants: Hexadecimal, decimal, and character literals with features to

imbed control characters.

Statements: ANSI 1966 standard with multiple statement lines, state-

ments may end with a ' ;'.

Controls: Map, List, and Symbol table output options.

I/O: Read, Write, Append, Rewind, Close, Delete, Rename, Search,

seguencial and Random I/O on disk files. Supports all CP/M
devices. The User can add device handlers to use custom I/O
devices.

Errors: Over 200 distinct compiler error messages, precision and

illegal instruction warnings during execution.

Interrupts: FORTRAN programs may be interrupted at any time: the stack

pointer is always preserved.

• • D E ATLCIM3 • m

SSS RATFOR

RATFOR is a preprocessor that compiles to SSS FORTRAN. SSS
RATFOR allows the use of contemporary loop control and struc-
tured programing techinques. SSS RATFOR is similar to FORTRAN
77 in that it supports such things as:
REPEAT . . . UNTIL WHILE IF . . . THEN . . . ELSE

Begin End Brackets Macro Defines

SSS RATFOR is supplied with source code. The source code
is distributed in both RATFOR and SSS FORTRAN. Not only does
this prevent obsolescence, but allows the user to add enhance-
ments as desired.

System Requirements & Prices

SSS FORTRAN requires a 32k CP/M system. Z80 only.
SSS FORTRAN with RATFOR: $325.00
SSS FORTRAN alone: $250.00

RATFOR alone: $100.00

(Sold only with valid SSS FORTRAN license)

CP/M Formats: 8" solt sectored, 5" Northstar. 5" Micropolis Mod II,
Vector MZ, Superbrain DD/OD

All Orders and General Information:

SUPERSOFT ASSOCIATES

P.O. BOX 1628

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(217) 359-2112

Technical Hot Line: (217) 359-2691

(answered only when technician is available)

•CP/M REGISTERED TRADEMARK DIGITAL RESEARCH

SSS FORTRAN is the copyright ot
Small Systems Services. Urbana. Illinois

SuperSoft

First in Software Technology

BYTE April 1981 155

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flMEG A Sales Company

call Toll Free 1-800-556-T586

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available in limited quantities

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4. Stock shipments shipped usually same day or next day.

5. All equipment factory fresh with manufacturer's warr.

6. STo hidden charges - We live by our published prices.

OMEGA Sales Co - East Coast - 12 Meeting St.
Cumberland, RI 02864 Tel 1-401-T22-102T

Prices subject to change without notice.

156 BYTE April 1981

WEST COAST GRAND OPENING!!!

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OMEGA Sales Co - West Coast - 3353 Old Cone jo Rd #102
Newbury Park CA 91320 Tel 1-805-499-36T8

Circle 61 on inquiry card.

BYTE April 1981 157

Clubs and Newsletters

Zips 00000—10000

1. Syntax ZX80

2. The Harvard Group,
Bolton Rd, RD 2, Box
457, Harvard MA 01451

3. Ann Zevnik, Editor,
(617) 456-3661

5. News about the Sinclair
ZX80 microcomputer.

1. Gosub TRS-80 Users
Group

2. POB 712
Worcester MA 01613

3. Jim Mercanti, (617)
845-1851, (617) 458-7263

4. Gosub TRS-80 Users
Group Buffer

5. Noncommercial.

1. TRUGEM (TRS-80 Users
Group of Eastern Mass-
achusetts)

2. 3 Driscoll Dr, Fram-
ingham MA 01701

3. Ronald M Egalka,
Secretary, (617) 877-4520

4. The TRUGEM Newsletter

5. TRS-80 hardware and
software; peripherals
from Radio Shack and
independents; Programs
Exchange Library (non-
commercial); demonstra-
tions and sales of com-
mercial hardware and
software encouraged.

1. New England Computer
Society

2. POB 198
Bedford MA 01730

3. Bob Waite, President
(617) 448-6351 home;
(617) 897-3221, ext 2499,
work

4. NECS Newsletter

5. User Groups: PET,
Apple, 6800, Digital
Group, and TRS-80.
CBBS (Computerized
Bulletin Board System),
(617) 864-3819.

1. The Boston Computer
Society

DIRECTORY

The following is the fourth BYTE Clubs and Newsletters
Directory. The directory was compiled from information sup-
plied by the various clubs listed. A form was sent to all clubs
and newsletters listed in the third directory requesting up-to-
date information. If the form was not returned, we deleted the
club from the fourth directory. In addition, the listing was cor-
related with back issues of the magazine and materials on file in
the BYTE offices. If information is missing in one or more
categories, it means the data was not provided. We will be keep-
ing the file available and updating it for the next directory; so, if
there are errors, omissions, or if you have a new club that has
just been formed, send the information to Charley Freiberg,
Clubs and Newsletters Editor, BYTE Publications Inc, POB 372,
Hancock NH 03449.

The listing follows this form: 1. Name of organization or
name of publication; 2. Mailing address; 3. Contact person
and telephone number; 4. Newsletter or publication; 5. Special
interests.

2. 3 Center Plz, Boston MA
02108

3. (617) 720-0597

4. The Boston Computer
Society Update (an enor-
mous publication with
nationwide industry ex-
clusives and news of New
England)

5. User Groups: PET,
Sorcerer, OSI, North
Star and others.
Subgroups: education,
business applications,
Pascal and beginner
tutorials.

1. Classroom Computer
News

2. POB 266, Cambridge MA
02138

3. Lloyd Prentice, (617)
787-0420

5. This bimonthly newslet-
ter is interested in educa-
tion, curriculum develop-
ment, and related topics.

1. Technical Education
Research Centers

2. 8 Eliot St, Cambridge
MA 02138

3. Robert Tinker, Director
or Susan Warner-Mills,
Assistant, (617) 547-3890

4. Hands On!(A Forum for
Science and Technology
Educators)

5. Applications to educa-
tion, especially science.

1. RICH (Rhode Island
Computer Hobbyists)

2. POB 599, Bristol RI
02809

3. Emilio D Iannuccillo

4. Yes

5. We are an active group
dedicated to keeping
abreast of current tech-
nology, plus lending a
hand to each other
regarding hardware and
software. We also give
help and advice to new-
comers into the world of
microprocessors .

1. PIE (PET Information Ex-
change)

2. 27 Leicester Way,
Pawtucket RI 02860

1. SNAC (Southern New
Hampshire Apple Core)

2. Computerland of
Nashua, 419 Amherst St,
Nashua NH 03060

3. Don Fairchild, Treasurer,
(603) 434-5626

4. S.N.A.C.

5. This group is involved in
all aspects of home com-
puting using Apple
systems.

1. Manchester Users Group

2. 346 S Taylor St, Man-
chester NH 03103

3. Scott, (603) 624-0089

4. Yes

5. TRS-80s.

1. Southern Maine TRS-80
Group

2. 15 Mountain View Rd,
Cape Elizabeth ME 04107

3. Douglas Stewart, (207)
767-2351

4. Byte Babble

5. TRS-80s.

1. Doctor's Computer Club

2. 42 E High St, East Hamp-
ton CT 06424

3. Dr Aziz Ghaussy, (203)
267-2400

4. Medical Computer Jour-
nal Newsletter

5. Application of computers
in medical practices.

1. The Pocket Computer
Newsletter

2. POB 232, Seymour CT
06483

1. Computers in
Psychiatry/ Psychology

2. 26 Trumbull St, New
Haven CT 06511

3 Marc D Schwartz, MD,
Editor, (203) 562-9873

5. This publication is for
professionals interested in
the use of computers in
their work.

1. Connecticut Computer
Club

2. 18 Ridge Ct W, West
Haven CT 06516

3. Leo Taylor, Secretary

4. CCC Newsletter

5. We have two talks per
meeting; generally one on
software and one on
hardware. The club does
not specialize in any one
machine.

1. API Market Newsletter

2. POB 5314, Mt Carmel
CT 06518

3. Raymond C Jordan, (203)
288-0283

158 April 1981 © BYTE Publications Inc

Circle 107 on inquiry card.

Cor vus Lowers the
Price of Admission to
the Winchester Club

■

Here's the price breakthrough you've been waiting for on Winchester
disk systems. It's our new5'i-inch 5-million byte Winchester that
adds cost effective mass storage to over 15 of the most popular
microcomputers. Now everyone can enjoy the improved reli-
ability, increased storage capacity, and faster speed of
sealed-environment Winchester technology.

You can start with 5 million bytes, then expand the
system with up to three add-on drives of 5. 10,
or 20 million bytes. Our 5 million byte system
has all of the advanced features of the
larger capacity Corvus systems,
including our low cost MIRROR back-
up and multi-user CONSTELLATION
network that allows up to 64 computers to
share the Corvus data base and peripherals
such as printers.

Want the full story? Contact your local computer
store.

\I

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WHEN: NOW!

WHERE: YOUR LOCAL
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\ CORVUS SYSTEMS

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408/946-7700 TWX: 910-338-0226

Clubs and Newsletters,

1. Amateur Computer
Group of New Jersey

2. 1776 Raritan Rd, Scotch
Plains NJ 07076

3. Sol Libes, (201) 277-2063

4. ACG-NJ News

5. User Groups: 8080/Z80,
6800, KIM-1, TRS-80,
PET, CP/M, 1802, S-100,
Apple, and Pascal. We
also have software
libraries and tutorials.

1. OSI Users Group

2. 4 Swimming River Rd,
Lincroft NJ 07738

3. Bob Childs, (201)
747-8888

1. Data Processing Club

2. c/o Dennis M Lloyd,
Business Studies Division,
Gloucester County Col-
lege, Tanyard Rd, Sewell
NJ 08080

3. (609) 468-5000, ext 242

4. Interested in microcom-
puter programs inside
and outside of the
classroom.

Zips 10000—20000

1. New York Amateur
Computer Club

2. POB 106, Church Street
Sta, New York NY 10008

3. Garry Sawyer, (212)
864-4595.

4. New York Amateur
Computer Club News-
letter

5. Anything to do with
computers.

1. Computer Careers News

2. 135 W 50th St, New
York NY 10020

3. Connie Winkler, Editor,
(212) 582-9617

5. Careers publication for
processing professionals.

1. Feedback From Fujitsu

2. c/o Ruder & Finn Inc,
110 E 59th St, New York
NY 10022

3. Darrell J Aherin, (212)
593-6317

5. News of the Japanese

• TRS-80 •

APPLE 2 • ATARI • SCORCERER

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ORDER TOLL FREE

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• APPLE 2 • ATARI • SCORCERER

o

BOX 3435

INTERNATIONAL

A DIVISION OF SCOTT ADAMS. INC

LOIMGWOOD.FLA. 32750

computer, telecom-
munications, and elec-
tronics industries.

1. Lifelines

2. 1651 Third Ave, New
York NY 10028

3. Mary Anna Feczo, (212)
722-1700

5. This publication is for
CP/M users.

1. Association for Com-
puters and the
Humanities

2. Queens College, Flushing
NY 11367

3. Joseph Raben, (212)
520-7407

4. ACH Newsletter

5. Humanities applications.

1. Small Computer News

2. Edwards Publications,
78-56 86th St, Flushing
NY 11385

3. (212) 441-4082

1. D G Independent User's
Group

2. POB 316, Woodmere NY
11598

3. Lloyd Kishinsky, (516)
374-6793

4. Bridge

5. Digital Group computers.

1. Long Island Computer
Association

2. 3788 Windsor Dr,
Bethpage NY 11714

3. A M Stone, Editor, (516)
731-1649

4. The Stack

5. User Groups: S-100,
TRS-80, and 6502.

1. Digiac Corporation

2. 175 Engineers Rd,
Smithtown NY 11787

3. James D Gobetz, Presi-
dent, (516) 273-8600

4. MAPS Digest

5. For MP/M users.

1. CAMS (Capital Area
Micro Computer Society)

2. POB 348, Ridge Rd, RD
#1, Scotia NY 12302

3. Stanley L Mathes, (518)
372-3767

4. Occasional

— Circle 108 on inquiry card.

Subgroups for Apple
(associated with Interna-
tional Apple Corps),
TRS-80, S-100, and other
groups.

1. Sphere Microcomputer
Group

2. 2 Tor Rd, Wappingers
Falls NY 12590

3. Jeffrey Brownstein, DDS,
(914) 297-3950

4. Sphere Newsletter

5. 6800 microcomputers.

1. CHIP-S Microcomputer
Club

2. POB 504, Syracuse NY
13201

1. Mohawk Valley
Microcomputer Club

2. 706 Lee St, Rome NY
13440

3. Rich Weaver

4. Micros Along the
Mohawk

5. Several special interest
groups: 6800, 8080/Z80,
and beginners.

1. RAMS (Rochester Area
Microcomputer Society)

2. POB 90808, Rochester
NY 14609

3. Erwin Rahn, (716)
473-3184

4. Memory Pages

5. Special interest groups:
UFORTH (University of
Rochester FORTH) and
6800/6809/68000. Users
groups: North Star and
CP/M.

1. Monroeville Apple Users
Club

2. Dr G J Harloff

3. 579 Carnival Dr, Pitts-
burgh PA 15239

1. Central Pennsylvania
Computer Club

2. 3263 Bull Rd, York PA
17404

3. Cletus Hunt III, (717)
764-4977

4. Data Dump

5. Special interests: SS-50
bus and TRS-80 systems.

1. Wyoming Valley TRS-80
Club

If you write software,
write Digital Research.

bring your products
to market.

Independent Software
Vendors (ISV's) are the key to
solving the software crunch in
the 1980's. To help you bring
your products to market,
Digital Research introduces
the ISV Support Plan —
designed to assist you in:
Developing Your Product
D With the fast and powerful

PL/I-80™ Programming

System
□ ISV Seminars covering high

level applications

programming

retting Esta
Your Market

ISV Seminars cover:

□ Designing a marketing
strategy

□ Advertising

□ Writing Manuals

□ Assuring software security

□ Supporting and updating
products

On-Going Support Includes.

□ Legal and technical
information

□ Distribution channels

□ Printing facilities

□ Free product listing in our
Applications Software
Catalog

s the world s
largest software marketplace
- — the GP/M® customer base.

So why do it alone? Write
Digital Research. We'll send
you our free brochure
detailing the ISV Support
Plan.

ED DJGiTflL RESEARCH'

P.O. Box 579
Pacific Grove, CA 93950
(408) 649-3896
TWX 910 360 5001

WTTTTT

Visit us at the W

heNCC

Circle 109 on inquiry card.

BYTE April 1981 161

Clubs and Newsletters,

2. 302 Wyoming Ave,
Kingston PA 18704

3. Art Prutzman, (717)
287-1014

5. Special interests: TRS-80
uses and modems.

1. Delaware Valley Com-
puter Society

2. POB 651, Levittown PA
19058

3. Howard Kalodner, (215)
742-6612

4. DVCS Newsletter

5. TRS-80 users group.

1. PACS (Philadelphia Area
Computer Society)

2. POB 1954, Philadelphia
PA 19105

3. Dick Moberg, Eric
Hafler; Hot line (215)
925-5264

4. The Data Bus

5. Users groups for all
major microcomputers,
courses on languages,
computers for children,
and other groups.

Zips 20000—30000

1. Buss: The Independent
Newsletter for Heath
Company Computers

2. 325-B Pennsylvania Ave
SE, Washington DC
20003

3. Charles Floto, (202)
544-0484

5. News on items that are
hardware- and software-
compatible with Heath
Company computers and
Zenith Data Systems.

1. Battery Lane Publications

2. POB 30214, Bethesda
MD 20014

3. Eric Balkan, (301)
770-2726

4. Computer Consultant

5. Information of interest to
free-lance and corporate
consultants.

1. Washington DC CP/M
Users Group

2. 7315 Wisconsin Ave,

The WORKSHEET Problem-Solving Language

Want to play "What-if"? Want to do Real Estate Analysis,
Family Budgeting, Taxes, Company Cash Flow; want to
simulate complex and interrelated processes'? WORKSHEET is
a powerful language designed for the purpose of writing
programs to solve these and all other problems that involve a
row-column "spreadsheet". Even novice programmers are solv-
ing complicated problems on the first day!

WORKSHEET is not a hybrid text editor or a toy. It is a
complete, self-documenting model-building system. List the
assumptions that went into your budget with the SHOWF1L
program — even the boss will understand!

Change the assumptions, the relationships, or the data, and
produce a new spreadsheet, neatly captioned, in minutes.

Model too big to fit on a single page? Format it dynamically —
one page of 12 (or any number) columns, or 2 pages of 6
columns, or whatever tells your story best.

Conditional evaluation of a variable? Reference to variables in
different rows, several columns back? No problem!

Sample models include portfolio valuation, real estate evalu-
ation, iterative solution of a Diophantine equation, family
budget, product profit based on exponentially damped growth
of sales.

Use it for tough, professional jobs — it's the only CP/ M modeling
system that can handle them!

Requires 48K CP/M system and Microsoft Basic . C Basic or
North Star Basic running under CP/ M with Matchmaker 11.

WORKSHEET Language disk (5" or 8" CP/ M) $199.95

(specify version)
80-Page Manual only $ 19.95

The SoHo Croup

140 Thompson St., Suite 4-B

New York, NY 10012

Note: CP. M, Microsoft, and North Star arc registered trademarks of Digital
Research. Microsoft, and North Star Computers, respectively.

Washington DC 20014
3. Winston Riley III, (301)

986-1234
5. Public-domain software
exchange, review of
operating systems,
languages, and packages.

1. WACS (Washington
Amateur Computer
Society)

2. 4201 Massachusetts Ave,
#168, Washington DC
20016

3. Robert Jones, Director

4. ]WACS

5. Interested in I/O Selectric
conversions; inexpensive
terminals and personal
systems; 9900, 6800,
8080/Z80 hardware and
software.

1. Washington Apple Pi

2. POB 34511, Washington
DC 20034

3. Bernie Urban, (301)
229-3458; club phone
(301) 468-2305

4. Washington Apple Pi

5. Education, medical,
Pascal, assembly lan-
guage, games, helping
neophytes in computer
programming.

1. TI Programmable
Calculator Club

2. 9213 Lanham Severn Rd,
Lanham MD 20801

3. Maurice E T Swinnen,
Editor

4. TIPPC Notes

5. All AOS system pro-
grammable calculators.

1. PEEK(65)

2. POB 347, Owings Mills
MD 21117

3. Al Peabody, (301)
268-0561

5. This is a journal for OSI
users.

1. CHUG (Capital Heath
Users' Group)

2. POB 341, Fairfax VA
22030

3. Dale Grundon, Secretary

4. >CHUG

5. Interested in all Heath
computers and related
equipment.

1. AMRAD (Amateur Radio
Research and Develop-
ment Corporation)

2. 1524 Springvale Rd,
McLean VA 22101

3. Paul L Rinaldo, (703)
356-8918

4. AMRAD Newsletter

5. Special interests: amateur
radio and computers,
computers and com-
munications devices for
the deaf, amateur com-
puter networking.

1. WAKE (Washington
Area KIM Enthusiasts)

2. 5112 Williamsburg Blvd,
Arlington VA 22207

3. Ted Beach

4. Monthly

5. KIM and other 6502
single-board computers.

1. The Microcomputer In-
vestors Association

2. 902 Anderson Dr,
Fredericksburg VA 22401

3. Jack M Williams, (703)
371-5474

4. The Microcomputer In-
vestor

5. Use of microcomputers to
assist in making and
managing investments.

1. Delmarva Computer
Club

2. POB 36, Wallops Island
VA 23337

3. Jean Trafford, (804)
824-3400

4. Peek-n-Poke

5. Special interests: 6502
processors, computer aids
for the handicapped,
education, business, and
entertainment programs.

1. Tidewater Computer
Club

2. 677 Lord Dunmore Dr,
Virginia Beach VA 23464

3. C D Yeoman, (804)
420-6379

4. Hard Copy

1. Triad Heath Users Group

2. 424 Cliff dale Dr,
Winston-Salem NC 27104

3. Hughes Hoyle, (919)
378-1050; Steve Minor,
(919) 765-7717

162 April 1981 © BYTE Publications Inc

Circle 110 on inquiry card.

• Upgrade 8 bit systems
All boards assembled & tested

Here's the nucleus of a truly exceptional S-100 system:

1. 16 bit/8 bit Dual Processor (w/6 MHz 8088)

2. System Support 1

3. Disk 1 DMA Floppy Disk Controller (w/BIOS for CP/M * 2.2)

4. 32K of fast static RAM (w/IEEE 24 bit extended addressing)

5. Sorcim's powerful PASCAL/M *-8086 software on disk

6. Digital Research's CP/M *-86 software on disk

7. I/O and Disk Controller cables, plus full documentation on all hardware and software

* PASCAL/ M is a trademark of Sorcim: CP/M is a registered trademark of Digital Research

Total Package Price: $2495

- ORDER BEFORE MAY 1ST

AND WE'LL ADD AN EXTRA 32K OF STATIC RAM FREE !

DON'T MISS OUT!

AVAILABLE AT FINER COMPUTER STORES, OR ORDER DIRECTLY FROM US.

omouPro

OAKLAND AIRPORT, CA 94614 (415) 562-0636

ELECTRONICS

Terms: Calilornians add tax. Allow for shipping (excess refunded). VISA and Mastercard orders call i415) 562-0636,
Circle 111 on inquiry card.

ude street address lor UPS

BYTE April 1981 163

WESTICO... Because
getting good software
fast is hard.

To get your software tomorrow,
call Westico todav. (203) 853-6880.

Westico understands your micro-
computer software needs. We know
you want a good selection of soft-
ware without the hassle of hunting
all over for it. , .We know you want it
f ast . . . And we a Iso know you wa nt a
product Packed by service. With
Westico you get all three.

We have an extensive list of

guality software products for the
serious microcomputer buyer —
accounting, professional time ac-
counting, text processing, planning
and analysis, telecommunications,
data management, development^
tools. And the list is growing.

Dial-up the 24-Hour
Hotline (203) 853-0816
(300 baud)

It's an on-line catalog, updated
each day! See displays of all prod-
ucts and the latest version numbers
and prices. Build a trial order with-
out any obligation. Complete the
order only if you wish. We also offer
24-hour delivery service. Call, write,
Telex or dial-up today. C.O.D., Master
Card and VISA accepted.

ASCOM program for time sharing
and data transfers. • Transfers files
between computers • Conversation
mode controls remote computers

• Batch mode by command files

• Commands to display directories
and type files

ASCOM can log-on a time
sharing system to retrieve stock
exchange data for storage and
analysis. Batch mode can make the
log-on, password, data guery, and
storage automatic. ASCOM can
transmit program files to another
micro running ASCOM — locally, or
remotely through a modem.

MINIMODEL™ Financial Planning'
Tool — does big financial planning
jobs at micro prices — for cash flow
projections, financial forecasting,
venture analysis, project planning
and risk analysis. • Model size
limited only by disk file size. •Operat-
ing results can be fed into models.

• Time horizon advances to elimi-
nate old data • Consolidates
models into higher level models

• Consolidated models are process-
ed u nder thei r own ru le set • Report
content and format totally under
user control.

■

CP/M™ programs for TRS-80 Model II, Apple with Soft-
Card,™ Vector Graphic, iCom, Cromemco, North Star,
Micropolis, Ohio Scientific, SuperBrain and more.

GENERAL LEDGER Peachtree 7 "

$550

$40

A,D,I,L

ACCOUNTS RECEIVABLE Peachtree

550

40

A,D,I,L

ACCOUNTS PAYABLE Peachtree

550

40

A,D,I,L

INVENTORY CONTROL Peachtree

650

40

A,D,I,L

PAYROLL Peachtree

550

40

A,D,I,L

CLIENT WRITE-UP Peachtree

990

40

A,D,I,L

PAS-3 MEDICAL Artificial Intelligence

990

40

A.CI,

PAS-3 DENTAL Artificial Intelligence

990

40

A.C.I

PROPERTY MANAGEMENT Peachtree

990

40

A,D,I,L

PTA Asyst Design

595

40

A.C.I

PTA Demo Asyst Design

75

40

A,C,I

ESQ-1 Legal Micro Information

1495

50

A,C,I,L

ESQ-1 Legal Demo Micro Information

75

50

A,C,I

DATEBOOK'" Organic Software

295

25

A,l

WOR DM ASTER™ MicroPro

145

25

A,K,L

WORDSTAR'" MicroPro

450

40

A.F.K.L

MAIL-MERGE'" MicroPro

125

25

A,F,K,L

WORDSEARCH'" Keybits

195

40

A,F

TEXTWRITER Organic Software

125

20

A

M I N I MO DEL Financial Planning

495

50

A,C,I,L

STATPAK NW Analytical

500

40

A.D.I

MILESTONE™ Organic Software

295

25

A.I

ASCOM DMA

125

10

A,T

CBS DMA

395

40

A,F,K

CBS LABEL OPTION DMA

80

10

A.F.K

MAGSAM III MAG

145

25

A.CorD.F

MAGSAM IV MAG

295

25

A,C,F,K

SELECTOR IV Micro-Ap

395

25

A.CG.K

PRISM/IMS MAG

495

55

A,C,F,K

PRISM/ADS MAG

795

55

A,C,F,K

PL/l-80'" Digital Research

500

35

B.F.L.P

BASIC-80 Microsoft

350

25

A,F,L

BASIC COMPILER Microsoft

395

25

A,F,L

S-BASIC" Topaz

295

25

A,F

NEVADA COBOL Ellis Computing

150

25

A

CBASIC-2™ Compiler Systems

120

15

A

PASCAL/M'" Sorcim

175

20

A,G

GENERAL SUBROUTINE PAK Asyst Design

295

30

A.C.K

APPLICATION UTILITIES Asyst Design

495

30

A,C,K

PASCAL/MT*-™ MT Microsystems

425

30

A,G

SUPERSORT I MicroPro

225

25

A,L

SURVEYOR Peachtree

550

40

A,D,I,L

STRING BIT'" Keybits

65

15

A

STRING/80'" Keybits

95

15

A

STRING/80 SOURCE Keybits

295

n/a

A

ULTRASORT II'" CCS

165

15

A

All software has specific requirements for proper operation such as computer type,
equipment configuration and support software.

Check the following codes for system requirements to be certain your system will
accept the software offered.

(A) CP/M version 1.4 or higher. (I) Business system: 48K memory. 200K

(B) CP/M version 2.0 or higher. dual disk drives, cursor addressable

(C) CBASIC-2. terminal, and 132 column printer.

(D) MBASIC version 4.51. (K) Cursor addressable terminal.

(E) BASIC-80 version 5.0 or higher. (L) signed license required for shipment.

(F) 48K memory or greater. (O) specify 8080. Z80, or CDOS.
(G)56K memory or greater. (P) give CP/M serial number.
(H) 64K memory. (T) serial port and modem

(Z) Z80CPU.

Specify disk format: North Star Single or Double, Micropolis Mod I or Mod II, 8" single
density, Ohio Scientific, SuperBrain or Apple.
Prices do not include shipping or C.O.D. In CT add 7%% sales tax.
"Manual price will be credited against later purchase or software.
Dealer inquiries invited. Copyright t 1981 Westico. Inc

WESTICO

The Software Express Service

25 Van Zant Street • Norwalk, Connecticut 06855
(203) 853-6880 • Telex 643-788

1. Carolina Apple Core

2. FOB 31424, Raleigh NC
27612

3. Joseph H Budge, (919)
489-4284

4. From The Core

5. Apple computer users
group.

1. TRS-80 Users Group

2. 7554 Southgate Rd,
Fayetteville NC 28304

3. R Gordon Lloyd

4. TRS-80 Users Group
Newsletter

5. We are interested in all
aspects of the TRS-80.

1. TIPS Users Group

2. 101 Brookbend Ct,
Mauldin SC 29662

3. Fred Holmes, (803)
288-5664

4. TIPS Newsletter

5. Special-purpose stand-
alone systems and home-
brew computers.

Zips 30000—40000

3.

4.

Digital Publications Inc

3169 Holcomb Bridge Rd,

Suite 307, Norcross GA

30071

John Rapp, Publisher,

(404) 451-1156

Mini-Micro, free software

exchange

Software exhanges and

publications for Data

General, IBM, and DEC

PDP-11 and PDP-8

systems.

1. Culpepper and Associates
Inc

2. 4922 Heatherdale Ln,
Atlanta GA 30360

3. Warren Culpepper, (404)
451-3797

4. Salt 'ri Pepper

5. Special interests: software
product management.

1. CSRA Computer Club

2. POB 284, Augusta GA
30903

3. Jim Graves, President,
(404) 738-1378

4. CSRA Computer Club
Newsletter

April 1981 © BYTE Publications Inc 165

T5€:HfiRDSID€

6 South St .Milford, NH 03055 (603)673-5144
TOLL FREE OUT-OF-STATE 1-800-258-1790

COLOR COMPUTER
$359.

POCKET
COMPUTER
WITH INTERFACE

$259.

MODEL III $919.

TRS-80 COMPUTERS

Mod I, 64K RAM (#26-4002) $3599.00

Mod III, 16K RAM (#26-1062) $919.00

Mod III, 48K RAM (#26-1062 + ) $1039.00

Pocket Compw/lnter (#26-3501+) — $259.00

Color Comp, 4K RAM (#26-3001) . .
Color Comp, I6K RAM (#26-3001+)
Color Comp, Ext BASIC (#26-3002)

.$359.00
.$399.00
.$529.00

MODEL I DISK DRIVES

HARDSIDE 40-track Dr ( #7-40) $329.00

PERC0M TFD-40 Dr(#7-99) $379.00

PERC0M TFD-100 Dr (#7-100-1) $399.00

HARDSIDE 80-trackDr (#7-80) $449.00

PERC0M Dual TFD-100 Dr (#7-100-2) . . $799.00

PERCOM Data Sep (#7-03) $29.95

PERCOM Doubler(#?-07) $199.95

HARDSIDE Ext Cable (#7-02) $15.95

HARDSIDE 2-Dr Cable (#7-04) $29.00

HARDSIDE 4-Dr Cable (#7-05) $39.00

MODEL I PERIPHERALS

COMM-80 Interf (#4-80) $159.00

CHATTERBOX Interf (#4-81) $239.00

DISK-80 Interf, 16K RAM (#4-82) .... $339.00
DISK-80 Interf, 16K RAM (#4-83). . . . $369.00

BUSY BOX Interf (#4-01) $99.95

LYNX Communications Interf (#19-80) . $229.00
RS Expan Interf 32K RAM(#26-H40-32) $399.00
16K Memory Kit TRS-keypad(#6-no2-i) $59.00
16K Memory Kit, TRS-lnterf (#5-1102) . . $59.00

Dual Joysticks for Color Comp (#26-3008)$24.95
VISTA Model II 8" Disk Dr 1 (#7-4001) . $939.00
VISTA Model II 8' ' Disk Dr 3 (#7-4002) $1795. 00

0RCHESTRA-80(#i5-03) $79.95

Upper/Lower Mod Kit (#15-02) $24.95

CPU Speed-up Mod kit (#15-04) $37.50

Video Reverse Mod kit (#15-05) $23.95

2-port TRS-BUS Ext (#15-12) $29.95

3-port TRS-BUS Ext (#15-13) $39.95

TRS-80 Model I Dust Cover Set (#16-01).. $7.95
TRS-80 Model I Carrying Case(#i7-201)$109.00
TRS-80 Monitor Carrying Case (#17-202) $84.00

CTR-80A Cass Recorder & Cable(#26-1206)$59.95
TRS-80 Model III Dust Cover (#16-05) . . . $7.95

TERMS: Prices and specifications are sub|ect to change. HARDSIDE accepts VISA & MASTERCARD.
Certified checks and Money Orders; Personal checks accepted (takes 3 weeks to clear). HARDSIDE Pays
all shipping charges (within the 48 states) on all PREPAID orders OVER $100.00. On all orders under $100
a $2.50 handling charge must be added. COD orders accepted (orders over $250 require 25% deposit)
there Is a $5.00 handling charge. UPS Blue Label, and Air Freight available at extra cost. TRS-80 Is a
trademark of Tandy Corp.

5. Users groups: TRS-80,
Apple, and 6800.

1. Albany Computer Club

2. Albany Junior College,
2400 Gillionville Rd,
Albany GA 31707

3. Dr Donald Cook, (912)
439-4205

5. Our interest covers all
microcomputers.

1. Level II Club

2. 4406 W Lawn Ave, Tam-
pa FL 33611

3. D Griffith

5. We are interested in
trading original software.

1. ASCII, Sol User's Group

2. POB 10325, Tampa FL
33679

3. J Brockway, (813)
837-4655

4. ASCII

5. Sol computers.

1.

CAMS (Central Alabama

Microcomputer Society)

6375 Pinebrook Dr,

Montgomery AL 36117

Lewis E Garrison, (205)

272-8462

READY

TRS-80 hardware and

software.

National Association of
Computer Stores

2. 3255 S US 1, Ft Pierce FL
33450

3. Steven W Koerner, Ex-
ecutive Director, (305)
465-9450

4. Monthly newsletter

Zips 40000—50000

1. ACSCO (Amateur Com-
puter Society of Central
Ohio)

2. 215 Delhi Ave, Apt J,
Columbus OH 43202

3. Paul Pittenger, President,
(614) 267-3412

4. I/O

5. Graphics and personal
networks.

166 April 1981 © BYTE Publications Inc

Circle 1 12 on inquiry card.

Circle 113 on inquiry card.

V

The
next

generation
of business
software

% v
v

If you've been searching for a complete line of
quality software for your small business com-
puter, your search is over. Designer Software is
pleased to announce Phoenix'", the first line of
business software to include both professional
word processing and general accounting.
Word Processing

We designed Phoenix'" Word Processing to
compete with high-priced, dedicated word pro-
cessors. It is completely new from top to bot-
tom and is unlike any other word processing
software currently available. Phoenix'" is more
powerful than WordStar 1 ", more flexible than
Magic Wand™ and easier to use than either. We
built "human engineering" into the product to
make it easy for non-technical personnel to
use. The commands are simple and logical; the
documentation is well-written and organized;
and the training program is something that,
frankly, you'll have to see to believe.

Accounting
Phoenix'" Accounting includes the five general
applications and a growing number of specific
applications. Each accounting package was
designed by CPA's and written in COBOL with
an underlying assembly-language database for

Designer Software

HOUSTON

speed. All of the general accounting packages
— General Ledger, Accounts Payable and
Receivable, Payroll and Inventory — have been
field-tested, some for as long as two years.
Specific applications include Fixed Assets Ac-
counting, Mailing List Maintenance, Tenant
Processing, Financial Projection, and Time/Bill-
ing. We are developing more all the time.

Documentation for Phoenix'" Accounting is as
revolutionary as it is for Phoenix'" Word Pro-
cessing. We don't just teach you which buttons
to push and leave it at that. We take the time to
explain the accounting principles behind the
packages, because we think that you can use
our products better if you understand why we
ask you to do certain things. And we've made a
special effort to make the manuals entertaining
as well as informative so that you will want to
read them.

See us at the Faire

We are unveiling Phoenix''" at the Sixth Annual
West Coast Computer Faire. If you are planning
to attend, we hope that you will drop by booth
1018-20 to see us. If you can't make it this year,
write, call or contact Us via The Source and
we'll send you more information.

Designer Software only sells through
dealers. Dealer inquiries invited.

3400 Montrose Boulevard • Suite 718

Houston. Texas 77006

(713) 520-8221 • SOURCE TCU671

Circle 113 on inquiry card.

BYTE April 1981 167

MICROMAIL HAS WHAT
YOUR SYSTEM NEEDS.

DIABLO

630

The Diablo Model 630 is a reliable, high quality, full-
character serial printer for anyone who is seeking superior
print quality at a low cost. This is the first Diablo printer to
offer complete interchangeability between metal and
plastic print wheels. And the sophisticated and discerning
user does not sacrifice print quality to obtain this versatility.
Every aspect of the Diablo 630 design has been focused on
maintaining outstanding print quality. Terminals also
have self-test, extensive internal diagnostics and
automatic bidirectional printing.

$1,999.00
With Adjustable Forms Tractor add $200.00

ANADEX

Standard features include expanded and com-
pressed print, underlining, true lower-case
descenders, RS-232C, Parallel, and 20mA inter-
laces, last bi-directional printing, and high-
resolution graphics.

DP-9599 $1299.00

DP-9501

2K Expanded Buffer Option $70.00

TEXAS INSTRUMENTS

Fast, reliable, and widely supported, the T.I. 810
has proven itseli to be a solid printer for business
or industry.

810/2 $1,549.00

(includes upper /lower case
option)

810/2VFC/CP $1,679.00

(includes u/1 case, forms
control & compressed print)

Prices good through May 15, 1981

PRINTERS

C.R.T.'s

ANADEX

Tele Video

DP9000
DP-9001

$1199
$1199

Just like the 9500/9501. but 5
inches narrower. Uses paper
up to 9.5 inches wide.

DIABLO

1640RO $2525

Uses plastic daisywheels,
prints up to 45 c.p.s.

1650RO $2675

Uses metal daisywheels, prints
up to 40 c.p.s.

912C $ 725

920C $ 795

950 $ 995

NEW! Features a detachable
keyboard & programmable
function keys.

SOROC

IQ.120 $ 689

IQ.140 $1099

IQ.135 $ 849

NEW! Microprocessor
controlled, programmable
function keys.

C. ITOH

CITIOO
DEC

$1625

VT-lOO

$1650

TELEPRINTERS

DEC

LA 34 $ 969

Dot-matrix, 30 c.p.i. Adjustable
character sizes & line spacing.

LA34AA $1099

Includes programmable forms
length control.

TELETYPE

43 $ 999

Very reliable 30 c.p.s.
teleprinter. Ideal for use with
300-baud acoustic couplers or
modems.

DIABLO

1640KSR $2830

Uses plastic daisywheels,
prints up to 45 c.p.s.

1650KSR $2940

Uses metal daisywheels, prints
up to 40 c.p.s.

i:MJCRaMflJL.,

MICROMAIL • BOX 3297 • SANTA ANA, CA 92703
(714) 731-4338

To Order: Send check to MICROMAIL. P.O. Box 3297, Santa Ana. CA 92703. Personal or company checks
require two weeks to clear Visa/MasterCard accepted. C O.D. requires a 15% deposit. Handling: Add 3% to
orders less than 3750, 2% to orders $751 ■ S2.000. 1% to orders over $2,000 NOTE: Handling charges are
waived on orders pre-paid in advance by check Shipping: We ship FREIGHT COLLECT via UPS or Motor
Freight Air and Express delivery is available.

1. Midwest Affiliation of
Computer Clubs

2. POB 20205, Columbus
OH 43220

3. Douglas Troughton, (614)
574-8152

4. MACC-Pack, and Cotn-
puterfest

5. Promoting personal com-
puting by helping mem-
ber clubs in any way
possible.

1. TI 99/4 Users of Cincin-
nati

2. 8075 Spring Garden Ct,
West Chester OH 45069

3. Larry Morrow, (513)
777-7042

5. Exchange of information
and ideas concerning the
TI 99/4.

1. DMA (Dayton Micro-
computer Association)

2. c/o Dayton Museum of
Natural History, 2629
Ridge Ave, Dayton OH
45414

3. Gary Turner, (513)
848-6911

4. Data Buss

5. Numerous special interest
groups and help for
beginners.

1. Apple-Dayton Users
Group

2. 4819 Leafburrow Dr,
Dayton OH 45424

3. Dick Peschke, Secretary,

Gone

with the

wind.

We could lose

our national symbol . . .

the majestic bald eagle.

Once man drives eagles
out of their nesting areas, they
rarely return. Today there are
only about 900 pairs of eagles
known to be nesting in the
lower 48 states.

We can save the eagle by
establishing eagle preserves.
You can help. Join the National
Wildlife Federation, Department
102, 1412 16th Street, NW,

.Washington, DC 20036.
Let's keep the eagle
£5^3 around another
hundred years.

168 April 1981 © BYTE Publications Ire

Circle 114 on inquiry card.

Circle 115 on inquiry card.

£ ■-

/ A

y > ////

osy ,.;.

/•■; ?t

'!:':•: I :

i : llll .-. : --v' L - .

//'ii

/ SAVE $50

We design and manufacture a complete line of industry
compatible microcomputer assembled and tested boards
and kits for your system. All are S-100 bus compatible
and use the Z-80 microprocessor.

With over 25,000 boards and hundreds of computer sys-
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you both proven and state-of-the-art products! We pro-
vide you with a complete family of kits for all your sys-
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SBC 100/200 — A 2.5/4 megahertz range of single
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ExpandoRAM till — For use with 250/200 nanosecond
\ RAM, these high density boards offer 16 to 64K memory;
\ the ExpandoRAM II can achieve RAM capacities up to
' 256K using 64K chips.

' Versafloppy //// — A floppy disk controller for up to four

drives, supporting single/double density and single/dou-
ble-sided disk formats.

VDB-8024 — A full function visual display board with a
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Z-80 Starter Kit — A low-cost entry into the world of
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Prom 100 A specialty board of SD Systems which
allows you to program 2708/2716/2732 proms.

SD SYSTEMS

P.O. Box 28810 • Dallas, Fexas 75228 • Telex 6829016

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by 10-15-81.

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Mississauga, Ontario Canada
416-274-6033

SIRTON PRODUCTS

Surrey, England, U.K.
UK-OI-660-5617

V.\»

GIFTS FROM PROMETHEUS

NEW for APPLE II

Advanced products at

Down-to-Earth

PRICES

DUAL SERIAL CARD-1.

All functions of two
independent serial
cards on one board -plus
more. Provides Apple ll (1) users
with two simultaneous asynchro-
nous serial channels. DSC-1 appears
as two separate logical serial cards to
the Apple ll (1) . Fully software
compatible with all Apple ll's (1) and
Microsoft software. 2716 EPROM
used for easy driver modification. In
addition, the second serial channel
supports these extra features:
• Strapable DCE/DTE. • Secondary
RS-232 handshake functions (DCD,
DTR, DSR) • Strapable logical slot
location and hardware looks like it's another
slot. Order: PP-DSC-1 @ $189.00 each

DUAL SERIAL/PARALLEL CARD-1. As with the Dual Serial Card-1
(above), the Dual Serial/Parallel-1 provides Apple users with simultaneous
use of one full serial port and one parallel port. Both ports strapable for
any Apple peripheral slot. Fully compatible with all Apple and Softcard
(CP/M) software. Drivers for serial interface and Centronics parallel
interface are contained in modifiable industry standard EPROM. Serial
port is configured like DSC-1 . Order: PP-DSP-1 @ $189.00 each.

MEMORY EXPANSION MODULE-1. Expand your Apple ll< 1 >to afull64K
RAM system with highest quality 1 6K dynamic RAMS. Fully buffered to
provide reliable operation - even with fully loaded Apples. Total compati-
bility with Microsoft Softcard (2) /CP/M (3) and all Apple software. Supplied
complete with installation instructions and test program.

Order: PP-MEM-1 @ $149.50 each.
PASCAL MT+ MEM-1. A modular native Z-80 code Pascal compiler.
ISO standard. Includes a MEM-1 (detailed above). Have a full Pascal
compiler at half the Apple price. Requires a Microsoft Softcard <2) and two
disk drives. Note that the Pascal MT+ alone is normally $250.00.

Order: PP-PMT-1 @ $299.00 each.

16K RAM ADD-ON rOTS. For TRS-80 and Apple ll (1) . Eight (8) full-
specification industry standard 1 6K RAMS. These are not seconds.

Order: PP-RAK-16 @ $29.00 each.

All Prometheus boards are completely tested and burned-in prior to shipment.
One-year warranty covers parts and labor. MONEY BACK GUARANTEE: Order
now without risk. Boards may be returned, in good condition, after up to 10 days
df trial for a full and prompt cash refund. California: add 6% tax; BART Counties,
6 1 /2%. Orders under $150, add $3.00 postage, for handling charge.
Freight allowed on orders over $150. Dealer inquiries invited.
Quantity discounts available.

PROMETHEUS

PROMETHEUS PRODUCTS INCORPORATED

4509 Thompson Ct. • Fremont, CA 94538 • (415)791-0266

Registered Trade Marks: (1) Apple Computers, Inc. (2) Microsoft Consumer Products (3) Digital Research. Inc.

VfSA

i

7*t

(513) 236-3619
Apple-Dayton Newsletter

1.

2.

TRI-STATE Computer
Club

2669 Highmeadow Ct,

RT 1, Wheelersburg OH

45694

Douglas Troughton, (614)

574-8152

Yes

Special interests: TRS-80,

Apple, OSI, KIM,

PDP-11, and 6800

systems.

AIM-65 User's Group
R R#2, Spencerville OH
45887

Donald Clem, (419)
647-6576
Target

Special interests: AIM-65-
and 6502-related informa-
tion.

1. Apple One Library

2. 51625 Chestnut Rd,
Granger IN 46530

3. Joe Torzewski, (219)
272-4670

5. We actively support the
Apple I computer.

1.

1.

Northern Indiana Com-
puter Hobbyist Exchange

927 S 26th St, South
Bend IN 46615
Eric Bean, (219) 288-2101
NICHE Newsletter

Evansville Computer
Club

2. c/o National Sharedata
Corporation, POB 3895,
Evansville IN 47737

3. Robert Heerdink

5. Special interests: S-100,
TRS-80, Bally, and Apple
systems.

1. The Midwest Buss

2. 441 E Bemhard, Hazel
Park MI 48030

3. Art Blundell, (313)
547-3011

5. Special interests: our
buy-and-sell forum and
swapping news from club
to club.

1. Sorcerer's Apprentice
Computer User's Group

170 April 1981 © BYTE Publications Inc

Circle 116 on inquiry card.

If you are the owner of an Apple, Pel, Atari, orTRS-80 ami also have a disk drive, we have some of the
those systems u/ith sound capability, our games have Crystalsonics — a newly developed concept in tone generation. For Apple and Atari (here are
some truely superlative hires graphics. In fact, Sands of Mars offers 3-D graphics and flight simulation landing. It includes over 186 full screen hires
maps of Martian terrain.

••***••****

We now serve over 30 countries around the world. Dealership and distrihutor inquiries are welcome. Special rates are available on larger orders. We
have 48 hours delivery to anywhere in the continental United States. We are also looking for experienced programmers and new game software. Our
royalty terms are extremely generous. If you have what you consider to be a quality product that you would like to have marketed please give us a call.
If you would like to be a member of the Crystal User's Club and be eligible to receive free user contributed software, please submit a program of any
type and a $10.00 membership fee. In return you will receive a Crystal Membership Card, a copy of The House of Usher, and a year's subscription to
Crystal Vision.

HOUSE OF USHER — Wander through a haunted house. Rooms and
scenery in 15 color lo-res graphics. We offer a $100.00 prize to the first
person to solve the mystery. Over 200 monsters, objects and perils.
$24.95

GALACTIC QUEST — Crystalsonics - hires graphics -the ultimate
space adventure. Vegan warships attack and fire in real time simula-
tion. Land on and trade with over 64 star systems in 3 galaxies. Allow
6-12 hours for play. $29.95

SUMER — Travel back through time to ancient Sumeria in the middle
cast. You are given 10 years as king to restore this kingdom to prosper-
ity. Plant, war, consult the astrologers - very hard to beat! $19.95

LASAR WARS — Crystalsonics - hires graphics - protect the planet
earth from a full scale alien invasion. Over three types ol invading craft
and hundreds of approach simulations. The games speaks for itself.
$29.95

WORLD WAR III — Crystalsonics - hires graphics - for you war game
freaks, this is it! Iran and Irag - nuclear missiles - hires 3 scene bat-
tlefield - demolition squads - tanks - strategy. Custom designed for two
arm chair generals. Save the world from nuclear holocaust! $29.95

BENEATH THE PYRAMID - Crystalsonics - hires graphics - brand
new! Explore the pyramids and miles of winding secret tunnels beneath
I hem. Enter at the Sphinx and find the hidden treasure chamber . All in
hires with very aggressive monsters and many many perils. To win you
must find the golden cat and your way out!!! $29.95

LITTLE CRYSTAL — Especially designed anthology for children from ages 5 to 80. Includes Mr. Music which turns your Apple into an organ ul
sorts, gunk where two weird monsters shoot it out and many other educational as well as entertaining programs for children. True unique addition for
kids who always feel left out of Dad or Mom's computerizing. $39.95

SANDS OF MARS — What we at Crystal believe to be the fittest advettlure game available to dale. In addition to hires graphics and super tone
routines where the user's system will support it, this game provides landing simulation, animation, and revolutionary 3-D graphics. It is the ultimate
in space adventure and may takeseveral weeks or months to play. It istheOydessy of the Slarship Herman on its maiden flight to Mars. Hie initial lilt-
off is animated and paddle controlled. The flight through space is in Hires 3-D Graphics with many animated scenarias. You must land your slarship
on Mars, it will lack enough fuel and supplies for a return voyage. You must lead your party through hundreds of Hires maps of Martian let rain and
subterrainian passages. You then will secure adequate resources for take off, navigate your ship back to earth and attempt a successful touchdown.
There is a mystery buried in the ancient city of Lemuria beneath the sands of Mars. We offer a $100.00 prize to the first space gamer to discover it.
Good luck! $39.95

For more information you may write or call:
Crystal Computer, 12215 Murphy Avenue, San Martin, California 95046 (408) 683-0696

atMicrohouse

Spring
Qeanirig

Sweep up savings on leading
hardware and software!

We at Microhouse would like to
thank you worldwide for your
tremendous response to our
wide range of discounted hard-
ware and software. To serve
you better, call or write us any-
time for your hardware and soft-
ware needs. If you don't see it,
ask!

We will attempt to meet or beat
any advertised price!

Software Manual
List & Manual/Only

Software

D WORDSTAR The premier word pro-
cessing, software from MicroPro
S49S.00 $322/840

:_■ MA1LMER0E option for Wordstar 2 X
S150.00 $110/825

D WORDMASTER by MicroPro.

S150.00 $118/825

D SUPERSORT I by MicroPro. Can be
used as a stand-aJone program or can
be linked to programs with a Microsoft
format $250.00 $189/825

O SUPERSORT II A stand alone-only ver-
sion of above. ...$200.00 $18S/$25

D DATASTAR by MicroPro.

$350.00 $289/535

O SPELLGUARD checks 20 pages of
copy for spelling mistakes and typos In
less than a minute. Can be used with
many CP/M® word processors (inclu-
ding WordStar). Lets operator review
words It judges as potential errors. Oper-
ator may then change the suspect word
or add if to SPELLGUARDs 20.000
word dictionary (dictionary size limited
onty by disk space). $295 $230/$20

D dBASE II, the assembly-language re
lalional Database Management System
for CP/M* . No need for host language
Handles up to 65.000 records (up to
32 fields of 1 K each). English-like com-
mands. Report generator with user-de-
finable fun-screen operation. Win read
existing ASCII files ..$700 S628/J20

D TCS/AManta INTERACTIVE AC-
COUNTING SYSTEM for small busin-
esses New release. Each package
can be used atone or post automatic-
ally to the General Ledger. Available
in complied version (no support lan-
guage needed) or in source (MBASIC
required). Needs 48K RAM. 132-col.
printer. 24x80 CRT and CP/M*

COMPARE AT UP TO J530/pkg.

GENERAL LEDGER $757125

ACCOUNTS RECEIVABLE . . $757$25

ACCOUNTS PAYABLE $75/825

ACCOUNTS PAYABLE $75/825

PAYROLL $7S/$25

ALL FOUR »259/$25

SAMPLE PRINTOUT BOOK of ALL

FOUR $15

D STRUCTURED SYSTEMS ACCOUN-
TING SYSTEM (Requires CBASIC2.
2 dsk drives, 24xS0 CRT. 132-cokjmn
width printer). . . LIST: $1250.00 each

GENERAL LEDGER $899/840;

ACCOUNTS RECEIVABLE . . $689/840

ACCOUNTS PAYABLE $6>0/$40

PAYROLL $698/840

INVENTORY $337/$40

□ BASIC 80 by Micro. Version 5.2 and
4.51 Included. . . . $350.00 $299/130

D BASIC COMPILER by Microsoft. Lan-
guage compatible with MBASIC. In-
cludes MACRO 80 assembler
$395.00 $33<V$30

D COBOL N Compter by Microsoft.
$750.00 $«40/$30

O MSORT by Microsoft $138/815

D COBOL 80 wfMSORT. Saving by
buying both at the same time. $759/$40

Q Whtte.mrth'1 "C" COMPILER. Con-
forms to fuR UNIX* version 7 C lan-
guage $630.00 CALL/130

D STACKWORKS FORTH. For Z80 or
8080 CPU (specify). Suppled in source
Assembler included If 75.00$1257$30

D FORTRAN 80 by Microsoft.

$500.00 $390/$30

D MACRO 80 by Microsoft Assembler
for 8080 and Z80$200.00 $140/$20

D PASCAL/M compter by SORCIM Ful
Wrln implementation. Produces P-corJe.
$175.00 $139/$20

□ PASCAL/Z compter by ITHACA INTER-
SYSTEMS. Produces Z80 native as-
sembly code $395.00 $359/$30

D UCSD PASCAL . ..$350.00 $299/$50

D muStMP/muMATH by Microsoft
muSIMP Is a fast, efficient interpreter
for sophisticated mathematical functions
of up to 61 1 digits. muMATH is a pack-
age of programs written In muSIMP.
Requires 40K . . . $250.00 S225/J25

D NAD (Name 8 Address).

$100.00 $68/820

□ OSORT by Structured Systems.

$100.00 J68/J20

□ ANALYST by Structured Systems.
$250.00 $195/120

D CBS • Configurable Business Sys-
tem. Requires no support language!
$383/$40

D DIAGNOSTICS I by Supersoft.

$75.00 $48l$20

D DIAGNOSTICS II.

$100.00 $82.50/820

DTERM $150.00 $94/*20

D DATEBOOK by Organic Software
$295.00 $25B/$25

D EDIT 80 by Microsoft

$/ 20. 00882/820

H TEXTWRITER III by Organic Software

$125.00 $110/820

D LETTERIGHT by Structured Systems.

$200.00 $138/820

D MAXELL 8" SINOLE-slded Double
Density Diskettes (Box 10).
$57.50 $43.75

D MAXELL 8" DOUBLE-slded Double
Density Diskettes (Box 1 0).
$87.50 $88.25

D MAXELL 5%" SINQLE-sided Double
Density (Box 10) ... $55.50 $37.50

O MAXELL 5 V." DOUBLE-skted Double
Density (Box 10) ....$82.50 $82.80

D WABASH 8" SJNOLE-slded. slngte-
densrty(BoxlO) $29.51 $27.24

D WABASH 8" DOUBLE-slded. doubte-
den«Jty(Box 10) $49.79 848.98

D SCOT CH HEAD CLEANING DIS-
KETTES Includes two diskettes and
bottle of cleaning solution. For single
or double sided drives $30.00 $20.70

Hardware

D EPSON MX80 DOT MATRIC PRINTER
with its ingenious removable printhead.
bidrectional and logic-seeking, adjust-
able tractor, fine print quality and stan-
dard features make this a real bargain
Parallel interface S645 00 $519.00

D SERIAL or IEEE 488 INTERFACE for

the MX80 $55.00 $43.70

D APPLE INTERFACE CARD for the
MX80 (when ordered with the MX80)
$85.00 $88.75

D TRS-80 EXPANSION CABLE.

(for MX 80) $35.00 $30.60

DAPPLE CABLE $25.00 $21.90

(for MX 80)

D EPSON MX70, pUn-Jane version of
the MX80. Monodi-ectional. 80 cps.
Graftrax II Graphics included. Adjust-
able tractor. Parasel version only.
$450 $376.00

i ! DIABLO 630 RO PRINTER uses plas-
tic and metal print wheels. Fewer
working parts mean less down time.
Speed: 40 cps bidirectional, logic-
seeking $2185.00 $1999.00

D IDS PAPER TIGER 860, the 15" tiger.
150 cps. bidirectional, logic-seeking.
9-wire staggered printhead. Fixed A
proportional text, automatic text justifi-
cation. Up to 220 col. Paratel 8 serial
Interfaces $1695 $1484

D IDS PAPER TIGER 460.

$1295.00 $1072.00

D C. rrOH STARWRITER I letter quality
printer. Uses Diablo pnnrwheei and rib-
bons. 25 cps. Bidirectional logic
seeking. Son-tost. Friction feed. Parasol
Interface $1895 $1431

I STARWRITER I Serial version
$1980 $1502

D TELEVIDEO 950C, the newest and
smartest Tetevideo Al features of the
920C plus detachable keyboard,
smooth scrolling, sptt screen, graphics
characters, 25th status Ine, 19.2 kilo-
baud max speed, buffered aux. port.
$1195 $995

D ANADEX 9500 or 9501.

$1437.00 $1380.00

D ANADEX DP6000 . $995.00 $776.00
D CENTRONICS 704-1.

$2280.00 $1838.00

D CENTRONICS 737-1.

$995.00 $770.50

' : BIG DISCOUNTS ON DYNABYTE,
CROMEMCO, NORTHSTAR AND IMS
SYSTEMS. Call or write for prices!

ASK FOR YOUR FREE DISKETTE CASE
WITH YOUR SPRING ORDER!

PflCES AND SPECIFICATIONS SUBJECT
TO CHANGE WITHOUT NOTICE.

CALL OR WRITE FOR FREE CATALOG

CP/M la a registered trademark of Digital

Research.

UNIX is s registered trademark of Bed

Labs.

APPLE Is a registered trademark of

Apple Computers.

Ill

511 North New Street Bethlehem, VA 18018 (215)868 8219

medicine, dentistry,
health sciences, and
micro- and minicom-
puters.

1. ICC A (International
Computer Chess Associa-
tion)

2. ICCA, Vogelback Com-
puting Center, North-
western University,
Evanston IL 60201

3. B Mittman, (312)
492-3682

4. ICCA Newsletter

5. Computer chess.

1. CHICATRUG (Chicago
TRS-80 Users Group)

2. 203 N Wabash, Rm 1510,
Chicago IL 60601

3. Emmanuel B Garcia Jr

4. CHICATRUG News

5. TRS-80s.

1. Quad City Computer
Club

2. 4211 7 Ave, Rock Island
IL 61201

3. John Greve, (309)
786-8187

5. General-interest club.

1. SCAMPUS (SC/MP
Users Society)

2. POB 132, Knob Noster
MO 65305

3. Tom Bohon, Coor-
dinator, (816) 563-2650

4. SCAMPUS Newsletter

5. Anything to do with Na-
tional Semiconductor's
SC/MP I and II inte-
grated circuits (systems,
controllers, etc).

1. Financial Systems Report

2. c/o Syntax Corporation,
4500 W 72nd Ter, Prairie
Village KS 66208

3. Vernon K Jacobs, (913)
362-9667

4. Financial Systems Report

5. This 8-page monthly
newsletter provides infor-
mation about computer
systems for financiers.

1. Lincoln Micro-Computer
Club

2. 1209 Garber Ave, Lincoln
NE 68521

3. Hubert Paulson Jr, (402)
435-1507

174 April 1981 © BYTE Publications Inc

Circle 119 on inquiry card.

Clubs and Newsletters,

2. POB 1131, Troy MI
48099

3. Don Gottwald, (313)
792-3867

4. Sorcerer's Apprentice

5. This club is interested in
any topics concerning the
Exidy Sorcerer microcom-
puter.

1. OSI-MUG (OSI Michigan
Users Group)

2. 3247 Lakewood Ave,
Ann Arbor MI 48103

3. (313) 761-5358

1. SEMCO (South Eastern
Michigan Computer
Organization)

2. POB 02426, Detroit MI
48202

3. Information number,
(313) 775-5320

4. Data Bus

5. Special interests: net-
working, TRS-80, Atari,
6800, 650X, Heath,
Digital Group, CP/M,
S-100, and any aspect of
computing.

1. Detroit Interact Group

2. 15356 Prevost, Detroit
MI 48227

3. Stephen Cook, (313)
272-7594

4. Interaction Newsletter

5. Special interests: the In-
teract computer.

1. Flint 6500 Users Group

2. POB 4310, Flint MI
48504

3. R Riley, (313) 695-1117,
7-8 PM weekdays

1. ERCC (Educational,
Recreational Computer
Club)

2. POB 325, Owasso MI
48867

3. John Horvath, (517)
725-2835

4. ERCC Newsletter

5. Emphasis on educational,
recreational, business,
and scientific uses of
computers.

1. Battle Creek Area Micro-
computer Club

2. 8587 Q Dr N, Battle
Creek MI 49017

3. Jeff Stanton, (616)
763-9685, evenings

4. Yes

5. Special interests: mostly
the TRS-80.

Heath User's Group

Hilltop Rd, St Joseph MI

49085

Bob Ellerton, (616)

982-3463

REMark

Heath hardware and soft-

2.

3.

Microcomputer Users In-
ternational

c/o Jack Decker, 1804 W
18th St, Lot #155, Sault
Ste Marie MI 49783
Jack Decker, (906)
632-3248; in Ontario,
Canada, Phil Barton or
Frank Gardner, (705)
942-1363
Northern Bytes
Serving microcomputer
users in Sault Ste Marie
Ontario/Michigan area.
We wish to exchange

newsletters with other
clubs.

Zips 50000—60000

1. Eastern Iowa Computer
Club

2. POB 1189, Cedar Rapids
IA 52406

3. Sam Dillon, (319)
377-0889

4. Bimonthly

FOR ALMOST A DECADE...

. AND STILL HOLDING

5V at 3A with
Built-in OVP

Model HB5-3/OVP
$24.95 Single Qty.

New 1981
Product Catalog...
plus our new
Tour Guide.
Phone or write for
your copies today!

wmiwsir-

Power One's Case models started
at $24.95. Over 200,000 models later,
they're still only $24.95!

■ 115/230 VAC Input

■ OVP Built-in

■ .05% Regulation

■ 2-Year Warranty
I 2-Hour Burn-in
■ UL Recognized

■ CSA Certified

Get all the details on our
125 standard linear and
switching power supplies.

**©

XJr'

" PRODUCT

,1m.

@pauierane*

o.c. power supplies

Power-One, Inc. • Power One Drive • Camarillo, CA 93010
(805) 484-2806 • (805) 987-3891 • TWX 910-336-1297

SEE OUR COMPLETE PRODUCT LISTING IN EEM & GOLDBOOK

Circle 117 on inquiry card.

April 1981 © BYTE Publications Inc 171

CPU's &

SUPPORT

CHIPS

RAM's

B251

B259

a257(AM9517) -

Z80A S10

9275

FD1791

UART's

AY5-1013 - 3.75

TRJ602B - 3.95

AY3-85O0 -"XSS

PT1482B - 3.25

INTERFACE
& DRIVERS

2.50
2.50
2.50
2.50
2.00
2.00
2.00
2.00

21141-3

4116-3

41 1 B-a

21 L02-3

21Q2-4

MK4027-3

MK4096-1 1

TMS4045-25

MS4050NL

2101-1

21078(5280

MM5270

MK4008P

- 3.95
-3.75
-6.75

-3.50

- 2.95
6.50

- 3.95
-2.45

- 1.75
-3.45

ROM's

4029

4030
4034
4036
4040
4042

4046
4049
4050
406 1
4052
4053
4066

55 4076 -

.35 4099 -

74C0D -

74C02 -

74C04 ■

74C08 -

74C10 -

74C20 -
74C32 -
74C73 -

74C74 -
74C76 -

70

74C83 - 1

30

7JC85 - 1

10

74CS6 -

50

90

96

74C161 - 1

75

75

20

15

74C163 - 1

15

74C165 - 1

25

74C173 - 1

30

74C174 - 1

30

74C192 - 1

50

74C926 -- 6

95

2516
2532
8223
82S23
82S112
825115
82S123
82S126
82S129
82S130
82S131
AM9218C

- 29.95
-3.95

- 2.95
-7.95
-6.95

- 4.95
-2.95

- 3.25
-3.45

- 3.95
-6.95

SHIFT
REGISTERS

MM 1402
MM 1403
MM 1404
MM5013
MM5016
MM5055
MM5056
MM5057
MM5058
MM5060

-1.75
-2.50
-2.50
-2.50
-2.50
2.50
-2.50
-2.50

PRINTED CIRCUIT BOARD

4" x 6" DOUBLE SIDED

EPOXY BOARD 1/16" thick

60 ea 5/S2.60

EPOXY GLASS VECTOR BOARD

1/16" thick with 1 /1 0" spacing

4%"x6%" $1.95

SPECIALS

4116-3 RAM'S - 8/$24.00

15% ALL74LS SERIES
LEADER OSCILLOSCOPES

WE CARRY A FULL LINE OF HIGH QUALITY,

LOW PRICED OSCILLOSCOPES WITH

A TWO YEAR WARRANTY.

COMPARE PRICE & FEATURES.

LB0517 50 MHz D.T. CAL. DELAY

$1950.00

OSCILLOSCOPES

LBO-302

LBO-308S

LBO-310A

LQO-507A

LBO-508A

LB0 511

L80 513

L8Q-514

LB0-515B

LBO-520

10 MHz, D.T., 3" Compact
20 MHz, D.T.. 3" Portable AODC
4MHi, S.T. Recur. Sweep

20 MHz, S.T.,5"

20 MHz. D.T., 5"

10MHz,S.T.,5"

1QMH2.S.T,. I my Sens. .

790.00
950.00
.275.00
.610.00
.835.00
.420 00
.495.00
.645.00
30 MHz. D.T. Ciii. Delayed Sweep 1 ,530.00

30 MHz, D.T. w/Dolay Lino . .1,100.00

SPECIALS GOOD THRU APRIL 1981

CRYSTALS $3.45 ea.

6.144 MHz
8.0O0MH;

DATEL'S DAC-08BC

"8bitDAC - $9.95

74S00
74S02
74S03
74S04
74S05
74S08
74S10

.30

74S74

.30

74S86

.40

.45

74S133 1

.40

74S135 1

.30

74S133 1

.36

74S139 1

.40

74S140 1

.40

74SI53 1

.40

.40

74S157 1

74S175
74S194
74S257
74 S 258
74S260
74S280
74S373
74S374

7 WATT LD 65 LASER
DIODE IR $8.95

25 watt Infra Red Pulse (SG 2006 equiv.)
Laser Diode (Spec sheet included) s „4 gc

2N3820 P FET $ .45

2N5457NFET $ .45

2N2646UJT $ .45

ER 900 TRIGGER DIODES 4/$1 .00

2N 6028 PROG. UJT $ .65

TTL REED RELAY - SPST 5V 20ma $1 .00

CLOCK CHIPS

MM5387AA $5.95

MM5314 $4.75

MM5316 $4.95

TANTALUM CAPACITORS

.22UF35V 67*1.00 10UF10V -$ .40

.47UF35V 5/$1.00 22UF10V -$ .30

.68UF35V 5/$1.00 15UF16V 3/$1.00

1UF35V 5/$1.00 30UF6V B /$1.00

2.2UF20V 5 $1.00 3 3 UF2 0V $ .60

ff «H" 100UF15V $-70

4.7UF15V 5/$1.00 1 cm ip 1 K\/ <: QR

6.8UF35V 3/51.00 150UF15V $ - 95

SANKEN

AUDIO POWER AMPS

Si 1 01 0G 10 WATTS .. 5 7.50
Si 1 020 G 20 WATTS . . $1 1 .00
Si 1030 G 30 WATTS .$13.50
Si 1050 G 50 WATTS .$25.00

200 PRV 1A LASCR .95

RS232
CONNECTORS

DB25Pmale $3.25

DB 25S female ... $4.25
HOODS $1.50

2.000 MHz
4.000 MHz
3.000 MHz
3.57 MHz
5.000 MHz
6.000 MHz

10.000 MHz
18.000 MHz
18.432 MHz
20.000 MHz

RIBBON CABLE

FLAT (COLOR CODED)

#30 WIRE

16cond. - .40/perfoot
40 cond. - .75/per foot
50cond. - .90/perfoot

MINIATURE MULTI-TURN TRIM POTS
100, 5K, 10K, 20K, 250K, ... $.75 each .

NO. 30 WIRE WRAP WIRE SINGLE STRAND

100' $1.40

ALCO MINIATURE TOGGLE SWITCHES

MTA 106 SPOT $1.05

MTA206DPDT $1.70

MTA 206 P-DPDT CENTR OFF $1 .85

MSD 206 P-DPDT CENTER OFF LEVER SWITCH $1.85

SCR's

600

TRIAC's

PRV

1A

10A

2SA

100

.45

.80

1.55

200

.84

1.30

2.10

400

1 30

1.90

3.10

600

2.00

2.75

4.30

FP 100 PHOTO TRANS $ .60

RED, YELLOW, GREEN OR AMBER LARGE LED's. 2" 6/51.00

RED/GREEN BIPOLAR LED's $ .55

MLED92 R LED $ .75

MRD14B PHOTO DARL. XTOR $ .75

TIL-1 18 OPTO-ISOLATOR $ .75

IL-5 OPTO-ISOLATOR $ .80

1 WATT ZENERS: 3.3, 4.7, 5.1 , 5.6, 6.8, 8.2, 9.1 , 10,

12, 15, 18, or 22V 6/$1 .00

SFC3301 - 50 PRV30A
FAST RECOVERY DIODE (35ns) . .$2.25
20KV250MA DIODE $1.90

SILICON POWER RECTIFIERS

PRV 1A 3A 12A 50A 125A 240A

.20 .40 1.30 4.25 12.00

.25 .65 1.50 6.50 15.00

.30 .80 2,00 8.50 18.00

.35 1.00 2.50 10.50 22.00

.45 1.25 3.00 12.50 26.00

I N4148(IN914) 15/$1.0Q

.1 or .01 uf 25V ceramic disc. caps.
16/$1.00, 100/$5.00

7 SEGMENT DISPLAYS

FSC 8024-4 digit DL-707 C.A. .3". . . . $.75

C.C. 8" display.... $5.95 DL747 C.A. .6" . . . .$1.50

FND503C.C. .5".. $ .85 HP3400 .8"CA. . . . $1.95

DL-704-.3"C.C... $ .85 HP3405 ,8"CC . . . . $1.95

^ i> 'i ^iaflh

TRANSISTOR SPECIALS

2N1307PNPGETO5

2N404APNPG£T0 5

HEPG6Q14 -PNPGETC3

TIP121 - NP\S SW.TCHING

2N6233-NPN SW Ti MING POWER.

MRF-BOOtaCi'lii l-.'.NSis'nflNPN. .. $ .

2N3772NPNS TO-3. ... . $1.

2N4908PNPR TO 3. $1.

2N50B6PNPS H)92 4/$1,

2N3137NPNSi=1r- . . . $ .

2N3319 NPN S. TO 3 PF .. $1,

2N1420NPN ~<TJ; 3 : $1.

2N3767NPNS1 fO 66 $ .

2N2222NPN!; rO-18 Si$1.

/;;- : .Hi/ 1 irj -.; is 4/81.

MPS

PNE

TIP 34 P

JPRi

SiUB

TTLIC

SERII

7400-

.17

7450-

.17

74161 -

7401 -

.1/

7472 -

.:lh

74162-

7402-

.17

7473 -

.35

74163-

7403-

.17

7474 -

47

74164 -

7404 -

?4

7475 -

41

7416b -

7405-

?4

7476-

45

74166 -

7406 -

.33

7480-

.45

74167 -

7407

:i<o

7483-

.60

74170 -

7408-

77

7485-

,7a

74173-

7409-

74

7486-

AV

74174 -

7410-

17

7489 -

.60

7417b -

7411 -

77

7490-

.b0

74176 -

7412 -

,77

7491 -

,bb

74177 -

7413-

47

7492 -

.60

74190 -

7414 -

m

7493-

.SO

74181 -

7416 -

33

7494 -

,m

74190 -

7417-

37

7495-

m

74191 -

7420-

17

7496-

,60

74192-

7425-

3fi

74107 -

,3b

74193-

7426-

aa

74121 -

.!tb

74194-

7427-

3S

74122-

,39

74195 -

7430-

17

74123-

.«

74196 -

7432-

77

74125 -

.4b

74197 -

74126 -

4b

74279 -

7438-

?7

74145 -

,75

74325 -

74148 -

1 Ml

7441 -

K>

74150-

1.10

74363 -

7442-

.50

74151 -

.6b

7445-

/()

7446 -

,75

75154-

1.10

7447 -

.75

74155 -

.7b

7448 -

,75

74157 -

.lib

8T98 -

FULL WAVE BRIDGE

PRV

2A

6A

25A

100

1.40

200

.80

1.30

2.20

400

1.00

1.6S

3.30

600

1.30

1.90

4.40

DIP SOCKETS

SPIN .17 22PIN .30
14 PIN ,20 24 PIN .3b
16PIN .22 28PIN .40

18PIN .25 40PIN .60

74LS SERIES

74LS01 -

74LS02 -

74LS03 -

74LS04 -

74LS05 -

74LS08 -

74LSD9 -

74L5I0 -

74LS11 -

74LS12 -

74LS13 -

74LS14 -

74LSI5 -

74LS2D -

74LSZ1 -

74L522 -

74LS26 -

74LS27 -

74 L 528 -

74LS3Q -

74LS32 -

74LS37 -

74LS74 -
74LS75 -
74LS76 -
74LSB3 -
74LS85 -

74LS96 -
74LS107 ■-

74LSI09 -
74LS112-
74LS113 -
74LE114
74LS123 -
74LS125 -
74LS126 -
74LS132 -
74LSI36 -
74LS138 -
74LS139-

74LS151 - 1.19
74LS153-1.19
74LS1 55-1.19

LINEAR CIRCUITS

136- .!
900 - .!
M307 -
M30a -
M324 -

LM348 - .90
LM358 - ,70
LM361 - 1.7!
LM377 -
LM382 -
LM336 -
LM3B7
LM553
LM555 - .45
LM553

,60

- 2.25

566

- 1.25

CA758 -
CA3018 -
CA3046 -
CA3078 -
CA3080 -
CA30B6 -
CA3094 -
NE540L -

REGULATORS

74LS157

74LS160-

1.00

74LS1B1 -

74LS163-

LOO

74LS16.1-

1.00

74LS16B ■

1.25

74L5169-

.75

74LS170-

74LS173-

.90

74LS174-

1.00

74LS175-

;.00

74L5181 -

2.50

a

74LS191-

74 LSI 92 -

.90

74LS193

74LS194 -

1.10

74LS195-

.90

74 LSI 96

1.00

74LS197-

.90

7JLS241

1.60

74LS242 -

1.60

;.'.i S2'ji

1.28

1.00

74LS258-

.90

74LS259 -

74LS273-

74LS283 -

.80

74LS290 -

71LS293

.80

74LS365-

74LS3G7 -

74LS373-

74LS38r, -

.50

74LS393 -

1.50

LM1B10 - 2.20
Ml 88

LM317T...

LM337

323K-bV3A.
73HGKC-5V;

..,.$2.50
... $2.50
. . . .$5.75
5A $6.95

LM305G $

340K-12, 15or24V S
340T-5, 6, 8, 12, 15

POSTAGE ADD 10% FOR ORDERS UNDER $20.00
RATES ADD 5% FOR ORDERS BETWEEN $20.00 AND $50.00

ADD 3% FOR ORDERS ABOVE $50.00

TERMS: FOB CAMBRIDGE, MASS. SEND CHECK
OR MONEY ORDER. MINIMUM TELEPHONE.
C.O.D. PURCHASE ORDER OR CHARGE $20.00
MINIMUM MAIL ORDER $5.00.

SEND 5.25 FOR OUR CATALOG
FEATURING TRANSISTORS &
RECTIFIERS. 145 HAMPSHIRE
ST., CAMBRIDGE, MASS. 02139

SOLID STATE SALES

P.O. BOX74B

SOMERVILLE, MASS. 02143

TEL. (617)547-7053

WE SHIP OVER 95%

OF OUR ORDERS WITHIN

24 HOURS OF RECEIPT

TOLL FREE 1-800-343-5230

1. H8SCOOP

2. 2918 S 7th St, Sheboygan
WI 53081

3. Henry E Fale, (414)
452-4172

5. Special interests: Heathkit
H-8 and H-89 computers.

1. Fox Valley Crab- Apples

2. Mathematics Department,
University of Wiscon-
sin — Oshkosh, Oshkosh
WI 54901

3. John Oman, (414)
424-1362

5. Use of the Apple II in the
classroom.

1. MICRO

2. 335 W Prospect St,
Appleton WI 54911

3. John Ensley, (414)
731-7183

4. Yes

5. Special interests: com-
puter networks, graphics,
and educational uses.

1. Mini 'Apples

2. 13516 Grand Ave S,
Burnsville MN 55337

3. D Buchler, President,
(612) 890-5051

4. Mini 'Apples Newsletter

5. Apple II users group.
Special interests: Pascal,
education, personal,
business, and industrial
applications.

1. XXX-11

2. POB 2017, Fargo ND
58107

3. C R Corner, (218)
233-7894

4. XXX-11 Newsletter

5. Special interests:
languages.

Zips 60000—70000

1. Dental Computer
Newsletter

2. 1000 North Ave,
Waukegan IL 60085

3. E Neiburger, Editor, (312)
244-0292

4. Monthly

5. Special interests:

172 April 1981 © BYTE Publications lnc

Circle 118 on inquiry card.

2716 (5V) $8.95

4116

200NS

$3.50

2114L

300NS

$3.75

NEW! IT TALKS
"FAST TALKERS S-100"

LOW DATA RATE S100 SPEECH BOARD

• UNLIMITED SPEECH POSSIBILITIES

• S100 INTERFACE

• USES TEXAS INSTRUMENT TMS 5200 V.S.P

• SOFTWARE. VOICE DATA ASSEMBLER

• 32 WORD VOCABULARY INCLUDED

• AUDIO AMP W/SPEAKER

• ASSEMBLED AND TESTED

NEW TECHNOLOGY SPEECH PROCESSOR

ALLOWING UNLIMITED SPEECH POSSIBILITIES

DELIVERY FROM STOCK

TMS-5200 VOICE SYNTHESIS PROCESSOR

Chip with Data Sheet $69.00

$329.

"CONTROL TALKER II"

110V 50/60 HZ

32 INPUT LINES

(TTL)

32 10 AMP (50V)

OUTPUT LINES

Z80 BASED

SYSTEM

8K PROM

(SOCKET)

1K RAM

VOICE OUTPUT

SINGLE BOARD

STEPPING MOTOR

CONTROL (UP TO 8)

Control Talker II can be used to control stepping motors,
relays, counters, etc., and support a variety of uses
including robotics, telephone dialer, digital access,
security, aulo drilling, measuring, counting and virtually
unlimited applications with added speech output to advise

of status etc. Put one to
work for you today!

$550.

Double Sided QUME DRIVES
DATATRAK 8

° R U , R CE $540.00

(Regularly) $808.00)

CALIFORNIA
COMPUTER SYSTEMS

Order

Number
2032A
32K Sialic
20338
32K Sialic
2032C

32K Sta

EM450NS

EM-300NS
EM-2C0NS

I MEM-200NS

2065C
6a K Dy
2116A
igk Static MEM-450NS

2M6B

16K Slahc MEM300NS

21I6C

16K Sialic W6M-20ONS

2116X

16K BD oniy

22C0A

Mainframe 110.60

2422A

Floppy Controller

2710A

4-Porr Serial I/O

271BA

SciauParaiiei I/O

2720A

4-Port Parallel HO

2810A

2 80 CPU BD

APPLE BDS:

1 560 00
640 00
649 00
569.00
257 00
26100
290 00
67 00
386 00
320 00
279,00
290 00
200.00
235 00

7470A

AID Converter

7490A

GP1B IEEE 4KB

77 IDA

Serial Asyncrt 9(

77I2A

Serial Syncn Ba

7720A

S 63 00
103 00

90 00
97 00
230 00
127 00
152 00
99 00
I 99 00

329 00

79L

VOLTAGE
REGULATORS

art" Case Price

,i 05 J 092 45

IL12 I"092 45

ItS T092 45

T092 65

TQ92 65

T092 65

TO220 1 20

TO220 1 20

TO220 1 20

TO220 1 25

TO220 1 25

TO220 1 25

79U5
7805 P
7B12P
78I5P
7905 P
7912P
7915P
7805K
7812K
78I5K
7905K
7912K
7915K
309M
309K
317P
317K
323K
337P
337K
350K

I03
T03

T039

T03

T022U

T03

T03

TO220

T03

T03

CRYSTALS

(Parte Includes
Iraquoncy
In MHZ)

Parl#

SYi

SYI 8432

SV2

SY2.4576

SY3.579

SY4

SY5 068

SY6

SY6 144

SYS

Price

575
5.75
5.75
5.75

5.75
4.50
450

CERAMIC DISC

CAPACITORS 50V

Value 1 + 25+100 +

4 7pf 07 06 04

lOpI 07 06 04

22pf 07 06 04

33pf 0/ 06 04

39pl 07 06 .04

47p( 07 06 04

68pl 07 06 .04

100pl 07 .06 .04

150pf 07 06 04

220pl 07 06 .04

270pl 07 06 04

330pt 07 06 .04

,0022ml
0033ml
0047ml

DIODES

Switching

IN914 12*1 00

1N414S 12S100

LOW-PROFILE SOLDER TIN

PartW 1 + 25+100 +

S8LT 15 n 08

SI4LT 18 16 14

S16LT 2t 18 16

S18LT 26 22 18

S20LT 31 26 20

S22LT 33 28 22

S24LT 35 29 24

S28LT 41 34 26

S40LT 53 4 7 40

WIRE-WRAP SOLDER TIN

Part* 1 + 25+100 +

SBWT 37 33 30

S14WT 48 43 39

S16WT 53 -18 -»3

S18WT 61 55 50

S20WT 65 77 69

S22WT 69 80 72

S24WT 96 86 77

S28WT 1.22 111 99

B40WT l 75 '57 1 40

WIRE-WRAP GOLD

Pari*
S8WG
S14WO

SI6WG
S18WG
S20WG
S22WG
S24WG
S28WG
J.".J0vVG

SOLID DIPPED TANTALUM
CAPACITORS 20%

ValuB Volls 1 + 25+100 +

2 2ml

3 3ml

4 7m)

T.55 1 29 1 05

V* WT &

5

VaWT CARBON I
% RESISTORS

2.2K

2.4K

2.7K

3K

3.3K

3.6K

3.9K

5.1K
5.6<

6.2<
6.8 <

2O0K
220K
240K
270K
300K
330K
360K
390K
430K
470K
5I0K
560K
620K
680K
750K
820K

2.2M

2.4M

2 7M

3M

3.3M

3.6M

3.9M

MINIMUM ORDER PER TYPE:
5 pes— any qty 5 pack @ $.25

MINIMUM ORDER PER TYPE:

100 pes

Price Per 100 Pk:

QTY 'AWT '/.WT

100 up 51.70 $1.80

1,000 up 1.50 1.60

5.000 up 1.30 1.40

10.000 up 1 10 1.20

ZENER
DIODES

Vi WT
Part# Price

1N5231B
1N5239B
1N5242B
1N5245B
1N5248B
1N5250B
1N5252B
IN5255B

1 WT

1N4733A
1N4739A
1N4742A
1N4744A
1N4746A
IN4747A
1N4749A

POLYESTER

CAPACITORS

+ & - 10%

TOLERANCE 50V

Valui

OOtrn'

0012ml

0015ml

OOlBmf

0022ml

0027 ml

0033ml

,0039ml

0047ml

0056ml

0068ml

.0082fnl

.01ml

012ml

015ml

018ml

.022ml

,027ml

,033ml

,039ml

047ml

.056ml

068ml

0B2ml

.27ml
.33ml
39ml
47ml

H

100 +

TRANSISTORS

2N2219A S .35

2N2222A .25

2N2905A ,30

2N2907A .25

2N2369A 25

2N3904 20

2N3906 20

PN2222A 19

PN2907A 19

RECTIFIERS
(1A)

1N4001
1N40O2
IN 4003

1N4004

12100
12100
1 2/1 .00
121.00

1N40O5 10/1.00 08
IN40O6 11/1.00 08
1N4007 10(1.00 08

74 LS

Part U Price

74LS00 32

74LS01 32

74LS02 32

74LS03 32

74LS04 32

74LS05 32

74LS08 .32

74LS09 .35

74LSIO .3B

74LS11 38

74LSI2 39

74LS13 32

74LS14 65

74LS15 35

74LS20 32

74LS21 36

74LS22 36

74LS26 35

74LS27 39

74LS28 37

74LS30 36

74LS32 40

74LS37 36

74LS3B 36

74LS40 36

74LS42 95

74LS47 1 15

74LS48 1 15

74LS51 .32

74LS54 .38

74LS55 .34

74LS73 49

74LS74 49

74LS75 63

74LS76 55

74LS83 95

74LS85 125

74LS86 .55

74LS90 79

74LS92 75

74LS93 75

74LS95 .99

74LS107 50

74LS109 .50

74LS112 52

74LSU3 52

74LS114 .52

74LS123 1.05

74LS125 70

74LS126 .70

74LS132 .95

74LS136 53

74LS13B 85

74LS139 .85

74LS148 1.75

74LS151 79

74LS152 79

74LS153 79

74LS154 2 05

74LS157 1 15

74LS15B 1 15

74LS160 85

74LS161 85

74LS162 .85

74 LS 163 95

74LS164 1 10

74LS165 1 10

74LS166 255

74LS170 1.90

74LS173 135

74LS174 l 25

74LS175 95

74LS1B1 235

74LS190 I 15

74LS191 1.15

74LSI92 1.15

74LS193 1 15

74LS194 1 15

74LS195 1 15

74LS196 99

74LS197 99

74LS221 .95

74LS240 1 05

74LS241 1 05

74LS242 1.45

74LS243 1.45

74LS244 1 05

74LS245 2 15

74LS251 129

74LS253 .99

74LS255 99

74LS257 1 15

74LS25B 1.15

74LS260 .95

74LS261 249

74LS266 65

74LS273 165

74LS283 1.05

74LS365 .85

74LS366 85

74LS367 85

74LS368 85

74LS373 1 65

74LS374 1 45

74LS375 99

74LS377 1.15

74LS3B6 59

74LS390 I 75

74LS393 1 75

81LS95 1.35

81LS96 135

81LS97 135

81LS9B 135

4000
CMOS

Part -i Price

4000

4001

4002

4006

4007

4008

4009

4016
4017
4018
4019
4020

4025
4026
4027
4028
4029
4030
4034
4035
4040

4043
4044
4046
4047

4052
4053
4060
4066

4072
4073
4075
4076
4077
4078
4081
4082
4093
4503
4508
4510

SERIAL PORT CARD
WITH 4 PORTS $289
WITH 2 PORTS $260

MIN ORDER: $10.00 SHIPPING: ADD $2.00
GA RESIDENTS ADD 3% SALES TAX

MASTERCARD AND
VISA WELCOME

MAILORDERSSOUTHERN SEMICONDUCTORS INC.

BOX 986

LAWRENCEVILLE, GA. 30246 PHONE ORDERS:

OEM AND INSTITUTIONAL INQUIRIES INVITED (404) 963-3699

Circle 120 on inquiry card.

BYTE April 1981 175

ENTREPRENEURS

Imli 1 ™!™! W m U I MORE THAN EVER IN THE MICRO-
IVkkl#hll# COMPUTER INDUSTRY.

The shortage of knowledgeable dealers/distributors is the «1 problem of microcomputer
manufacturers Over 300 new systems houses will go into business this year but the number
falls short of the 1200 needed It is estimated thai the nal "in wide shortage of consultants will be
over 3000 by 1981 The HOW TO manuals by Essex Publishing are /out best guide lo start
participating in the continued microcomputer boom

(36

HOW TO START YOUR OWN SYSTEMS HOUSE

6th edition March 1980

Written by the lounder of a successful systems house, this

tai Milled 220-page manual covers virtually all aspects of

starting and operating a small systems company It is abundant

with useful, real-lite samples contracts proposals, agreements

and a complete business plan are included in lull, and may be

used immediately by the reader

Proven, field-tested solutions lo the many problems lacing the

small systems house are presented

From the contents:

• New Generation of Systems Houses • The SBC Marketplace

• Marketing Strategies • Vertical Markets & lAPs • Competitive
Position/ Plans ot Major Vendors • Market egment Selection &
Evaluation • Selection ol Equipment & Manufacturer • Make or
Buy Decision • Becoming a Distributor • Getting Your
Advertising Dollars Worth • Your Salesmen Where to Find
Them • Product Pricing • The Selling Cycle • Handling the 12
Most Frequent Objections Raised by Prospects • Financing foi
the Custom©! • I easing • Questions You Will Have to Answer
Before the Prospect Buys • Producing the System • Installation,
Acceptance, Collection • Documentation • Solutions to the

Service Problem • Protecting Your Product • Should You Start Now'' • How to Write a Good
Business Plan • Raising Capital

HOW TO BECOME
A SUCCESSFUL

COMPUTER
CONSULTANT

HOW TO BECOME A SUCCESSFUL COMPUTER
CONSULTANT

by Leslie Nelson, 2nd revised edition Jan 1981
Independent consultants are becoming a vitally important factor
in the microcomputer field filling the gap between the computer
vendors and commercial/industrial users The rewards ol the
consultant can be high treedom, more satisfying work and
doubled or tripled income HOW TO BECOME A SUCCESSFUL
COMPUTER CONSULTANT provides comprehensive back-
ground information and step-by-step directions for those
interested to explore this lucrative field

• Established consulting markets* How to get started • Itemized
start-up costs • Are you qualified 7 • Beginning on a part time
basis • The Marketing Kit • Should you advertise? • Five
marketing tips • Getting free publicity • How much to charge

• When do you need a contract 9 • Sample proposals • Which
|Obs should be declined • Future markets • The way to real big

money • Avoiding the legal pitfalls • How consultants' associations can help you • The National
Register of Computer Consultants • How others did it real-life sample cases «and much more.

ESSEX PUBLISHING

$28.

No, 16

FREE-LANCE SOFTWARE MARKETING 3rd edition. June 1980
Writing and selling computer programs as an independent is a
business where • you can get started quickly, with little capital
investment • you can do it full time or part time • the potential
profits are almost limitless Since the demand lor computer
software ol all kinds is growing al an explosive rate, the
conditions lor the small entrepreneur are outstanding

This manual will show you how to sell your own computer programs
using these proven techniques • direct to industries • through
consulting firms • through manufacturers of computer hardware
• in book form • mail order • through computer stores It will
show you how to profitably sell and license all types of software
ranging from sophisticated analytical programs selling lor thou-
sands of dollars, down to simple accounting routinesand games
for personal computers

The book will guide you step by step through the process ol
S30. No. 32 marketing, advertising, negotiating a contract, installing software,

training users and providing maintenance and support It also contains sample software contracts
that have been used in actual software transactions Also included are tips on how to negotiate
with a large corporation ways of avoiding personal liability techniques for obtaining free computer
time and hints on how to run a free-lance software business while holding a full-time job

ESSEX PUBLISHING CO. Dept «■

;J«.'j nioomlield Avenue • Caldwell, N.J 07006 I- ■ I

" lei books by numt lend hei I m • • . • lei i ■ r Ma ite e ». Publ rier pa

i riipping ForUPS di| ping IA only) addSLOOpei I idd ! pei book in

II i 1 1 ' ' i nd Central America , I i N .... iiesta

DNo 10 ONo 16 ONo32 □ Che iss OUPS OAir

Name

A Ho

State

Card H r

F or taster shipment on credit card orders call (201 1 783-6940 between 9 and 5 Eastern lime

. Exp

Zip

5. We have an ABBS

(Apple Bulletin Board
System) on (402)
423-8086.

Compusers

POB 2064, Hastings NE
68901

Rocky Friend, President;
or Dorothy Friend
Secretary
(..orrijiusers

We have a number of
different makes ot micro-
computers and are in-
terested in all subjects
concerning computer use.

3.

Zips 70000—80000

1

99 4 Home Computer

Users Group

'

POB 95148, Oklahoma

City OK 73143

.'..

Charles LaFara, (405)

787-8521

4.

Monthly newsletter

5.

We have a program ex-

change and are looking

fi 'i more information on

TI BASIC.

1.

The Tulsa Computer

Society

2,

POB 1133, Tulsa OK

74101

3.

Mike Parr, (918)

492-8292

■i

I i I Port

5.

Everything!

Theatre Computer Users
Group

104 N St Mary, Dallas

TX 75214

Mike Firth, (214)

827-7734

TCUG Notes

Spec ial interests: the use

of computers in live

drama.

1. FWAUG (Fort Worth
Apple Users Group)

2. 1401 Hillcrest Dr. Arling-
ton TX 76010

3. Lee Meador, (817)
461-1981

4. FWAUG Newslettri

5. Apple hardware and soft-
ware.

176 April 1981 = BYTE Publication* btc

Circle 121 on inquiry card.

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GgGgGgGgGgGgGgGgGg

GgGgGgGgGgGgGgGgGg

GgGgGgGgGgGgGgGgGg

HhHhHhHhHhHhHhHhHhl

HhHhHhHhHhHhHhHhHhH

HhHhHhHhHhHhHhHhHhHl

HhHhHhHhHhHhHhHhHhHh

IgGgGgGgGgGgGgGgGgGgGgGg

g GgGgGgGgGgGgGgGgGgGgGg

^GgGgGgGgGgGgGgGgGgGgGg

GgGgGgGgGgGgGgGgGgGgGg

ihHhHhHhHhHhHhHhHhHhHh

. iHhHh'HhHhHhHhHhHhHhHh

^HhHhHhHhHhHhHhHhHhHh

m 'HhHhHhHhHhHhHhHhHh

APPLE H Computer -
now with genuine
upper/lower case

We used to think the sophistication of the Apple 11/
PLUS could not be improved upon. With increasing
availability of business software capital letters on the
screen are not sufficient. Especially for wordprocessing
and the PASCAL editor the lack of lower case was
disturbing.

After searching for a better solution we developed
a new keyboard-encoder to implement upper and lower
case in the keyboard and on the screen.

• typewriter mode or ALPHA-LOCK mode operation

• all keys with AUTOREPEAT

• four character sets including
FULL ASC II, and EUROPEAN sets

• no soldering, no wiring

• simply replace the plug-in
encoder-board

Fix your system today, so tomorrow you're not stuck
with just capital letters.

Ask your Apple dealer for the new keyboard-encoder
from BASIS. For S 125,00 you save time and get a
new clear screen.

INCORPORATED

Apple II is the registered trademark of apple computer, inc.

BASIS, Inc., P. O. Box 2029, Los Gatos, CA 95030

Clubs and Newsletters,

1. Club 1802

2. POB 985, Dickinson TX
77539

3. John L Hubisz, (713)
938-4098

4. Newsletter

5. Our activities are for
beginners in microcom-
puting. We use ELFs and
other 1802-based boards
that employ simple con-
trols,

1 . High Plains TRS-80 Users
Group

2. POB 30545, Amarillo TX
79120

3. Tom Whittenburg, (806)
374-971 J

1. Permian Basin Amateur
Computer Group

2. c/o Ector School District,
POB 3912, Odessa TX
79760

3. John Rabenaldt, (915)
697-4607 (after 6 PM) or
(915) 332-9151 (9 AM to
5 PM)

5. Special interests: Selectric
interlaces, color displays,

MECA tape, and Altair
8800 systems.

Zips 80000—90000

1.

2.

3.
5.

Apple it

415 E 43rd, Odessa TX

79762

Larry Brown

Apple 11 microcomputers.

1.
2.
3.

Denver Amateur Com-
puter Society

POB 1235, Englewood

CO 80150

Lam,' Costa, (3031

1.
1.
3.
5.

Permian Basin TRS-80

Users Group

Rt #4, POB 1455, Odessa

TX 79763

Allan D Emert, (915)

381-3138

TRS-80 Model 1.

4.
5.

1

428-2929

INTERRUPT

We are a broad-interest

dub.

Southern Colorado Com-
puter Club

* WRITE OR CALL FOR FREE CATALOGUE *

CALIFORNIA COMPUTER SYSTEMS Hir.HlNQU Mil) /< WIN PRh i
7.80 CPU 4 Mli/, wiili one serial port 12 slut S too mainframe disk controllei oil.
Dynamic Ram, CP M2.2" $1,645.

Interfaced to 2 Shugarl 8*, single sided double density drives mounted in our own
beautiful MAX BOX with power suppl) and fan $1,250.

A complete S-100 system for under $3,000 ("HE BES1 BLh ON ["HE MAR1 I I

IMS 5000 and 8000 Systems

Outstanding long term reliability and performani e I hese systems Feature a '80 A < I'l '
S 100 bus; ill ml ilc density drives (eithei single or double sided), DMA disl conti oiler,
64K RAM, 2 serial .s; I parallel port. Prices include the verj finest implementation <>l
I I' \P available in the entire industry Hard disk .in<l multi usei software options.
Desk top or desk enclosed 5000 1 1 1 with dual, single sided mini di $3,225.

80001.11 with dual single sided 8 drivi 54,755.

PER SCI— THE h INC AND QUI 1 \ I >/ DRIVES!

Model 299B: Dual headed drives total I 2 MB unformatted $2,300.

Model 277: I )iul 8 mcli drives voice coil positioned IBM compatible 16001 BYTES

pel drive unformath d Si .210.

Slimline abinel and power Foi eithi \ ' 7oi '■" ! $ (00

DRIVES

[lie MAX BOX: Manufactured bj lohnD Owens \ iciates. 8 dual drive cabinel
complete with powei supply .^ fan Will holdQumes Shugartsoi Siemen Excellent
design and engineering . .. S 325.

With 2 Shugarl 800 R drives St, 250. With 2 QUME Doubli sided drives St, 650.

MPI 1551

$265.

B52

U

Bsi2

S500. Shugarl $ 450.

HAZELTINE 1500

1510

S925.
si 030

AMPEX DIALOGUE 80 CRT saso.
Removable keyboard, 2 page memory

M optional) bloi I- h ansinil

CENTRONICS 737 $ '80

Same as I RS 80 Model IV
Apple serial parallel interface $195.

EPSON MX801S

$ ISO

IMS MEMORY u- K t.,tn $350.

32 K si. in, $650.

64 K Dynamic with parity $755.

TEI MAINFRAMES, S 100

12 slot, table top $500.

22 slot, table top $670.

Hack moiinls add $ 50.

50 Hj ' v volts add S 50.

TELEVIDEO CRTs

s>12 $780. s>20 $850. 950 $1,050.

\AW CYPnDT Overseas Callers: TWX 710 588 2844
WttATUKi: Phone 212 448-6298 or Cable: OWENSASSOC

JOHN D. OWENS

Associates, Inc.

12 Schubert Street

Staten Island, New York 10305

212 448-6283 212 448-2913 212 448-6298

Computer Shack, 1635 S

Prairie, Pueblo CO 81005

Tom Thomas, (303)

564-3545

Monthly newsletter

1 . Utah Computer Associa-
tion

2. 378 E 9800 S, Sandy UT
84070

3. Lawrence N Barney,
(801) 571-9661

4. UCA Bits

5. Special interests: ad-
vanced software, hard-
ware, CP/M, and Pascal.

1. SNPCS (Southern
Nevada Personal-Com-
puting Society)

2. 1405 Lucilee St, Las
Vegas NV 89101

3. Cy or Edna Wells, (702)
642-0212

4. Hard Copy

5. Both hardware and soft-
ware; exchange id iiiim
mation and experience;
and guidance and en-
couragement for new
hobbyists. We participate
in fairs and exhibitions.

Zips 90000—99999

1 . Poly 88/8813 Users
Group

2. 13022 Psomas Way, Los
Angeles CA 90000

3. Pat or Roger Lewis

4. Poly 88/8813 Users
Group Newsletter

5. Software exchange.

1. LA Apple Users Group

2. 9513 Hindry PI. Los
Angeles CA 90045

3. Philip A Wasson, (2131
649-1428

178 April 1981 S BITE Publications In<

1. The San Fernando Valley
6502 Users Club

2. 3816 Albright Ave, Los
Angeles CA 90066

3. Larry Goga, (213)
398-6086

5. This club is open to all
owners of 6502-based
computers including
KIM, SYM, and AIM.
PET and Apple owners
are also welcome.

1. SuperLetter

2. Abrams Creative Ser-
vices, 369 S Crescent Dr,
Beverly Hills CA 90212

3. (213) 277-1588

5. Newsletter for SuperBrain
users.

1. OSI Users Independent

2. 6061 Lime Ave #2, Long
Beach CA 90805

3. Charles Curley, (213)
422-3673

4. OSI Users Independent
Newsletter

5. OSI computers and soft-
ware.

1. ELF of the Valley

2. 2670 Calle Abedul, Thou-
sand Oaks CA 91360

3. Richard Cox, (805)
492-4128

5. RCA 1802 microcom-
puters.

1. Compucolor/Intecolor
Users Group

2. 5250 Van Nuys Blvd,
Van Nuys CA 91401

3. Stan Pro, (213) 788-8850

4. Bulletin

5. We are an international
group of color-computer
users, with over 1000
programs in our library.

1. The Cursor Group

2. POB 266, North
Hollywood CA 91603

4. The Cursor

5. User group of the Bally
Arcade.

1. ET-3400 Users Group

2. 11231 Oak St, El Monte
CA 91731

3. Charles Van Dyke, (213)
443-2237; CompuServe
acct 70250,413

1. San Diego Heath User's
Group

2. 12202 Kingsford Ct, El
Cajon CA 92021

3. Jim Quinn, President,
(714) 561-2540; Cliff
Dudley, Secretary, (714)
697-8796

4. Coming soon

5. Special interests: the ex-
change of ideas, informa-
tion, and assisting Heath
computer users.

1. CIE (Computer Informa-

tion Exchange)

2. POB 158, San Luis Rey
CA 92068

3. Bill McLaughlin, (714)
757-4849

4. CIE People's Software
News

5. Special interests: TRS-80.

1. Apple for the Teacher

2. 9525 Lucerne St, Ventura
CA 93004

3. David Miller, Editor,

(805) 647-1063; Ted
Perry, President, (916)
961-7776

4. Apple Educators'
Newsletter

5. Education using Apple II
microcomputers .

1. International Apple Core

2. POB 976, Daly City CA
94017

3. Ken Silverman, (415)
878-5382

4. The Apple Orchard

* TELETYPE MODEL 43 INVENTORY SALE *

TELETYPE

Model 4320 AAA $ 885.

220V. model with transformer installed

inside cabinet $ 985.

Model 43ASR, 8 level, 1" tape . S2,595.
Limited supply of Model 45 available.

TELEBUFFER 43 ASR $945.

Circuit card designed for internal instal-
lation in the Model 43 Teletype.
Changes the 43 into a buffered send/
receive device, enabling it to function as
a Telex without paper tape. Provides
from 4K to 16K bytes of internal mem-
ory for storage of message. Contents of
memory may be edited and manipulated
in preparation for transmission. Options
include forms control and answer back.

IBM 3101 CRT Model 10 51,195.

Model 20 $1,395.

Selectric-like, detached keyboard. 9x16
dot matrix. Maintenance contract from
IBM only $70 per year

ITHACA INTERSYSTEMS

Full S-100 IEEE Compatibility! Full 24
address bits. DMA disk controller. SYS-
TEM 2A includes 20 slot mainframe
with front panel, 64K Dynamic RAM.
Z80 CPU, 4 MHZ, extended addressing
capability. 4 parallel, 2 serial I/O floppy
controller. Our discounted price, $3,415.

MARINCHIP SYSTEMS M9900

Elegant 16 bit CPU, S-100 compatible,
multi user, multi processor operating
system. BASIC, FORTH, META, PAS-
CAL, Word processor, text editor.
CPU kit and software package . $ 550.

Assembled $ 700.

Complete system, 64KB,

two drives $4,995.

MICROANGELO $2,280.

High resolution graphics system. 15",
22MHZ, green phospher screen, 72 key
keyboard; includes complete cabling
and software. From SCION.
S-100 Graphics card $ 960.

GRAPHICS SOFTWARE

On line, real time, for the M9900 to
drive the Microangelo. For use in design
of PC board masks, IC masks and other
applications $1,000.

CORVUS HARD DRIVES

We are the S-100 CORVUS dealer in the
New York area.

MODEL 11, Hard Disk System $4,820.
Mirror Backup System $ 715.

TARBELL

Double density controller $420.

Cables $ 40.

Complete TARBELL Product Line
Available.

UPGRADE DEC LA 35/36 . $750.

Increases baud rate to 1200. Micropro-
cessor controlled. Many options avail-
able. Enthusiastic user response. Long-
term reliability. From DataSouth.

Communications Software from
from Hawkeye Grafix

Enables communications from a micro
to a terminal or to another micro, mini
or maxi computer.
Object Code $75. Source Code $250.

3M SCOTCH" Diskettes

5
BOXES
1 BOX Price
of len per box

Model 740,8" single sided,

single density. .$29.00 $26.50
Model 741,8" single sided,

double density. 38.00 35.00
Model 743,8" double sided

double density. 46.50 42.50
Model744,5'/T soft sectored single sided,

single density. . 29.00 26.50

CAT from NOVATION

Originate/Answerback $175.

CAT-D $185.

Connects directly to telephone line with
a plug-in jack. Eliminates need for
acoustic coupler.
AUTO-CAT $240.

WE OFFER A FULL RANGE OF EXPERT CONSULTING SERVICES

JOHN D. OWENS

Associates, Inc.
SEE OUR AD ON FACING PAGE

April 1981 © BYTE Publications Inc 179

Clubs and Newsletters

5. Apple hardware and soft-
ware.

1. Homebrew Computer
Club

2. POB 626, Mountain View
CA 94042

3. Robert Reiling, (415)
967-6754

4. Homebrew Computer
Club Newsletter

5. Information exchange on
all systems.

1. Proteus

2. 1690 Woodside Rd, 219,
Redwood City CA 94061

1. FORTH Interest Group

2. POB 1105, San Carlos
CA 94070

3. Roy Marteus, (415)
962-8653

4. FORTH Dimensions

5. The FORTH language.

1. San Francisco Apple Core

2. 1515 Sloat Blvd, Suite 2,
San Francisco CA 94132

3. Randy Fields, (415)
775-7965

4. Cider Press

5. Apple computers.

1. CUssP

2. POB 784, Palo Alto CA
94302

3. Dave Dameron, Editor

4. CUssP Newsletter

5. Cromemco computers
and systems.

INSUA (International
North Star User's
Association)

2. POB 1318, Antioch CA
94509

3. William Banaghan

4. The Compass

5. For North Star computer
users.

1. Arcadian

2. 3626 Morrie Dr, San Jose
CA 95127

3. R Fabris, (408) 742-6048
(8 AM to 4 PM) or (408)
258-4586 (6 to 10 PM)

5. For the Bally /AstroVision
Arcade.

1. CUE (Computer-Using
Educators)

2. Independence High
School, 1776 Education
Park Dr, San Jose CA
95133

3. Don McKell, (408)
926-7378

4. Bimonthly newsletter

5. Computers in education.

1. Pascal/Z Users Group

2. 7962 Center Pky,
Sacramento CA 95823

5. The purpose of our

group is to encourage the
use of Pascal.

1. 68XX(X) User Group

2. POB 18081, San Jose CA
95158

3. Ray Boaz, (408) 269-9522
5. All 68XX(X) microcom-
puters and related hard-
ware and software.

1. SYM-1 Users Group

2. POB 315, Chico CA
95927

3. H R Luxenburg, (916)
895-8751

4. SYM-Physis

5. Graphics, voice, music,
word processing, and in-
tercomputer communica-
tions for the SYM-1.

1. Group/380

2. POB 1131, Mt Shasta CA
96067

3. Mokurai Cherlin

4. Group/380 News

5. IBM 370-compatible
microcomputers .

1. The Aloha Computer
Club

2. POB 4470, Kailua HI
96734

3. Roger Wickenden, Presi-
dent, (808) 262-4673

4. The Debugga

5. Anything to do with
microcomputers.

1. Z80 Microfans— A
Sorcerer Users Group

2. POB 12504, Portland OR
97212

3. C Douglas Auburg,
Editor, (206) 694-7769,
evenings

4. Z80 Microfans Newsletter

5. Special interests: sharing
problems, tips, and solu-
tions in the use of the Ex-
idy Sorcerer.

1. Portland Computer
Society Inc

2. POB 17371, Portland OR
97217

3. Neal J Bonome, (503)
654-5932

4. Portland Computer
Society Newsletter

5. Information exchange for

all types of microcom-
puters.

1. Salem Area Computer
Club

2. POB 7715, Salem OR
97303

3. Kenneth Ernst, (503)
393-1173

4. SACC Newsletter

5. Users groups: Apple,
TRS-80, PET, and
VisiCalc.

1. Home Computers

2. POB 616, Silverton OR
97381

5. General information on
personal computers.

1. Atari Computer En-
thusiasts

2. 3662 Vine Maple Dr,
Eugene OR 97405

3. M R Dunn, Editor,

4. A.C.E. Newsletter

5. This group is dedicated
to the use of Atari
microcomputers.

1. Hex Users Group

2. 36012 Military Rd S,
Auburn WA 98002

3. Charles Worstell, (206)
927-6038

4. Newsletter on an ir-
regular basis

5. Special interests: 6800
and 6809 small systems.

1. PN HUG (Pacific North-
west Heath Users Group)

2. c/o POB 993, Bellevue
WA 98009

3. Jan N Johnsen, (206)
464-5666

VAK-4 16K STATIC RAM BOARD

• Designed specifically for use with the AIM-65, SYM-1, and KIM-1 microcomputers

• Two separately addressable 8K-blocks with write protect.

• Designed for use with the VAK-1 or KIM-4* motherboards

• Has provisions for mounting regulators for use with an unregulated power supply

• Made with 1st quality 2114 static ram chips

• All IC's are socketed

•' Completely assembled, burned-in, and tested
We manufacture a complete line of high quality expansion boards. Use reader service
card to be added to our mailing list, or U.S. residents send $1.00 (International send $3.00
U.S.) for airmail delivery of our complete catalog.
"Product of MOS Technology

VAK-4 DUAL 8K-RAM $Wfc6fr $325.00 plus shipping
VAK-2 8K-RAM (Vi populated) $239.00

Special thru 4/30/81
VAK for $299.00

^Jrnb>

ENTERPRISES

INCORPORATED

2951 W. Fairmount Avenue • Phoenix, AZ 85017 • (602) 265-7564
Please note new address

180 April 1981 © BYTE Publications Inc

Circle 122 on inquiry card.

This

printer

costs less

than $450.

Beat that...

if you can.

Epson

This is the Epson MX-70. The lowest priced dot
matrix printer you can buy. Now, that in itself
should make it very attractive to a lot of people.
But you ain't heard the half of it.

To begin with, the MX-70 has a lot more in
common with our now-famous MX-80 than just
the name. Like unequalled Epson reliability.
And technological breakthroughs like the
world's first disposable print head. But frankly,
the MX-80 packs a lot more power than some
people need. So we built the
MX-70 to be a no-frills print-
er. At a no-frills price.

But the MX-70 is still a great
little printer. We give you
80 CPS unidirectional print-
ing. Top-of-form recognition.
Programmable line feed and
form lengths. Plain paper
printing. An easy-to-read 5x7
matrix. Self test. And an
adjustable tractor feed.

That's what you'd expect

from a basic little printer. But here's something
you wouldn't expect: the finest graphics package
on the market today. Free.

We call it GRAFTRAX II. And it means 480 dots
across the page, resolution to 60 dots per inch,
and a graphic image free of the jitter and overlap
that plagues other printers. You get cleaner grays
and finer point resolution.

So now you've got a choice. You want more
power and extra functions, you buy the MX-80.
You want a basic little printer
that prints, and keeps on
printing, you buy the MX-70.
They're both at your dealer
now.

But at this price, you'd bet-
ter hurry.

EPSON

EPSON AMERICA, INC.

23844 Hawthome Boulevard • Torrance, California 90505 • (213) 378-2220

Circle 123 on inquiry card.

BYTE April 1981 181

Clubs and Newsletters,

4. Newsletter published
every other month

5. Special interests: Heath
H-8 and H-89 microcom-
puters.

1. NW PET Users Group

2. 2565 Dexter N #203,
Seattle WA 98109

3. Richard Ball, (206)
284-9417

4. Newsletter

5. PET users group.

1. Apple Puget Sound Pro-
gram Library Exchange

2. 304 Maine Ave S, Suite
300, Renton WA 98055

3. Dick Hubert, (206)
271-4514

4. Call-A.P.P.LE.

5. Everything related to the
Apple II.

1. SPOHUG (Spokane
Heath Users Group)

2. RFD #1, Box 676,
Spokane WA 99204

3. Charles K Ballinger,
President, (509) 448-9727

4. SPOHUG Newsletter

5. Special interests: Heath
H-8 and H-89 computers.

Foreign Clubs and Newsletters

1. Computer Education
Group of Victoria

2. POB 245, Niddrie, Vic-
toria 3042, Australia

3. Greg Johnstone, (03)
336-1855

4. COM-3

5. Educational uses of com-
puters.

1. Brazilian Microcomputer
Club

2. Rua Sambaiba, 516,
Leblon, Rio de Janeiro
22450, Brazil

3. Douglas Gilson, 274-2439
5. Special interests: ex-
changing programs and
ideas with other clubs.

1. Apple's British Columbia
Computer Society

2. #101-2044 W 3rd Ave,
Vancouver, British Col-
umbia, V6J 1L5, Canada

3. Gary Little, (604)

731-7886

4. Applegram

5. Apple II microcomputers.

1. Apple-Can

2. POB 696, Station B,
Willowdale, Ontario,
M2K 2P9, Canada

3. Louis H Milrad, (416)
961-6691 or 223-0599

4. Yes

5. All areas concerning
microcomputers.

1. Association of Computer
Experimenters

2. c/o B Murphy, 102 Mc-
Craney St, Oakville, On-
tario, L6H 1H6, Canada

3. B Murphy, (416)
845-1630

4. Ipso Facto

5. Special interests: CDP
1802 microprocessor-
based hobby computers.

1. I-SUG

2. POB 1542, St Catharines,
Ontario, L2R 7J9,
Canada

5. Interested in Exidy

Sorcerer microcomputers.

1. Kitchener — Waterloo
Microcomputer Club

2. Reading Room — E2-3354,
Electrical Engineering
Department, University
of Waterloo, Waterloo,
Ontario, N2L 3Gl,
Canada

3. Roger Sanderson, work
(519) 885-1211, ext 3815

5. Special interests: 6800
and 6809 SwTPC
systems.

1. OSMIE (Ontario Society
for Microcomputers in
Education)

2. Unit for Computer
Science, McMaster
University, Hamilton,
Ontario, L8S 4K1,
Canada

3. N Solntseff, (416)
525-9140, ext 4689

5. All educational uses of
microcomputers.

1. The Ottawa Computer
Group

2. POB 5691, Station F, Ot-
tawa, Ontario, K2C
3M1, Canada

3. John Mainwaring, Presi-
dent, (613) 725-9441; or
Dennis Tubie, Secretary,
(819) 561-1645

4. OCG Newsletter

5. Special interests: micro-
processors and computer
bulletin board.

1. TRACE (Toronto Region
Association of Computer
Enthusiasts)

2. POB 6922, Station A,
Toronto, Ontario, M5W
1X6, Canada

3. Ross Cooling, (416)
488-3314

4. TRACE

1. CPE (Central Program
Exchange)

2. Department of Com-
puting & Mathematical
Sciences, The Polytech-
nic, Wulfruna St,
Wolverhampton, WVI
1LY, England

3. Judith Brown, 0902
27371, ext 93

4. Program Exchange

5. Microcomputer usage in
schools and educational
computer-aided learning.

1. North London Hobby
Computer Club

2. c/o D.E.C.E. Polytechnic
of North London,
Holloway Rd, London
N7 8DB, England

3. Robin Bradbeer,
01-607-2789

4. Gigo

5. Special interests:
business, homebrew, and
games workshops. PET
users group.

1. Microtel— Club

2. 9, rue Huysmans 75006
Paris, France

3. M Perdrillat, 33 (1) 544
70 23

4. Microtel-Infos

5. This group is interested
in microcomputers and
telecommunications .

Bower-Stewart Si Associates

SOFTWARE AND HARDWARE DESIGN

$GOLD DISK$ CP/M Compatible Z-80 Software

Available for all 8-5" SS-SD IBM format systems including TRS-80®, Northstar, SD Systems. Also available on 5" double density Superbrain."

$175.

ppd

Un-can your canned software!

Z-80 Disassembler Feel couped up with your
canned software? Our Z-80 Disassembler
recreates assembly language source files from
absolute code enabling users to easily tailor
programs to meet their specific needs. The
Preconditioner works with the Disassembler to
decode ASCII.

Credit cards Immediate service, free 24 hr phone - we will
credit invoice Checks. M.O.'s: Ten workday hold CA res Add tax

$50.

ppd

^B -^g

Great looking letters & reports!

E-Z Text A unique word processor organized
around user-created text files, embellished
with simple control commands, which supports
such 'BIG GUYS' features as Automatic Foot-
noting, Table Spacing, Heading, Paging, Left
& Right Margins, Proportional Spacing and
MORE, at a 'LITTLE GUYS' price tag.

State system & controller Allow time for surface mail
Trademarks Digital Research. Radio Shack. Intertec

POST OFFICE BOX 1389 HAWTHORNE, CALIFORNIA 90250 213 / 676-5055

182 April 1981 © BYTE Publications Inc

Circle 124 on inquiry card.

The PRACTICAL MICROCOMPUTER PROGRAMMING™ books. .

WHAT DO THE CRITICS SAY?

BYTE: "It was apparently Mr. Welter's goal from the beginning to pre-
sent the fundamental concepts of assembly language programming in
a completely nonthreatening way. He has accomplished this better
than any other author to date. . . Practical Microcomputer Program-
ming is a very powerful series. It is well written and full of essential
techniques for the assembly language programmer.". . . "The authors
know the difference between a novice and a ninny. They never talk
down. . . on every page the authors spot and clear up the small ambi-
guities of technical jargon that can block understanding."

Kilobaud: "A powerful plus for this book is the author's determination
to demonstrate why and how to use each instruction, not merely to ex-
plain how it works. . .At no point do the authors resort to rehashing
material available from the manufacturer. . . but instead choose a less
theoretical, more practical approach. "

Leventhal:

pies, and
topics."

". . .large numbers of documented, well structured exam-
a clear readable style, a logical development of major

Digital Design: "This book is the best and most lucid introduction to
Z80 programming that we have seen."

CACHE: "This is an EXCELLENT book. . .dirt cheap for such great
software and documentation."

IF YOU'VE TRIED THE "CHEAPIES" AND AREN'T SATISFIED WITH WHAT YOU GOT, IT'S TIME TO TRY THE REAL
THING, THE ACKNOWLEDGED WORLD STANDARD OF TECHNICAL EXCELLENCE IN ASSEMBLY LANGUAGE
PROGRAMMING INSTRUCTION— THE PRACTICAL MICROCOMPUTER PROGRAMMING BOOKS.

- FOR THE 6502 ■
PRACTICAL MICROCOMPUTER PROGRAMMING: THE 6502 toy W. J. Weller $32.95

20 chapters, 6 appendices, 475 page Smythe sewn hardcover covering all fundamental assembly language techniques for the 6502 processor. The
text explanation is re-enforced with 1 18 verified, real world programming examples that run on real computers. An extended 6502 language, sup-
ported by a new editor/assembler which comes with the book, circumvents many of the problems which have made the 6502 so difficult to pro-
gram in the past. In addition to the fundamental technique chapters, there are special chapters covering simple graphics, elementary cryp-
tography and random number generation and use. The source texts of both the editor/assembler and a powerful new debugging monitor for the Ap-
ple II and Apple II + included in appendices. The object code for this software is supplied FREE to book purchasers on Apple cassette or for $7.50
on disk when the licensing agreement from the book is returned to the publisher. The editor/assembler is also available on paper tape for users of
other 6502 based systems.

- FORTHEZ80-
PRACTICAL MICROCOMPUTER PROGRAMMING: THE Z80 toy W.J. Weller $32.95

18 chapters, 4 appendices, 481 page Smythe sewn hardcover which details assembly language technique as applied to the Z80 processor. The Z80
is treated as an 8080 superset in an 8080 extension language, which means that you don't have to discard your hard won 8080 knowledge to pro-
gram the 180. In addition to the fundamental chapters there are chapters on graphic output and full four function decimal arithmetic. The text ex-
planation is re-enforced with 104 tested, verified programming examples. A powerful editor/assembler and debugging monitor, in source form, are
provided to support the language used in the book. This software will run on any 280 based computer with 1 0K RAM beginning at 0. Object code for
both editor/assembler and debugging monitor is sent to book purchasers FREE on paper tape or, in modified form, on TRS-80 Level II cassette
when the coupon from the book is returned to the publisher.

■ FOR THE 8080 -
PRACTICAL MICROCOMPUTER PROGRAMMING: THE INTEL 8080 toy Weller, Shatzel and Nice $23.95

18 chapters, 3 appendices, 318 page Smythe sewn hardcover which applies fundamental assembly language technique to this most popular of
processors. The text is supported by 84 separate programming examples. The book includes a special section on the handling of complex
peripheral devices and exotic typefaces. Appendices give the source for an 8080 resident debugging monitor and a minicomputer cross assembler
for the 8080. Also available (not shown above) are a workbook for use with this text ($9.95) and Mi EDITOR/ASSEMBLER SYSTEM FOR 8080/8085
BASED COMPUTERS ($15.95) which supports the language used in the text. These three books together make a complete teaching package for
the 8080.

• FOR THE 6800 ■
PRACTICAL MICROCOMPUTER PROGRAMMING: THE M6800 toy W.J. Weller $23.95

16 chapters, 2 appendices, 299 page Smythe sewn hardcover text which details the application of fundamental assembly language technique to
the 6800. 104 separate programming examples re-enforce the text explanation. Contains in addition special chapters on low precision
trigonometry and random number generation and use. A resident debugging monitor for 6800 systems is included in an appendix.

NO GAMES, NO NONSENSE, NO RE- |
PRODUCTIONS OR REHASHES OF |
MANUFACTURER'S DATA SHEETS, |
JUST TESTED, ACCURATE, RELE- |
VANT PROGRAMMING INFORMA- |
TION BACKED UP BY REAL EXAMP- |
LES THAT RUN ON REAL COMPUT- |
ERS-THE PRACTICAL MICROCOM- |
PUTER PROGRAMMING BOOKS, i
THERE IS NOTHING ELSE AS GOOD i
ANYWHERE, AT ANY PRICE.

Mail to: Northern Technology Books, Box 62, Evanston, IL 60204

□ Practical Microcomputer Programming: The 6502

□ Practical Microcomputer Programming: TheZ80

□ Practical Microcomputer Programming: The Intel 8080

□ Practical Microcomputer Programming: The M6800
D Workbook for Practical Microcomputer Programming: The Intel 8080

□ An Editor/Assembler System for 8080/8085 Based Computers

$32.95
$32.95
$23.95
$23.95
$ 9.95
$15.95

D Check enclosed (U.S. funds only)

Name

Street

City

D Money order enclosed

. State

-Zip

Illinois residents add 5% sales tax

The time has come for computers
to talk and listen

^

Introducing COGNIVOX series VIO,
the affordable voice I/O peripherals

If you have a

PET - TRS-80 - APPLE II
AIM 65 - SORCERER

or any Z-80 CPU based system with at least 1 6K ol RAM, COGNIVOX will
add a whole new dimension to your computer.

Imagine being able to use your voice for entry of commands and data
and then listen to the computer talk back to you! This exciting possibility
has now become a reality at a very affordable price.

COGN I VOX. series VIO, is a family ol voice input and output peripherals
especially designed for personal computers that are easy to use and have
excellent software support. You need only plug in COGNIVOX, load one ol
the programs provided and you will be able to have a voice encounter with
your computer 1

COGNIVOX can be trained to recognize words or short phrases from a
vocabulary of up to 32 entries of your choice, with an accuracy of up lo
98%. The voice response vocabulary can also have up to 32 entries
chosen by the user. COGNIVOX requires that your computer has at least
16K of RAM. If it has less memory or if you are only interested in
recognition, ask us about our SR-100 series of voice input peripherals

COGNIVOX comes complete with microphone, power supply, (as
required), built-in amplifier/speaker and extensive user manual. What
makes COGNIVOX truly unique, though, is the software that comes with it
on cassette. Some of the programs included are: DIALOG, a program that
lets you conduct a dialog with your computer (or translate from one
language to the other); VDUMP, a vocal memory dump that reads the
memory contents out loud; VOTH, a voice operated talking board game
and VOICETRAP, a voice operated video game.

Adding voice I/O to your own programs can be done very easily too. All
that is needed to have your computer recognize a word or say a word is a
single USR statement in BASIC. No machine language programming is
necessary.

With all these features, you'd expect COGNIVOX to cost a small fortune
(after all, even talking chess games sell for over $300), yet it only costs
$149 (add $4.50 fcr shipping in the U.S., 10% ol order overseas. CA res.
add 6% tax). This low price has been made possible by innovative
hardware and a technological breakthrough in recognition algorithm
design that uses powerful non-linear pattern matching techniques and
adaptive learning.

COGNIVOX is simply the most (un, most exotic peripheral you can buy
for your computer. Write or call (805) 685-1854 for more information.
giving us the make and model of your computer Or better yet. order a
COGNIVOX today and bring your computer to life.

VOICETEK

Dept B, P.O. Box 388
Goleta, CA 93116

Clubs and Newsletters ,

1. Japan Microcomputer
Club

2. Rm 313, 3-5-8,
Shibakoen, Minato-Ku,
Tokyo 105, Japan

3. Keigo Aono, Director
03-438-1869

4. Microcomputer Circular

5. This is the largest, non-
profit, nationwide group
in Japan. An English-lan-
guage version of the
club's newsletter is
available.

Microcomputer Club

Fte de Quijote §5,

Tecamachalco, Mexico

10-D F, Mexico

Alfredo Buzali, (905)

589-2279

Bulletin

Primarily concerned with

the Apple computer.

1. HCC (Hobby Computer
Club)

2. Christinastraat 171, 5 615
RK Eindhoven, Nether-
lands

4. Hobby Computer Club
Nieuwsbrief

5. The goals of the HCC are
to increase contacts be-
tween computer amateurs
and to exchange ideas
and experiences.

1. Club de Com-
putation Lampas de
Carabobo

2. Apartado 716, Valencia,
Venezuela 2001A,
Venezuela

5. Use of microcomputers in
civil engineering, basic
sciences, and administra-
tion. ■

A

nswers to

Micro

Shakespeare Quiz

1 -m

2-j
3 -a
4-f
5-h

6 -
7-

8 -

9 -
10 -

b

q

l

s

11 - i 16 - e

12 - c 17 - t

13 - r 18 - k

14 - g 19 - n

15 - p 20 - d

Number of
Correct Matches

MicroShakespeare
Rating

20

Hit "START" with con-
fidence.

17- 19

One short debug session and
you're home free.

13 - 16

Check your system monitor.

9-12

Must have mixed up the pin-
outs.

5 -8

Blame it on a power surge.

4 or fewer

Back to collecting stamps. ■

184 April 1981 © BYTE Publications Inc

Circle 14 on inquiry card.

SOLVE THE STORAGE

SHORTAGE

with ten multi-user megabytes

CompuStar's 8-inch Winchester

CompuStar Cable Assembly

If you could think of just one way to im-
prove our phenomenally popular Super-
Brain, what would it be? More disk
storage? Well, we already thought about
it. And for only a few thousand dollars for
a whopping 10 megabytes of lightning-
fast storage, it's nothing short of another
major breakthrough! From the company
that wrote the book on price/perfor-
mance . . . Intertec.

Our New CompuStar™ 10 Megabyte
Disk Storage System (called a DSS)
features an 8 inch Winchester drive
packaged in an attractive, compact
desktop enclosure. Complete with disk,
controller and power supply. Just plug it
into the Z80 adaptor of your SuperBrain
and turn it on." It's so quiet, you'll hardly
know it's there. But, you'll quickly be as-
tounded with its awesome power and
amazing speed.

'Some models require hardware/software modification.

The secret behind our CompuStar DSS
is its unique controller/multiplexor. It
allows many terminals to "share" the
resources of a single disk. So, not only
can you use the DSS with your Super-
Brain, you can configure multiple user
stations using our new series of Compu-
Star™ terminals, called Video Processing
Units or VPU's™.

Four CompuStar VPU's are available.
At prices starting at less than $2,500.
Some models are designed to operate as
stand-alone microcomputers, with inter-
nal disk storage. Just like your Super-
Brain. Each model features its own 64K of
RAM and can be "daisy-chained" into a
powerful multi-user network. Just connect
one VPU into the next. Using easy-to-
install cable assemblies. Connect up to
255 users in a single system. One at a
time. As you need them.

Whether you need an extra 10
megabytes for your SuperBrain or an
enormous multi-user network, the
CompuStar™ DSS solves your storage
shortage problems. Sensibly. And
economically. Plus, your investment is
protected by a nationwide service net-
work with outlets in most major U.S.
cities. Providing efficient on-site or depot
maintenance.

Get a demonstration of this extraor-
dinary new system today. Call or write
now for the name and address of your
nearest CompuStar dealer.

j= INTERTEC

Cdata
s systems.

2300 Broad River Rd. Columbia. S.C. 29210
(803) 798-9100 TWX: 810-666-2115

THE EGYPTIANS LOVED
LARGE NUMBERS, AND...

ts

THE GREEK-5CAME
UP WITH A WHOLE
5ET OF VARIABLES:

THE A LPHABET
loo^zoei/) (wov?)j

PEOPLE COULD NOW HAVE A
HARD COPY OF ANYTHING.
IT WAS EVEN USED BY OUR

FOUNDING FATHERS.

BUT WHEN REPLACING TUBES
BECAME MORE COSTLY THAN
THE FIGURING WAS WORTH,
SOLID STATE TECHNOLOGY
TOOK OVER. SO INSTEAD
OF MASSIVE COMPUTERS
FILLING UP AN ENTIRE
FLOOR, THEY WERE BUILT
TINY. ABOUT THE SIZE
OF A REFRIGERATOR.

FINALLY CAME THE

IN VENT I ON OF THE

MICRO- PROCESSOR!

BACK IN PRE -HISTORIC
TIME5 5 CAVEMEN DID ALL
THEIR FIGURING ON THEIR
FINGERS. BUT THE ONLY
TROUBLE WAS 10 WAS
AS HIGH AS THEY
COULD COUNT

LET5 5E£ WOW.
TWEy/M »s...UH,HMM
.W/ELL.ITMuoTBE 10 *

SO THEY INVENTED A
CRUDE ADDING MACHINE

COUNTING REMAINED
THAT WAY UNTIL SOME
GREAT SUMERIAN
DISCOVERED THAT NUMBERS]
CAN EXIST HIGHER
THAN lO.

IT EVEN HAD ITS
OWN SET OF GRAPHIC
CHARACTERS.

AS TIME PROGRESSED
50 DID MAN'S NEED FOR I
EVEN MORE COMPLICATED)

NUMBER WORK.

o ,

THE CHINESE PUT IT
TO IMMEDIATE (J5E

THEN PASCAL
INVENTED THE BUILT
IN POWER SUPPLY.

WITH THAT, THE FIRST TRUE DIGITAL C0MPUTER5 WERE
BUILT. THEY WERE GIANT AND USED MILLIONS OF TUBES.

G-UTENBERG INVENTED
THE F/R5T MOVABLE
PRINT. HEAD-

- OO o

o o o a o

O 4

% % \\f %

rare

#88®

DESPITE THEIR SMALL
SIZE, THEY STILL WERE

NOT QUITE SMALL ENOUGH

--FOR HOM E US E.

GET THAT TWINS
Ol/T OF M* HoWE'

WHICH MADE IT POSSIBLE -H
FOR MICRO-SIZE COMPUTERS
WflWi/jniH»«n///fJ»||| f|| "

AND NOW OUR 5MALL

PORTABLE COMPUTERS

ARE THOUSANDS OF TIMES

MORE POWERFUL AMD C05T T

THOUSANDS OF TIMES LESS.

r — ^

* FACT: BfN FRANKLIN COINED THE ELECTRICAL TEftMJ "POSITIVE AND N64ATIVE''

30 NOW IT IS EASIER
THAN EVER TO WRITE A
COMPLICATED PRO&Ri

186 April 1981 © BYTE Publications Inc

Circle 127 on inquiry card.

Orange micro

CENTRONICS 737 (

RADIO SHACK \
LINE PRINTER IV )

Word Processing Print Quality

• 18 x 9 dot matrix; suitable tor word
processing • Underlining • proportional
spacing • right margin justification • serif
typeface • 50/80 CPS • 9V2" Pin
Feed/Friction feed • Reverse Platen •
80/132 columns

CENTRONICS 737-1 (List $995) $765

CENTRONICS 737-3 (List $1045) $815

EPSON MX80

I

Low-Priced
Professional Print Quality

• 9 x 9 dot matrix • Lower case descenders

• 80 CPS • Bidirectional, Logic seeking •
40, 66, 80, 132 columns per line • 64 special
graphic characters: TRS-80 Compatible •
Forms handling • Multi-pass printing • ad-
justable tractors

EPSON MX80
EPSON MX70

.(List $645)
.(List $495)

OKIDATA MICROLINE SERIES

TRS-80 Graphics Compatibility

• 9 x 7 dot matrix • 80 CPS • 80, 132
columns — 64 shapes for charts, graphs &
diagrams • Double wide characters • 6/8
lines per inch • Up to 3 part copy • Friction
& pin feed • 200 M character head warranty

OKIDATA MICROLINE 80 (List $800) $520

OKIDATA M82 Bidirectional, Forms handling (List $960) $750

OKIDATA M83 Wide carriage, 9 x 9 dot matrix (List $1 260) Scall

IDS PAPER TIGERS

Dot Resolution Graphics, quality print

• 7 wire printhead (445); 9 wire printhead
(460) with lower case descenders • Over
150 CPS • bi-directional, logic seeking
(460) • 8 character sizes; 80-132 columns

• Adjustable tractors • High-resolution dot
graphics • Proportional spacing & text
justification (460).

IDS445G 7 wire printhead, graphics (List $895)

IDS460G9wire printhead, graphics (List $1394)

$ 795
$1150

CALL FOR FREE CATALOG

(800) 854-8275

CA,AK, HI (714) 630-3322

At Orange Micro, we try to fit the right printer to your application.
Call our printer specialists for free consultation.

'SPECIALIZING IN PRINTERS
AND CRT'S"

VISTA — C. ITOH

Daisy Wheel Letter Quality

• 25 CPS (Optional 45 CPS) • Typewriter
quality • Centronics parallel • RS 232
Serial (Optional) • Proportional spacing •
Bidirectional • Programmable VFU • Self
test • Diablo compatible • Friction feed
(Optional tractors) • 136 printable
columns. • Manufactured by C. ITOH.

VISTA V300 (C. ITOH) (List $1895) $ Call

ANACOM

Low Cost, High Speed, Wide Carriage

• 9 x 9 dot matrix • Lower case descenders • Wide carriage •
Adjustable tractors to 16" • 150 CPS, Bidirectional, Logic Seeking

ANACOM 150 (List $1 350) S Call

ANADEX

Dot Graphics, Wide Carriage

• 11 x9dot matrix; lower case descenders • Dot resolution graphics

• Bi-directional, logic seeking • Up to 200 CPS • RS 232 Serial &
Parallel • Forms control • X-ON/X-OFF* Up to 6 part copy.
ANADEX9501 (List$1650) $1450

NEC SPINWRITER

High Speed Letter Quality

• 55 CPS • Typewriter quality • Bidirectional • Plotting • pro-
portional spacing.

5510-5 RO, Serial, w/tractors (List $2995) $2625

5530-5 RO, Parallel, w/tractors (List $2970) $2599

QUANTITY PRICING AVAILABLE

TELEVIDEO CRT'S

PRICES SLASHED!

TVI912C
TV I 920C
TVI 950

}

Please Call Toll Free
Prices are too low to
advertise

PRINTERS

MALIBU 1 65 wide carriage, graphics, letter quality .. (List $2495) $1975
QUME 5/45 typewriter quality (List $2905) $ 2559

INTERFACE EQUIPMENT

CCS APPLE PARALLEL Interface & cable $ 150 |

APPLE II- EPSON MX80

parallel graphics intertace board & cable $ 110

SSMAIO BOARD Apple Serial/parallel interface (List $225)$ 175

MICROTRONICS Atari parallel interface $ 69 I

ATARI 850 Interface module, serial/parallel $ 199

TRS-80 CABLES to keyboard or Exp. interface * Ca "

NOVATION D-CAT direct connect modem $ Call

TELEPHONE ORDERS: Mon.-Fri. 8:30 - 5:00

The Orange Micro Printer Store (Retail):

Mon. -Fri. 10:00 - 6:00, Sat. til 4:00

*Ss

Phone orders WELCOME; same
day shipment. Free use of VISA &
MASTERCARD. Personal checks
require 2 weeks to clear. Manu-
facturer's warranty included on all
equipment. Prices subject to
revision.

Oronge

fTlfCrO, Inc.'

3148 E. La Palma, Suite E
Anaheim, CA 92806

Software Review

Three Versions of APL

Gregg Williams, Senior Editor

BYTE POB 372

Hancock NH 03449

When BYTE magazine published its APL language
issue in August 1977, APL was far beyond the capabilities
of any microcomputer. To show how rapidly things have
evolved since then, the Digital Group, in that same issue,
was advertising a 32 K-byte static-memory board for
$995, and another advertisement began, "Introducing
Apple II...." Times have changed: 32 K bytes of dynamic
memory, now commonly used in several major micro-
computer lines, can be bought for less than $120 — and
Apple is one of the oldest computer lines in the industry.

Times have changed for APL as well: several com-
panies have announced software and hardware support-
ing this unique programming language. This review com-
pares three versions of APL: Softronics APL, Ramware
APL80 for the Radio Shack TRS-80, and Vanguard
APL/V80. (For additional information, see the "At a
Glance" boxes. Tables 1 thru 4 give timing comparisons
and further information.)

Softronics APL: I/O Options and Documentation

Softronics APL runs on any Z80-based computer that
supports at least 44 K bytes of memory and the CP/M
operating system. It was written by Eric Mueller of Soft-
ronics, who, in 1977, authored a subset of APL called
EMPL for 8080-based microcomputers. Softronics APL
(Version 2.3C), which sells for $350, has both good and
bad features; a summary is given in table 2.

The most welcome feature of Softronics APL is the
ability to use it with several types of keyboards and
display devices. The default mode of operation is for the
software to respond to a standard ASCII (American Stan-
dard Code for Information Interchange) terminal through
standard CP/M input and output routines. Three other
modes allow the user to use an assortment of APL-type
devices.

For those of us who do not have several thousand extra
dollars to spend on an APL-type I/O (input/output)
device, the ASCII mode of Softronics APL is very
welcome. In this mode, all APL characters that are not on
a normal keyboard are replaced by either a single key (eg:
an underline character to replace the APL assignment ar-
row) or a 3-character mnemonic (eg: $TP for the
transpose operator or $RO for the Greek rho symbol).
Although some users object to this arrangement, my
reaction to running Xerox APL for an extended period,
using such mnemonics, was one of gratitude — better this

APL than no APL at all.

Listing 6 shows the output of the APL function
CIRCLE. Listing 3a shows the output with slight changes
in regular APL notation. I have also found that by chang-
ing the value of the system variable DCS, you can cause
the APL mnemonics to be displayed with angle brackets
around them instead of the preceding dollar signs — on
printout only (ie: not input). For example, you will still
have to type in $RO for the APL reshape operator, but it
will be displayed to the screen or printer as < RO> . This
is a nice feature that adds to the readability of APL pro-
grams printed in ASCII mode.

Provisions are also made for using Softronics APL with
the two most prevalent types of APL terminals (bit-
pairing and typewriter-pairing terminals). Softronics
APL begins executing in the ASCII mode but can be con-
verted to APL terminal mode by assigning a new value to
the system variable DCS, or it can be modified to begin
executing in terminal mode by making a 1-byte patch to
the APL.COM machine-language file. Nonstandard ter-
minals or video boards can be interfaced by adding user-
supplied input and output machine-language subrou-
tines. The manual explains what routines need to be writ-
ten and where they should be placed in memory.

Finally, the manual gives documentation on still
another I/O option: the use of APL input and output
through a video board with a programmable character
generator. The documentation includes the software
driver (which works with an Objective Design Inc
character generator), a Kent-Moore Alpha-VDM-II video
display board, and a listing that defines all APL special
characters for a character generator as a series of hexa-
decimal numbers. All this code is included in the
APL.COM file.

The ease with which I understood these four display
options is an indication of the quality of the documenta-
tion. The Softronics APL documentation is the best of the
three packages reviewed here. It includes a short tutorial
on APL for the complete novice, a description of all func-
tions, sample programs (including APL defined functions
that simulate certain APL operators not defined in ma-
chine language), and several useful appendices. One sec-
tion of the documentation, "Bugs and Common Perplex-
ing Error Messages," is a great time saver. It is extremely
helpful in explaining some quirks of Softronics APL and
how to circumvent them. This section saves the user from

188 April 1981 © BYTE Publications Inc

Circle 128 on inquiry card.

The VP-111 hobby computer:
Start programming for only $ 99.

$99.

New! VP-111
Microcomputer
Assembled* and tested.

Features:

• RCA 1 802 Microprocessor.

• 1 K Bytes static RAM.
Expandable on-board to 4K.
Expandable to 32K Bytes total.

• 51 2 Byte ROM operating system.

• CHIP-8 interpretive language or
machine language programmable.

• Hexidecimal keypad.

• Audio tone generator.

• Single 5-volt operation.

• Video output to monitor or modulator.

• Cassette interface— 1 00 Bytes/sec.

• Instruction Manual with 5 video game

listings, schematics, CHIP-8, much more!

Ideal for low-cost control applications.

Expandable to full VP-71 1 capability with

VP-114Kit.

'User need only connect cables (included), a

5-volt power supply and speaker.

*199.

New low price!
VP-71 1, only....
Completely assembled
and tested.

All the features of the VP-111 plus:

• A total of 2K Bytes static RAM.

• Power supply.

• 8 Bit input port.

• 8 Bit output port.

• I/O port connector.

• System expansion connector.

• Built-in speaker.

• Plastic cover.

Three comprehensive manuals:

• Instruction Manual— 20 video game
listings, schematics, much more.

• User's Guide— operating instructions
and CHIP-8 for the beginner.

• RCA 1 802 User's Manual (MPM-

201 B)— complete 1 802 reference guide.

RCA

Add computer power a
board at a time.

With easy-to-buy options, the versatile
RCA hobby computer means even
more excitement. More challenges in
graphics, games and control functions.
For everyone, from youngster to serious
hobbyist.

Built around an RCA COSMAC micro-
processor, our hobby computer is easy
to program and operate. Powerful
CHIP-8 interpretive language gets you
into programming the first evening.
Complete documentation provided.

Send the coupon now...

Complete the coupon below and mail to:
RCA Microcomputer Customer Service,
New Holland Ave., Lancaster, PA 1 7604.

Or call toll free (800) 233-0094

to place your Master Charge or VISA
credit card order. In Pennsylvania,
call (71 7) 397-7661 , extension 31 79.

Please send me the items indicated.

D VP-111 New low cost Microcomputer

$ 99

(See description above)
C VP-114 Expansion Kit for VP-111— Includes

3K RAM, I /O Port and connectors $ 76
D VP-711 The original VIP Microcomputer

(See description above) $199

□ VP-44 RAM On-Board Expansion Kit— Four

2114 RAM ICs. Expands VP-71 1
memory to 4K Bytes $ 36

□ VP-590 Color Board— Adds color. Four

background and eight

foreground colors $ 69

D VP-595 Simple Sound Board— Provides

256 programmable frequencies. For

simple music or sound effects.

Includes speaker $ 30

D VP-550 Super Sound Board— Turns

VP-1 1 1 /71 1 into a music synthesizer!
Two independent sound channels.
Outputs to audio $

D VP-551 4-Channel Super Sound— Includes
VP-576 and demo cassette. Requires
VP-550 and 4K RAM $

□ VP-570 Memory Expansion Board—

Plug-in 4K RAM memory $

□ VP-580 Auxiliary Keypad— Adds two-player

interactive capability. Connects

to VP-590 or VP-585 $

D VP-585 Keypad Interface Board— Interfaces
two VP-580 Auxiliary Keypads
toVP-111/711 $

□ VP-560 EPROM Board— Interfaces two

271 6 EPROMS to VP-1 11/711 .. $ 34

74

95

20

15

Keyboards & Terminals

O VP-601 Keyboard— 128-character ASCII

encoded alphanumeric 8-bit parallel
output $ 69

D VP-606 Keyboard— Same as VP-601.

Asynchronous serial output $ 99

□ VP-611 Keyboard— Same as VP-601 plus
16-key numeric keypad $89

□ VP-616 Keyboard— Same as VP-606 plus
16-key numeric keypad $119

D VP-620 Cable— Connects VP-601 /611 to

VP-1 11/711 $ 20

□ VP-623 Cable— Unterminated for
VP-601 /611 $ 20

D VP-626 Connector— Male "D" mates to

VP-606/616 $ 7

□ VP-3301 Interactive Data Terminal $369

D VP-3303 Interactive Data Terminal

with built-in RF output $389

.for items checked plus shipping & handling charge of $3.00.

Add your state and local taxes $ Total enclosed $

I enclose □ check or □ money order. Or charge my □ VISA □ Master Charge.
Credit card account No.

D VP-565 EPROM Programmer Board-
Programs 271 6 EPROMs.
With software

□ VP-575 Expansion Board— Provides 4

buffered and one unbuffered
expansion sockets

□ VP-576 Two-Board Expander— Allows

use of 2 Accessory Boards in either

I/O or Expansion Socket $ 20

□ VP-700 Tiny BASIC ROM Board— BASIC

code stored in 4K of ROM

D VP-701 Floating point BASIC for

VP-71 1 on cassette. Requires 1 6K
Bytes RAM (avail. 7/80)

□ VP-710 Game Manual— Listing for 16

exciting games

D VP-720 Game Manual-ll— More games ..

« Enclosed is $_

$ 99

$ 59

$ 39

$ 49

Master Charge Interbank No.

Signature (required for credit orders):

Name (please type or print):

Street address:

State & Zip:

Expiration date .

. Telephone^ ) .

.City:

Make checks payable to RCA Corp. Prices and specifications are subject to change without notice.

spending quite a bit of time swearing that the language
"just doesn't work right."

So f Ironies APL: Some Problems

Despite its excellent performance in other areas,
Softronics APL (Version 2.3C) has a number of deficien-
cies that range from minor annoyances to critical defects.
The most serious defect is that Softronics APL does not
notify the user of an error situation. Any computation
that has a result over 9.2 X 10 18 is replaced by a seemingly
random value between 10 18 and 10 19 . The low limit on
computation size is not what makes this error dangerous;
rather, the danger lies in the language substituting an in-
accurate answer and not stopping the computation with
an error message.

A second problem with Softronics APL is that it re-
sponds with the message SYNTAX ERROR to any num-
ber over 7 digits long. I feel that the inability of this
language to accept a longer number by rounding it off
and, when necessary, putting it into scientific notation is
a serious defect.

Many numeric operations that should come out "even"
result in numbers ending in ...9999 or ...9997. For
example, any variable assigned either the value 0.1 or
1/10 is printed as .099999. The dyadic power function
has, for integral exponents, a cumulative round-off error
that results in some incorrect answers. For example, 5 s is
calculated to be 390,622 (it is 390,625) and 3 12 is
calculated to be 531,436 (it is 531,441), with higher
powers also being incorrect.

IEEE-488 TO TRS-80* INTERFACE

Everything needed to add powerful basic GPIB-488
controller capability to TRS-80 Model 1 or 3, Level 2 or
DOS with a minimum of 16K.

MODEL 488-80B
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Jl

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For Model 3 Operation

Price of Model 488-80B or 488-80C $225.

+ shipping, insurance & tax

Optional Relocatable Machine Level GPIB Driver
for Assembler Level Programming-$35.00

WHEN ORDERING SPECIFY DISK OR TAPE

SCIENTIFIC ENGINEERING LABORATORIES

11 Neil Drive • Old Bethpage, NY 11804
Telephone: (516) 694-3205

'Trademark of Tandy Corp.

There is no affiliation between Scientific Engineering Laboratories and

Tandy Corp. or Radio Shack.

When using the power function for fractional powers,
such as square roots, the results seem to be one or two
units off in the least significant digit. Even though 6
significant digits are given in all calculations, I would
recommend using only 5 significant digits when using the
dyadic power function to calculate a root.

The trigonometric functions, such as sine, cosine,
tangent, and arctangent, agree with the results found in
the Chemical Rubber Company's CRC Standard Math-
ematical Tables. However, the arctangent function seems
to work with a scalar (ie: a single value) but not with a
vector (ie: a one-dimensional array of values).

Softronics APL still lacks several useful functions that
are found in the more expensive Vanguard APL: arc-
cosine, arctangent, and all hyperbolic trigonometric
functions; rotation on three-dimensional and higher
matrices; the grade-up and grade-down functions; and
the deal (ie: dyadic question-mark) function. Other,

Name

Language Used

Softronics APL, Version

8080 machine language

2.3C

Computer Needed

Type of Software

An 8080-, 8085-, or

Package

Z80-based computer with

Version of APL program-

at least 44 K bytes of

ming language

programmable memory,

running the CP/M

Manufacturer

operating system

Softronics, 35 Homestead

Ln, Roosevelt NJ 08555

Documentation

112 pages, 22 by 28 cm

Price

ifiVi by 11 inches)

$350

Audience

Format

APL users, programming

8-inch standard CP/M

language enthusiasts

floppy disk

Name

Computer Needed

APL80 (by Phelps Gates)

Radio Shack TRS-80

Model I with one floppy-

Type of Software

disk drive, Level II

Package

BASIC, and 32 K bytes

Version of APL program-

of memory

ming language

Documentation

Manufacturer

Twenty pages, 13 by 20

Ramware, 6 South St,

cm (5 by 7 3 A inches)

Milford NH 03055 (603)

673-5144

Audience

APL users, programming

Price

language enthusiasts

$39.95

Comments

Format

Cassette-tape version

5-inch floppy disk

with 25% fewer features

available for 16 K

Language Used

TRS-80 at $14.95

Z80 machine language

190 April 1981 © BYTE Publications Inc

Circle 129 on inquiry card.

standard on our 900 SERIES

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STANDARD ON THE 900 SERIES:

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□ IBM 3740 format compatible

□ 48 kilobytes of dynamic RAM,
expandable to 65 Kb.

D CP/M" Disk Operating System
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□ RS232 or TTY serial port for system
console.

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OPTIONS FOR THE 900 SERIES:

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DISTRIBUTOR AND REPRESENTATIVE INQUIRIES WELCOME

Circle 96 on inquiry card.

more advanced operators that are also missing are not
mentioned here. See table 2 for a more complete defini-
tion of the language.

Ramware APL80

In its version of APL for the Radio Shack TRS-80
Model I, Ramware of Milford, New Hampshire, has
made available a remarkable product. When I first saw
the advertisements for the tape version of APL80, its low
price ($14.95) led me to dismiss it as some kind of toy,
probably written in BASIC and too slow to be useful.
Even though the tape version has about 25% fewer
features than the more expensive disk version ($39.95), it
is still written in Z80 machine language and is a fairly
usable version of the language. Author Phelps Gates has
reason to be proud of this package.

Table 3 lists the operators available within APL80. The
fullness of the language is due to the use of the ROM
(read-only memory) modules implementing Level II
BASIC. Because the author was able to use the numerical
routines from Level II BASIC, much of the work of
creating an entire programming language had been done
for him, and he could concentrate on making it behave
like APL. (APL80 has been tested and found to work on
the newer TRS-80s that have Level II BASIC in two
rather than three ROM devices. Until a correction can be
made to the current version of APL80, however, the
down-arrow symbol used for the APL drop and grade-
down operations must be displayed by simultaneously
Text continued on page 196

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Name of System

Features

Vanguard APL/DTC

APL/ASCII keyboard

(desk-top computer)

and 12-inch APL/ASCII

memory-mapped video

Manufacturer

display of twenty-four

Vanguard Systems Cor-

80-character lines housed

poration, 6812 San

in separate video terminal

Pedro, San Antonio TX

enclosure; display of all

78216 (512) 828-0554

APL characters

Price

Software Included

$7995

CP/M operating system,

APL/DTC software

Terminal Dimensions

32 by 45.5 by 53.5 cm

Hardware Options

(12 Vi by 18 by 21

Communications option

inches)

(Hayes Microcomputer

Products Micromodem

Computer Dimensions

plus special software);

19 by 51 by 43 cm {7V%

high-resolution

by 20 by 17 inches)

(256-by-240 black-and-

white or 128-by-120

Processor

sixteen-gray-level )

Z80, 8-bit

graphics; letter-quality

APL/ASCII printer, real-

System Clock Frequency

time clock.

4 MHz

Software Options

Memory

APL * PLUS file system

80 K bytes of static

simulator

memory (34 K bytes left

for APL workspace)

Audience

APL users, programming-

Mass Storage

language enthusiasts

Two quad-density 5-inch

floppy-disk drives

Name

mable memory; a Z80

Vanguard APL/V80

processor card; at least

one floppy-disk drive

Type of Software

Package

Documentation

Version of APL program-

Seventy-six pages, 22 by

ming language

28 cm (8V2 by 11 inches)

Manufacturer

Audience

Vanguard Systems Cor-

APL users, programming

poration, 6812 San

language enthusiasts

Pedro, San Antonio TX

78216 (512) 828-0554

Features

APL defined functions

Price

(programs) simulate some

$500

APL functions, APL *

PLUS file system, and

Format

other functions

CP/M or CDOS

operating system, 5-inch

Comments

or 8-inch disk

This version is identical

to the software reported

Language Used

on for the APL/DTC

Z80 machine language

computer, except for the

reduced workspace size

Computer Needed

and the availability of the

Computers with at least

inner product function as

48 K bytes of program-

a defined function.

192 April 1981 © BYTE Publications Inc

Circle 130 on inquiry card.

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•DEALER INQUIRIES INVITED*

Listing 1: Listing of the APL function SETUP. This routine
defines certain variables used in the execution of benchmark
programs.

V SETUP
[10] A-i-10 lOpilOO
[20] B*M
[30] OlOxloiM
[40] D+-A*(°2)ilOQ
[50] E+llO

[60] F+-1000 365 24 60 60
[70] RA^,A
[80] RB+.B
[90] M3D<-2 5 lOpRA V

Listing 2: Listing of the APL function TIME. When this routine
is used as a benchmark program, the function to be tested
replaces each occurrence of the phrase (EXP) on lines 10 thru 60.
(See table 1.)

V TIME N;LP
[10] LP+0
[20] BGN-.(EXP)
[30] (EXP)
[40] (EXP)
[50] (EXP)
[60] (EXP)

[70] ^(N>LP^LP+1)/B0N
[80] 'DONE ';/Jx5;' TIMES'
[90] 'UNIT TIME IS '; (4ffx5)x[];

1 SECONDS PER ITERATION' V

Listing 3: Listing and sample execution of the APL function
CIRCLE. Listing 3a shows the function, which has the purpose
of adding a set value to all matrix elements that fall within an
imaginary circle with a given center and radius. Listing 3b shows
a 10 by 10 array filled with zeros and, below it, the same circle
after execution of the statement B— (6 5 4 8) CIRCLE A. On
one of the printers used to generate these listings, the backarrow
character, — , appears as an underscore,

VB+-AR CIRCLE A ;RD;ROW;COL
[10] AR CONTAINS: ROW COORD, COL COORD, RADIUS, VALUE ADDED
[20] B^A

[30] BCW*-/!fl[l]-/lJ?[3] + l
[40] NEXTROW: ROWi-ROW+1
[50] CO/>vli?[2]-/«?[3] + l
[60] NEXTCOL: C0L*C0L-H

[70] ->(ARl3~]<(((ROW-ARlll)*2) + (COL+ARL2'})*2)*Q.5'i/ENDLP
[80] BlROW;COL1*BLROW ,C0L]+/lfl[4]
[90] ENDLP:-+(COL<ARl2~]+ARt3l)/ NEXTCOL
[100] ->-(0,NEXTROW)[l+ROW<ARlll+ARl3HV

O

O

O

O

O

O

O

O

B_(6

5

4 8 )

CIRCLE

A

B

O

8

O

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

8

O

8

8

8

8

8

O

O

O

8

O

O

194 April 1981 © BYTE Publications Inc

Circle 131 on inquiry card.

THE ORIGINAL MAGAZINE FOR
OWNERS OF THE TRS-80™* MICROCOMPUTER

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BYTE April 1981 195

Listing 4: Listing and sample execution of the APL function
TRANS. Listing 4a shows the function, which translates a
numeric array similar to the one in listing 3b to a character ar-
ray that reflects the contents of the numeric array. Listing 4b
shows the result of executing TRANS B, where B is the matrix in
the lower half of listing 3b.

1B*-TRANS A ;AA ;MX ;MN ;MAXX ; CHAR

[10] CHAR+-'LMNOPQRSWVWX¥Z-123UttlB<3ABCDEF+*#'

[20] MN*-L/AA*-,A

[30] MXH/AA

[40] UAXXHMX[-MN)ilb

[50] AM.0.5tl6+AH*iU2

[60] BHpA)pCHAR\_AA] V

— FFFFF

-FFFFFFF —
-FFFFFFF —
FFFFFFFFF-
-FFFFFFF —
-FFFFFFF —
— FFFFF

Listing 5: Listing of the APL function IVER. This function,
written by Kenneth Iverson (the inventor of APL), will generate
a vector of all prime numbers up to and including the scalar A.
(A must be greater than or equal to 7.)

V B*-IVER A

B«-(2=+/<90 = (i/4)°.| \A)/\A
V

STOP PLAYING GAMES

TRS-80 (Level II)

APPLE
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I Calculate odds on HORSE RACES with ANY COMPU
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I YOU GET: f) TRS-80 (Level II) or Apple Cassette

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Yes. I want to use my computer for FUN and PROFIT Please send me programs

at $24.95 each. ^gm

I need a □ TRS-80 Cassette or G Apple Cassette. ^P'

Enclosed is: n check or money order □ Master Charge □ Visa

Card No.
NAME

Exp. date

ADDRESS .
CITY

START USING YOUR COMPUTER FOR

FUN and PROFIT!

Listing 6: Listing of the APL function CIRCLE as generated by
Softronics APL using a non-APL video terminal. APL functions
can be printed on a standard printer through the use of
mnemonic phrases, which begin with a $ sign. The backarrow
appears here as an underscore.

[i]

[2]
[3]
[4]

[5]
[6]
[7]

[a]

[9]
[10]

[11]
[12]

SDL B_AR CIRCLE
5LP

A;RD;ROW;COL

AR CONTAINS: ROW £, COL COORD, RADIUS, VALUE ADDED

(EG: (6 5 4 9) CIRCLE
VALUE 9 AND RADIUS 4,

A ADDS TO ARRAY A CIRCLE OF
WITH CENTER AT (6,5))

5LP
SLP
SLP
5 LP
B_A

ROW_ AR [ 1 ] -AR [ 3 ] +1
NEXTROW : ROW_ROW+l

COL_AR[2]-AR[3]+l
NEXTCOL : COL_COL+l
SGO ((AR[3]*2)<( (ROW-AR[l] )«2 ) + ( COL-AR[2 ] )*2)/ENDLP
B[R0W;C0L]_B[R0W;C0L]+AR[4]
[13] ENDLPiSGO (C0L$LE AK[ 2 ]+AR[ 3 ] )/NEXTC0L
[14] SGO (0,NEXTROW)[1+ROW<AR[1]+AR[3]]
$DL

Text continued from page 192:

pressing three keys: the shift key, the down-arrow key,
and the Z key.)

Because Ramware APL80 has almost all the capabilities
of Level II Disk BASIC, it has some functions and
features that the other versions reviewed here do not;
several examples are: single-precision or double-precision
variables, inverse trigonometric functions, exponents,
logarithms, and character editing within a line. Even in
the benchmarks (see table 1), this version does fairly well
against the other two versions when you consider the dif-
ferences in price ($39.95 vs $350 and $500) and in pro-
cessor speed (the TRS-80 is running at 1 MHz, while the
other two are running the same type of Z80 processor,
but at 4 MHz).

The method used to represent APL on an unmodified
TRS-80 is odd, but it is probably the best way that could

Text continued on page 204

OPERATION

UNIT TIME TO PERFORM OPERA TION, SECONDS

SOFTRONICS
APL

RAMWARE
APL80

VANGUARD

APL/DTC

SOFTWARE

Q — A *B

0.79

4.6

1.2

Q~A>B

0.48

0.42

0.091

Q-B

0.059

0.051

0.012

Q— 20D

5.0

2.9

8.6

Q — $C

140.

11.

3.1

Q~FT100000000

NA

0.61

0.13

Q — _ 50tRA

0.086

0.18

0.014

q-ODni

180.

NA

66.

Q — 4<t>[l]M3D

NA

0.74

1.8

Q— E°.+ E

0.41

0.31

0.082

Q—+/C

0.25

0.25

0.19

CIRCLE

160. *

230. *

150.

TRANS

9.0 *

28. •

11.

IVER

28.

160. «

120.

Table 1: Timing results of APL benchmark
details on this and tables 2 thru 4, see the
Benchmarks" text box on page 204.

programs. For
'Notes on APL

196 April 1981 © BYTE Publications Inc

H

&

E

CQMPJTRQNICS

N

EVERYTHING FOR YOUR TRS-80* • ATARI* • APPLE* • PET* •

•TRS-60 is a trademark of the Radio Shack Division of Tandy Corp. - 'ATARI is a trademark of Atari Inc. - 'Apple is a trademark of Apple Corp. - *Pet is a trademark of Commodore

BUSINESS PAC 100

100 Ready-To-Run
Business Programs

* 30-Day money °«
Software

(ON CASSETTE OR DISKETTE) Includes 110 Page Users Manual 5 Cassettes (Or Diskettes)

Inventory Control Payroll Bookkeeping System Stock Calculations

Checkbook Maintenance.... .Accounts Receivable.. ...Accounts Payable

BUSINESS 100 PROGRAM LIST

1 RCILE78

2 ANNU1

3 DATE

4 DAYYEAR

5 LEASE1NT

6 BREAKEVN

7 DEPRSL

8 DEPRSY

9 DEPRDB

10 DEPRDDB

11 TAXDEP

12 CHECK2

13 CHECKBK1

14 MORTGAGE/A

15 MtlLTMON

16 SALVAGE

17 RRVARJN

18 RRCONST

19 EFFECT

20 FVAL

21 PVAL

22 LOANPAY

23 REGWTTH

24 S1MPDISK

25 DATEVAL

26 ANNUDEF

27 MARKUP

28 SINKFUND

29 BONDVAL

30 DEPLETE

31 BLACKSH

32 STOCVAL1

33 WARVAL

34 BONDVAL2

35 EPSEST

36 BETAALPH

37 SHARPE1

38 OPTWRrTE

39 RTVAL

40 EXPVAL

41 BAYES

42 VALPRINF

43 VALADINF

44 UTILITY

45 SIMPLEX

46 TRAMS

47 EOQ

48 QCIEUEl

49 CVP

50 CONDPROF

51 OPTLOSS

52 FQUOQ

NAME

53 FQEOWSH

54 FQEOQPB

55 QC1ECJECB

56 NCFANAL

57 PROFIND

58 CAP1

Circle 133 on inquiry card.

Interest Apportionment by Rule of the 78's

Annuity computation program

Time between dates

Day of year a particular date falls on

Interest rate on lease

Breakeven analysis

Straightline depreciation

Sum of the digits depreciation

Declining balance depreciation

Double declining balance depreciation

Cash flow vs. depreciation tables

Prints NEBS checks along with dairy register

Checkbook maintenance program

Mortgage amortization table

Computes time needed for money to double, triple.

Determines salvage value of an investment

Rate of return on investment with variable inflows

Rate of return on investment with constant inflows

Effective interest rate of a loan

Future value of an investment (compound interest)

Present value of a future amount

Amount of payment on a loan

Equal withdrawals from investment to leave over

Simple discount analysis

Equivalent & nonequivalent dated values for oblig.

Present value of deferred annuities

% Markup analysis for items

Sinking fund amortization program

Value of a bond

Depletion analysis

Black Scholes options analysis

Expected return on stock via discounts dividends

Value of a warrant

Value of a bond

Estimate of future earnings per share for company

Computes alpha and beta variables for stock

Portfolio selection model-i.e. what stocks to hold

Option writing computations

Value of a right

Expected value analysis

Bayesian decisions

Value of perfect information

Value of additional information

Derives utility function

Linear programming solution by simplex method

Transportation method for linear programming

Economic order quantity inventory model

Single server queueing (waiting line) model

Cost-volume-profit analysis

Conditional profit tables

Opportunity loss tables

Fixed quantity economic order quantity model

DESCRIPTION

As above but with shortages permitted

As above but with quantity price breaks

Cost-benefit waiting line analysis

Net cashflow analysis for simple investment

Profitability index of a project

Cap. Asset Pr. Model analysis of project

59 WACC Weighted average cost of capital

60 COMPBAL True rate on loan with compensating bal. required

61 DISCBAL True rate on discounted loan

62 MERGANAL Merger analysis computations

63 FINRAT Financial ratios for a firm

64 NPV Net present value of project

65 PRINDLAS Laspeyres price index

66 PR1NDPA Paasche price index

67 SEASIND Constructs seasonal quantity indices for company

68 T1METR Time series analysis linear trend

69 T1MEMOV Time series analysis moving average trend

70 FUPR1NF Future price estimation with inflation

71 MAILPAC Mailing list system

72 LETWRT Letter writing system-links with MAILPAC

73 SORT3 Sorts list of names

74 LABEL I Shipping label maker

75 LABEL2 Name label maker

76 BCJSBCJD DOME business bookkeeping system

77 TTMECLCK Computes weeks total hours from fimeclock info.

78 ACCTPAY In memory accounts payable system-storage permitted

79 INVOICE Generate invoice on screen and print on printer

80 INVENT2 In memory inventory control system

81 TELDIR Computerized telephone directory

82 TIMUSAN Time use analysis

83 ASSIGN Use of assignment algorithm for optimal job assign.

84 ACCTREC In memory accounts receivable system-storage ok

85 TERMSPAY Compares 3 methods of repayment of loans

86 PAYNET Computes gross pay required for given net

87 SELLPR Computes selling price for given after tax amount

88 ARBCOMP Arbitrage computations

89 DEPRSF Sinking fund depreciation

90 (JPSZONE Finds GPS zones from zip code

91 ENVELOPE Types envelope including return address

92 ACJTOEXP Automobile expense analysis

93 INSF1LE Insurance policy file

94 PAYROLL2 In memory payroll system

95 DILANAL Dilution analysis

96 LOANAFFD Loan amount a borrower can afford

97 RENTPRCH Purchase price for rental property

98 SALELEAS Sale-leaseback analysis

99 RRCONVBD Investors rate of return on convertable bond

1 00 PORTVAL9 Stock market portfolio storage-valuation program

D CASSETTE VERSION
D DISKETTE VERSION

$99.95
$99.95

NEW

-- ofio T E fi u ;r: eE

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■cqmplJtrqnicS":

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LINE
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Scalar Dyadic Operators, Softronics APL

s
<

COMMENTS

ADD

SUBTRACT

E

MULTIPLY

DIVIDE

EXPONENT

LOGARITHM

FLOOR

CEILING

Dyadic version innaccurate in
last decimal place; see text.

a:
o

H
<

cr

L±J

0-
O

LU

s
<

z

o

Q

<

Z

o

S

O

o
<

>
a

1

RESIDUE

1

1

FACTORIAL

o

CIRCLE

< <
> >

LESS THAN, ETC.

= *

EQUAL TO,
NOT EQUAL TO

AV

AND, OR

AV

NAND, NOR

COMMENTS

Gamma function missing.

Only sin, cos, tan, arctan im-
plemented.

Nondyadic Scalar and Mixed Operators, Softronics APL

~

NOT

?

ROLL

i

IOTA (INDEX)

p

RHO (RESHAPE)

•

RAVEL

XT

DECODE, ENCODE

H

TAKE, DROP

f

MEMBERSHIP

H

GRADE-UP
GRADE-DOWN

s

MATRIX DIVIDE
OR INVERSE

COMMENTS

Dyadic available as defined
function only.

Catenation for vectors only; no
lamination.

Available as defined function
only.

Both available as defined func-
tion only.

tr

LU

a.
o

UJ

<

Z

<

z
o

S

a
<

>~

Q

s

TRANSPOSE

(D

ROTATE OR
REVERSE

e

ROTATE

/

COMPRESS

i

COMPRESS

\

EXPAND

\

EXPAND

<}>

EXECUTE

?

FORMAT

COMMENTS

Dyadic "diagonal" transpose

missing.

Dyadic function available for
vectors and two-dimensional
matrices only available as
defined function.

Available as /[1] only.

Converts a vector or array to a
character string (with embedded
carriage return) for printing.

Composite Operators, Softronics APL

IE

O

1-
<

a:

UJ

m

<

HI

SE

<

O-

<

>

o

z

<

•/

REDUCTION

fr

REDUCTION

-I
to
<

3
>
<

fg

INNER PRODUCT

OUTER PRODUCT [7]

Notes:

"Y" and "N" mean that a given operator is either present in all its forms or totally absent from this verion of APL. "Y*" means that the
operator is only partially present in this version. "N*" means that the operator is not present in this version but that part or all of it is avail-
able through an APL defined function supplied with this version. Further information explaining "Y*" and "N*" is given in the "Comments"
column.

A scalar is an object (number or character) with no dimension. A vector is a string of objects that have one dimension. An array is a
matrix of objects that have two or more dimensions.

Other features: standard APL commands, system functions, and system variables; line editing only of defined functions; PEEK and POKE
functions; 8080-type port IN and OUT functions; shared variable mechanism for interaction with disk files (sequential read and write only, in
standard CP/M format); mixing of APL data structures (arrays, vectors, scalars) in records of same file; user choice of standard terminal,
APL terminal, or video board with programmable character generator; and good documentation.

Other limitations: several much-needed operators are missing (see body of this table) and there is no random access to disk files' char-
acter-editing of defined functions.

Table 2: Summary of Softronics APL features.

198 April 1981 © BYTE Publications Inc

E

CQMPUTRQMCS

N

• • EVERYTHING FOR YOUR TRS-80™ • •

MODEL III

* All orders processed within 24-Hours
* 30-Day money back guarantee on all TRSDOS Software
• Add $2.00 for shipping in UPS Areas
• Add $4.00 for COD. or NON-UPS Areas
* Add $5.00 outside U.S.A., Canada & Mexico
•k We will match any bonafide advertised price
in any of the Major Computer Magazines

TUS-Mh l trademark ol Tandy Com.

) GENERAL LEDGER, ACCOUNT8 RECEIVABLE, ACCOUNT8 PAYABLE, PAYROLL,

INVENTORY CONTROL AND INVOICING (Small Business Group) an extensive business

system for the serious user can be used one module at a time or as a coordinated system

$198.95 per module $1199.95 for the complete system.*

!) MASTER PAC 100 100 essential programs BUSINESS PERSONAL FINANCE

STATISTICS MATH GAMBLING GAMES includes 125 page manual and 5 diskettes

$59.95

i) BUSINESS PAC 100 100 essential business programs INVENTORY CONTROL PAY-
ROLL BOOKKEEPING SYSTEM STOCK CALCULATIONS CHECKBOOK MAINTEN-
ANCE ACCOUNTS RECEIVABLE ACCOUNTS PAYABLE includes 125 page manual

and five diskettes $99.95

l) INFORMATION SYSTEM (The Bottom Shelf) An in-memory information system for small

mailing lists, inventories (i.e. books, articles, records, program reference files) Can be used

for anything that you would use rolodex or index card files Up to ten user define fields

Programmable printouts for rolodex cards, mailing labels, etc Will identify all records that

contain a group of characters you've entered even if that group is in the middle of a line Sorts

data base by any field $49.50*

I) DATA MANAGER II (The Bottom Shelf) RANDOM ACCESS Disk based DATA MANAGE-
MENT SYSTEM (Similiar to INFORMATION SYSTEM above but RANDOM ACCESS

STORAGE expands the amount of storage space available) Used to replace index cards for

medium sized mail lists, inventories, personnel records, sates prospects, etc Uses up to four

disk drives on line Up to twenty user defined fields, programmable printouts for rolodex

cards, etc will identify all records that contain a group of characters you've entered even if

that group is in the middle of a line maintain up to 5 changeable presorted "key" files

variable length random records (the smaller the record you define, the more records yu can
store) $99.95*

i) BUSINESS MAIL SYSTEM (The Bottom Shelf) Handles large mailing lists (up to 150.000

names) supports 3 or 4 line addresses files automatically in zip code order, alphabetical

within zip code formats for 1 to 4 across mailing labels supports quick disk location of

single or multiple names meets all industry and postal standards numeric code fields

included for printing selected records $125.00*

') ANALYSIS PAD (The Bottom Shelf) A Columnar Calculator for financial analysis, line item

budgeting, cost analysis, sales analysis and almost any financial function (and many statistical

functions) create matrixes of 29 * 39 make all entries at one time either by row or column

add. delete, move or switch columns and rows edit any data from full screen display add.

subtract, multiply and divide one column by another and put results in designated column (up
to six calculations can be made and placed in designated column) define columns as con-
stants save calculations and formulas on disk results can be printed in a variety of report

formats $99.95*

i) CHECKBOOK II (The Bottom Shelf) A complete in memory checkbook balancing and

reconcilliation program five column keyboard input with 5 characters for check number. 16

for payee. 4 for code numerical sort routine $49.50*

I) CHECK REGISTER ACCOUNTING SYSTEM (The Bottom Shelf) A complete random access

checkbook system set and define up to 60 accounts with as many income accounts as you

choose complete checkbook balancing and reconcilliation single entry input where

transaction can be dispersed over several accounts enables user to make a 64-character note

on each transaction printout your own check after data entry prints monthly summaries of

each account with month and year-to-date totals create a suspense file to remind you of

coming expenses Reports generated included Check Register (for any month), notes to

Check Register, Income/Expense Distribution Report. Statement of Selected Accounts. Bank
Reconcile Statement, Suspense File and Full Account Distribution Statement $74.95*

l) LIBRARY 100 (The Bottom Shelf) 100 Programs on a broad range of topics Finance

Education Graphics Home Games CASSETTE VERSION $49.50

DISK VERSION $74.95

) ADVENTURE (by Scott Adams) A series of games (for ages 10-99) wander through en-
chanted worlds seeking treasures 1. Adventureland 2. Pirate's Adventure 3. Mission

Impossible Adventure 4. Voodoo Castle 5. The Count 6. Strange Odyssey 7. Mystery

Fun House 8. Pyramid of Doom 9. Ghost Town (#1 and #2 recommended for the movie

adventure) Each adventure $14.95 (jon cassette) Diskette versions sold in groups of three

at $39.95 per three programs (#1 - #3. #4 - #6, #7 - #9).

I) HORSE SELECTOR II (Dr. Hal Davis) New simplified version of the original Horse Selector

(for flats) The first Horse Selection System to actually calculate the estimated offs for each

horse easy to follow rules uses 4 factors (speed rating, track variant, distance of the

present race, distance of the last race) calculated estimated odds FREE DUTCHING

TABLES allows betting on 2 or more horses with a guaranteed profit $50.00

I) MON-3 and MON-4 (Howe Software) Powerful utility programs enabling you to interact

directly with your TRS-80 in MACHINE LANGUAGE The monitor comes with complete

40-page instruction manual making it useful for both the beginner and advanced programmer....

simple commands make it easy to use functions include DISPLAY, DISASSEMBLE, MOVE

and COMPARE, SEARCH. MODIFY, RELOCATE. PRINT, READ and WRITE. UNLOAD, SAVE

and READ, INPUT and OUTPUT, SEND and RECEIVE MON-3 $39.95 (for cassette)

MON-4 $49.95 (for disk).

(14) SMART TERMINAL (Howe Software) enables your TRS-80 to be used as a remote terminal

to a time sharing computer system $69.95

(15) FA8T 80RT (Howe Software) a series of machine-language subroutines to sort data from

BASIC programs data may be alphabetic (string) or numeric easily interfaced with your

BASIC programs (no machine language knowledge is necessary) $9.95

(16) MAILING LIST (Howe Software) maintains mailing lists of over 1000 names commands

allow adding, changing, deleting, and finding names. Sorting is done in machine language
subroutine labels printed in 1, 2 or 3 columns $69.95

(17) HOME BUDGET (Howa Software) combines the maintenance of your checkbook with

analysis of your income, expenses and monthly bills. Handles data including bills, income,
deposits, checks and debits to your checking account, and cash expenses. Computes check-
book balance, list of unpaid bills, monthly and year-to-date summaries of income and expenses

showing income tax deductions All output printed on video display or line printer comes

with complete instructions manual $49.95*

(16) SMALL BUSINESS ACCOUNTING (Howe Software) Based on the DOME BOOKKEEPING

SYSTEM keeps track of all income, expenditures and payroll for a small business of up to 16

employees income and expenditures can be entered on a daily, weekly or monthly basis

computes monthly and year to date totals manual contains complete instructions for custom-
ization Cassette version $29.95 Diskette version $49.95

(19) REMODEL-PROLOAD (Racet Computes) Renumber program lines move statements from

one part of a program to another $34.95

(20) GSF (Racet Computes) Lightning fast in-memory machine language sort utility that can be

made part of your BASIC progams without any machine language knowledge includes

several other utilities to speed up your BASIC programs no machine knowledge necessary

to use GSF in your BASIC programs $30.00

(21) DOSORT (Racet Computes) includes GSF (above) extends the in memory sort to sorts

on multiple disk drives $45.00*

(22) COPSYS (Racet Computes) allows the user to make copies of machines language cassettes

without any knowledge of machine language $20.00

(23) COMRPOC (Racet Computes) an auto load program for disk users allows the user to

insert a diskette into their MOD-HI and have the computer take over all loading load a

machine language program, BASIC, RUN a certain program all without pressing a single button

allows your computer to perform 10. 20. 30 or more functions without pressing a single

button $30.00*

(24) INFINE BASIC (Racet Computes) adds a variety of machine language subroutines to your

BASIC programs (without any machine language knowledge) fast sorts matrix operations

compress and uncompress data and more $60.00

(25) INFINITE BUSINESS (Racet Computes) an add on package to INFINITE BASIC adds a

variety of routines important to the businessman (increase accuracy of calculations and more)

$30.00

(26) DMS (Racet Computes) lightning fast machine language sort sorts up to 4 disk drives of

information $90.00*

(27) BLINK (Racet Computes) allows you to RUN new programs without losing the variables

stored in your previous program line many programs together without losing important

variables $30.00*

(28) KFS-80 (Racet Computes) now you can use ISAM (Index Sequential Access Files) on your

MOD-MI using ISAM in your BASIC programs allows instant access of your items in your

data files use with mail programs inventory programs etc. $100.00*

(29) MAIL LIST (Racet Computes) all routines are in machine language allowing for quick

access $75.00

• for disk only Circle 134 on Inquiry card.

•CQMPLITRQNICS:

NAATV«\AAT CAl APRXAIOfc b* t*yt 1

50 N. PASCACK ROAD
SPRING VALLEY, NEW YORK 10977

NEW TOLL-FREE

ORDER LINE

(OUTSIDE OF NY. STATE)

(800) 431-2818

HOUR

ORDER

LINE

(914) 425-1535

Scalar Dyadic Operators, Ramware APL80

+

ADD

m

h

-

SUBTRACT

X

MULTIPLY

E

*

DIVIDE

*

EXPONENT

®

LOGARITHM

L

FLOOR

r

CEILING

h

0-

o

<

o
2

>-

Q

COMMENTS

1

RESIDUE

1

FACTORIAL

Gamma function missing.

o

CIRCLE

Hyperbolic and hyperbolic
inverse not defined.

< <
> >

LESS THAN, ETC.

= *

EQUAL TO,
NOT EQUAL TO

AV
AV

AND, OR
NAND, NOR

Assumes nonzero values are
equivalent to 1 or true (non-
standard).

H
i

H
a

Nondyadic Scalar and Mixed Operators, Ramware APL80

1 5

NOT (T)

? ROLL 0] [T]

i IOTA (INDEX) 0| 0|

p RHO (RESHAPE) [7] W\

RAVEL \T\ [7T]

IT DECODE, ENCODE 0j

TAKE, DROP (Tj

MEMBERSHIP |Tj

COMMENTS

Catenation for arrays, vectors,
along last coordinate only; no
lamination.

Right argument of encode
limited to scalars only.

grade-up nr\

GRADE-DOWN LU

MATRIX DIVIDE
OR INVERSE

o

Q

/
/
\
\

¥

COMMENTS

transpose (yTI [771 Monadic transpose is nonstan-

L - 11 — ' dard for 3-dimensional or larger

ROTATE OR
REVERSE

ROTATE

COMPRESS

COMPRESS

EXPAND

EXPAND

EXECUTE

FORMAT

Sr—n arrays; dyadic "diagonal'
I— I transpose missing.

[n*] Available as (A [1] only.

Available as / [1] only.

Available as \ [1].

Fl

Sets field width and number of
decimal places for future output.

Composite Operators, Ramware APL80

o

f/ REDUCTION

(■/■ REDUCTION

< COMMENTS

<

Available as f/[1]

fg

INNER PRODUCT
OUTER PRODUCT

CO
<

>

Notes:

"Y" and "N" mean that a given operator is either present in all its forms or totally absent from this version of APL. "Y*" means that the
operator is only partially present in this version. "N*" means that the operator is not present in this version but that part or all of it is avail-
able through an APL defined function supplied with this version. Further information explaining "Y*" and "N*" is given in fhe "Comments"
column.

A scalar is an object (number or character) with no dimension. A vector is a string of objects that have one dimension. An array is an
matrix of objects that have two or more dimensions.

Other features; five tutorial programs on APL included in package; standard APL commands, automatic execution of latent expression;
tracing of function execution; choice of single (6-digit) or double (1 5-digit) precision in output; real-time clock, line and character editing of
defined functions; print formatting and system control variables(APL l-bar functions); positioning of screen output (equivalent to PRINT @
in BASIC); use of periods and dashes in variable names; PEEK, POKE, and CALL functions; random or sequential access of file records; up-
dating of file records; and mixing of APL data structures (ie: arrays, vectors, scalars) in records of same disk file.

Other limitations: only one assignment operator per line; maximum of thirty-two functions per workspace and 255 lines per defined
function; arrays limited to sixty-three dimensions; uses one-letter substitutions for APL operators (but these substitutions are differentiated
from normal text).

Table 3: Summary of Ramware APL80 features.

200 April 1981 © BYTE Publications Inc

The Hard

Facts About

Software

I THREADED INTERPRETIVE LANGUAGES

9 by Ronald Loeliger
Threaded languages (such as FORTH) are compact, giving the speed of assembly language
with the programming ease of BASIC. They combine features found in no other pro-
gramming languages. This book develops an interactive, extensible language with specific!
routines for the Zilog Z80 microprocessor. With the core interpreter, assembler, and i *
data type defining words covered in the text, it is possible to design and implement
programs for almost any application and equivalent routines for different processors.

£ Threaded Interpretive
<M1g(U3gQS

0f

«y

2

272 pages ■*,

hardcover

illustrated ISBN 0-07-038360-X

BASIC SCIENTIFIC SUBROUTINES, VOLUME I

by Fred Ruckdeschel

Designed for the engineer, scientist, experimenter, and student, this book presents a
complete scientific subroutine package in BASIC. Volume I covers plotting, complex
variables, vector and matrix operation, random number generation, and series approx-
imations. This volume features routines written in both standard Microsoft and North
Star BASIC, extensive appendices, and subroutine cross-references.

VOLUME I
336 pages
hardcover
illustrated

ISBN 0-07-05420 1 -5

Circle 135 on inquiry card.

BEYOND GAMES: System's Software
For Your 6502 Personal Computer

" by Kenneth Skier

At last, a complete programming guidebook
for owners of personal computers utilizing
the 6502 microprocessor. A self-contained
course in structures programming and top-
down design, this book presents a powerful
set of tools for building an extended
monitor, disassembler, hexadecimal dump
routine, and text editor programs. Pro
grams are thoroughly explained, with clear
instructions for modifications.

ISBN 0-07-057860-5
440 pages
softcover
illustrated

Circle 135 on inquiry card.

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Scalar Dyadic Operators, Vanguard APL

a.
o
h-
<

UJ

a.
o

LU

<

Z

o
o
<

O

S

o

<

>

+

ADD

m

E

-

SUBTRACT

s

X

MULTIPLY

m

*

DIVIDE

e

•

EXPONENT

h

®

LOGARITHM

L

FLOOR

r

CEILING

<
a.

I

o

< <
> >

= *
AV
AV

RESIDUE

COMMENTS

factorial (Tj Gamma available as a defined

function.

circle FTI (yTI Hyperbolic, inverse yjQ 2 - 1 ,

LESS THAN, ETC.

EQUAL TO,
NOT EQUAL TO

AND, OR
NAND, NOR

VB=n not defined.

Nondyadic Scalar and Mixed Operators, Vanguard APL

Q.
O

<

z

O
S

>-

Q

~

NOT

?

ROLL

I

IOTA (INDEX)

P

RHO (RESHAPE)

•

RAVEL

XT

DECODE , ENCODE

u

TAKE, DROP

i

MEMBERSHIP

H

GRADE-UP
GRADE-DOWN

B

MATRIX DIVIDE
OR INVERSE

COMMENTS

Catenation for arrays, vectors,
along all coordinates; lamination
available as defined function.
Right argument of encode
limited to scalars only.

Both available as defined func-
tion only.

o

s

(D

/
t
\
\
&
?

TRANSPOSE

ROTATE OR
REVERSE

ROTATE

COMPRESS

COMPRESS

EXPAND

EXPAND

EXECUTE

FORMAT

COMMENTS

Monadic transpose for arrays

available as defined function

only.

Both forms work for vectors

only; for all arrays, available as

defined functions only.

Available as / [1] only.

Available as \ [1] only.

Left argument is print width and
|T| number of decimal places; right
argument is vector or array to
be formatted.

a.
o

l-
<

UJ

n.
hi
_i
to

<

-I

LU
Q.
O

S
<
z

<

5

COMMENTS

'/

REDUCTION

.r

REDUCTION

Available as f / [1] only.

Composite Operators, Vanguard APL

p 3

< <

£ uj -l

uj S <

Q- < >

O Z <

f.g INNER PRODUCT

o.f OUTER PRODUCT [7|

Notes:

"Y"and "N" mean that a given operator is either present in all its forms or totally absent from this version of APL. "Y*" means that the
operator is only partially present in this version. "N*" means that the operator is not present in this version but that part or all of it is avail-
able through an APL defined function supplied with this version. Further information explaining "Y*" and "N*" is given in the "Comments"
column.

A scalar is an object (number or character) with no dimension. A vector is a string of objects that have one dimension. An array is a
matrix of objects that have two or more dimensions.

Other features: standard APL commands, system functions, and system variables; line editing only of defined functions; shared variable
mechanism for interaction with disk files (sequential and random access); mixing of APL data structures (arrays, vectors, scalars) in
records of same disk file; the ability to share with any Z80 I/O port.

Other limitations: only way to use this software with a non-APL terminal or video board uses one-letter substitutions of a standard ASCII
character for APL operators (plus these substitutions are not differentiated from normal text); documentation is adequate but terse; no
character editing of defined functions.

Table 4: Summary of Vanguard APL/DTC software features.

202 April 1981 © BYTE Publications Inc

"WITH THE UCSD p-SYSTEM;
WE CAN WRITE ONE APPLICATION
THAT GOES FROM APPLE TO ZENITH!'

HARRY BLAKESLEE, President, Denver Software

UCSD p-System and UCSD Pascal are trademarks of the Regents of the University of California.

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Circle 136 on inquiry card.

BYTE April 1981 203

Notes on APL

The following information specifies the tests that
are run on all versions of APL that are examined at
BYTE magazine. Defined function SETUP, shown in
listing 1, creates the APL variables that will be used in
the tests shown in table 1. A and B are 10 by 10
matrices used in tests like A + B to perform an opera-
tion 100 times with one statement. C is a ten-element
vector giving the values from it to 10ir. D is a 10 by 10
matrix of trigonometric values. E is a ten-element vec-
tor of the values from 1 to 10 (used to test the outer
product operator). F is a vector used to convert sec-
onds to years, days, hours, minutes, and seconds in
the test F T 100000000, using the encode (i) operator.
RA and RB are 100-element vectors made from the
elements of matrices A and B. Finally, M3D is a three-
dimensional array used to test rotation around a non-
default axis.

The function TIME in listing 2 was used in timing
the performance of a function. Statements 20 thru 60
are performed N times, with the (exp) in each line
replaced by the function being tested (for example,
Q—A-r-B). Statement 80 displays the total number of
times the function has been performed, while state-
ment 90 requests the number of seconds used in the
test (timed by a stopwatch) and displays the time used
to perform the function once. Each function is per-

Benchmarks

formed five times within TIME to maximize the time
spent executing the function when compared to the
time spent executing statement 10 and repeatedly
executing line 70 N times. In addition, the TIME func-
tion was performed with increasing values of N until
the unit time agreed to three significant places. The
timing values in table 1 are rounded to two significant
places.

Three short APL functions, CIRCLE, TRANS, and
IVER, are used as benchmarks to grade the perfor-
mance of an APL implementation in less abstract
terms. (See listings 3, 4, and 5.) CIRCLE takes a
numeric matrix and adds a set value to all matrix
elements in an imaginary circle with a given center and
radius. (This function was used to set up a "picture"
matrix of geometric shapes in a pattern-recognition
algorithm.) The TRANS function transforms a matrix
of numbers into a matrix of symbols, with the in-
dividual symbols used to reflect the value of the cor-
responding numeric matrix entry. The IVER function
was presented by Dr Kenneth Iverson in the article
"Understanding APL" (August 1977 BYTE, page 36).
When given a right argument of seven or larger, it
returns a vector containing all the prime numbers up
to and including that number. (For example, IVER 11
returns the vector 2 3 5 7 11.)

Notes:

• All of the above tests are performed on either 10 by
10 matrices or 100-element vectors; in addition, the
tests were carried out to minimize the amount of time
outside the operation being timed.

• In some cases, a version of APL could not operate
on a given size matrix. An asterisk denotes an
estimated entry made by adjusting the time an opera-
tion took for a smaller matrix.

• CIRCLE, TRANS, and IVER (shown in listings 3
thru 5) are APL defined functions used to compare the
versions of APL in a working environment.

• All numbers here are given to 2 significant digits.

• In the cases where a version of APL gives the user an
APL defined function (a short program written in
APL) to use when the operation is not in the machine-
code version of APL, the defined function is used in
the above timing tests. For example, none of the above

versions of APL incorporate matrix divide in their ver-
sions, but Softronics and Vanguard supply an APL
defined function to do the same operation.

• NA means the function is not available in a given
version of APL.

• The Ramware APL80 was run on an unmodified
Radio Shack TRS-80 Model I with one disk drive and
48 K bytes of memory. The TRS-80 runs at 1 MHz; all
timing figures should be halved for users running
modified TRSSOs at 2 MHz.

• The Softronics APL was run on a Cromemco Z2D
with 56 K bytes of memory, running at 4 MHz.

• The Vanguard APL/DTC software was run on an
APL/DTC computer with 80 K bytes of memory, run-
ning at 4 MHz. Users buying the Vanguard APL/V80
software should expect slightly decreased performance
varying with the amount of memory in the system.

Text continued from page 196:

be devised. APL operators that normally do not appear
on the keyboard have a 1-character substitution. For ex-
ample, the character % replaces the APL division
operator +, and parentheses () replace the square
brackets [] used in APL to denote subscripts. Other
characters are represented by a shifted keyboard letter;
for example, shift-q is used for the APL character □ (a
quad), and shift-i is used for the APL iota operator t. On
the TRS-80 video screen, these characters are displayed
as their uppercase alphabetic equivalents (because an un-
modified TRS-80 has no lowercase letters) with a little
graphic dot just below and to the left of the uppercase let-

ter. This, plus one space on the left of the single letter
substitution, makes this system more readable. (See
photo 1 for the APL80 equivalent of the CIRCLE function
of listing 3a).

Many other Level Il-related features make Ramware
APL80 a usable product and certainly the best buy
dollar-for-dollar. Several other features that must be
mentioned are sequential and random access of APL disk
files and access to the real-time clock; other features are
listed in table 3.

Vanguard APL/DTC Computer and Software

Two of the 'At a Glance" boxes describe the last ver-

204 April 1981 © BYTE Publications Inc

circle 737

'nquiry

card.

Ste-Julie. Quebec Canada JOL 250

(514)649-6185

BYTE

April

1981

205

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* CP/M trademark of Digital Research, Inc.
Z80 Softcard trademark of Microsoft, Inc.

1

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1

Photo Is The APL function CIRCLE as presented by Ramware
APL80. In this version of APL for the TRS-80 Model I, nonstan-
dard APL characters are replaced by either a 1-character
substitution or by a single letter marked by a graphics dot below
and to the left of the letter.

Photo 2: The Vanguard Systems Corporation APL/DTC. The
system includes: the APL/DTC (desk-top) computer, on the
left; its associated APL terminal, on the right; and, on top of the
computer, documentation and two floppy disks of soft-
ware — customized CP/M and Vanguard APL.

sion of APL, which was reviewed as a computer/soft-
ware combination called APL/DTC. The computer and
software have been optimized for each other, creating a
version of APL that is slightly more powerful than its
stand-alone software counterpart, APL/V80.

The APL/DTC system, which carries a label of the
same name (see photo 2), is actually a Vector Graphics
microcomputer with modifications made at Vanguard
Systems Corp. (One modification results in the computer
holding 80 K bytes of memory.) Its associated terminal,
which displays all APL characters (as shown in photo 3)
has an APL keyboard and is a Vector Graphics "Mindless
Terminal" (a keyboard and video display that connects to
a memory-mapped video board inside the computer
proper). Its associated video board has a PROM (pro-
grammable read-only memory device) that generates the
APL character set. The APL/DTC computer runs CP/M
as customized by Lifeboat Associates and Vanguard. The

206 April 1981 © BYTE Publications Inc

Circle 138 on inquiry card.

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PC Board: Glass epoxy, plated through holes with
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HEX KEYPAD/DISPLAY SPECIFICATIONS
Calculator type keypad with 24 system-r'efined and 16
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LEVEL "B" SPECIFICATIONS
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□ 12" Video Monitor (10MHz bandwidth) . . . $139.95 plus $5
posl. & insur.

□ Beginner's Pak (see above) $169.95 plus $4 post. & insur.

□ Experimenter's Pak (see above) . . . $219.95 plus $6 posl. &
insur.

D Special Microsoft BASIC Pak Without lermlnal (sra above).
$329.95 plus $7 post. & insur.

□ Same as above plus ASCII Keyboard Terminal With Cabinet,
Gel Free RF Modulator (see above) . . . $499.95 phis $10 posl.
& insur.

□ Special 8" Disk Edition Explorer/85 (see above) . . $1496.95

plus $26 posl. & insur.

□ Wired & Tested ... $ 1 799.95 plus $26 post . & insur.

□ Extra R" CDC Floppy Drives. . . $499.95 plus $12 posl. & insur.

□ Cabinet & Power Supply For Drive $69.95 plus $:t post. &
insur.

□ Drive Cable Set-up For Two Drives ... $25 plus $1.50 post. &

□ Disk Controller Board With 1/0 Ports. . $199.93 plus $2 posl.
& insur.

□ Special: Complete Business Software Pak (see above)
$699.96 postpaid.

SOLD SEPARATELY:

□ CP/M 1.4... $IOOposlpaid.

□ CP/M 2.0... $l50poslpaid.

□ Microsoft BASIC . . . $325 postpaid.

□ Intel 8085 cpu User Manual . $7 .50 postpaid.

□ Level "A" Monitor Source Listing ... $25 postpaid.

^ Continental USA. Credit Card Buyers Outside Connecucul ^

M CALL TOLL FREE: 800-243-7428 m

^H To Order From Connecticut Or For Technical ^V
^ Assistance, call (203) 354-9375 ^

Tola! Enclosed (Conn res. add sales lax) S

Paid By:

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Add, No. Exp. Dale

Signature

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Name

Address

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Slab

. Zip_

NETRONICS Research & Developmenl Ltd.
333 Litchfield Road, New Milford, CT 06776

rig] *1l%Ss I M* J COT, RflDIUS. UfUE fffiDED

J gfigWi

f|] ^[3]i'((I-«n])'2)«!J-flR[2] !»Z)«B.SMMP

m LOOP 'iJ'ffC2]*ffii31)/JT
SM0.1Ti[l<I':*m<fM3

c 3 n u 1 il ,

Photo 3: Lisfmg o/ f/ie API function CIRCLE on the APL/DTC
terminal screen and, below, a listing of special APL characters as
they appear on the APL/DTC terminal. The last row is com-
posed of characters that are created using an overstrike.

price tag of $7995 is rather steep for an APL machine, but
a large body of CP/M software, including other com-
puter languages, is available for the machine, somewhat
mitigating the expense.

The language itself, called APL/V80 and available for
$500 in a variety of formats, is the undisputed winner in
every category except cost and documentation. The fact
that it is more expensive is reasonable; after all, it does
offer a faster APL that implements more operators.
However, its weakness in the documentation, though
slight, is disturbing.

POCKET/?
TERMINAL

Here's $395 worth of convenience for anyone
working with digital systems. Carry it
anywhere in a pocket, valise or toolkit to enter
and retrieve data, run diagnostics, change
constants, test aata links, etc.

Look at its facilities:

•Transmits 128
I ASCII codes
• Can display last 30
characters received
• Displays full
64-character ASCII
set on dearie-
segment LEDs
25-line RS232/C
compatible interface
I •Single 5V supply
required at 400mA
typical
110 or 300 baud
transmission selectable
• Parity codes, stop bits
settable to your standard
, •Obeys bell, cursor and

data format control codes
Phone or write us tor more details now:
GR ELECTRONICS,
, v ...-- 1640 Fifth Street,

rr " Santa Monica, CA 90401. |

Telephone: (213) 395-4774.
Telex: 65-2337 (BT Smedley SNM).

Because its documentation is not of the same caliber as
the rest of the package, the software must stand on its
own merits. (Fortunately, it does.) The documentation is
terse, sometimes cryptic. Much of the language is defined
in charts that give only the name of the operation being
performed. Only one or two examples are given for each
operator, far too few to be able to generalize. Comparing
the Vanguard documentation to the Softronics documen-
tation (which takes up to a half page to describe an
operator and includes examples), I can summarize by
saying that the Softronics documentation is much more
"friendly" and much more useful as both a tutorial and a
reference.

On the positive side, APL/V80 includes information
on customizing the software and on building and using
auxiliary processors (software) that allow the language to
interface to custom external devices through Z80 I/O
ports. In addition, Vanguard provides a set of APL
defined functions (in both printed and disk file form) that
implements almost all of the functions not in its APL.
Data files can be accessed either sequentially or randomly
through a mechanism called shared variables; this
method is used by the IBM 5100 computer and other
computers to provide an APL-like mechanism for inter-
acting with disk files.

Vanguard has solved the problem of using its APL/V80
on an unmodified ASCII computer. According to Dr
John Howland of Vanguard Systems Corporation, a
defined function is included in the APL/V80 package
that, when executed, allows the user to edit and list APL
functions using mnemonic substitutes of any length for
the APL characters that are not on a regular ASCII
keyboard. Although I have not seen this system at work,
it sounds like a viable solution.

Several notes are in order in relation to tables 1 and 4.
The information in these tables is based on the APL soft-
ware supplied with the APL/DTC computer, not the
APL/V80 software. Again, according to Dr Howland,
the APL/V80 software should run at the same speed as
the software running on the APL/DTC computer (assum-
ing that the Z80 board of the host computer runs at 4
MHz, the system clock frequency of the APL/DTC). This
means that the timing figures of table 1 are valid for the
APL/V80. In addition, the software features in table 4,
listed as available on the APL/DTC, are also in the
APL/V80 software, with the exception of the inner prod-
uct function (available as a defined function in
APL/V80). The APL/DTC allows an APL workspace of
34 K bytes, while the APL/V80 software allows a work-
space of about 27 K bytes when running on a 64 K-byte
CP/M system. The additional memory space used by the
APL/DTC software is devoted to the implementation of
hardware-related features (such as access to the real-time
clock and a machine-related security function).

Conclusions

Versions of APL are available to fit every budget. The
Ramware APL80 is a usable version of APL for the
TRS-80, and it is quite a bargain at $39.95. Softronics
APL, although it does have some serious limitations, is in
a medium price range at $350. Vanguard APL/V80, at
$500, is the fullest and fastest APL. Your needs and the
amount of money you can spend will determine which
version is best for you.B

208 April 1981 © BYTE Publications Inc

Circle 139 on inquiry card.

Finally,
there is a

magazine that

speaks to the beginner.

onComputing is the new McGraw-
Hill quarterly that tells what's ahead —
without talking over your head — in the
1980s with persona] computers.

onComputing puts you on target
with all the applications that go beyond
your imagination.

□ Personal computers in the home.

□ Classrooms.

□ They bring computer music.

□ Electronic mail.

□ Robots.

□ They manage your personalized
investment.

□ The list goes on and on in onComputing.
If you're a beginner with personal

computers, get the most understood
magazine on computers, onComputing
And even if you're an experienced
computer user, onComputing has the
information you need in today's fast-
growing personal computer market.

Get onto onComputing. Call 800-258-5485.

onComputing

1 onComputing Subscription Dept. P.O. Box 307, Martinsville, NJ 08836

1 DOMESTIC subscription rate:

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©onComputing, Inc. 1981

+

•#\t r >\

mv- : :

7

«T

RAM 17 T 1 *^^

-the memory that took
18 months to hatch !

18 months ago, we designed RAM 17 around a brand new 16K static RAM from Hitachi that not only had
the reliability and speed of static memory, but also consumed less power than dynamics.

Unfortunately, pricing on this VLSI chip back then was such that we didn't feel RAM 17 would meet our
tough standards for cost-effectiveness. In the past few months, however, volume production has lowered chip
prices to where RAM 17 now represents an exceptional value in S-100 memory.

Features include a stunningly low 250 mA typical power consumption, guaranteed operation (no wait
states) at 6 MHz with CPU Z and 10 MHz with CPU 8085/8088, full compliance with all IEEE 696/S-100
specifications (including 24 bit addressing and standard board size), four optional 2K windows to accommodate
memory mapped disk controllers, pinout compatibility with 2716 EPROM (allows RAM/ROM mix on a single
board), plus all the other features that make CompuPro memory the first choice of system designers world-wide.

$1595 CSC (2 year limited warranty), $1395 A/T (1 year limited warranty), $1095 Unkit.

These features may appear to be those of a dream memory of the future. . .
but CompuPro is delivering RAM 1 7 now at finer computer stores near you.

CompuPro™

#

division of

(OjlBB i

"ELECTRCmI :,

OAKLAND AIRPORT, CA 94614 (415) 5620636

MEMBER

on

CompuPro computers don't JUST work:

they WORK, and WORK, and WORK, and WORK, and

If there's anything more important than throughput, it's reliability: that's why CompuPro System Components are painstakingly
engineered not just to work, but to keep on working. Say goodbye to unexplained system hardware glitches - CompuPro products
conform to all IEEE696/S-100 specifications, thereby ensuring well integrated (and predictable) system performance. Also, should a
system malfunction ever occur, the bus oriented nature of S-100 machines allows you to simply pull out the bad board and plug in a
replacement. . .and when you depend on a computer, you know what it means to minimize down time.

All CompuPro products meet the most demanding mechanical and electrical standards, and are backed with one of the best
warranties in the business (1 year limited warranty on all products, 2 year limited warranty with exchange program for products
qualified under the Certified System Component program).

Sure, computers can be great intelligent toys ; but for scientific, industrial, and commercial applications, toys aren't good
enough. You need a computer that works, works right, and keeps on working : you need CompuPro system components.

NEW! DISK 1: THE ULTIMATE

a/t $495, csc $595 DISK CONTROLLER.

Finally, a disk controller worthy of the CompuPro name. This
state of the art design uses properly implemented DMA with
artibration, meaning that Disk 1 can co-exist - without any
conflict whatsoever- on the same bus as other DMA devices. And
because Disk 1 has 24 bit DMA addressing (not memory mapped),
you have access to a full 16 megabyte memory map.

What about speed? Disk 1 transfers data independently of CPU
speed, allowing operation with 6 MHzZ80s®* . Versatility? Disk 1
handles up to four 8" or 5.25" floppy disk drives (including 96
track high density minifloppies), single or double sided, single or
double density (soft sector). Convenience? Disk 1 includes BIOS
for CP/M-80®* ■, as well as on-board boot for automatic startup
and on-board serial port for system initialization startup.
Compatibility? Disk 1 is compatible with MP/M®* , OASIS,
CP/M-80, and CP/M-86. Reliability? Uses industry-standard,
third generation controller chips and the same design excellence
that is a part of every CompuPro product.

We weren't going to put out another me-too disk controller...
and we didn't. The CompuPro Disk Controller is here.

SYSTEM SUPPORT 1
MULTIFUNCTION BOARD

$295 Unkit, $395 A/T, $495 CSC
This multi-purpose S-100 board provides sockets for4K of extended
address EPROM or RAM (2716 pinout) with one battery backup socket;
battery backup month/day/year/time crystal clock with BCD outputs;
optional math processor (9511 or 951 2); full RS-232 serial port; three 16
bit interval timers (cascade or use independently); two interrupt
controllers service 15 levels of interrupts; power fail indicator; and
comprehensive owner's manual with numerous software examples.
Conforms fully to all IEEE 696/S-100 standards. (Add $195 to the above
prices for the optional 9512 math processor.)

SOFTWARE

8088/8086 MONITOR-DEBUGGER : Supplied on single sided, single
density soft-sector 8" disk. CP/M®* compatible. Great development
tool; mnemonics used in debug conform as closely as possible to
current CP/M®* DDT mnemonics. $35.

PASCAL/M* FROM SORCIM: PASCAL-easy to learn, easy to
apply - can give a microcomputer with CP/M®* more power than many
minis. We supply a totally standard Wirth PASCAL/M* 8" diskette

and comprehensive manual. Specify Z-80* or 8080/8085 version. $175.

Most CompuPro products are available in Unklt form, Assembled/Tested, or
qualified under the high-reliability Certified System Component (CSC) program (200
hour burn-in, more). Note: Unkits are not intended for novices, as de-bugging may
be required due to problems such as IC infant mortality. Factory service is available
for Unkits at a flat service charge.

r\

<j

XJ>

COMPUTER ENCLOSURE 2

Introductory price: $795 (specify rack mount or desk top version)
Includes fused, constant voltage power supply ( + 8V at 25 Amps,
±16V at up to 6 Amps); 20 slot shielded/active terminated
motherboard; and deluxe enclosure with dual AC outlets on rear,
heavy-duty line filter, circuit breaker, quiet ventilation fan, and reset
switch. Rack mount version includes slides for easy pull-out from rack
frame.

Also available: COMPUTER ENCLOSURE 1. Same as above, but
less power supply and mortherboard. $289 desktop, $329 rack mount.

PRICE BREAKTHROUGH ON 16K
MEMORY EXPANSION - 8 RAMS/S29

These top quality, low power, high speed (200 ns) 16K dynamic
RAMs expand memory in TRS-80* -I, -II, and -III computers (color
model too) as well as machines made by Apple, Exidy, Heath H89,
newer PETs, etc. Backed by 1 year limited warranty. Add $3 for two dip
shunts plus TRS-80* conversion instructions. Limited quantity.

S-100 MEMORIES FROM THE
MEMORY LEADER

CompuPro memories feature fully static design to eliminate dynamic
timing problems, full conformance to all IEEE 696/S-100 specifica-
tions, high speed operation (4/5 MHz Unkit, 10 MHz A/T and CSC), low
power consumption, extensive bypassing, and careful thermal design.

Unkit A/T CSC

8K RAM2A $159 $189 $239

16K RAM 14(extended addressing) $279 $349 $429

16K RAM 20-16

(extended addressing and bank select) $319 $399 $479

24K RAM 20-24

(extended addressing and bank select) $429 $539 $629

32K RAM 20-32

(extended addressing and bank select) ...$559 $699 $799

NEW! 64K STATIC RAM 17 . Amazingly low power in a 64K
fully static RAM board: less than 500 mA maximum, 250 mA
typical! It's fast, too; runs with 6 MHz Z-80®* CPUs, or 10 MHz
8080-family CPUs (8085, 8088, etc.). Uses IEEE extended
addressing protocol, and may optionally turn off 2K windows
from EOOO to FFFF in order to accommodate North Star or
Morrow disk controllers (the CompuPro disk controller can use
the full 64K since it employs properly implemented DMA
techniques). $1095 Unkit, $1395 A/T, $1595 CSC.

TERMS: Prices shown do not include dealer Installation and support services. Cal res add tax.

Allow at Ieast5%shlpping; excess refunded. Orders under $15 add $2 handling. VISAW and
Mastercard ® orders {$25 min) call our 24 hour order desk at (415) 562-0636. Include street
address (or UPS delivery. Prices are subject to change without notice.

FREE CATALOG : Want more information? Then send for our free catalog. For fast
1st class delivery, add 41 cents in stamps; foreign orders add $2 (refundable with
order).

•LEGAL CORNER: 280A is a registered trademark ot Zilog; TRS-80 is a Irademark of the Tandy Corporation.
PASCAL/M is a Irademark of Sorcim; CP/M and MP/M are registered trademarks of Digital Research.

COMPUPRO PRODUCTS ARE AVAILABLE AT FEVER COMPUTER STORES
WORLD-WIDE. . .CALL (415)562-0636 FOR THE STORE NEAREST YOU.

Circle 140 on inquiry card.

CompuPro"

division of

pi»EJiJ

ELECTRONICS^

OAKLAND AIRPORT, CA 94614 (415) 562-0636

BYTELINES

News and Speculation About Personal Computing

Conducted by Sol Libes

Jony Enters Word-Pro-
cessing Arena: The Sony
Corporation is a real in-
novator. First, it decided to
enter the word-processing
market. Then it introduced a
new concept in word pro-
cessing that's surely a win-
ner. Called the Typecorder,
it consists of a small key-
board/ microcassette unit
[about the size of two issues
of BYTE. ...CW] that has a
microcomputer and 1-line
LCD display; it costs $1400.
Small enough to fit into your
briefcase, it permits you to
create text, edit it, and store
it on tape. The tape can be
run off on a companion
printer, available for $800,
or through a word-processor
system due later this year.
You can transmit the text
over telephone lines via an
optional acoustic-coupler
modem, or you can process
the text through a non-Sony
system. Typecorder lets you
mix audio and digital infor-
mation on cassette, so you
might devise some interest-
ing computer-assisted soft-
ware.

I have no doubt that
Sony's concept, features,
and low price will be popu-
lar and will lead to applica-
tions beyond word process-
ing.

^Hk Close Look At The
IBM Olsplaywrlter: IBM is

now delivering its new low-
cost Displaywriter word-pro-
cessing system; it's only
$1000 more than the Radio
Shack TRS-80 Model II, and
it's really a general-purpose
microcomputer that uses the
Intel 8088 microprocessor.

IBM rents word-process-
ing software for $50 per
month, which sounds rather
steep; however, consider the
TRS-80 owner who uses
WordStar. WordStar costs
$500, plus another $150 for
the CP/M operating system.

Further, MicroPro Interna-
tional issues WordStar up-
dates about four times a
year at $25 to $40 apiece.
Hence, WordStar can cost a
user about $850 for the first
year of operation.

My point is that the price
difference between a word-
processing system using an
IBM (or Wang, Lanier, etc)
and a Radio Shack system is
really not that great. Add to
this IBM's terrific service
and its promises of extended
I/O, communications, and
applications packages for
the Displaywriter, and you'll
see that IBM is competing
aggressively in the micro-
computer marketplace.

W.

ord-ProcessIng
Prices Dropping: Word-
processing-system prices are
dropping. Following on the
heels of IBM's new low-cost
word-processing system,
Wang Laboratories has intro-
duced a new stand-alone
system for $7500, with dis-
counts offered on multiple
units. Lanier Business Sys-
tems is expected to intro-
duce an inexpensive system.
A B Dick is planning a $7500
system that includes soft-
ware (the others do not), and
is drawing up plans for a
local-network system that
shares a printer, which will
further reduce costs.

Vomputer Hobbyists
Gather For Huge Flea
Market: On Saturday and
Sunday, April 25th and 26th,
several thousand computer
hobbyists will flock to Tren-
ton State College, Trenton,
New Jersey, for the Trenton
Computer Festival, the
world's largest personal-com-
puter-equipment flea market.
This annual outdoor event is
now in its sixth year. A
multitude of swap and seller
tables covering more than 5

acres of real estate feature
everything from complete
computer systems to tiny
electronic parts. There will
be speakers, user-group
meetings, an indoor exhibi-
tion area, and a banquet on
Saturday night.

The Festival is sponsored
by the Amateur Computer
Group of New Jersey, the
Philadelphia Area Computer
Society, and the Trenton
State Computer Society. The
funds raised help support
these nonprofit organizations
and their activities. For infor-
mation, call (609) 771-2487,
or write to TCF-81, Trenton
State College, Trenton NJ
08625.

Wredlt Cards With In-
telligence? The Battel le
Memorial Institute is study-
ing the feasibility of a credit
card with a built-in micro-
processor. Such a card has
already been developed in
Europe and will soon be
tested. It is expected that in-
telligent credit cards will
provide added security with-
out requiring large computer
networks.

H

ome- Inform at Ion
Market Takes Shape:

Several tests are underway
to determine the best way to
capture the lucrative home-
information market. In the
meantime, there's a battle
brewing for control of the
market, and the major con-
testants are the telephone
companies, principally
AT&T (American Telephone
and Telegraph) and the
cable-television companies.

By 1 983, AT&T is expected
to launch its home-informa-
tion systems. A user will
probably have to buy a spe-
cial video-display terminal,
about $250, plus pay a
monthly service fee in the $4
to $8 range.

The cable-television com-
panies plan to provide the
same two-way services.
Companies such as Westing-
house, General Electric, and
American Express are
snatching up cable-tele-
vision outfits. Several cable-
television home-information
systems are already in opera-
tion. However, the real bat-
tle is at least two years away
when AT&T actually enters
the market.

I he Terminal You
May Have Been Waiting
For: Hewlett-Packard has
introduced a super-intelli-
gent terminal, called the
Model 2626A. It displays 119
lines with 160 characters per
line; moreover, the display
can be divided into four win-
dows. There are two inde-
pendent I/O ports, so that
you can simultaneously
communicate through sepa-
rate windows with two dif-
ferent computers. There are
user-programmable keys,
and the bell has fifteen
pitches, sixteen intensities,
and two volumes— which
means that you can play
decent-sounding music on it.

I Icrosoft And DEC
Join Forces: Microsoft's
first software product was a
4 K-byte BASIC interpreter,
which used keywords similar
to DEC's (Digital Equipment
Corporation's) BASIC-Plus. It
launched Microsoft on the
road to success with expand-
ed BASICs and other lan-
guage packages. DEC has
now adopted Microsoft
BASIC for its GIG I (general
imaging generator and inter-
preter) color-graphics sys-
tem. Microsoft's BASIC is
contained in ROM (read-
only memory) in a micropro-
cessor-based unit. GIGI is
used with the PDP-11 and
VAX-1 1 systems.

212 April 1981 © BYTE Publications Inc

Whether the job is building a home
or a world MILESTONE helps...

With today's concerns about increasing costs
and declining productivity it is true more than ever
that any project worth doing deserves careful planning.
Whether your're planning a construction project or
the opening of a new retail store, you must carefully
schedulue your manpower, dollars and time in order
to maximize productivity.

MILESTONE is a critical-path-network-analysis
program. It runs on a desktop microcomputer, is
inexpensive and simple enough for anyone to use.

MILESTONE'S design is a product of many years
of experience in the "real world" of small-project
management. In such an enivornment the primary
purpose of planning is to help the project leader clar-
ify the task at hand and to help him communicate his
ideas to his subordinates and superiors. For these two
reasons the designers of MILESTONE stressed it's
interactivity and comprehensive reporting.

Most of the design effort was put into eliminating
unnecessary or redundant operator input and to
checking all entries for validity. By organizing the
project data for you, you can interactively modify
your project plan leaving MILESTONE to perform
the tedious calculations and to display the results.

Internally, MILESTONE treats your project as
a series of activities. Each activity has a name, dura-
tion, capitol cost, mix of manpower, and an asso-
ciated list of other activities that must be completed
first. The list of associated activities (or prerequisites)
provides a thread that MILESTONE uses to link all
the jobs together into an overall project schedule.
Every time you add a new activity or make a change
to an existing one, the entire schedule is recomputed
and the results are immediately redisplayed on the
screen.

For MILESTONE a project is simply any task
made up of steps that must be performed in sequence.
After dividing a project into it's composite steps,
MILESTONE can help you plan, schedule and control
the project.

Specifically here are some of the things you can
do,

Find out which activities are time critical and
can't be delayed

Discover which activities have slack time and can
be delayed without delaying the entire project
Prepare a detailed cost estimate based upon a
summation of each activity's individual equip-
ment and manpower expenses
Change an activity and instantly see the impact
on the overall project schedule
Investigate tradeoffs between manpower, dollars,
and time

Keep track of your project's progress by period-
ically updating the schedule to reflect changes in
the plan and completed activities

MILESTONE requires 54K RAM and CP/M, Apple
Pascal, or UCSD Pascal. CP/M versions need no sup-
port language. All Apple II versions require 24 x 80
video card. Formats: 8" single denisty IBM soft-
sectored, NorthStar DD, Micropolis Mod II, Super-
brain 3.0, Apple II. Price is $295. Manual alone - $30.
Add $7.00 for shipping.

SOFW/1RE
SOFTWARE
DIGITAL AMRKETING

DIGITAL/MARKETING

2670 CHERRY LANE

WALNUT CREEK • CALIFORNIA 94596 • (415) 938-28BO

MILESTONE trademark Organic Software CP/M trademark
Digital Research Apple Pascal Trademark Apple Computer
UCSD Pascal trademark Regents University California

Circle 141 on inquiry card.

BYTE April 1981 213

BYTELINES

diagnostic Disk
Troubleshoots Your
Disk Drive: Dysan Corpora-
tion will introduce a floppy
disk that checks disk-drive
operation. It contains soft-
ware and geometric patterns
that test radial positioning,
linearity, hysteresis, eccen-
tricity, index timing, skew,
relative head positioning,
azimuth, drive rpm (revo-
lutions per minute), head
load, access time, and head/
media compliance. The first
model to be introduced will
be a $40 IBM 3740-compati-
ble 8-inch disk.

w.

ord-Processor Dic-
tionary Introduced:

IBM's new Displaywriter
word-processor system fea-
tures an optional dictionary-
software package that
checks the spelling of up to
70,000 words. Similar pack-
ages will soon be available
for other systems. The first is
Microspell, to be distributed
by Lifeboat Associates. It
checks the spelling of any
ASCII-text file stored on disk
under CP/M. Thus, the pro-
gram can be used with files
created by WordStar, Word-
Master, Magic Wand, and
other word-processing pack-
ages.

I

BM Status Report:

Many critics want you to be-
lieve that IBM's dominance
in the data-processing mar-
ket is eroding rapidly. Don't
believe it, because more
than a third of the $60
billion 1980 computer mar-
ket was IBM's. In all in-
dustry, IBM's $23 billion in
sales ranked eighth, and its
$3 billion in total profits was
third. By contrast, the sec-
ond largest computer maker,
Burroughs, had $2.83 billion
sales and $305.5 million in
profits.

IBM is not always the
technological leader.
Rather, it has used market-
ing clout to establish domi-
nance in any market it
enters. For example, IBM
sells 70% of the large main-
frame computers in the USA.

However, during the last
few years, DEC (Digital

Equipment Corporation),
Data General, Wang Labora-
tories, and Amdahl have
grabbed an increasing share
of the computer market.
Several Japanese com-
panies, such as Fujitsu,
Hitachi, and NEC (Nippon
Electric Company), are also
moving in on IBM's territory.
On the horizon, IBM faces
strong competition from
AT&T, Xerox, and Exxon, as
they move into local and
interoffice data-communica-
tion network markets.

These factors have had a
serious impact on the value
of IBM's stock. In the 1960 s,
it sold for as much as 66
times earnings; it now sells
for 15 to 20 times earnings.

IBM's strategy for the
1980s is based on a coming
generation of mainframes
that will set new levels in
price versus performance
and emphasize telecom-
munication networks. In ad-
dition, IBM has opened
retail stores and is entering
several new markets via
joint ventures, such as a
videodisk project and
satellite communications.
However, it is likely that
these projects will be a
minor part in the whole IBM
strategy for the 80s. Al-
though IBM will become
more involved in data net-
working, its focus will con-
tinue to be large central
data-processing operations.

IM,

lew 8-Inch Win-
chester Has 1 36 Mega-
bytes: Ontrax Corporation
has unveiled the largest
capacity 8-inch Winchester-
type disk drive to date. It
stores 1 36 megabytes on five
platters using sixteen read/
write heads. With a control-
ler, the drive sells for $5000
in quantity. That's 0.004
cents per byte, compared to
about 0.2 cents per byte for
a typical single-density
floppy-disk drive.

R,

random News Bits:

Computerland, High Tech-
nology, and The Computer
Store plan to stock at least
one Japanese-made personal
computer. Japanese sup-

pliers currently being con-
sidered are NEC, Casio,
Canon, Sharp, and Pana-
sonic. ...Tandy Corporation
and the Professional Farmers
of America (PFA) have intro-
duced Instant Update, a
data-base service that uses
TRS-80 videotext terminals
(actually TRS-80 Model II).
Via telephone connections,
the service provides infor-
mation affecting commodity
prices and crop yields and
gives access to Washington
Watch News. Commodity
prices are updated every 10
minutes. The service costs
$95 per month. ...Sony has
introduced a 3'/2-inch micro-
floppy-disk drive. (Editor's
note: See this month's
editorial.) It is currently be-
ing marketed to OEMs and
systems houses; its capacity
is reputed to be over 800 K
bytes (unformatted) per disk.
...Two teenagers have been
charged with masterminding
a scheme that shut down
DePaul University's comput-
er during enrollment week.
The shutdown cost DePaul
$22,252 in computer time,
repairs, and manpower. The
teenagers said they did it to
disprove the school's claim
that it couldn't be done.
...Intel Corporation an-
nounced its figures on net in-
come and revenues for the
year that ended December
31, 1980. Net income was
$96.7 million, up 24% from
the previous year, and
revenues were $855 million,
up 29% from 1979. Most of
the growth occurred in the
first half of the year....

R,

random Rumors: In-
formed sources say that Tan-
dy will lower the price of its
Videotext terminal to com-
pete with AT&T's projected
home-information terminal.
...Apple Computer is devel-
oping a new microcomputer
using the 16-bit Motorola
68000 microprocessor. ...At
least one software-develop-
ment house has leaked that
it is seriously negotiating
with Apple on a disk oper-
ating system for a machine
called the Apple IV. ...Look
for a lower-priced version of
Hewlett-Packard's HP-85

desk-top computer— maybe
less than $2000— to be call-
ed the HP-83. It lacks some
of the HP-85's features, but
it has a plug-in disk-drive op-
tion. ...Exxon's Kylex division
is developing a 40-row by
80-character LCD (liquid-
crystal display) for
computer-display terminals.
...Sony might be developing
a personal-computer system
for this year's market. Sony
may include an interface for
its new Typecorder word-
processor terminal. ...Digital
Equipment Corporation is
developing a new line of per-
sonal-computer products
with extensive software sup-
port, including an operating
system based on RT-11 with
VAX-compatible BASIC...

WOBOL For The 8086
Announced: The software
picture for 8086-based 16-bit
microcomputer systems
keeps improving. Seattle
Computer Products has an-
nounced an 8086 version of
Microsoft BASIC. Now
Microsoft has COBOL-86,
which runs under the
CP/M-86 operating system.

The projected execution
time of these packages is
three times as fast as the
8080/Z80 versions. As a re-
sult of the 8086's multitask-
ing capabilities, the pack-
ages will be better suited for
multiple-user systems than
the 8-bit versions.

MAIL: I receive a large
number of letters each month
as a result of this column. If you
write to me and wish a
response, please include a
stamped, self-addressed
envelope.

Sol Libes
POB 1992
Mountainside NJ 07092

214 April 1981 © BYTE Publications lnc

ALL THESE FEATURES...
IN THIS SMALL SPACE...

AT THIS LOW PRICE!

Greater computer power . . . fewer separate
components . . . larger capability . . . simpler to
operate . . .. modular maintenance . . .

These are the unique benefits of the Quasar
Data QPD-100 Floppy Disk Computer . . . plus
unsurpassed reliability... plus 12-month warranty on all PC boards.

Its highly reliable, industry-standard MFE drive is compact.
Accepts both single AND double-sided disks.

Upgradeable from the Z-80® microprocessor-based
system to our ZSOOO^ microprocessor-based system by simply
plugging in extra PC cards. Hard disk and multi-user
systems available.

As your requirements grow, your QDP-100 can grow
to fit them.

The Quasar Data QDP-100H is a larger version with
6-megabyte capacity; includes one double-sided floppy
and one 5 1 /t microwinchester hard disk.

Both the Quasar Data QDP-100 and QDP-100H are
fully compatible with all standard terminals.

Phone or write for descriptive bulletin and specifica-
tions. And ask for a demonstration. Dealer inquiries invited.

QUASAR DATA'S QDP-100
COMPUTER SYSTEM.

4,695

1 8" wide
16%" deep
11" high

Complete systems available

'" Z-80 and Z-8000
are trademarks of Zilog Corporation

~CP/MandMP/M

are trademarks of Digital Research Corp

Circle 142 on inquiry card.

10330 Brecksville Road, Brecksville (Cleveland), Ohio 44141

Phone: 216/526-0838 / 526-0839

Telex: 241596

BYTE April 1981 215

SiiperSofft's

Gallery of CP/M Ma§{erwork§

u

SUPER-M-LIST: A complete, easy to use mailing list program
package. Allows for two names, two addresses, city, state, zip and
a three digit code field for added flexibility. Super-M-List can sort
on any field and produce mailing labels direct to printer or disk file
for later printing or use by other programs. Super-M-List is the
perfect companion to TFS. Handles 1981 Zip Codes!
Requires: 48K CP/M
Supplied with complete user manual: $75.00 manual alone: $10.00

TFS-Text Formatting System: An extremely powerful formatter.
More than 50 commands. Supports all major features including:

• left & right margin justification • userdefined macros

• dynamic insertion from disk file * underlining and backspace
TFS lets you make multiple copies of any text. For example: Per-
sonalized form letters complete with name, address & other inser-
tions from a disk file. Text is not limited to the size of RAM making
TFS perfect for reports or any big job. Text is entered using CP/M
standard editor or most any CP/M compatible editor.
Requires: 24K CP/M

Supplied with extensive user manual: $85.00 manual alone: $20.00
Source to TFS in 8080 assembler (can be assembled using stan-
dard CP/M assembler) plus user manual: $250.00.

TEXT PROCESSING

R

DIAGNOSTICS I: Easily the most comprehensive set of CP/M compatible

system check-out programs ever assembled.

Tests:

• Memory • CPU (8080/8085/Z80) • Terminal • Disk • Printer
To our knowledge the CPU test is the first of its kind anywhere. Diagnostics
I can help you find problems before they become serious. A good set of
diagnostic routines are a must in any program library. Minimal re-
quirements: 32K CP/M. Supplied with complete user manual: $75.00 Manual
alone: $15.00

DIAGNOSTICS II: Includes all of Diagnostics I, plus:

• Every test is "submit"-able

• A complete Spinwriter/Diablo/Qume test has been added
(Serial Interface only)

• Output may be logged to disk

• Expanded memory test

• Expanded terminal test
Expanded disk test

Diagnostics ll provides the next level in system maintenance.

Requires: 32K CP/M

Price: $100.00 Manual only: $15.00

SYSTEM MAINTENANCE

A i tit i tut i t A A A * * i A * * A A faA

'TINY' PASCAL II: We still call it Tiny' but it's bigger and better than ever! This is
the famous Chung-Yuen 'Tiny' Pascal with more features added. Features include:

• recursive procedures/functions • integer arithmetic * CASE

• FOR (loop) • sequential disk I/O • 1 dimensional arrays

• IF.. .THEN. ..ELSE • WHILE • PEAK & POKE

• READ & WRITE ■ REPEAT.. .UNTIL • more

Tiny' Pascal is fast. Programs execute up to ten times faster than similar BASIC
programs. SOURCE TOO! We still distribute source, in Tiny' Pascal, on each
discette sold. You can even recompile the compiler, add features or just gain in-
sight into compiler construction.

Requires: 36K CP/M. Supplied with complete user manual and source on discette:
$85.00. Manual alone: $10.00

STACKWORK'S FORTH: A full, extended Forth interpreter/compiler produces
COMPACT, ROMABLE code. As fast as compiled FORTRAN, as easy to use as in-
teractive BASIC.
SELF COMPILING: Includes every line of source code necessary to recompile

itself.
EXTENSIBLE: Add functions at will.
Z80 or 8080 ASSEMBLER included.
Single license, OEM licensing available.
Please specify CPU type: Z80 or 8080
Supplied with extensive user manual and tutorial: $175.00
Documentation alone: $25.00

SSS FORTRAN: The SSS FORTRAN compiler is fast, efficient, and complete
(full 1966 ANSI standard with extensions). The RATFOR compiler compiles into
FORTRAN allowing the user to write structured code while retaining the
benefits of FORTRAN. The FORTRAN supports many advanced features not
found in less complete implementations, including: complex arithmetic,
character variables, and functions. Complete sequencial and random disk I/O
are supported. SSS FORTRAN will compile up to 600 lines per minute! Recur-
sive subroutines with static variables are supported. ROMable ".COM" files
may be generated. SSS RATFOR allows the use of contemporary loop control
and structured programming techniques. SSS RATFOR is similar lo FORTRAN
'77 in that it supports such things as:

• REPEAT.. .UNTIL " WHILE • IF.. THEN. ..ELSE
SSS RATFOR is supplied with source code in FORTRAN and RATFOR.
System Requirements & Prices:

SSS FORTRAN requires a 32K CP/M system.
SSS FORTRAN with RATFOR: $325.00
SS FORTRAN alone: $250.00

RATFOR alone: $100.00

(Sold only with valid SSS FORTRAN license)

i

^f* 1 ♦ **$** ♦ W ♦ "*♦ * * 1 PROGRAMMING LANGUAGES fr** f w f" j M j w f'"^

UTILITIES I: A collection of programs that you will find useful and

maybe even necessary in your daily work (we did!).

Includes:

GREP: Searches files for a specified string

SORT: In core sort of variable length records

CMP: Compare two files for equality

PRINT: Formatted listings to printer

PG: Lists files to CRT a page at a time

. . . plus more . . .
Requires: 24K CP/M
Supplied with manual on discette: $60.00

UTILITIES II: Many new programs not available elsewhere. Includes these
"file" utilities:

DIFF: Source comparitor

PR: Powerful multicolumn output formatter

CAT: Concatenate files

RPL: Substitute strings in files

. . . plus more . . .
Requires: 24K CP/M $60.00
Supplied with manual on discette

UTILITIES

TERM: A complete intercommunications package for linking your com-
puter to other computers. Link either to other CP/M computers or to large
timesharing systems. TERM is comparable to other systems but costs
less, delivers more and source is provided on discette! With TERM you
can send and receive ASCII and Hex files (COM too, with included conver-
tion program) with any other real time communication between users on
separate systems as well as acting as timesharing terminal.

• Engage/disengage printer • errorchecking and auto retry

• terminal mode for timesharing between systems

• conversational mode • send files • receive files
Requires: 32K CP/M

Supplied with user manual and 8080 source code: $150.00
Manual alone: $15.00

^INTERCOMPUTER COMMUNICATIONS!

Mii

ANALIZA: An amazingly accurate
simulation of a session with a
psychiatrist. Better than the famous
"ELIZA" program. Enlightening as
well as fun. An excellent example of
Artificial Intelligence.
Requires: 48K CP/M, CBASIC2
Cost: $35.00

ENTERTAINMENT

ft

, ,..- : , : :; : ,-, "■"'.;- , '"■■.;,',;. '" :;

u

Cl>

Z8000CROSSASSEMBLER:Supports:

full Z8000 syntax, segmented and

: , :

unsegmented mode, full 32-bit
arithmetic, hex output, listing output,

U-.

'■>.-'

"downloader".

V.

:""'.

Requires: 56K CP/M $500.00

1 year maintenance $300.00

W

:' l"i

manual alone $ 50.00

; -

$

> .;- -■,_'■ - - A zeoootoo! J - :< =; ^

^

ENCODE/DECODE: A complete software security system for CP/M.
Encode/Decode is a sophisticated coding program package which trans-
forms data stored on disk into coded text which is completely unrecog-
nizable. Encode/Decode supports multiple security levels and passwords.
A user defined combination (One billion possible) is used to code and
decode a file. Uses are unlimited. Below are a few examples:

• databases • payroll files • programs • tax records

Encode/Decode is available in two versions:

Encode/Decode I provides a level of security suitable for normal use.
Encode/Decode II provides enhanced security for the most demanding
needs.
Encode/Decode I: $50.00 Encode/Decode II: $100.00 manual alone: $15.00

^ ^ SOFTWARE SECURITY f

On line "Help" system provided with every program package.

SuperSoft

First in Software Technology

CP/M Formats: 8" soft sectored, 5" Northstar, 5" Micropo-
lis Mod II, Vector MZ, Superbrain DD/QD

All Orders and General Information:

SUPERSOFT ASSOCIATES

P.O. BOX 1628

CHAMPAIGN, IL 61820

(217)359-2112

Technical Hot Line: (217) 359-2691

(answered only when technician Is available)

CP/M REGISTERED TRADEMARK DIGITAL RESEARCH

SuperSofffs
DIAGNOSTICS I & II for CP/M

Since the beginning, programs have been written to verify the correctness of computer systems. This task has
usually fallen on the manufacturers of computer equipment. However in the case of microcomputers, the manufacturers
have been reluctant to supply such programs along with their hardware. First, because they often are not the ones
called on to fix that hardware, and second, because the low cost of such systems often does not allow for such a large
programming effort. The tremendous number of CP/M systems have made it possible for us to offer both DIAGNOSTICS — I
& II at an affordable price, since we do not have to deal with a myriad number of console devices and disk systems, we
simply use the standardized system calls.

Both packages perform tests on the five critical areas of your computer system:
• Memory • CPU • Printer • Terminal • Disk drive

DIAGNOSTICS-I provides an excellent level of testing. DIAGNOSTICS — II is simply the finest set of system
maintenance routines ever written for microcomputers. DIAGNOSTICS — II includes all of DIAGNOSTICS — I. but
goes much further in providing the user with even more checks, tests, and reports.

DIAGNOSTICS-I Features

The MEMORY TEST allows every byte of user memory to be tested. Both a quick test as well as a walking bit' test
are included. Error reports summarize errors by bit as well as address.

The CPU TEST interprets a program that is designed to execute all single instruction sequences and many multiple
instruction sequences. After each instruction sequence, the program tests all of the CPU registers to see that the
proper registers changed correctly, and only those registers changed. This will detect, for instance, if storing into the A
register affects the B register. The CPU test will automatically recognize the type of CPU you have. To the best of our
knowledge, nothing as powerful as the CPU test is available anywhere else.

The PRINTER TEST prints a one line pattern, then rotates the pattern one character and prints again. This barber
pole' scheme is simple, yet elegant, since it checks that every printable character can be printed in every printer
column, and does so in a manner that makes any error obvious at a glance.

The TERMINAL TEST prints a 'barber pole' and then exercises cursor positioning, foreground, background, erase-
all, erase-to-end-of-line, erase-foreground, and erase-background. If some of these features are not available on your
terminal, they can be skipped. The test can be used with any terminal; many standard types are supplied pre-patched.
any other can be patched by the user.

The DISK TEST writes a unique pattern in each sector, and then does a pseudo-random seek/read test within the file
area.

DIAGNOSTICS-II Features

Every test is "submit'-able. In fact, a sample submit file is provided with each disk. This means that the user can run
a series of tests without operator interaction. To further decrease the need for the user to "baby sit' the tests, the
output of tests may be logged to disk for later review. This makes overnight testing very easy yet informative.

We started with DIAGNOSTICS — I and added all the features that users wanted as well as some of our own. Below is
a description of some of the enhancements.

MEMORY TEST:

• Default to size of CP/M TPA • Bank select (a necessity for more than 64k)

• Memory map of system displayed • Memory speed test • Burn in test

PRINTER TEST:

• Spinwriter, Diablo, Qume test which checks all head and carriage motions as well as ASCII printing features.
(This is a very thorough test!)

DISK TEST:

• Writes a unique pattern to each sector on disk, verifying as it runs.

• User defined seek patterns allowed (This is great for drive allignment and testing!)

• Tests user specific user defined sectors.

The TERMINAL TEST is the same as for DIAGNOSTICS — I except that it is submit -able.

The CPU TEST is the same except that it is "submit -able and output may be logged to disk.

Also, a QUICK TEST has been added which willcheckthe memory, disk drives, and CPU in your system in less than
four minutes! The test is, of course, not as thorough as the ones described above, but provides a measure of
confidence. It is particularly useful if used every time the system is powered up.

SISSIES !i $ I?£?™ *» Orders and General Information:

DIAGNOSTICS II: $100.00 Cfm*rOi# P^S^ SUPERSOFT ASSOCIATES

DIAGNOSTICS II: $100.00 ft/rwCV/ F^S^ SUPERSOFT A

(manual only): $15.00 JUJjXLSf^i \mmm* P.O. BOX 1628

Both require 32K cp/m First in Software Technology

CHAMPAIGN, IL 61820

(217)359-2112

Technical Hot Line: (217) 359-2691

__,.._ „„ _,„„.., „,,., (answered only when technician Is available)

CP/M Formats: 8 soft sectored, 5 Northstar, 5 Micropo-

lis Mod II, Vector M2, Superbrain DD/QD -civm nEosre»fD tiudem»mhhgit«l heseauch

An Introduction to
Data Compression

Harold Corbin

11704 Ibsen Dr

Rockville MD 20852

Even though the cost of data storage continues to
decrease fairly rapidly, there are still a number of situa-
tions where it is desirable to squeeze more data into a
physical storage device. Often the typical microcomputer
has limited memory, small disks, or slow cassettes. With
any of these storage limitations, data compression may
offer a method of using the existing device to store larger
quantities of data or to provide improved access time to
the data. The use of data compression can also provide
significant improvement in the transmission of data over
communication networks since there are fewer bits to
send in order to convey the information.

ASCII code does not consider that

the frequency of the characters in

the file is not uniform.

The basic idea in data compression is to use more effi-
cient codes to represent the information in a file or to re-
move redundant and unnecessary information from the
file. With data compression in effect, the system stores or
sends only the minimum data necessary to convey the
original information.

In a typical file, the individual characters are
represented by fixed-length codes such as ASCII
(American Standard Code for Information Interchange).
This representation does not consider that the frequency
of occurrence of the characters in the file is not uniform.
In typical English text, E is the most common letter and Z
is the least frequently used letter. Table 1 presents a fre-
quency analysis for letters in English text. Using a code
such as ASCII for storing or transmitting text means that

the same number of bits is used for the most frequently
occurring letter as well as for the least frequently occur-
ring letter. This method of encoding data uses more bits
to represent the information in the file than is necessary.
In this article, I will illustrate ways to store data more
efficiently.

Encoding the data in a more efficient form is called
data compression. There are a variety of methods that
have been used to compress data, but all of them attempt
to reduce the redundancy of the original data. Most large
data-processing systems provide some form of file com-
pression, since storage costs money. Also, it is often less
expensive to pay for the computer time to compress and
expand the data than to pay for mass storage. The user of
a large system usually has PACK and UNPACK com-
mands available to allow compression and expansion of
his files.

Typical data-processing systems use some form of zero
or space suppression to do their data compression. This
method is easy to implement and not very expensive to
run, and produces fairly good compression for many
types of data. The efficiency of this compression method
is dependent upon how many spaces or zeros occur in the
file. Typically, a source file of assembly-language state-
ments is a good candidate for data compression. Fifteen
to twenty percent compression of an assembly-language
source file is not uncommon.

Data-Compression Methods

A space-compression capability can be implemented in
several ways. Two common ones are bit mapping and
recurrence coding. In the bit-mapping scheme, a bit map
exists that is long enough to match one bit of the bit map
to each byte of data in the original file. In the map, a is
stored for each byte in the data that is a space, and a 1 is

218 April 1981 © BYTE Publications tac

THE PERFECT MARRIAGE

CHRISLIN 256KB MEMORY

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NOW AVAILABLE! 256KB memory on a dual height board only $1925. CHRISLIN INDUSTRIES
now offers state-of-the-art 64K RAM Memory system designs. Like our recently introduced
512KB MULTIBUS® compatible single card memory our 256KB LSI 11/23 memory is an
industry first.

Free up critical and expensive backplane space. Saves you 3 dual slots.

Addressable in 4K increments up to 4 Megabytes.

On board parity generator checker totally DEC hardware and software compatible.

Single 5 volt power requirement.

Battery back-up capability. 256KB unit draws less than 300 ma at 5 volts in battery back-up
mode.

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DON'T ASK WHY WE CHARGE SO LITTLE, ASK WHY THEY CHARGE SO MUCH.

£

Chrislin Industries, Inc.

Computer Products Division
31352 Via Colinas • Westlake Village, CA 91362 • 213-991-2254

Multibus is a trademark of the Intel Corp LSI II is a trademark of Digital Equipment Corp

Circle 143 on inquiry card.

BYTE April 1981 219

stored in the map for each corresponding byte in the data
that is not a space. This way, the data can be stored with
all spaces removed and still be easily reconstructed by
first examining the bit map to determine where the ex-
panded file needs to have a space or spaces inserted as the
next data byte.

Recurrence coding takes a string of more than two
repetitive characters and replaces the string with a special
character. It is then followed by the count of how many
occurrences of the repeated character are being com-
pressed. A variation of this method is used in the IBM
VM/370 Operating System with the PACK option of the
COPYFILE command.

If the string "ABbbbbCD" (where b is a space) were to
be compressed using the bit-mapping technique, 5 bytes
would be required to store the data and the bit map. The
map would be 11000011 (1 byte) and the data would be
"ABCD" (4 bytes). Since only 5 bytes are required to
store the original data in compressed form instead of 8
bytes, the data is compressed to 62.5% of its original
length. Storing the same string using recurrence coding
would result in a compressed string of "AB*4CD", where
"*4" replaces the four spaces. In this case, the data is
compressed to 75% of its original length. You can see
that the efficiency of a given method is dependent upon
both the method itself and the characteristics of the data's
redundancy.

Another method of compression is known as pattern
substitution. In this method, each occurrence of a specific
pattern is replaced by a unique code. For example, in the
above text, the pattern "compression is" could be
replaced by a single 8-bit byte — say, 11111001. This
would compress each occurrence of the 14 ASCII bytes in
the pattern to a single byte. Obviously, if there were
more than 256 patterns, the code pattern would have to
be bigger than 8 bits to maintain uniqueness.

Variations of this method could mix the ASCII code
and the pattern code. One scheme would place a unique
code — for example, the ASCII ESC (escape) character —
ahead of the pattern code. When the PACK routine en-
counters the ESC character, the next byte is replaced with
its equivalent pattern.

Another scheme that would permit ASCII and pattern
codes to be mixed would tag the pattern codes by setting
the high-order bit to 1. This would restrict the ASCII to
128 codes and the patterns to 128 codes.

The efficiency of the pattern-substitution compression
methods can be very useful if the pattern is long and its
number of recurrences is high. Some compression
systems based upon this method have sophisticated pro-
grams that search the data for patterns and assign codes
to the patterns in an optimal manner.

Some compression methods are data-value dependent.
One of these methods is difference compression. For
example, if succeeding records had a field with the
following values:

1,732,517
1,732,217
1,732,200
1,732,190

either the difference between succeeding fields or the dif-
ference from a base value could be stored as the com-

pressed data. In the first case, the values

1,732,517
300
17
10

would be stored. Obviously, if the field is of fixed length,
nothing is gained by compression. However, if a variable
field-length capability exists in the system, some space
savings can be achieved with this compression method.
Again, the amount of compression is highly dependent
upon the data and its characteristics.

Another compression method makes use of the
statistical properties of the occurrence of the data to be
compressed. In this method, shorter codes are used for
the more frequently occurring data elements. Longer
codes are used for less frequently occurring data
elements. One code used in data compression that op-
timizes the encoding values is the Huffman code. There

Letter

Frequency (%)

E

13.0

T

10.5

A

8.1

7.9

N

7.1

R

6.8

1

6.3

S

6.1

H

5.2

D

3.8

L

3.4

F

2.9

C

2.7

M

2.5

U

2.4

G

2.0

Y

1.9

P

1.9

W

1.5

B

1.4

V

0.9

K

0.4

X

0.15

J

0.13

Q

0.11

Z

0.07

Table

1: Relative fre-

quency

of the alphabet in

the English language. In

most ch

aracter codes (in-

eluding

the common 7-bit

ASCII),

every letter is

represer

ted by the same

number

of bits. But one

method

of data compres-

sion assigns shorter codes

to the frequently used let-

ters (ie:

E, T, and A) and

longer

codes to seldom

used letters (ie: Q and Z).

A message stored in this

kind of

code should be

significantly shorter in bits

than th

e same message

stored in ASCII.

Letter

Huffman Code

E

100

T

001

A

1111

1110

N

1100

R

1011

1

1010

S

0110

H

0101

D

11011

L

01111

F

01001

C

01000

M

00011

U

00010

G

00001

Y

00000

P

110101

W

011101

B

011100

V

1101001

K

110100011

X

110100001

J

110100000

Q

1101000101

Z

1101000100

Table 2: A Huffman code.

There

are many Huffman

codes;

this is the one that

is used in figure 2 and

listings

1 thru 4. Note that

the shorter codes are used

for frequently occurring

letters,

and that no code is

a beginning substring of a

longer

code.

The

average number of

digits

used to represent a

letter

can be reduced

toward the entropy limit

H if

the Huffman tech-

nique

is used to encode

blocks

of letters rather

than individual ones.

220 April 1981 © BYTE Publications Inc

A

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BYTE April 1981 221

are actually many Huffman codes, but they are similar in
structure.

Before explaining how to construct a Huffman code, I
will describe a typical Huffman code and how it works.
The code that is used in the two compression programs in
this article is given in table 2.

To compress the word "compression", the appropriate

CODE LENGTHS L
ARRANGED IN
ASCENDING ORDER

I

. IS NEW

CODE SAME
] LENGTH AS F
I LAST CODE |

ADD 1 TO
LAST CODE

TACK ON
ZEROS EQUAL
TO THE
DIFFERENCE
IN CODE
LENGTH ONTO
RIGHT-HAND
END OF CODE

( END J

Figure 1: Flowchart for assignment of Huffman codes. This
algorithm will produce a series of codes (Huffman codes) with
the following two characteristics: the length of the code (in bits)
is inversely proportional to the relative frequency of the symbol
being encoded; and no code is a beginning substring of the Huff-
man code of another symbol. Together, these properties define
a code with a unique decoding that uses the smallest number of
bits to encode an average message.

binary code is assigned to each letter, which produces the

binary string:

, 01000111000011110101101110001100110101011101100 ,
\ AAA A A A A A A A /

COM

R E S S I O N

A quick count shows that 47 bits were required to en-
code the word "compression" with Huffman coding as
compared to the 88 bits required with ASCII code. This
gives a compressed text that is 53.4% of its original
length. This level of compression is not too surprising
since it is well known that the English language is highly
redundant.

Of course the above example is a very short one. A
larger piece of data should be used to find a more exact
value of the amount of compression that can be expected
from using Huffman coding. The actual efficiency can
also be determined mathematically, but an explanation of
that method is beyond the scope of this article. Using the
program code described above with English text, approx-
imately 4.18 bits would be required for each letter. Com-
pared to 8-bit ASCII code, the compressed text is com-
pressed to 52.2% of its original length.

Earlier in this article I mentioned that Huffman codes
are optimized based upon the probability of the occur-
rence (ie: frequency) of the data element being encoded.
In the program-code table (table 2), the more frequently
occurring letters have the shorter codes, (eg: an E is coded
with 3 bits). The number of bits, b, needed to encode a
letter can be determined by the following formula:

b = /(-log 2 p)

where p is the probability of occurrence of the letter, and
f(x) is the closest integer greater than or equal to x.

From table 1, the probability of occurrence of an E in
English text is 0.13; since — log 2 0.13 = 2.94, the integer
length is 3. If you were to continue to compute the code
lengths from the probabilities in table 1, the lengths
would differ from the code lengths used in the programs.
This is because the program code lengths were deter-
mined from text that differs slightly in frequency from the
text used to prepare table 1.

There are several ways the actual codes can be con-
structed. One method is shown in figure 1. To use the
algorithm in figure 1, the letters must be arranged by

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222 April 1981 © BYTE Publications Inc

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BYTE April 1981 223

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Figure 2: Binary tree for a Huffman code. The Huffman code for
a letter is defined as the sequence of binary digits encountered
when tracing the path from the root node, *, to the letter. Thus,
the code for G is 00001, and the code for E is 100. This is the
code used in the programs of listings 1 thru 4. Although this
code cannot be produced by the algorithm of figure 1, it is a
valid Huffman code (there are many) that can be validly used to
illustrate the structure and implementation of Huffman codes in
general.

ascending code length. Then the letter with the shortest
length is assigned a code consisting of all Os. Execution of
the algorithm will result in the assignment of a unique
code to each letter.

With any set of codes that are constructed, it is impor-
tant that no code has a shorter code as part of its begin-
ning. For example, if E is 100, then 10010 cannot be the
code for another letter. This is because in scanning the bit
stream from left to right, the decoding algorithm would
think that 10010 is E (100) followed by 10 and not the dif-
ferent letter that was intended.

Regardless of the method used to construct the codes,
the full set of binary Huffman codes can be represented as
a binary tree. Figure 2 shows the binary tree that is
equivalent to the Huffman code used in the programs of
listings 1 thru 4. (These codes were not produced by the
algorithm of figure 1.) This code structure allows the
code to be uniquely decoded by simply starting at the top
of the tree and walking down the tree, taking each branch
that corresponds to the bit value, 1 or 0, as the coded
data stream is scanned from left to right. This is the way
the expansion program recreates the original data.

It is possible to combine various compression methods
to increase the storage efficiency even more than when
working with single letters. For example, Huffman codes
could be assigned to patterns. Instead of working with
the frequency of letters, you would use the frequency of
the patterns. Thus, the pattern "code" might be
represented by 010 and the pattern "data compression"
might be represented by 10110. Obviously, a lot of com-
pression could be achieved, particularly if single-letter
and pattern methods are combined and certain patterns
have a high frequency of occurrence.

Sample Programs

Two versions of both the compression and the expan-

224 April 1981 © BYTE Publications Lie

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BYTE April 1981 225

sion programs have been prepared to demonstrate two
different uses of data compression. The compression pro-
gram, COMPl, demonstrates the basic concept. (See
listing 1.) Characters are entered from the keyboard and
the output of the program is a serial bit stream that could
be sent to a cassette for storage of the compressed data.
Such a scheme could result in reduced writing time and
faster access to the data. The tradeoff involved is the
usual one in many data-processing situations; namely,
storage space saved versus computer time used to encode
and decode the data.

The amount of compression is

highly dependent upon the data

and its characteristics.

Since COMPl is for demonstration purposes only, the
program is simplified somewhat by storing the serial data
1 bit per byte of memory. This is just a convenience that
simplifies the expansion program, EXPl. (See listing 2.)
If the data were actually being sent to a serial output
port, only minor changes in the code would be required.

The second compression program, COMP2, uses the
same basic compression method as COMPl. (See listing
3.) However, the resulting serial bit stream is broken into
8-bit bytes for use by a parallel storage medium such as
programmable memory. This provides maximum com-
pression in a fixed-word-length computer. The program

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EXP2 expands the compressed text created by COMP2.
(See listing 4.) The description of the compression and ex-
pansion programs emphasizes the table structure, since
both programs use tables to facilitate changing codes.

COMPl Description

This program takes characters entered via the
keyboard, checks for a legal character, finds the Huffman
code corresponding to the entered character, and stores
the bit stream sequentially in memory. Each bit is stored
in the lowest-order bit of a byte for demonstration conve-
nience and for interfacing with EXPl. The first two words
of the output buffer contain a count of the number of bits
that are stored in the remainder of the buffer. This infor-
mation is used by EXPl to stop the decoding process on
the bit stream. The input need not come from the
keyboard and could be from another buffer, simply by
changing a few lines of code related to the input function.

The heart of the program's operation is the table
lookup and the shifting function. Based upon a letter's
ASCII code, an index is computed that is then added to
the base address of the encoding table. This table has the
following format: two 8-bit words are required for each
letter to be encoded; the low-order 4 bits of the first word
in memory contain a count of the number of bits required
to encode the letter. The remaining 12 bits, 8 in the
second byte followed by 4 in the top half of the first byte,
are used to store the compressed code. (Note that the
word order in the source statement and in memory is
reversed because of the assembler's treatment of the DW
(Define Word) instruction. The code is stored left-
justified in the 12-bit area. This format makes processing
simple when the two words are loaded into the D and E
register pair for shifting.

With the compressing code located, it is serialized by
shifting left according to the count in the 4-bit part of the
table. The DAD (add register pair to H and L) instruction
effectively shifts the DE register pair's high-order bit into
the carry register. As each bit is shifted out, the total bit
count in the buffer is updated. The processing of the in-
put stream continues until a period is detected, and con-
trol returns to the system monitor.

It should be noted that the only characters that are en-
coded are the twenty-six alphabetic letters. Any other
characters (including blanks) are ignored. In a non-
demonstration environment, spaces, punctuation, and
other symbols would have to be included; this would re-
quire enlarging the lookup table to include the represen-
tation of the new symbols.

EXPl Description

The expansion program, EXPl, operates on the bit
stream prepared by COMPl. (See listing 2.) It expects
this data to be in the buffer defined by COMPl, with the
bit count in the first two words and the data bit in the
lowest bit of each byte. This program is also table-driven;
but the table is more complex than the encoding table and
the processing is more involved. Basically, the program
searches a binary tree to decode the bit stream. The
binary tree shown in figure 2 is converted to a table. The
program then steps through the table, selecting the ap-
propriate branch in the tree structure depending upon the
value of each bit in the data stream. The data in the table

Text continued on page 246

226 April 1981 © BYTE Publications Inc

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Listing 1: COMF1 text-compression routine. This routine takes only alphabetic text entered from the keyboard and converts it to the
Huffman code given by the tree in figure 2. The Huffman code is stored 1 bit per byte. The routine is written in 8080 machine code.

7 500

?5oo

->500

9500

9500

?500

7500

?5no

9500

2500

7500 31

00

00

7503 21

00

no

■7506 ??

00

41

7509 21

02

41

250C 22

8C

25

?50F DB

08

7511 OF

251? Da

OF

?5

2515 DB

0\

2517 FE

2E

2519 CA

OC

00

251C CD

00

C5

251F E6

7F

2521 D6

41

2523 DA

OF

25

2526 FE

l.A

2528 D2

OF

25

252B 87

252C 4F

252D 06

00

252F 21

58

2.5

2532 09

9 53 3 5E

2 534 73

■?535 56

7536 7B

2537 E6

OF

7539 47

7 53A EB

753B AF

253C 29

253D 17

253E E6

01

2560 E5

2541 2A

8C

25

2544 77

2545 23

7546 22

8C

25

2.549 2 A

00

41

754C 23

754D 22

00

41

2550 El

2551 05

2552 C2

3B

25

2 .5*5 C3

OF

25

7558

7558

2558

2558 04

FO

255A 06

70

25 SC 05

40

25^ 05

D8

7560 03

80

756? 05

48

2564 05

08

2566 04

50

2568 04

AO

756A 09

DO

256C 89

Dl

256E 05

78

0001
0002
0003
0004
0005
0006
0007
0010
0011
0012
0020
0021
0077
0023
0024
0040
0041
0042
0043
0060
0070
0073
0075
0080
0082
0084
0086
0090
0100
0110
0120
0130
0140
0150
0160
0170
0180
0185
0187
0190
0192
0200
022.0
0225
0226
0228
0229
0231
0232
0235
0236
0238
0260
0270
0300
0305
0306
0307
0310
0320
0330
0340
0350
0360
0370
0380
0390
0400
0410
0420

*THIS ROUTINE TAKES TEXT, (LETTERS ONLY)

*AND COMPRESSES THEM USING HUFFMAN CODING. FOR

*TEST PURPOSES THERE IS ONE BIT PER BYTE IN THE

*DATA BUFFER. THE FIRST TWO BYTES IN THE DATA BUFFER

*ARE THE BIT COUNT. ENCODED DATA IS STORED IN DBUF AS 1 BIT

*PER BYTE FOR TEST PURPOSES. NORMALLY DATA WOULD BE PACKED

*OR OUTPUTTED SERIALLY.

ECHO: EQU 0C500H ;OUTPUT DRIVER

SP: ECU 6

MON: ECU OCH

LXI SP,0
LXI H,0
SHLD DBUF

•.MONITOR RETURN

INCH:

;END OF TEXT
;NO MORE

; CLEAR PARITY
; COMPUTE INDEX

A'+l

COMPRESSED BIT COUNT

LXI H.DBUF+2

SHLD DADD ;NEXT BIT LOCATION

IN 8

RRC

JC INCH

IN 10

CPI ' .'

JZ MON

C-\LL ECHO

.AN I 07FH

SUI 'A'

JC INCH

CPI 'Z'-'

JNC INCH

.ADD A

MOV C,A

MVI B,0

LXI H,TABL

DAD B

MOV E,M

INX H

MOV D,M

MOV A,E

.AN I OFH

MOV B,A

XCHG

XRA A

DAD H

RAL

AN I 1

PUSH H

LHLD DADD

MOV M,A

INX H

SHLD DADD

LHLD DBUF

INX H

SHLD DBUF

POP H

RCR B

JNZ NEXT

JMP INCH
♦ENCODE TABLE FORMAT- LOW ORDER 4 BITS ARE NUMBER OF BITS
*IN ENCODED CHARACTER. REMAINING 12 BITS .ARE FOR CODE.
*CODE IS LEFT JUSTIFIED. E.G., AN M IS 00011

; MULT I PLY BY 2

; INDEX

;GET ENCODE VALUE

GET BIT COUNT
MASK COUNT
KEEP COUNT

NEXT:

SHIFT OUT BIT

MSB FIRST

SETUP OUTPUT BIT

; STORE BIT

.UPDATE BIT COUNT

[REDUCE COUNT

STREAM

TABL:

DW 0F004H
DW 7006H
DW 4005H
DW 0DR05H
DW 8003H
DW 4805H
DW 805H
DW 5004H
DW 0A004H
DW 0D009H
DW 0D189H
DW 7805H

228

April 1981 © BYTE Publications Inc

Listing 1 continued on page 230
Circle 150 on inquiry card. >

COMPUTERS-TERMINALS-MODEMS!

MODEMS AND COUPLERS

Connect your Apple, TRS-80 or any other computer or terminal to the phone lines!

Penril

Penril
300/1200

Penril 300/1200— Bell 212A style $799

Bell 21 2A style. 1 200 baud and 300 baud. Manual origi-
nate, auto-answer. Full duplex. RS232. Direct connect
to phone lines via RJ11C standard extension phone
voice jack. 1 year warranty.

U.S. Robotics

USR-330A

Bell 103/113 style

USR-330D

Bell 103/113 style

USR-330D $339

Bell 103/113 style. 330 baud. Manual originate, auto-
answer. Half/full duplex. RS232. 1 year warranty. Direct
connect to phone lines via RJ11C standard extension
phone voice jack.

USR-330A $399

Same as USR-330D but includes auto-dial capability.

U.S. Robotics

The

Phone Link
Acoustic
Modem

Bell 103/113 style $179

300 baud. Sleek, low profile. Originate and answer cap-
ability. Half/full duplex. Self-test. RS232. Light displays
for On, Carrier, Test, Send Data, Receive Data. 15 oz.

Perkin-Elmer Corporation

Bantam 550B .... $694 1

Compact. Silent. Upper/lower

case. 80th col. wrap-around.

Bell. Integrated numeric pad.
_ Printer port. Transparent
I mode. Editing features.

Tabbing.
Bantam 550E...$755|

Same as 550B plus
separate numeric key-
pad and cursor direction I
keys.
Bantam 550S $879

Same as 550E plus block mode. 8 function keys, and
protected fields, reverse video fields, half intensity
fields, blinking fields.

550 Options

20mA Current Loop Interface $70

Non-Glare Screen $25

2nd page of memory (550S only).. $100

Digital Equipment Corporation

DECVT100

. DEC VT100... $1668

Detachable keyboard. Separate numeric keypad with
function keys. Business forms character set. Reverse
video. Selectable double-size characters. Bidirectional
smooth-scrolling. 80 cols or 132 cols. Split screen. Set-
table tabs. Line drawing graphic characters. Status line.
Key-Click.

HARDCOPY TERMINALS

Teletype
Model 43

CRT's

Perkin-Elmer
Corporation

Superowl 1251

Perkin-Elmer Superowl 1251 $1564

Intelligent, editing CRT. Detachable keyboard. 32 fully
programmable function keys. Intelligent printer part.
Business forms character set. Block mode. Protected
fields. Blinking fields. Numeric fields. Reverse video.
Half intensity. Polling. Down line loading of options. Re-
mote control of all options by host computer. Settable
tabs. Status line. Separate numeric keypad. Transpar-
ent mode.

Teletype
Corporation

Teletype Model 43 KSR with RS232
and Connector Cable $999

30CPS. Dot matrix. 132 cols. True descenders on lower
case. Excellent print quality for dot matrix printer. Pin
feed.

NEC Corporation
NEC Spinwriter 5510 & 5520

5520 KSR Spinwriter $3088

55 CPS. Impact printer. Selectric print quality. Change-
able print fonts. 110, 300 and 1 200 baud data rate. Nu-
meric keypad. Friction and tractor feed.
5510 Spinwriter $2754

55 CPS. Impact printer. Selectric print quality. Change-
able print fonts. 110, 300 and 1 200 baud data rate. Fric-
tion and tractor feed.

Digital Equipment
Corporation

DECLA120... $2388

1 80 CPS. Dot matrix. Upper/lower case. 1 K buffer. De-
signed for 1200 baud communications. 30 character
answerback message. Adjustable line spacing. Adjus-
table character sizes including double sized characters.
Settable horizontal and vertical tabs. Top-of-form capa-
bility. RS232.

Perkin-Elmer
Corporation

Pussycat 650/655
CRT Screen Printer

650/655 Pussycat CRT Screen Printer . $899

100 CPS. Extremely compact and quiet. 110 to 9600
baud rate. 2K buffer. Ideal for producing rapid, reliable
hardcopy of your CRT screen display. Can be added to
any CRT with our interface option.

Digital

Equipment

Corp.

DECLA34DA... $939

30 CPS. Dot matrix. Upper/lower case. 4 character
sizes. Up to 217 cols per line. 6 lines per inch settings.
Friction feed. Settable tabs. RS232.
DECLA34AA $1095

30 CPS. Dot matrix. Upper/lower case. 8 character
sizes including double size characters. 6 lines per inch
settings. Up to 21 7 cols per line. Friction feed. Settable
horizontal and vertical tabs. Top-of-form capability.
Options for LA34AA and LA34DA

Tractor Feed Mechanism $114

Numeric Keypad w/ Function Keys . . $69

Pedestal $100

Paper Out Sensor $25

APL Capability with APL Keycaps .. $499
2K Buffer with Text Editor and 1200 Baud
Communications Capability $499

m

Leasing rates and lease/purchase plan information is available on request.

All equipment is shipped with a 10 day money back guarantee.

We offer full service, on site maintenance plans on all equipment.

All equipment in stock.

SI3liiP?f™l"T"II™**2t

SALES

GENERAL OFFICES

SERVICE

C3ISJ 34B-5B50
C3I2) 346-5651
C3I2) 733-0497

listing

l con

tinued

2570

05

18

2572

04

CO

2574

04

EO

2576

06

D4

2578

4A

Dl

257A

04

BO

257C

04

60

257E

03

20

2 580

05

10

2582

07

D2

2584

06

74

2586

89

DO

258*

05

00

2 58 A

0A

Dl

258C

00

00

258E

4100

0430

DW

1805H

M

0440

DW

0C004H

N

0450

DW

OE004H

0455

DW

0D406H

P

0460

DW

0D14AH

0470

DW

0B004H

R

0480

DW

6004H

S

0490

DW

2003H

T

0500

DW

1005H

U

0510

DW

0D207H

V

0520

DW

7406H

W

0530

DW

0D089H

X

0540

DW

5H

Y

0550

DW

0D10AH

Z

0600 DADD:

DW

N

0605

ORG 4100H

0610 DBUF:

DS

1000

NEXT BIT LOCATION

Listing 2: EXP1 text-expansion routine. This routine takes the output of COMP1, information expressed in a Huffman code, and
decodes it using the binary tree of figure 2. The decoded character is displayed via a user-supplied subroutine named DISP. The
routine is written in 8080 machine code.

3000

3000

3000

3000

3000

3000

3000

3000

3000

3000

3000

01

00

00

3003

21

02

41

3006

22

97

30

3009

21

00

41

300C

4E

3 OOP

23

300E

46

300F

C5

7010

21

4B

30

701?

E5

3014

3 A

97

30

3017

4E

3019

23

3019

06

00

301B

3?

97

30

301E

El

301F

09

30?0

7E

30?1

17

3022

DA

32

30

3025

IF

3026

5F

3037

16

00

3039

19

3 03 a

CI

303B

CD

44

30

303E

C5

302F

C3

13

30

3032

IF

3033

E6

7F

3035

5F

3036

16

00

3038

19

3039

7E

303A

CD

00

C5

30 3D

ri

3 03E

CD

44

30

3041

C3

OF

30

0000
0001
0002
0003
0004
0005
0006
0007
0008
0009
0010
0020
0030
0040
0050
0060
0070
0080
0090
0100
0110
0120
0130
0140
0150
01*0
0170
0180
0190
0200
0205
0210
0220
0230
0240
0250
0270
0280
0290
0294
0296
0297
0298
0299
0305
0310
0320
0330

*THIS PROGRAM ACCEPTS DATA PREPARED BY THE DATA COMPRESSION
♦(HUFFMAN CODE) PROGRAM. THE DATA BUFFER HAS THE BIT COUNT
*IN THE FIRST TWO BYTES. THE PROGRAM RUNS UNTIL ALL BITS
*HAVE BEEN PROCESSED. THE PROCESSING CONSISTS OF ADDING A
*DATA BIT TO THE TABLE ENTRY POINT, GETTING AN INCREMENT
*VHICH POINTS TO THE NEXT 0-1 PAIR AND CONTINUING UNTIL
*A TAG IS FOUND IN BIT 7. THIS SIGNIFIES THAT THE NEXT
*TABLE ENTRY IS THE DESIRED CHARACTER. IN A NON-TEST MODE
*DATA WOULD BE EITHER PACKED IN 8 BIT BYTES OR ARRIVING
*VIA A SERIAL PORT.

EXP:

NEXT:

OUTCH:

LXI SP,0
LXI H.DBUF+2
SHLD DADD
LXI H.DBUF
MOV C,M
INX H
MOV B,M
PUSH B
LXI H.XTAB
PUSH H
LHLD DADD
MOV C,M
INX H
MVI B,0
SHLD DADD
POP H
DAD B
MOV A,M
RAL

JC OUTCH
RAR

MOV E,A
MVI D,0
DAD D
POP B
CALL DECB
PUSH B
JMP NEXT
RAR

AN I 7FH
MOV E,A
MVI D,0
DAD D
MOV A,M
CALL DISP
POP B
CALL DECB
JMP EXP

; FIRST BIT

;NEXT DATA ADDRESS

;BIT COUNT

; DECODE TABLE

;DATA VALUE

; TABLE + DATA BIT
GET POINTER

;TABLE+DATA BIT + POINTER

: REDUCE BIT COUNT

; REMOVE TAG

;GET DECODED CHARACTER

Listing 2 continued on page 232

230 April 1981 © BYTE Publications Inc

The Text Solution for APPLE II®

Now APPLE II® Owners Can Solve Text Problems

With VIDEOTERM 80 Column by 24 Line Video Display

Utilizing 7 X 9 Dot Character Matrix

Perhaps the most annoying shortcoming of the Apple II'*' is its limitation of displaying only 40 columns by 24 lines of
text, all in uppercase. At last, Apple II® owners have a reliable, trouble-free answer to their text display problem.
VIDEOTERM generates a full 80 columns by 24 lines of text, in upper and lower case. Twice the number of characters as
the standard Apple II® display. And by utilizing a 7 by 9 character matrix, lower case letters have true descenders. But
this is only the start.

VIDEOTERM, MANUAL,
SWITCHPLATE

VIDEOTERM

BASICS

Other
Boards

i " h n ' ( ) * + , - . /

0123456789: ;(»>?
t A | C D E F G H I J K L M N

P 6 R S T U V H X Y Z [ \ ] A .

y z ( ! )

7X12 MATRIX
18X80 OPTIONAL

I'MII ' t }*♦■- ./

1123456 789 i j < = >?
CABCDEFSHIJKLHNO
POBSTUVUXYZI\]t_

'jbcdefghijlclino
pgr5ti/vwxyz(l}"|

7X9 MATRIX
24X80 STANDARD

VIDEOTERM lists BASIC programs, both Integer and Applesoft, using the entire 80
columns. Without splitting keywords. Full editing capabilities are offered using the
ESCape key sequences for cursor movement. With provision for stop/start text
scrolling utilizing the standard Control-S entry. And simultaneous on-screen display
of text being printed.

Installation of VIDEOTERM in slot 3 provides Pascal immediate control of the
display since Pascal recognizes the board as a standard video display terminal and
treats it as such. No changes are needed to Pascal's MISC. INFO or GOTOXY files,
although customization directions are provided. All cursor control characters are
identical to standard Pascal defaults.

The new Microsoft Softcard' is supported. So is the popular D. C. Hayes Micro-
modem II' , utilizing customized PROM firmware available from VIDEX. The power-
ful EasyWriter" Professional Word Processing System and other word processors
are now compatible with VIDEOTERM. Or use the Mountain Hardware ROMWriter*
(or other PROM programmer) lo generate your own custom character sets. Natural-
ly, VIDEOTERM conforms to all Apple OEM guidelines, assurance that you will have
no conflicts with current or future Apple II' expansion boards.

VIDEOTERM's on-board asynchronous crystal clock ensures flicker-free character display.
Only the size of the Pascal Language card, VIDEOTERM utilizes CMOS and low power con-
sumption ICs, ensuring cool, reliable operation. All ICs are fully socketed for easy
maintenance. Add to that 2K of on-board RAM, 50 or 60 Hz operation, and provision of power
and input connectors for a light pen. Problems are designed out, not in.

The entire display may be altered to inverse video, displaying black characters on a white
field. PROMs containing alternate character sets and graphic symbols are available from
Videx. A switchplate option allows you to use the same video monitor for either the
VIDEOTERM or the standard Apple II" display, instantly changing displays by flipping a
single toggle switch. The switchplate assembly inserts into one of the rear cut-outs in the
Apple II' case so that the toggle switch is readily accessible. And the Videx KEYBOARD
ENHANCER can be installed, allowing upper and lower case character entry directly from
your Apple II' keyboard.

Firmware 1K of on-board ROM firmware controls all operation of the VIDEOTERM. No machine

language patches are needed for normal VIDEOTERM use.

Firmware Version 2.0

Characters 7x9 matrix Display

Options 7x12 matrix option;

Alternate user definable

character set option;

Inverse video option.

Want to know more? Conlact your local Apple dealer today for a demonstration. VIDEOTERM is available
through your local dealer or direct from Videx in Corvallis, Oregon. Or send for the VIDEOTERM Owners
Reference Manual and deduct the amount if you decide to purchase. Upgrade your Apple II' to full terminal
capabilities for half the cost of a terminal. VIDEOTERM. At last.

Advanced
Hardware
Design

Available
Options

24 x 80 (full descenders)

18 x 80 (7 x 12 matrix with full descenders)

Apple II* is a trademark of Apple Computer Inc.

ROMWnter* is a trademark ol Mountain Hardware Inc.

Micromodem II* 15 a trademark ot D C. Hayes Associates Inc.

Softcard' is a trademark ol Microsofl

EasyWriter" is a trademark ol Information Unlimited Software Inc

PRICE: • VIDEOTERM includes manual $345

• SWITCHPLATE $ 19

• MANUAL refund with purchase .... $ 19

• 7x12CHARACTERSET $ 39

• MICROMODEM FIRMWARE $ 25

APPLE II® OWNERS!

introducing the

KEYBOARD & DISPLAY

ENHANCER

■ PUT THE SHIFT AND SHIFT LOCK BACK WHERE IT BELONGS
■ SEE REAL UPPER AND lower CASE ON THE SCREEN
•ACCESS ALL YOUR KEYBOARD ASCII CHARACTERS

Videx has the perfect companion for your
word processor software: the KEYBOARD
AND DISPLAY ENHANCER Install the
enhancer in your APPLE II and be typing in
lower case just like a typewriter. If you want an
upper case character, use the SHIFT key or the
CTRL key for shift lock. Not only that, but you
see upper and lower case on the screen as you
type. Perfectly compatible with Apple Writer
and other word processors like, for example.
Super-Text.

If you want to program in BASIC, just put it
back into the alpha lock mode; and you have
the original keyboard back with a few im-

provements. Now you can enter those elusive 9
characters directly from the keyboard, or re-
quire the Control key to be pressed with the
RESET to prevent accidental resets.

KEYBOARD AND DISPLAY

ENHANCER is recommended for use with all
revisions of the APPLE II. It includes 6 ICs. and
EPROM and dip-switches mounted on a PC
board, and a jumper cable. Easy installation,
meaning no soldering or cutting traces. Alter-
nate default modes are dip-switch selectable.
You can even remap the keyboard, selecting an
alternate character set. for custom applications.

PRICE • KDE-700 (REV. 7 or greater) $129.

» KDE-000 (REV. 6 or less) $129.

Apple II'" is a trademark of Apple Computer. Inc.

ffl B

VIDEX
897 N.W. Grant Avenue
Corvallis, Oregon 97330
Phone (503) 7580521

Circle 151 on inquiry card.

BYTE April 1981 231

Listing 2

3044
3045
3046
3047
304A
304B
3 04B
304B
3 04B
3 04B
304B
306B
3 04C
304P
304E
3 04F
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
305A
305B
305C
305P
305E
305F
3060
3061
3 062
3 063
3 064
3065
3066
3067
3068
3069
3 06A
306B
306C
306D
3 06E
306F
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
307A
307B
307C
307D
307E
307F
3080
3081
3082
■'083
''084
3085
3086
3087

continued:

OB
79

BO

CA OC 00

C9

2A
01
02
08
82
02
45
82
82
49
52
06
01
82
82
4F
41
82
02
4E
03
81
44
03
81
50
03
81
56
02
05
82
82
4A
58
03
81
4B
82
82
5A
51
02
OE
03
81
54
02
05
82
82
59
47
82
82
55
4D
02
08
03
81

0340
0350
0360
0365
03 70
4000
4010
4020
4030
4040
4050
5000
5010
5020
5030
5040
5050
5060
5070
5080
5090
5100
5102
5104
5106
5108
5110
5120
5130
5140
5150
5160
5170
5180
5190
5200
5210
5220
5230
5240
5250
5260
5270
5280
5290
5300
5310
5320
533
5340
5350
5360
5370
5380
5390
5400
5410
5420
5430
5440
5450
5460
5470
5480
5490
5500
5510
5520
5530
5540
5550
5560

DECB: DCX B

MOV A,C

ORA B

JZ MON

RET
*THE DECODE TABLE HAS
*THE TABLE VALUE IS T
*NEXT 0-1 PAIR AS THE
*THE TABLE VALUE JUST
*SET IN BIT 7, IN ADD
*THAT THE NEXT VALUE
XTAB:

; REDUCE BIT COUNT

THE FOLLOWING FORMAT:
HE INCREMENT NECESSARY TO GET TO THE

PROGRAM STEPS THROUGH THE DATA.

PRECEEDING A CHARACTER HAS A TAG
IT ION TO THE INCREMENT, TO INDICATE
IA A CHARACTER.

DB

42

DB

1

DB

2

DB

8

DB

130

DB

2

DB

'E'

DB

130

DB

130

DB

•I'

DB

'R'

DB

6

DB

1

DB

130

DB

130

DB

'0'

DB

•A'

DB

130

DB

2

DB

i N i

DB

T

DB

129

DB

•D'

DB

3

DB

129

DB

ipi

DB

3

DB

129

DB

'V

DB

2

DB

5

DB

130

DB

130

DB

•J'

DB

'X'

DB

3

DB

129

DB

'K'

DB

130

DB

130

DB

'Z'

DB

• Ql

DB

2

DB

14

DB

3

DB

129

DB

i f i

DB

2

DB

5

DB

130

DB

130

DB

•Y«

DB

'G'

DB

130

DB

130

DB

>U'

DB

'M'

DB

2

DB

8

DB

3

DB 129

1

1

2

3

1

4

5

1

6

7

8

1

9

10

11

12

1

13

14

1

15

16

17

18

1

19

20

21

1

22

23

24

1

25

26

27

1

28

29

30

1

31

32

1

3^

34

35

36

1

37

38

39

1

40

41

42

43

1

44

45

1

46

47

48

1

49

50

1

51

52

53

54

1

55

56

57

58

1

59

60

1

Listing 2 continued on page 234

232 April 1981 © BYTE Publications Inc

DIGITAL HARMONY

A new synthesis

of sight and sound

Digital Harmony
by John Whitney

Digital Harmony lays the foundation for the whole new
field of audio-visual art made possible by microcom-
puters. John Whitney, a pioneer of the special effects
technology used in STAR WARS and 2001: A
SPACE ODYSSEY, explains the special
union of computer graphics and music. His
computer-generated visual art graphically
depicts the laws of harmonic motion com-
mon to all music.

Digital Harmony includes a complete
description of Whitney's computer,
peripherals, and film techniques. Col-
orful illustrations are included, as well
as the program listings that generated
them. The descriptions are sufficient
for anyone to begin to explore this new
territory as a composer and computer
experimenter — transforming the small
computer into an ideal instrument for
creating compositions in aural and
visual art.

'John Whitney is on the Faculty in the
Department of Art at the University of
California, Los Angeles.

ISBN 07-07001 5-X
$21.95

Please remit in U.S. funds or draw on a U.S. Bank

Please send □ copies of

Digital Harmony

Available Now

Toll Free # 1-800-258-5420

Name

Title

Company

Street

City

State/Province

Code

□ Check enclosed in the amount of $

D Bill Visa □ Bill Master Charge

Card No

Exp. Date.

Add 75c per book to cover
postage and handling.

H V I K 70 Main Street

R'l'IVI Peterborough, New Hampshire 03458

Circle 152 on inquiry card.

BYTE April 1981 233

Listing

2 continued

3088

48

3089

82

308A

82

308B

43

308C

46

308D

82

308E

02

3 08F

53

3090

03

3091

81

3092

4C

3093

82

3094

82

3095

42

*09*5

57

''097

02 41

309">

4100

44E8

44E8

44E8

5570

DB

•H' ;

61

5580

DB

130

62

5590

DB

130

63

1

5600

DB

i C i

64

5610

DB

• pi

65

5620

PB

130

66

5630

DB

2

67

1

5640

DB

■S'

68

5650

DB

3

69

5660

DB

129

70

1

5670

DB

'L'

71

5680

DB

130

72

5690

DB

130

73

1

5700

DB

■B'

74

5710

DB

. W i

,75

5720

DADD:

DW

DBUF+2

NEXT DATA ADDRESS

5909

ORC

■ 4100H

6000

DBUF:

DS

1000

9000

DISP:

EQL

0C500H

DISPLAY A CHARACTER

9010

MON

ECU

0OOCH

MONITOR RETURN

9020

SP:

ECU

Listing 3: COMP2 text-compression routine. This routine is identical to COMP1 (listing 1) except that the Huffman code information
is packed and stored 8 bits to the byte. The routine is written in 8080 machine code.

2600

0001

♦THIS

! ROUTINE TAKES TEXT (LETTERS ONLY)

2600

0002

*AND

COMPRESSES THEM USING HUFFMAN CODING.

2600

0004

*THE

FIRST TWO BYTES IN THE DATA BUFFER

2600

0005

*ARE

THE BIT COUNT. ENCODED DATA IS STORED IN

DBUF

2600

0006

*1N A PACKED FORM, 8 BITS TO THE BYTE.

2600

0010

ECHO:

ECU 0C500H

; OUTPUT DRIVER

2600

0011

SP:

EQU 6

2 600

0012

MON:

ECU OCH

• MONITOR RETURN

2600

31

00

00

0020

LXI SP,0

2603

21

00

00

0021

LXI H,0

2606

22

00

41

0022

SHLD DBUF

•.COMPRESSED BIT COUNT

2609

21

02

41

0023

LXI H, DBUF+2

260C

22

BA

26

0024

SHLD DADD

;NEXT BIT. LOCATION

260F

AF

0025

XRA A

2610

32

BC

26

0026

STA POS

2613

DB

08

0040

INCH:

IN 8

; INPUT CODE

2615

OF

0041

RRC

2616

DA

13

26

0042

JC INCH

2619 DB

OA

0043

IN 10

261B

FE

2E

0045

CPI '.•

;END OF TEXT

261D

C2

37

26

0047

JNZ PROS

2620

2A

BA

26

0050

LHLD DADD

; CLEAN UP PARTIAL BYTE

2623

3A

BC

26

0052

LDA POS

2626

47

0054

MOV B,A

; COMPUTE SHIFT COUNT

2627

3E

08

0056

MVI A, 8

2629

90

0058

SUB B

262A

E6

07

0060

ANI 7

262C

47

0062

MOV B,A

;KEEP SHIFT COUNT

262D

7E

0064

MOV A,M

;GET PACKED BYTE

262E

CA

OC

00

0066

SHFT:

JZ MON

; FINISHED

2631

17

0068

RAL

2632

05

0070

DCR B

2633

77

0071

MOV M,A

•.REPLACE PACKED BYTE

2634

C3

2E

26

0072

JMP SHFT

2637

CD

00

C5

0073

PROS:

CALL ECHO

263A E6

7F

0075

ANI 07FH

•.CLEAR PARITY

263C

D6

41

0080

SUI 'A'

;COMPUTE INDEX

263E

DA

13

26

0082

JC INCH

2641

FE

1A

0084

CPI 'Z'-'A

+1

2643

D2

13

26

0086

JNC INCH

2646

87

0090

ADD A

; MULTIPLY BY 2

2647

4F

0100

MOV C,A

2648

06

00

0110

MVI B,0

264A

21

86

26

0120

LXI H.TABL

264D

09

0130

DAD B

; INDEX Listing 3

continued on

page 236

234 April 1981 © BYTE Publications Inc

THE ADVANTAGES OF
THE FUNCTIONAL GROUP

Diversity of projects.

Varied technical
challenge.

Involvement from con-
cept through implementation.

Broadinteraction and
cooperation between software
and hardware.

We've got it all at Harris
Composition Systems in Mel-
bourne, Florida.

We're pioneers in word
processing. And the world's
first and leading supplier of
total word processing systems
for use in the newspaper
industry.

And we're now extending
that "system-oriented" ap-
proach into the office systems
field— integrating data proc-
essing, word processing,

electronic mail, advanced
communications and net-
working. With an ambitious
program representing the
largest investment Harris
Corporation has ever made to
develop a new product.

That means the opportu-
nity for personal participation
and immediate contribution—
across the board— in both
newspaper word processing
and office systems.

For experienced pro-
fessionals with expertise in

□ Real Time Software and
Hardware/Firmware Devel-
opment □ Digital Design

□ Analog Design □ Applica-
tions Programming.

All supported by a billion
dollar, Fortune 500 corpora-
tion. All in a modern, stimu-

lating work environment.
All in beautiful, affordable
Melbourne, Florida— on the
shores of the deep blue
Atlantic.

Send your resume and
salary history to: Daphne
Cumberland, Composition
Systems Division, Dept. BT,
P.O. Box 2080, Melbourne,
Florida 32901. Or call COL-
LECT (305) 242-5321, in
Florida. Outside Florida call
1-800-327-1493.

Share the advantages
with ;

COMMUNICATION AND
INFORMATION PROCESSING

An Equal Opportunity Employer M/F/V/H.

Listing 3 continued:

264E 5E
264F 23

2650 56

2651 7B

2652 E6 OF

2654 47

2655 EB

2656 AF

2657 29

2658 17

2659 E6 01
265B E5

265C 2A BA 26
265F 57

2660 3A BC 26

2663 5F

2664 7E

2665 17

2666 B2

2667 77

2668 1C

2669 7B
266A FE 08
266C C2 74 26
266F AF

2670 23

2671 22 BA 26
2674 32 BC 26
2677 2A 00 41
267A 23

267B 22 00 41
267E El
267F 05
2680 C2 56 26
2683 C3 13 26
2686
2686
2686

2 686 04 FO
2688 06 70
268A 05 40
2 68C 05 D8
268E 03 80
2690 05 48
2692 05 08
2 694 04 50
2696 04 AO
2698 09 DO
269A 89 Dl
269C 05 78
269E 05 18
2 6A0 04 CO
26A2 04 EO
26A4 06 D4
2 6A6 4A Dl
2 6A8 04 BO
26AA 04 60
26AC 03 20
26AE 05 10
26B0 07 D2
26B2 06 74
26B4 89 DO
26B6 05 00
26B8 OA Dl
26BA 00 00
26BC
26BD
4100

0140

MOV E,M

GET ENCODE VALUE

0150

INX H

0160

MOV D,M

0170

MOV A,E

GET BIT COUNT

0180

AN I OFH

MASK COUNT

0185

MOV B,A

KEEP COUNT

0187

XCHG

0190

NEXT:

XRA A

0192

DAD H

SHIFT OUT BIT STREAM

0200

RAL

,MSB FIRST

0220

AN I 1

; SETUP OUTPUT BIT

0225

PUSH H

0226

LHLD DADD

0228

MOV D,A
LDA POS

0229

0231

MOV E,A

.KEEP CURRENT POSITION

0233

MOV A,M

;GET OLD PACKED DATA

0235

RAL

.MAKE ROOM

0237

ORA D

.PACK

0239

MOV M,A

.PUT IT AWAY

0240

INR E

.UPDATE POSITION

0242

MOV A,E

0244

CPI 8

;FULL BYTE?

0246

JNZ STOR

0248

XRA A

[INITIALIZE POSITION

0250

INX H

[UPDATE DADD

0252

SHLD DADD

0258

STOR:

STA POS

0260

LHLD DBUF

02 62

INX H

jUPDATE BIT COUNT

0264

SHLD DBUF

0266

POP H

0268

DCR B

.REDUCE COUNT

0270

JNZ NEXT

0300

JMP INCH

0305

♦ENCODE TABLE FORMAT- LOW ORDER 4 BITS

0306

*IN ENCODED CHARACTER. REMAINING 12 BITS

0307

*CODE

IS LEFT JUSTIFIED. E.G., AN M IS

0310

TABL:

DW 0F004H

;A

0320

DW 7006H

;B

0330

DW 4005H

,C

0340

DW 0D805H

;o

0350

DW 8003H

;E

0360

DW 4805H

;F

0370

DW 805H

;G

03 80

DW 5004H

;H

0390

DW OA004H

;I

0400

DW 0D009H

;J

0410

DW 0D189H

;K

0420

DW 7805H

;L

043

DW 1805H

;M

0440

DW 0C004H

;N

0450

DW OE004H

;0

0455

DW 0D406H

,P

0460

DW 0D14AH

;Q

0470

DW 0B004H

R

0480

DW 6004H

,S

0490

DW 2003H

J

0500

DW 1005H

U

0510

DW 0D207H

V

0520

DW 7406H

w

0530

DW 0D089H

X

0540

DW 5H

Y

0550

DW 0D10AH

Z

0600

DADD:

DW

;NEXT BIT LOCATION

0603

POS:

DS 1

.BIT POSITION

0605

ORG 4100H

0610

DBUF:

DS 1000

ARE NUMBER OF BITS
ARE FOR CODE.

236 April 1981 © BYTE Publications Inc

IF YOU CAN
VAIT A MINUTE,

WE CAN S/y E

YOU H J

iii

With the Storwriter™ Daisy
Wheel 25 cps printer from C. Iron.

A business letter, written on a 45 cps
word-processing printer, might take
about two minutes to print.

With the Starwriter, it might take
closer to three.

The typical 45 cps printer retails for
about $3, 000.

But the Starwriter 25 retails for about
$1, 895— thus saving you about $1, 000.

And therein lies the biggest difference
between the Starwriter 25 and the more
expensive, daisy wheel printers.

The Starwriter 25 comes complete
and ready-to-use, requiring no changes
in hardware or software. It uses indus-
try-standard ribbon cartridges, and it's
"plug-in" compatible to interface with a

wide variety of systems, to help lower
system-integration costs.

Using a 96-character wheel, it
produces excellent letter-quality print-
ing on three sharp copies with up to 163
columns, and offers the most precise
character-placement available, for out-
standing print performance.

Cltoh's warranty;

3 months on parts and labor, sup-
ported by one of the best service organi-
zations in the industry.

1000 OFF

Leading Edge Products, Inc.,
225 Turnpike Street,
Canton, Massachusetts 02021

Dear Leading Edge:

I'd like to know more about the Starwriter, and
how spending a minute can save me a grand.
Please send me the name of my nearest dealer.

Name-
Title-

Company.

Street

State

Jip_

Phone: Area Code -
Number

LEADING
EDGE.

Leading Edge Products, Inc., 225 Turnpike Street, Canton, Massachusetts 02021

Dealers: For immediate delivery from the Leading Edge Inventory Bank™call toll free 1-800-343-6833

In Massachusetts, call collect (617)828-8150. Telex 951-624

Listing 4: EXP2 text-expansion routine. This routine takes the output of COMP2, information expressed in a packed Huffman code,
and decodes it using the binary tree of figure 2. The decoded character is displayed via a user-supplied subroutine named DISP. The
routine is written in 8080 machine code.

3000

3000

3000

3000

3000

3000

3000

3000

3000

3000

3000

3000

3000

3000 31

00

00

3003 21

02

41

3006 22

CO

30

3009 21

00

41

300C 4E

300D 23

300E 46

300F 3E

01

3011 32

C2

30

3014 C5

3015 21

74

30

3018 E5

3019 2A

CO

30

301C 3A

C2

30

301F 47

3020 7E

3021 17

3022 05

3023 C2

21

30

3026 3E

00

3028 17

3029 4F

302A 06

00

302C 22

CO

30

302F El

3030 09

3031 7E

3032 17

3033 DA

43

30

3036 IF

3037 5F

3038 16

00

303A 19

303B CI

303C CD

55

30

303F C5

3040 C3

18

30

3043 IF

3044 E6

7F

3046 5F

3047 16

00

3049 19

3 04 A 7E

304B CD

00

C5

304E CI

3 04F CD

55

30

3052 C3

14

30

3055 OB

3056 79

3057 BO

3058 CA

oc

00

305B 3A

C2

30

305E 3C

305F 32

C2

30

3062 FE

09

0000
0001
0002
On 03
0004
0005
0006
0007
0008
0009
0010
0011
0012
0015
0020
0030
0040
0050
0060
0070
0074
0076
0080
0090
0100
0110
0120
0122
0124
0126
0128
0130
0132
0134
0136
0140
0150
0160
0170
0180
0190
0200
0205
0210
0220
0230
0240
0250
0270
0280
0290
0294
0296
0297
0298
0299
0305
0310
0320
0330
0340
0350
0360
0365
0370
0380
0385
0390

*THIS PROGRAM ACCEPTS DATA PREPARED BY THE DATA COMPRESSION
•(HUFFMAN CODE) PROGRAM THE DATA BUFFER HAS THE BIT COUNT
*IN THE FIRST TWO BYTES. THE PROGRAM RUNS UNTIL ALL
*BITS HAVE BEEN PROCESSED THE PROCESSING CONSISTS OF
•ADDING A DATA BIT TO THE TABLE ENTRY POINT, GETTING AN
•INCREMENT WHICH POINTS TO THE NEXT 0-1 PAIR AND CONTINUING
*UNTIL A TAG IS FOUND IN BIT 7 THIS SIGNIFIES THAT THE
*NEXT TABLE ENTRY IS THE DESIRED CHARACTER.
*THIS IS THE PACKED VERSION WHICH PROCESSES DATA FROM
*8 BIT BYTES, MSB FIRST.

DISP: EQU 0C500H
MON: ECU OOOCH

SP: EQU 6

LXI SP,0
LXI H.DBUF+2
SHLD DADD
LXI H.DBUF
MOV C,M
INX H
MOV B,M
MVI A, 1
ST A POS
EXP: PUSH B

LXI H.XTAB
NEXT: PUSH H

LHLD DADD
LDA POS
MOV B,A
MOV A,M
BIT: RAL

DCR B
JNZ BIT
MVI A,0
RAL

MOV C,A
MVI B,0
SHLD DADD
POP H
DAD B
MOV A,M
RAL

JC OUTCH
RAR

E,A
D,0
D
B
CALL DECB
PUSH B
JMP NEXT
RAR

7FH
E,A
D,0
D

A,M
CALL DISP
POP B
CALL DECB
JMP EX"
DECB: DCX B

MOV A,C
ORA B
JZ MON
LDA °OS
INR A
STA POS
CPI 9

;DISPLAY CHARACTER
; MONITOR RETURN

OUTCH:

MOV
MVI
DAD
POP

AN I
MOV
MVI
DAD
MOV

FIRST BIT
NEXT DATA
BIT COUNT

ADDRESS

{INITIALIZE POSITION

;DECODE TABLE

;GET BIT POSITION

;GET
;GET

DATA
DESIRED

BIT INTO CARRY

; RE STORE SINGLE BIT
-.DATA VALUE

; TABLE + DATA BIT
;GET POINTER

;TABLE+DATA BIT + POINTER
; REDUCE BIT COUNT

;REMOVE TAG

;GET DECODED CHARACTER

{REDUCE BIT COUNT
{UPDATE BIT POSITION

;8 BITS PROCESSED?

Listing 4 continued on page 240

238 April 1981 © BYTE Publications Lie

DYNACOMP

Quality software for^ :

ATARI

PET

APPLE II Plus

TRS-80 (Level II)*
NORTH STAR
CP/M 8" Disk

GAMES, SIMULATIONS, EDUCATION and
MISCELLANEOUS

BRIDGE 2.0 (Available for all computers) Price: $17. 95 Cassette /SI 1.95 Diskelle

An all-inclusive version of this mm! popular of card games. This program bolh BIDS and PLAYS either :ontracl or duplicate bridge.
Depending on the contract, your computer opponents will either play the offense OR defense. If you bid loo high, the compuler u ill
double youi contract! BRIDGE 2.0 provides challengint entertainment for advanced players and is an eicellenl learning tool for the

Price: $14.95 Cas.se II* /SIS. 95 Diskette
game. Hearts is a trick -oriented game in which the purpose is no! lo
:r opponents who are armed with hard-lobeal playing strategies

Price: SI 1.95 DuMtle/S 15.95 Diskelle

en nip

iet(

alsll

e cards one

alalimc

and you (and ilie compu

cr) bet on what you s

c. The

if Oil Lis

Ho

s bluffs

Also included is a fivee

ird draw poker beltin

6K ATARI

Colo

. graphics

sound.

HEARTS 1.5 (Available for all computers)

An exciting and entertaining compuler version of this popular c;
take any hearts or the queen of spades. Play againsl two comp

STUD POKER (ATARI only)

computer does not cheat and usually bets
lice program. This package will run on a

POKER PARTY (Available for all computers) Price: S17.95 CasMfte/S21.95 Diskette

POKER PARTY is a draw poker simulation based on the book. POKER, by Oswald Jacoby. This is Ihe mosi comprehensive version
available for microcomputers. The party consists of yourself and six olhcr (computer) players Each or these players (you will gel lo
know them) has a different personality in ihe form of a varying propensity lo bluff or fold under pressure. Practice with POKER PAR-
TY before going lo thai expensive game lonight! Apple Cassette and diskette versions require a 32 K (or larger) Apple II.

V AI.DEZ (Available for all computers) Price: S14.95 Cassette /SIB. 95 Diskette

A simulation of supertanker navigation in the Prince William Sound and Valdci Narrows. The program uses an extensive 256X256 de-
ment radar map and employs physical models of ship response and tidal patterns. Chan youi own course through ship and iceberg traf-
fic. Ant standard terminal may be used for display.

FLIGHT SIMULATOR (Available for all computers)

ion of take-off, flight and landin

>fa real airfoil. Yoi

d flyer ei

o perform loops, half-ri

nilar acrobatic

Price: 517.95 Cause lie/ $2 1. 95 Diskette

The program ulili/cs aerodynamic equations and the
galion using radials and compass headings. The more

Price: $14.95 Cassetle/SIB.W Diskette

ed version of the classic card game, cribbogc. It is an eicellenl program for the crib-
is the beginner wishing to learn Ihe game, in particular ihe scoring and jargon. The
K ihe top of the display (utilizing the TRS-80's graphics capabilities), with ihe cards
loints using the (radilionil phrases.

CRIBBAGE 2.0 (TRS-80 only)

This is a well-designed and nicely execute
bage player in search of a worthy oppont
standard cribbage score board is continu;
shown underneath. The compuler auton

CHESS MASTER (North Star and TRS-80 only I price: $19.95 Cassette/ $23. 95 Diskette

This complete and very powerlul program provides five levels of play. It includes castling, en passant captures and the promotion of
pawns. Additionally, the board may be preset before ihe start of play, permitting the examination of "book" plays. To maximize execu-
lion speed, ihe program is written in assembly language (by SOFTWARE SPECIALISTS of California). Full graphics are employed in
Ihe TRS-80 version, and two widths of alphanumeric display are provided lo accommodate North Star users.

S I A KTREK 3.2 (Available Tor all computers)

This is Ihe classic Startrek simulation, but wiih several new features. For example, il
warning while also attacking starbases in olher quadranls. The Klingons also attack v.
shot at! The situation is hectic when the Enterprise is besieged by three heavy cruisers a

Price: S 9.95 Cass* I le/S 13.95 Diskette

Klingons now shooi at the Enterprise without
h bolh light and heavy cruisers and move when
la starbaseS.O.S. is received! The Klingons gel

Price: $10.95 Cass* t le/S 14. 95 Diskelle
lie TV screen to "roll" a ball into a hole in the screen. Sound simple? Not when the hole gels
smaller and smaller! A built-in timer allows you to measure your skill againsl others in this habit-forming action game.

GAMES PACK I (Available for all computers) Price: $9.95 Casaelle/S 13.95 Diskette

GAMES PACK I contains the classic computer games or BLACKJACK. LUNAR LANDER. CRAPS. HORSERACE. SWITCH and
more. These games have been combined into one large program for ease in loading. They are individually accessed by a convenient

GAMES PACK II (Available for all computers) Price: $9.95 Cassette /SI 3. 95 Diskette

GAMES PACK II includes Ihe games CRAZY EIGHTS, JOTTO. ACEY-DUCEY, LIFE. WUMPUS and others. As with GAMES

PACK I, all the games are loaded as one program and are called from a menu.

Why pay 17.95 or more per program when you can buy a DYNACOMP collection for jusl J9.95?

NOM1NOES JIGSAW (ATARI and TRS-M oily)

NOM INOES JIGSAW is an intriguing and sophisticated graphical puzzle. The jigsaw c(
domly chosen shapes (nominees), of which there are 60 types. By knowing thai the shi
Ihe shape at each location, all the nominocs may be eventually deduced. Scoring is basei

MOVING MAZE (Apple only)

MOVING MAZE employs ihe games paddles lo direct a puck from one side of a
(and randomly) buill and is continually being modified. The objective is lo crosr
Scoring is by an elapsed time indicator, and three levels of ploy are provided.

Price: $16.95 Ciuwette/S20.9S Diskette

siits of a 9 by 9 board partially filled with ran-
is must be legally connected, and by guessing

Price: $10.95 Cassette/S 14.95 Diskette
o Ihe other. However, Ihe maze is dynamically
iaze without touching (or being hit by) a wall.

BLACK HOLE (Apple only)

This is an exciting graphical simulai

that the tidal stress destroys i

Price: $14.95 Cassetle/S 18.95 Diskette

n of the problems involved in closely observing a black hole with a space probe. The object is lo
nc, an orbil close to a small black hole. This is to be achieved without coming so near the anomaly
-. Control of the craft is realistically simulated using side jets for rotation and main thrusters for

mploys Hi-Rcs graphics

TEACHER'S PET I (Available for all computers) Price: $ 9.95 Caiselte/S 13.95 Diskelle

This is the first of DYNACOMP's educational packages. Primarily intended for pre-school to grade ), TEACHER'S PET provides ihe
young student with counting practice, letter. word recognition and three levels of math skill exercises.

Price: S 9.95 Cassette/S 13.95 Diskelle

n used in local

CRYSTALS (ATARI onlyl

A unique algorithm randomly produces fascinatii
two patterns are the same, and Ihe combined eff

CRANSTON MANOR ADVENTURE (Norlh Star only)

At last! A comprehensive Adventure game for the Norlh Star. CRANSTON MANOR ADVENTURE lakes you into myslerious
CRANSTON MANOR where you attempt (o gather fabulous treasures. Lurking in the manor arc wild animals and robots who will not
give up the treasures without a Tight. The number of rooms is greater and the associated descriptions are much more elaborate than Ihe
H popular series of Adventure programs, making ihis game (he lop in its class. Play can be stopped ai any lime and the status

Price: $19.95

:. Rcqui:

i J2K.

NORTH STAR SOFTWARE EXCHANGE (NSSE) LIBRARY
DYNACOMP now distributes ihe 20 • solume NSSE library. Mosl of (hese diskel

Price $9.95 Diskette

Circle 154 on inquiry card.

Availability

DYNACOMP software is supplied with complcli
TRS-HOlLevel III and Apple (Applesoft) cassette

alien containing clear explanations and example!
:e (ATARI requires 24K). Except where noted, programs
d diskette as well as North Star single density {double den
rd (IBM format) 8" CP/M floppy disks for systems m

Ml Olherwise specified, all
vailable on ATARI, PET.
impaiiblOdiskette.Addi-
under M8ASIC.

BUSINESS and UTILITIES

MAIL LIST II (Apple and North Star diskettes only)

This many-featured program now includes full alphabetic and lip code sorting as well as Til
defined code, client name or Zip Code. The printout format allows the use of standard size i
thin 1 100 entries (single density Norlh Star or Apple DOS 3.2; over 2200 with double dc:

Price: $24.95

meiging. Entries can be retrieved by user-
Idress labels. Each diskette can store more
ily North Star or Apple DOS 3.3)!

EORM LETTER SYSTEM (FLS) (Apple and North Star diskette only) price: $17.95

FLS may be employed to generate individually addressed form letters. The user creates the address Tile and separately composes the let-
ter. FLS will ihen print form letters using each address. FLS is completely compatible with MAIL LIST II. which may be used lo
manage your address Tiles.

FLS and MAIL LIST 11 are available as

TEXT EDITOR I (Letter Writer)

suited for composing letters and is quile

combined package for 137. 9S.

Price: $14.95 Cass*lle/SlS.95 Diskette

widths and simple paragraph indexing. This text editor is ideally
arger jobs. Available for all computers.

Price: $34.95 Diskette

iplify your personal finances. Features
payee; optional priming of

Price: $19.95

; name). Commer-

Rcference records

PERSOMAL FINANCE SYSTEM (ATARI only)

PFS is a single disk menu oriented system composed of 10 programs designed to organize a
include a 300 transaction capacity: fas! access; 26 optional user codes; data retrieval by
reports: checkbook balancing; bar graph plotting and more. Also provides on the diskelle is ATARI DOS 2.

FINDIT (North Star only)

This is ■ (hree-in-one program which maintains information accessible by keywords of three types: Personal (eg: la
cial (eg: plumbers) and Reference (eg; magazine articles, record albums, elc). In addition to keyword searches, [he
niversary and appointment searches for Ihe personal records and appointment searches for the c
are accessed by a single keyword or by cross-referencing two or three keywords,

DFILE (North Star only)

This bandy program allows North Star users to maintain a specialised data base o
variably accumulates. DFILE is easy lo set up and use. It will organize your disks
gram.

COMPARE (North Star only) Price: $12.95

COMPARE is ■ single disk utility software package which compares two BASIC programs and displays Ihe Tile sizes of the programs in
byres, the lengths in terms of the number of slalemenl lines, and [he line numbers at which varioui listed differences occur. COMPARE
permits the user lo examine versions of his software to verify which are the more current, and lo clearly identify ihe changes made dur-
ing develop men l.

COMPRESS (North Star only)

COMPRESS is a single-disk utility program which re
BASIC programs. The source Tile is processed one

-. File ci

Price: SI 2.95

ves all unnecessary spaces and (optionally) REMark statements from North Star
at a time, thus permitting very large programs to be compressed using only a
of 20-50* are commonly achieved.

GRAFIX (TRS-80 only) Price: $12.95 C*ia«lle/$16.95 Diskette

This unique program allows you lo easily create graphics directly from the keyboard. You "draw" your figure using the program's ex-
tensive cursor controls. Once the figure is made.it is automatically appended to your BASIC program as a siring variable. Draw a "hap-
py face", call il HI and then print il from your program using PRINT HSI This is a very easy way lo creale and save graphics.

TIDY (TRS-80 only) Price: $10.95 Cass*lt*/$ 14.95 Diskette

TIDY is an assembly language program which allows you to renumber ihe lines in your BASIC programs. TIDY also removes un-
necessary spaces and REMark statements. The result is a compacted BASIC program which uses much less memory space and executes
significantly faster. Once loaded. TIDY remains in memory; you may load any number of BASIC programs without having to reload
TIDYI

STATISTICS and ENGINEERING

DATA SMOOTHER (Not available for ATARI) Price: $14.95 CasMtte/$18.95 Diskette

This special data smoothing program may be used to rapidly derive useful information from noisy business and engineering data which
are equnlly spaced. The soflware features choice in degree and range of fit, as well as smoothed first and second derivative calculation.

FOURIER ANALYZER (Available for all computers) Price: $14.95 Cassetie/$18.95 Diskette

Use this program to examine the frequency speclra of limited duration signals. The program features automalic scaling and plotting of
the input data and results. Practical applications include Ihe analysis of complicated patterns in such fields as electronics, communica-

TFA (Transfer Function Analyzer)

This is a special soflware package which may be used lo evaluate the in
examining their response (o pulsed inputs. TEA is a major modifica
□rienled decibel versus log-frequency plol as well us data editing featuri

miHc u

. TFA is

n engineering tool. Available for all computers.

Price: $19.95 Casselle/S23.95 Diskette

sfer functions of systems such as hi-fi amplifiers and Tillers by
in of FOURIER ANALYZER and contains an engineering-
s FOURIER ANALYZER is designed for educational

HARMONIC ANALYZER (Available for all computers)

HARMONIC ANALYZER was designed for the spectrum analysis of repetitive
editing and storage/ retrieval as well as data and spectrum plotting. One particula
equally spaced or in order. The original data is sorted and a cubic spline intcrpolat:
algorithm.

Price: S24.95 Cass* I le/S 2*. 95 Diskelle

waveforms. Features include data file generation,
y unique facility is that the input data need not be
n is used lo create Ihe data file required by ihe FFT

REGRESSION I (Available for all computers) Price: $19.95 Cas*ette/$23.9S Diskelle

REGRESSION I is a unique and exceptionally versatile one -dimensional least squares "polynomial" curve fitting program. Features in-
clude very high accuracy; an automalic degree delermination option; an extensive inlerno! library of filling functions; data editing;
automalic dala and curve plotting; a statistical analysis (eg: standard deviation, correlation coefficient, elc.) and much more. In addi-
tion, new Ills may be tried without reentering the dala. REGRESSION I is certainly Ihe cornerstone program in any data analysis sofl-
ware library.

REGRESSION II (PARAFIT) (Available for all computers) Price: $19.95 Caisel le/S23.95 Diskette

PARAFIT is designed to handle those cases in which Ihe parameters are imbedded (possibly nonlinearly) in Ihe filling function. The
user simply inserts the functional form, including the parameters (A(l), A(2), elc.) as one or more BASIC statement lines. Data and
nipulated and plotted as with REGRESSION I, Use REGRESSION I for polynomial Tilling, and PARAFIT for [hose

ariablcs. Besides perfor

MULTILINEAR REGRESSION (MLR) (Available Tor all computers)

MLR is a professional soflware package Tor analyzing dala sets containing two or more linearly indc;

ing the basic regression calculation, (his program olio provides easy to use data entry, storage, relri

[ion, [he user may interrogate ihe solution by supplying values for the independent variables. The r

limited only by the available memory,

REGRESSION 1, II and MULTILINEAR REGRESSION may be purchased together for 149.95 (three cassellcs) or 161.95 [three

diskette*).

BASIC SCIENTIFIC SUBROUTINES, Volume I (Not available for ATARI)

DYNACOMP is ihe exclusive distributor for Ihe software keyed lo the text BASIC Scientific Subroutines. Volume I by F. Ruckdeschel
(see ihe BYTE/McGraw-Hill advertisement in BYTE magazine. January 1981). These subroutines have been assembled according to

cclion II: Chapter
cction Hi Chapter
cclion «: Chapter

2 and 3: Dala and function plotting, complex variables
I: Matrix

operal:

Random number generaiors, series approximations
: $14.95 Cajselte/JI8.9J Diskelle
All three collections arc available (or S39.95 (three cassettes) and 149.9! (three diskettes).
Because the text is a vital pari of the documentation, BASIC Scientific Subroutines, Volume I is
SI9.95 plus 75* postage and handling.

a DYNACOMP for

ROOTS (Available for all computers)

In a nutshell, ROOTS simultaneously

of the polynomial, and because Ihe proccdi

and the calculated roots are substituted bu

Price $9.95 Cus«tte/$13.95 Diskette

ill the zeroes of a polynomial having real coefficients. There is no limit on the degree
eralive, [he accuracy is generally very good. No initial guesses are required as input,
the polynomial and ihe residuals displayed.

ATARI. PET. APPLE II. TRS-ftO. NORTH STAR. CP/M and II

! registered trade n

Ordering Information

1 orders are processed and shipped postpaid within 48 hours. Please enclose payment with o
. by VISA or Master Card, include all numbers on card. For orders ouiside North Ameri

Add 12.50 to diskelle price for 8" floppy disk (IBM format sofi sectored, CP/M. Mict
•TRS-80 diskettes are nol supplied with DOS or BASIC.

Deduct 10% when ordering 3 or more programs.

a add 10% for shipping and handling.

e for detailed descriptions of these and other programs from

DYNACOMP, Inc.

1427 Monroe Avenue

Rochester, New York 14618

24 hour mail order phone: (716)586-7579

Office phone (9AM-5PM EST): (716)442-8960

Nct, York Stal* roMrati pkuc *rfd 7* NYS ufe. in.

Listing

i continued:

3064

CO

3065

3E 01

3067

32 C2 30

306A

E5

306B

2A CO 30

306E

23

306F

22 CO 30

3072

El

3073

C9

3074

3 074

3074

3074

3074

3074

3074

2A

3075

01

3076

02

3077

08

3078

82

3079

02

307A

45

307B

82

307C

82

307D

49

307E

52

3 07F

06

3080

01

3081

82

3082

82

3083

4F

3084

41

3085

82

3086

02

3087

4E

3088

03

3089

81

308A

44

308B

03

308C

81

308D

50

308E

03

308F

81

3090

56

3091

02

3092

05

3093

82

3094

82

3095

4 A

3096

58

3097

03

3098

81

3099

4B

309A

82

309B

82

309C

5A

309D

51

309E

02

309F

OE

30A0

03

30A1

81

30A2

54

30A3

02

3 0A4

05

30A5

82

30A6

82

30A7

59

3 OAR

47

30A9

82

30AA

82

30AB

55

30AC

4D

0400
0410
0420
0430
0440
0442
0444
0450
0460
4000
4010
4020
4030
4040
4050
5000
5010
5020
5030
5040
5050
5060
5070
5080
5090
5100
5102
5104
5106
5108
5110
5120
5130
5140
5150
5160
5170
5180
5190
5200
5210
5220
5230
5240
5250
5260
5270
5280
5290
5300
5310
5320
5330
5340
5350
5360
5370
5380
5390
5400
5410
5420
5430
5440
5450
5460
5470
5480
5490
5500
5510
5520

; RESET POSITION

; UPDATE BYTE ADDRESS

RNZ

MVI A,l

ST A POS

PUSH H

LHLD DADD

INX H

SHID DADD

POP H

RET
*THE DECODE TABLE HAS THE FOLLOWING FORMAT:
*THE TABLE VALUE IS THE INCREMENT NECESSARY TO GET THE
*NEXT 0-1 PAIR AS THE PROGRAM STEPS THROUGH THE DATA
*THE TABLE VALU JUST PRECEEDING A CHARACTER HAS A TAG
*SET IN BIT 7, IN ADDITION TO THE INCREMENT, TO INDICATE
*THAT THE NEXT VALUE IS A CHARACTER.
XTAB:

DB

42

DB

1

DB

2

DB

8

DB

130

DB

2

DB

•E'

DB

130

DB

130

DB

•I'

DB

•R'

DB

6

DB

1

DB

130

DB

130

DB

•0'

DB

•A'

DB

130

DB

2

DB

• N i

DB

3

DB

129

DB

'D'

DB

3

DB

129

DB

i P i

DB

3

DB

129

DB

lyi

DB

2

DB

5

DB

130

DB

130

DB

'J'

DB

•X'

DB

3

DB

129

DB

•K'

DB

130

DB

130

DB

<z«

DB

•Q"

DB

2

DB

14

DB

3

DB

129

DB

i •pi

DB

2

DB

5

DB

130

DB

130

DB

i Y "

DB

•G'

DB

130

DB

130

DB

•U'

DB

'M'

1

1

2

3

1

4

5

1

6

7

8

1

9

10

11

12

1

13

14

1

15

16

17

18

1

19

20

21

1

22

23

24

1

25

26

27

1

28

29

30

1

31

32

1

33

34

35

36

1

37

38

39

1

40

41

42

43

1

44

45

1

46

47

48

1

49

50

1

51

52

53

54

1

55

56

Listing 4 continued on page 244

240 April 1981 © BYTE Publications Inc

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Familiar, typewriter-like key-
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Accounting software is avail-
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Flexible text editing features,
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Boilerplate library of commonly
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Dual 8" floppy disk drive.
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Standard 30 cps draft printer.
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'Software and destination charges not included. Prices quoted apply in U.S. only.

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DATABOOK DICTIONARY

242 BYTE April 1981

List $4.95

Circle 155 on Inquiry card.

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Please accept my Membership in The Computer Book Club
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(Valid for new members only, I-'oreign and Canada add 20%. Orders outside U.S.
must be prepaid witb international money orders in U.S. dollars.) BY-4H1

Circle 155 on Inquiry cara.

BYTE April 1981 243

Listing

i continued

3 0AD

02

3 0AE

08

3 OAF

03

30BO

81

3 OBI

48

30B2

82

3 0B3

82

3 0B4

43

3 0B5

46

3 0B6

82

3 OB 7

02

30B8

53

30B9

03

30BA

81

3 0BB

4C

30BC

82

30BD

82

30BE

42

30BF

57

30C0

02 41

30C2

30C3

4100

5530

DB

2 ;

57

5540

DB

8

58

1

5550

DB

3

59

5560

DB

129

60

1

5570

DB

•H'

61

5580

DB

130

62

5590

DB

130

63

1

5 600

DB

• c

64

5610

DB

■ F i

65

5620

DB

130

66

5630

DB

2

67

1

5640

DB

'S'

68

5650

DB

3

69

5660

DB

129

70

1

5670

DB

■L'

71

5680

DB

130

72

5690

DB

130

73

1

5700

DB

'B'

74

5710

DB

i w i

,75

5720

DADD:

DW

DBUF+2

NEXT DATA ADDRESS

5990

POS:

DS

1

BIT POSITION

5999

ORG 4100H

6000

DBUF:

DS

1000

Listing 5: BASIC frequency-analysis program FREQ. Written in Microsoft BASIC, this program receives text entered by the user and
prints the frequency distribution of all letters and symbols. One symbol that does not appear by itself in a line of text is defined as
marking the end of text; the symbol, defined in line 100, is presently "%".

LIST FREQ (FREPUENCY ANALYSIS PROGRAM)

10 CLEAR 3000
12 D=45
15 S=0

20 DIM B$(2550)
30 DIM C(D)
^0 DIM L$(D)
50 FOR N=0 TO D
60 L$(N)='"%"
70 NEXT N

75 PRINT "ENTER ANALYSIS TEXT, TERMINATE WITH %"
80 FOR N=0 TO 10
90 INPUT B$(N)
100 IF B$(N)="" / o" GOTO 120
110 NEXT N
120 F=N-1
125 FORN=0 TO F
130 L=LEN(B$(N))
140 FOR K= 1 TO L
150 A$=MID$(B$(N),K,1)
160 FOR J=0 TO D
170 IF L$(J)=A$ GOTO 220
180 NEXT J
190 L$(S) = A$
200 C(S)=C(S)+1
205 T=T+1
210 S=S+1
215 GOTO 230
220 C(J)=C(J)+1
225 T=T+1
230 NEXT K
2^0 NEXT N
2^5 M=l

250 FOR K=l TO S- 2
25 5 FOR N=l TO S-M
260 IF C(N-l)c=C(N) GOTO 274
262 T$=L$(N-1)
264 U=£(N-1)
266 L$(N-1)=L$(N)
268 C(N-1)=C(N)

Listing 5 continued on page 246

244 April 1981 © BYTE Publications Inc

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IMP prints 80, 96 or 132 columns of crisp hardcopy at a speed of

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Listing 5 continued:

2 70 L$(N)=T$
272 C(N)=U
274 NEXT N
276 M=W+1
278 NEXT K

291 PRINT "LETTER FREOJENCY ANALYSIS"

292 PRINT

2°3 PRINT "LETTER", "COUNT", "PROBABILITY"

?9A PRINT "

295 PRINT

?0n FOR N= TO D

'10 PRINT L$(N),C(N),C(N)/T

320 NEXT N

OK

Text continued from page 226:

is uniquely dependent upon the code being used. How-
ever, the basic structure and program can be used with
any Huffman code.

There are three parts to the table structure: the index
values that allow the program to step through the ap-
propriate number of table entries (ie: tree branches) as the
data-stream bit values are serially examined; the decoded
character that results from the search; and a flag to in-
dicate to the program that the next table entry found is a
character and not an index value. The index values are
always in pairs, with separate index values for a 1 or a
bit-stream value. Therefore, as the program scans
through the table at each pair of index values, one or the
other is selected, depending upon whether the bit in the

BYTE

BACK ISSUU

TOU MLE

The following issues are available:

1976: July and November

1977: March, May thru December

1978: February thru October, December

1979: January thru December except March

1980: January to current issue except February and October

Cover price for each issue through August 1977 is $1.75

Domestic; $2.75 Canada and Mexico; $3.75 Foreign.

September 1977 through October 1979 issues are $2.50

Domestic; $3.25 Canada and Mexico; $4.00 Foreign.

November 1979 to current is $3.00 Domestic; $3.75 Canada

and Mexico; $4.50 Foreign.

Send requests
with

payment
to:

BYTE

Publications

70 Main St.

Peterborough

NH

03458

Attn:

Back Issues

data stream is a 1 or a 0.

The table-scanning process consists of adding the data
bit to the current table address. This gives a new address
whose contents, an index value, is added to the address of
the index value itself. This new table address is the ad-
dress of the next node in the tree of figure 2.

This process continues until a flag is detected, in-
dicating that the next entry is the desired letter. This test
is performed each time an index -value address has been
computed. The flag is the most significant bit in the table
entry. The remaining 7 bits are interpreted as an ASCII
character if the flag is on (logical 1) or as an index value if
the flag is off (logical 0). This limits the index value to
127, the maximum distance in the table that can be
skipped when processing 1 data bit. To help explain this
process, a portion of the table is shown in figure 3.

In the Huffman code used in this program, the letter "I"
is 1010. The decoding program identifies the correspon-
ding letter by using the data bit stream and the decoding
table previously described. The first data bit is added to
the table address, TAB, giving a new address, TAB + 1.

TABLE

TABLE

DATA

ADDRESS

ENTRY

FLAG

BIT

B to

42

OFF

\

+ l

ADD 1

fTi

OFF

m

> CHOOSE FIRST BIT

U->

J

♦ ,J

ADD 2

r^i

OFF

a

^

&

) CHOOSE SECOND BIT

+ 3 1

8

OFF

i

J

♦4

130

ON

1

* 5

ADD 2

r"?l

OFF

B

) CHOOSE THIRD BIT

\£)

J

+ 6

E

OFF

130 ■ I2B + 2

ON

a

1

■ 130

) CHOOSE FOURTH BIT

♦ 8

130

ON

i

/

+ 9

ADD 2

■

1010

1

DECODED

+ 10

R

+ 11

6

+ 12

1

1

Figure 3: Use of the binary tree tables in programs EXPl and
EXP2. This annotated table interprets the first 13 bytes of the
lookup table in both the code-expansion routines. It cor-
responds to the part of the binary tree in figure 2 that leads to
the letters E, I, and R. This figure shows the process by which
1010 is decoded as the letter I.

246 April 1981 © BYTE Publications Inc

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The index value here, a 1, is added to the previous result,
giving TAB + 2. The first bit has now been processed.

Beginning on the second bit, is added to the previous
result and the new index value pointed to is 2. This is
added to the previous result, giving a new address of
TAB + 4.

The second bit has now been processed. The next data
bit, a 1, is added to the previous result, giving the address
TAB + 5. Adding the index value at this location, a 2,
gives the new address, TAB + 7. The third bit has now
been processed.

Adding the last data bit, a 0, gives the entry 130. The
fact that this value is greater than 128 proves that it is
really an index value of 2 with the flag bit set; 130 = 128
+2. This tells the user that the next entry, two locations
further, is the desired character. Adding the index value
of 2 points you to the letter "I". Since a letter was found,
the process is repeated from the beginning, continuing
with the next bit in the data stream (providing that the
supply of data has not been exhausted).

Shorter codes are used for the more

frequently occurring data elements,

and longer codes are used for less

frequently occurring data elements.

COMP2 Description

The COMP2 program, given in listing 3, is similar to
COMPl except for one significant difference — the serial
bit stream that results from the encoding process is
packed and stored 8 bits to the byte. This provides true
compression and is useful when the compressed file is
stored in main memory or when the mass-storage device
requires an 8-bit word. An interesting occurrence in using
a compression scheme like this is that a low degree of
data encryption occurs automatically when the bit stream
is broken into 8-bit bytes. Referring back to the example
where the word "compression" was represented by 47
bits, you can see that the 8-bit bytes look like the follow-
ing:

(Binary)

(Hexadecimal)

(ASCII Meaning)

01000111

47

G

00001111

OF

SI (Control character)

01011011

5B

Left bracket

10001100

8C

Not defined in 7-bit ASCII

11010101

D5

Not defined in 7-bit ASCII

1101100

D(?)

Insufficient data

If someone looked at this data, it would not be im-
mediately obvious that this is the word "compression".
Some knowledge about the processing method or some
effort in decoding it would be necessary to retrieve the
original word.

EXP2 Description

The EXP2 program, given in listing 4, is similar to
EXP1 except that it expects to find the data to be decoded
in a packed form of 8-bit bytes. It works in conjunction
with COMP2. As in EXPl, the decoded data is sent to
some sort of terminal device. Any other destination could
be used with a slight code change.

248 April 1981 © BYTE Publications Inc

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Listing 6: Listing of the execution of program FREQ (listing 5).
This listing is the result of running the FREQ program, using
eight lines of BASIC code as the text to be analyzed.

OK

RUN OF FREQUENCY ANALYSIS PROGRAM

ENTER ANALYSIS TEXT, TERMINATE WITH %
? "120 f=n-l"

? "125 forn=0 to f"

? "130 l=len(b$(n))"

? "140 for k= 1 to 1"

? "150 a$=mid$(b$(n),k,l)"

? "160 for 5=0 to d"

? "170 if l$(j)=a$ s°to 220"

? "ISO next j"

? %

LETTER FREOJENCY ANALYSIS

LETTER COUNT PROBABILITY

3
A
M
6
7
G
8
X
5
E
B
K
A
I
D

»
R

J

2

L
T
(
)
F
N
$

O

1

7.75194E-03

7.75194E-03

7.75194E-03

7.75194E-03

7.75194E-0?

7.75194E-0''

7.75194E-0''

7.75194E-03

7.75194E-0- 5

2

1.55039E-02

2

1.55039E-02

2

1.55039E-02

2

1.5 c; 039E.02

2

1.55039E-02

2

1.550" 5 9E-02

2

1.55039E-02

2

1.5 I >039E-02

•?

2. o 2558E-02

3

2.32558E-02

4

3.10078E-02

4

3.10078E-02

5

, .87597E-02

5

3.87597E-02

5

3.87597E-02

6

4.65116E-02

6

4.65116E-02

6

4.65116E-02

7

5. 42 63 6E- 02

8

6.20155E-02

10

7.75194E-02

11

8.52713E-02

21

.162791

Line

Operation Performed

10

Assign string space.

12

Maximum number of unique sym-

bols expected.

15

Number of unique symbols

entered.

20

Text working buffer.

30

Symbol count array.

40

Symbol array.

50 thru 110

Entry of text to be analyzed.

80

Loop control for number of lines

(may be increased).

120

F is number of text lines entered.

125 thru 180

Input line is transferred to text

buffer.

190 thru 240

Count number of each type of

symbol; T is total count; C is

count of corresponding symbol in

symbol array.

245 thru 278

Sort symbols by count in ascend-

ing order.

291 thru 320

Computer probability and output

results.

Table 3: Operations performed by lines of code in the

BASIC program

FREQ of listing 5.

FREQ Description

To aid in doing frequency analysis, a small program,
FREQ, was written in Microsoft BASIC. (See listing 5.)
This program counts the occurrence of symbols (letters,
spaces, punctuation marks, etc) that have been entered

and prints the frequency analysis. In order to include
spaces in the count, the input array should be initialized
to be filled with a symbol not occurring by itself in the
text stream. The same symbol can be used to terminate
the text-entry operation: I used a percent sign (%).

The size of the text block to be analyzed is limited only
by available memory. To get a reasonably accurate
analysis, the text block should be more than several hun-
dred characters and be representative of the entire text. It
is not necessary to do a frequency analysis every time a
code is constructed. However, the closer the code lengths
correspond to the frequency of occurrence, the more effi-
cient the resulting compression will be.

A sample run of FREQ is shown in listing 6 with the
text input being part of the program itself. By comparing
this output with the figures of table 1, you can see how
the letter frequency for a BASIC source program com-
pares to that of plain English text.

Finally, since there are no remarks in the FREQ pro-
gram, the information in table 3 will help you understand
the program. ■

References

1. Hoffman, L J, Modern Methods for Computer Security and
Privacy, Prentice-Hall, 1977.

2. Huffman, D A, A Method for Construction of Minimum-
Redundancy Codes, Proceedings of the Institute of Radio
Engineers, September 1952.

3. Tao, W Y, A Firmware Data Compression Unit, University of Il-
linois, January 1974.

4. Williams, Gregg and Rick Meyer, "The Panasonic and Quasar
Hand-Held Computers: Beginning a New Generation of Consumer
Computers," BYTE, January 1981, pages 34 thru 45.

250 April 1981 © BYTE Publications Inc

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BYTE April 1981 251

Build an Intercomputer
Data Link

Mike Wingfield

93 Pine Hill Rd

Bedford MA 01730

Have you ever wanted to share a
program or data with someone, but
had no way to get it from your
machine to his without typing it by
hand? While this facility is lacking on
most microcomputers, it is so
necessary to scientific and business
computers that it has long been taken
for granted. The power of a computer
is greatly enchanced when it can com-
municate with geographically distant
computers. Computers can attain in-
creased efficiency by sharing both
resources and data, or by distributing
the work load among connected com-
puters. These capabilities also in-
crease the versatility of the computer
as a tool, and make possible such ser-
vices as electronic mail and quick ac-
cess to data. These and similar advan-
tages will become available to the
hobbyist and the small businessman
through the use of intercomputer data
links.

This article describes a specific im-
plementation of a connection be-

About the Author

Mike Wingfield graduated from the Univer-
sity of California at Los Angeles in 1972 with a
PhD in computer science. Presently, he is
working for the computer consulting firm of
Bolt, Beranek, and Newman in Cambridge,
Massachusetts, where his specialty is the design
and implementation of intercomputer com-
munication software. His hobbies include
gardening and experimentation with 6800- and
6809-based microcomputers.

The power of a com-
puter is greatly en-
hanced when it can
communicate with
geographically distant
computers

tween two computers that provides a
symmetrical facility for terminal link-
ing and memory-to-memory file

USER A

1

TERMINAL

COMPUTER

transfers. Terminal linking implies
that the output from each terminal is
echoed on the remote terminal. File
transfer implies the error-free
transmission of a block of data from
one computer to the other. The pur-
pose of this article is to provide in-
sight into the requirements of large-
scale network design through an ex-
amination of one specific implemen-
tation.

System Overview

As presented in figure 1, each end

USER B

COMPUTER

TERMINAL

DATA LINK

Figure 1: Typical data-link system configuration. Although the connection between the
terminal and the computer is hardwired (ie: a direct electrical connection), the data link
between computers (bridging a large distance) is usually accomplished via radio or
telephone link.

252 April 1981 © BYTE Publications Inc

Why is the 88G Printer
the new industry

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CONTROLLED INTERFACE

The microprocessor array provides the
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Both inputs are fully buffered to allow
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the printer each
time power is applied

VERSATILITY

The 88G prints a full upper and lower
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clear 7x7 matrix in 80, 96, or 132 column
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The dual tractor/pressure-feed paper
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Complete forms control allows the
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The wide use range of the 88G makes
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RIBBON CARTRIDGE

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v....

Computers can attain

increased efficiency by

sharing both resources

and data.

of the connection consists of a com-
puter and a terminal (such as a
teletype or a video display terminal).
The local computer is connected to
the remote computer via a data link
that is implemented by an asyn-
chronous serial hardware interface
and the software necessary to support
data transfer. The data link may be
hardwired if the distance between
computers is short; or, it may consist
of a pair of modems connected by a
telephone line if a hardwired line is
inconvenient. Figure 2 illustrates the

hardware configuration of each com-
puter — in this case, a 6800-based
system. Two ACIAs (asynchronous
communications interface adapters)
provide the necessary interfaces to
the terminal and to the line. The soft-
ware involved occupies approximate-
ly 700 bytes of memory.

The user interface can be defined as
the view the user has of his computer.
The interface to the data-link soft-
ware was designed to be as simple as
possible (to reduce the amount of
software), and yet provide the user
with two capabilities:

• Echoing of characters typed by one
terminal on the other terminal. This
feature enables two persons to com-
municate with each other. This is the
transparent or linking mode, which is
the default state of the software.

• Initiation of a file transfer from one

6800
MICROPROCESSOR

t

c

c

c

Ul

READ-ONLY
MEMORY

u.

PROGRAMMABLE
MEMORY

3Jl

ASYNCHRONOUS
COMMUNICATIONS
INTERFACE
ADAPTER (ACIA)

.TO OTHER
/\/ COMPUTER

Ul

ASYNCHRONOUS
COMMUNICATIONS
INTERFACE
ADAPTER (ACIA)

TERMINAL

DATA
BUS

ADDRESS
BUS

Figure 2: Hardware configuration of a 6800-based computer. The computer com-
municates across the data link by means of the ACIA, which converts the 8-bit bytes of
information to a continuous (serial) stream of bits. This serial bit stream is transmitted
by use of the modem, which translates between the binary signal and a signal that can
be carried across telephone lines.

254 April 1981 © BYTE Publications Inc

FOR OVERWORKED COMPUTER OPERATORS,
OUR SLC-1 MAKES THE PERFECT ASSISTANT.

Your computer may lose track of things once in a
while. The time, for example. When it does, your operator
has to make sure it gets things right again - which costs
you time and money. If they make a keying error, these
costs go up.

That's one good reason to get your computer a
smart new assistant like the SLC-1. It listens to everything
your computer says. When it recognizes a key phrase, it
flashes back the answer instantly. A battery backup system
keeps the SLC-1 running, come power failure or system
crash. And unlike your regular operator, the SLC-1
doesn't make mistakes.

Plus the SLC-1 does a lot more than timekeeping. It
also provides instant answers to a variety of mainframe
questions. You pick the key phrase it looks for, and type in
the responses. Then -for example -if your computer goes

down, it can be automatically re-booted back into action
under the SLC-1 's supervision.

The SLC-1 does all this because it's driven by its own
computer, a 6502 microprocessor. So when you want to
use your main computer for something else, you still have
- for backup - the SLC-1 , with its own 1 K bytes of RAM
(expandable to 12K).

But even with its optional 10-digit display, the SLC-1
is inexpensive to hire. And it's simple to train. Just plug it
into the RS-232 or 20-mA current loop serial link between
your computer and terminal, enter your message responses,
and you're all set.

So give yourself a break: talk to our personnel counselor
today at Digital Pathways, 1260 L'Avenida, Mountain View,
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379-5034. We'll introduce you to
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7T

MEET THE ASSISTANT COMPUTER OPERATOR
THAT NEVER TAKES A COFFEE BREAK.

Ciicio ii-iti on inquiry card.

GENERAL FRAME FORMAT

DLE

STX

(OPC)

ETX

(CHECKSUM-
HIGH)

(CHECKSUM-
LOW)

DATA BYTES

Figure 3: Frame format for data transmission. A frame is information that will be transmitted across the data link as a unit and
checked for accuracy upon receipt. For the purposes of transmission accuracy, the data is preceded by a header and followed by a
trailer. DLE and STX are both 1-byte ASCII characters. (OPC) stands for opcode, which is a 1-byte quantity that tells the receiver
what kind of data follows. A running 2-byte total of the data bytes is kept. This is deposited as a checksum, high byte first, and is
used by the receiving computer as a check against transmission errors.

(o) ADDRESS FRAME:

DLE

STX

30

(ADDR-
LOW)

(ADDR-
HIGH)

DLE

ETX

(CHECKSUM-
HIGH)

(CHECKSUM-
LOW)

(b) DATA FRAME:

DLE

STX

31

DLE

ETX

(CHECKSUM-
HIGH)

(CHECKSUM-
LOW)

DATA BYTES

(c) ACKNOWLEDGE FRAME:

DLE

STX

32

DLE

ETX

(CHECKSUM-
HIGH )

(CHECKSUM-
LOW)

DLE

STX

33

DLE

ETX

(CHECKSUM-
HIGH)

(CHECKSUM-
LOW)

(d) NEGATIVE

ACKNOWLEDGE FRAME:

Figure 4: Frame formats for different types of data. The third byte in each frame dictates the type of data sent in that frame. A hexa-
decimal 30 means that the current frame contains a 2-byte hexadecimal address, sent high byte first: this is an address frame, with for-
mat as illustrated in figure 4a. A hexadecimal 31 denotes a data frame, which is the only frame that has a variable length. (See figure
4b.) Because the end of the data is marked by a DLE ETX sequence, a DLE within the data byte area is transmitted twice to indicate
that it is data, rather than the end of valid data. A hexadecimal 32 denotes an acknowledge or A CK frame (figure 4c), while a hexa-
decimal 33 denotes a negative acknowledge or NAK frame (figure 4d). The address and data frames are sent to the computer that is
receiving data. The ACK and NAK frames are sent from the receiving computer to acknowledge error-free or faulty transmission of
the previous frame, respectively.

computer to the other. This is done
by specifying a local starting address
of the file, the remote loading-start
address, and the byte count of the
file. This is accomplished by a simple
command interpreter that asks for
these three parameters and initiates
the transfer. Data blocks are
transmitted by one computer, and
their reception acknowledged by the
other. This is the file-transfer mode of
the software.

The following information outlines
the sequence of events leading to the
transfer of a file between computers.
User A dials up user B over the
telephone and both computers are
connected via modems. (See figure 1.)
User B tells user A, via the link, the

name and loading location of the
desired file. The file can be a BASIC
program, an assembly program, a let-
ter, or any other kind of file.

User A types a control-F that in-
itiates the local command interpreter,
resulting in "S:" being displayed. User
A keys in four hexadecimal digits
(representing the source address) and
a carriage return. The command in-
terpreter types "D:" and waits for
four more hexadecimal characters
and a carriage return (representing
the destination address).

Finally, a "#:" directs user A to
type in the byte count and a carriage
return; this begins the file transfer.
When the transfer is complete, user
A's computer returns to the linking
mode. Further file transfers can then

be negotiated before the telephone
connection is manually broken.

During specification of the ad-
dresses and byte count, a backspace
erases the previously typed character
and a control-X aborts the command
interpretation and returns the com-
puter to the linking mode. Any illegal
hexadecimal characters typed are ig-
nored and the terminal bell is sound-
ed for each occurrence.

Communication Protocol

To insure correct interpretation of
a sequential stream of bytes, a com-
munication protocol that imposes
meaning on the data stream must be
specified. Computer protocols, like
human protocols, are those modes
of behavior agreed upon between

256 April 1981 © BYTE Publications Inc

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Circle 164 on Inquiry card. BYTE April 1981 257

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parties. Bridge-bidding sequences are
an example of a human protocol,
although the complete protocol
agreement between partners must be
negotiated. Computers require
precisely specified protocols.

To encode meaning into a data
stream, the concept of a frame must
be introduced. A frame is a stream of
bytes with a beginning-of-frame
mark, a coded portion (which deter-
mines the use of the data), the data,
and an end-of -frame mark. To enable
more reliable communications along
a noisy channel, a checksum is ap-
pended to the end of the frame; this is
used by the receiver to verify that no
bits have been dropped. Figure 3
presents the structure of the frames
selected for this file-transfer applica-
tion.

Computer protocols,
like human protocols,

are those modes of

behavior agreed upon

between parties.

Since each byte in a stream can
assume any one of 256 values, a
special technique is used to denote the
beginning and ending of a frame. One
particular byte is selected to be the
data-link escape (DLE), to signify that
the next byte is to be interpreted as
either start of frame (STX) or end of
frame (ETX). The receiver, when see-
ing a DLE and a STX in series, knows
that a frame has begun. When the
DLE ETX pair is received, it knows
that the end of frame has been
reached and that the next 2 bytes con-
tain the checksum. To preclude the
appearance of a DLE STX or DLE
ETX pair within the data portion of
the frame, all DLEs in a data frame
are doubled — that is, transmitted as
DLE DLE. The receiver, seeing two
sequential DLE bytes, simply discards
one of them to restore the frame to its
original length.

The byte following the DLE STX is
assigned the function of an operation
code (ope) that is used to give mean-
ing to the data portion of the frame.
Four types of frames are defined: an
address frame (hexadecimal 30), a
data frame (hexadecimal 31), an
acknowledge frame (hexadecimal 32),

and a negative acknowledge frame
(hexadecimal 33). These four frames
represent the minimum set required
to successfully get a file transferred
from one computer to another in a
simple, yet reliable fashion.

One design possibility not used
here would put the address field in the
data frame so that the start-load ad-
dress for each frame would be
available just before its associated
data. This would have eliminated the
necessity for the address frame;
however, it would require a buffer in
the receiver equal to the length of the
frame. The buffer would be used to
hold the data until the checksum
verified that the received data is
perfect. If the data were not buffered,
but was simply stored at the address
specified, then an error in the address
bytes would cause the data to be
stored in the wrong portion of
memory. With a separate address
frame, the address will be verified as
correct before the data arrives so that
no receive buffering is required.

Following receipt of the address or
data frame, the receiver returns either
an acknowledge (ACK) or a negative
acknowledge (NAK) frame, thus in-
dicating whether the frame received is
perfect. The sender uses this informa-
tion to decide whether or not to
retransmit the frame. Thus, both
computers must communicate to get
the whole file transferred without
error.

Figure 4 illustrates the structure of
each of the four types of frames. Data
bytes corresponding to the code for
DLE are doubled only in the data
frame, which has variable length.
This is unnecessary in the other three
frames because they have a prede-
fined length.

The checksum is simply a 16-bit
sum of all the bytes in the frame (ex-
cept the first DLE and the trailing
ETX). This provides an undetected
bit-error rate which is adequate for
this application.

The frame structure is used only in
file-transfer mode; in linking mode,
each character is sent immediately;
no error checking is considered to be
necessary.

The lowest level of protocol in-
volves the hardware interface be-
tween the two computers. In this ap-
plication, the two computers are con-
nected over an asynchronous bit-
serial channel. This technique was
selected for several reasons. A serial

258 April 1981 © BYTE Publications Inc

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Circle 165 on inquiry card.

BYTE April 19B1 259

NEW!!! THE *

ELECTRIC MOUTH

for SlOO, Elf II, Apple, TRS-80 Level II*

From $99.95 kit
Now — teach your computer to
talk, dramatically increasing
the interaction between you
and your machine.

That's right: the ELECTRIC MOUTH actually lets
your computer talk! Installed and on-line in just
- inutes, it's ready for spoken-language use in office,
business, industrial and commercial applications,
in games, special projects, R&D, education, secu-
rity devices — there's no end to the ELECTRIC
MOUTH's usefulness. Look at these features:

* Supplied with 143 words/letters/ phonemes/
numbers, capable of producing hundreds of words
and phrases.

* Expandable on- board up to thousands of words
and phrases (just add additional speech ROMs as
they become available).

* Four models, which plug directly into SlOO. Apple,
Elf II and TRS-80 Level II computers.

* Get it to talk by using either Basic or machine
language {very easy lo use, complete instructions
with examples included).

* Uses National Semiconductor's " Digital ker"
system.

* Includes on-board audio amplifier and speaker,
with provisions for external speakers and
amplifier.

* Adds a new dimension and excitement to pro-
gramming; lets you modify existing programs and
games to add spoken announcements of results,
warnings, etc.

* Installs in just minutes.

Principle of Operation: The ELECTRIC MOUTH
stores words in their digital equivalents in ROMs.
When words, phrases, and phonemes are desired,
they are simply called for by your program and then
synthesized into speech. The ELECTRIC MOUTH
system requires none of your valuable memory
space except for a few addresses if used in memory
mapped mode. In most cases, output ports (user
selectable) are used,

second d

space f
speed g

Spoken Material Included!

one eighteen m dollar inches numl

iwo nineteen cancel down is df

Ihree Iwenty case equal U <>■■

four 'n'rty cenl error kiln on

five forty 400het1z lone feet left oul

six BBS eoherlz lone flow less over

seven s ' xI y 20ms silence fuel lesser parenthesis start i z

eight seventy 40ms silence gallon limil percent slop j

nine eighty nflms silence go low please than k

tan !!' ne j^Lj I 60 ™ 5 silence gram lower plus ihe |

eleven hundred azfJms silence great mark point time m

twelve thousand camj greater meter pound Iry n

thirteen million check have mile pulses up o

fourteen zero comma high milli rale volt p

fifteen again control higher minus re weight q

sixteen ampere danger hour minuli; ready a r

seventeen and degree in near right b s

*"EJ/ JJ" ond "The EJeciric Mouth" are reg. trademarks 0/
Netronics R&D Ltd. "Apple" is a reg. trademark of Apple
Computer Inc. "TRS-80 Level JJ" is a reg. trademark 0/ Tandy
Corp.

Continental U.S.A. Credit Card Buyers Outside Connecticut

CALL TOLL FREE 800-243-7428

To Order From Connecticut Or For Technical Assistance, Etc.,

Call (203) 354-9375

NETRONICS R&D LTD.De P tB4

333 Litchfield Road, New Milford, CT 06776

Please send the items checked below:

□ S 1 00 "Electric Mouth" kit soo.tir.

□ Elf II "Electric Mouth" kit S99.95

U Apple "Electric Mouth" kit $1 10.95

D TRS-80 Level II "Electric Mouth" kit SI 19.05

Add $20.00 for wired & tested units. All plus $3.00 postage & in-
surance. Conn res. add sales tax.

Total Enclosed S

D Personal Check D Cashier's Check/Money Order

□ Visa □ Master Charge (Bank No. |

Acct.No.

Signature

Print

Name

-Exp. Dale.

Address

City

State

260 April 1981 © BYTE Publications Inc

.JZhi_

SIGNAL
LEVEL

START
BIT

DO

Dl

D4

D5

D7

STOP
BIT

Figure 5: Serial transmission of data. When transmitting data between two computers
on an asynchronous serial line, the data is transmitted 1 bit at a time with each byte of
data (8 bits) framed by a start bit and a stop bit; a parity bit usually comes between the
last data bit (D 7 ) and the stop bit but is omitted in this application due to the error
checking already provided. Here, the byte being transmitted is binary 11010011 (read
from right to left).

COMPUTER A

COMPUTER B

SEND FILE

SEND

SERIAL

LINE

RECEIVE

UJ

£ z

, UJ
O W5

a

£ z
° <

■x. <

° <

; < V>

*: E

a E

* 2
U 5

< O

OS

UJ_

o s

<c o

> =

o

3 s

UJ <

oz

UJ

or cc

"SEN
NAK'

UJ

Z i

I 3

o

1

I %

r

RECEIVE

SERIAL LINE

SEND

SEND FILE

Figure 6: The interconnection of send and receive software modules. When computer A
sends a data frame to computer B, the receive module of computer B tells its send
module to transmit an ACK frame (if the data agrees with the checksum) or a NAK
frame (if it does not). This acknowledge frame is received by computer A, which then
informs its send module to transmit new data, or retransmit the previous frame, as
necessary.

channel uses few wires when a direct
connection is possible. For longer
distances, the link can be made by a
telephone line and standard modems.
Also, there are integrated circuits in-
terfacing directly to the micro-
processor that can handle this format
very well. Figure 5 demonstrates how
8-bit bytes are transmitted along with
their start and stop bits. To improve
efficiency, no parity bit is used
since the checksum provides error
control.

Software Description

The software is organized into
three cooperating modules: the send
routine, the receive routine, and the
command interpreter. The send and
receive modules are used mainly for
file transfer. The conceptual connec-
tion of these two software modules in
both computers is detailed in figure 6.
The send routine of computer A sends
to the receive routine in computer B,
and vice versa.

When the send module in A sends a
frame, the receive module in B

verifies the checksum and tells the
send module in B to send either an
ACK or a NAK back to A. The send
module in B sends the ACK or NAK
to A's receive module, which then in-
forms A's send module that an ACK
or a NAK was received. Thus, two
flags are necessary for communicat-
ing between the send and receive
modules: one commanding "send
ACK or NAK," and the other stating
"received ACK or NAK." A "send
file" flag to the send module of A in-
itiates the file transfer.

Note the symmetry. Because the
send and receive sections in each
computer are independent, and
because they communicate by flags,
the send output can be fed directly in-
to the receive input in the same com-
puter for test purposes during debug-
ging. Files can be moved from one
place in memory to another within
the same machine, simulating the ac-
tions of two coupled machines.

The third module of code is the
command interpreter, which is used
to specify the source starting address,

Text continued on page 266

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Circle 166 on inquiry card.

BYTE April 1981 261

( IOINT J

NO /CHARACTER

^\ ? ^/^

PRINT AND
SEND CHARACTER

Tyes

PRINT "S."ON CONSOLE

( RETURN J

KBSTATE= 1

f RETURN J

KBSTATE=

( RETURN )

DECREMENT
KBBUFF POINTER
BY 1

f RETURN )

O

PUT CHARACTER

IN BUFFER;

PRINT CHARACTER

f RETURN J

GET CHARACTER

ACTER \ YES
RETURN,

f RETURN J

CONVERT KBBUFF
TO BINARY VALUE

BYTECNT^VALUE

XMITFILE = 1

KBBLOCK= 1

( RETURN j

SRCADDR* VALUE

PRINT "D:" ON
CONSOLE

KBSTATE = 2

f RETURN J

DESTADDR = VALUE

PRINT "H:" ON
CONSOLE

KBSTATE= 3

( RETURN J

Figure 7: Flowchart for the command interpreter, IOInt. This routine gathers the information necessary to initiate the transfer of a
given block of information between computers. An interrupt from the keyboard causes this routine to be executed (from the begin-
ning) every time a key is pressed. The value of KBSTATE (keyboard state) causes the routine to ask for the starting address of the
block to be sent (with the prompt "S:"). This is followed by a request for the destination address for the first byte (prompted with
"D:"), and the number of bytes to be transferred (prompted with "#:"). Once this information has been given, the routine disables the
keyboard from further input (KBBLOCK = l) and sets a flag that tells the software send module to begin sending the block of data
(XMITFILE=1).

262 April 1981 © BYTE Publications lnc

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BYTE April 1981 263

( XMITLOOP J

I WAIT""!
' LOOP I

XMITFILE=0

YES /RECDAClO
=

?

RECDACK=0

YES

■©

RING BELL

BLOCKKB=0

RETRANS=3

SEND ADDRESS FRAME:
SEQUENCE IS: DLE.STX,
30,DESTADDR H ,DESTADDR L
DLE,STX,CHECKSUM H ,
CHECKSUM L

XMITLOOP

WAIT FOR"ACK RECEIVED"
SIGNAL (RECDACK=1)

©-

YES

WAITFLAG=0

XMITACK\ YES

( RETURN J

SEND NAK
FRAME

XMITACK=0

0-

RETRANS=RETRANS- 1

PRINT ERROR MESSAGE-
TRANSMISSION OF DATA
FRAME FAILED

Figure 8: Flowchart for the send module. This routine, when activated by the condition XMITFILE=1, causes the computer to
transmit a block of data in the form of an address frame, followed by a data frame. It waits in a loop until XMITFILE is set to 1,
signaling that a block of data is ready to be transmitted. It then sends the address data frames, waiting after each for an ACK frame
response from the receiving computer. If either frame is received imperfectly, the process begins again with the address frame. Soft-
ware limits repetition to a total of three tries. All numbers used in this figure are hexadecimal. Also, the variables ADDRESS,
BYTECNT, CHECKSUM, DESTADDR, INDEX, and SRCADDR are all 2-byte variables. The subscripts H and L refer to the high
and low bytes, respectively, of a 2-byte variable. If the block to be transmitted is more than decimal 256 (hexadecimal 100) bytes
long, it is transmitted in blocks of 256 bytes.

On Flowcharting Interrupt-Driven
Routines

The perceptive reader may
notice that the flowchart of figure
9 (on page 266) does not have a
return or end block. Although it
may not be immediately obvious,
the same is true of the flowchart in
figure 8. (The one return block that
does exist is used only when the
XmitLoop routine is returning
from calling itself.) The reason for
this and other seeming omissions
has to do with the function of in-
terrupts in the data-link routines.

When the data-link software (see
listing 1) is running, it is usually in
the XmitLoop routine, repeating
the wait loop marked in the
flowchart of XmitLoop. (See figure
8.) If an interrupt comes from the
keyboard, control transfers to the
IOInt routine, flowcharted in
figure 7, and returns to the routine
that was executing before the inter-
rupt.

If an interrupt comes from the
serial line, control transfers to
some location within the Linelnput
routine, but, instead of starting at

the beginning of the routine (as is
done with the IOInt routine), con-
trol transfers to the instruction
directly after the "bsr GetByte"
(branch to GetByte subroutine) in-
struction most previously ex-
ecuted. (See figure 9.) This can be
accomplished because the GetByte
subroutine stores the return ad-
dress in the variable ACIAState; it
is this address that is jumped to
upon a serial line interrupt (see
routine IOInt in listing 1).

264 April 1981 © BYTE Publications Inc

Circle 168 on inquiry card.

SEND BEGINNING
OF DATA FRAME;
SEQUENCE IS: DLE, STX.31

YES

INDEX* BYTECNT L

INDEX = 100

ADDRESS — SRCADDR

GET MEMORY BYTE,
UPDATE CHECKSUM,
AND SENDONE BYTE
OF DATA FROM BODY
OF DATA FRAME

YES

UPDATE CHECKSUM AND
SEND SECOND DLE

INDEX = INDEX -1
ADDRESS = ADDRESS+1

SEND END OF DATA
FRAME, SEQUENCE IS:
DLE, ETX, CHECKSUM H ,
CHECKSUM L

XMITLOOP

WAIT FOR "ACK RECEIVED"
SIGNAL (RECDACK*!)

BYTECNT=BYTECNT -100
DESTADDR= DESTADDR+100
SRCADDR= SRCADDR+100

I

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April 1981 © BYTE Publications Inc 265

(line INPUT J

Text continued from page 260:

the destination starting address, and
the byte count. This code is activated
by a control-F character depressed on
the keyboard. The final carriage
return sets the XMITFILE flag, which
is polled by the background send
routine.

Command Interpreter Structure

Figure 7 presents the flowchart for
the command interpreter, IOInt,
which is driven by interrupt signals
received from the keyboard.

Each character from the keyboard
generates an interrupt, which starts
the command interpreter. If the send
module is currently sending a file, as
evidenced by the relation "BLOCKKB
> 0", then the character is to be ig-
nored and is merely echoed as a bell.

STORE BYTE
AND INCREMENT
ADDRESS

GET CHECKSUMu
ANDCHECKSUM L

NO /tHECKSUrr-
OK

XMIT ACK=1

I

RECDACK= -1

Figure 9: Flowchart for the receive module, Linelnput. Whenever an incoming byte on
the serial line causes an interrupt to occur, control of the program transfers to a point
within this routine just after the previous "get byte" request, and executes until another
"get byte" request is encountered. Control then returns to the routine that was running
before the serial line interrupt (usually the wait loop marked in figure 8) until another
serial line interrupt causes the Linelnput routine to resume execution where it stopped.
This routine stops for every byte of an ACK, NAK, address, or data frame.

266 April 1981 © BYTE Publications Ire

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BYTE April 1961 267

The operation of the interpreter is a
function of the state variable,
KBSTATE. If the state is zero, the
transparent mode case, the character
is echoed locally and sent to the
remote computer. Otherwise, the
character is tested for being a carriage
return (CR).

The carriage return causes the
keyboard buffer (which collects ad-
dress or byte-count hexadecimal
characters) to be converted to a
binary value. If the character is a
control-X, the interpreter mode is
aborted and KBSTATE is returned to
zero.

If the character is a BS (backspace),
the pointer into the keyboard buffer
is decremented (after first checking
for underflow). If none of the above
is true, the character is checked for
being a proper hexadecimal character
and is then put in the keyboard buffer
(after checking for overflow). The
keyboard buffer holds as many as
four hexadecimal characters, which is
the largest buffer needed to specify a
16-bit address or a byte count.

The sequence of characters echoed
on the terminal following the carriage
return, as well as the location of the

binary value, are dependent on the
current state of the interpreter. After
each carriage return, the state is in-
cremented to ensure that the correct
control path is executed for each of
the three parameters collected. Final-
ly, the last carriage return after the
byte count specification sets the
BLOCKKB flag and the XMITFILE
flag. The BLOCKKB flag prevents
any keyboard characters from ap-
pearing on the line during a file
transfer. The XMITFILE flag tells the
send module to begin sending the
specified file.

Send Routine Structure

The send module, XmitLoop, is
responsible for sending address, data,
ACK, and NAK frames to the remote
receive module. Figure 8 shows the
flowchart for the program flow of the
send routine. This routine operates in
background mode, testing three flags
to see if any work is pending. If the
XMITACK flag is -1, a NAK frame
is sent; if it is +1, an ACK frame is
sent.

If the RECDACK flag is not zero,
and the send routine is waiting for an
ACK or a NAK, then a return is made

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to the data transfer routine to com-
plete the data or address frame
transfer. (This will be explained in
more detail later.) If the XMITFILE
flag is non-zero, then file transfer
begins.

As explained earlier, the address
frame is sent first so that no buffering
in the receiver is necessary in case of
an address error. Once the address is
correctly received and acknowledged,
a data frame is sent. If the data frame
is acknowledged, the next address
and data frames are sent, and the pro-
cess is repeated.

If a NAK frame is received, then
the address frame received in error is
retransmitted and verified before the
data block is retransmitted. When
sending either an address or a data
frame, the send routine employs the
same mechanism in waiting for an
ACK or NAK. When the wait for an
ACK or NAK signal is necessary, the
send module XmitLoop calls itself by
storing the return address on the
stack and branching to the beginning
of the routine. When the send routine
finds that the RECDACK flag is set,
control is returned to the proper loca-
tion in the send routine via an RTS
(return from subroutine) instruction.
The RECDACK flag indicates
whether a new frame should be sent
or the old one retransmitted.

A retransmission index is main-
tained and decremented each time a
frame retransmission is necessary,
and no more than three retransmis-
sions are allowed. (The number of
retransmissions allowed is a
parameter that is easily changed.) If
more than three failures occur, an
error message is typed on the sender's
console and control returns to the
transparent mode. When all of the file
has been successfully transmitted,
control returns to transparent mode
and the keyboard is enabled.

In data frames, data bytes that hap-
pen to have the same hexadecimal
value as the DLE code are doubled
(repeated) so that a false end of frame
is prevented; the receive routine
drops the second DLE so that the data
is received correctly. In the worst
case, this has the effect of doubling
the length of the frame.

Receive Routine Structure

The flowchart for the receive pro-
gram, named Linelnput, is shown in
figure 9. This routine handles the in-

Text continued on page 286

268 April 1981 © BYTE Publications Inc

Circle 169 on inquiry card.

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Circle 170 on inquiry card.

BYTE April 1981 269

Listing 1: Software for data transfer between two 6800-based systems linked by a serial line. The software here consists primarily of a
data-sending routine (labeled XmitLoop), a data-receiving routine (labeled Linelnput), and a command interpreter (labeled IOInt).
All numbers preceded by a dollar sign ($) are hexadecimal numbers. Also, references to '0, '1, '2, and '3 are actually to the characters
"0", "1", "2", and "3". These characters, when represented in ASCII, have values of hexadecimal 30, 31, 32, and 33 and are referred to
in text and in flowcharts as such. Flowcharts 7 thru 9 correspond to the code given in this listing.

rr*9i'

rile

eau

Ppfti

et x

e«u

H9B2

St X

equ

"(1710 7

bel 1

equ

OH! 1ft

*X

equ

P0P6

*F

equ

PP08

bs

equ

P90D

C r

equ

1 ft

IOPt P

eou

F9Pn

Ac 1 aCsM

equ

Fq01

Ac 1 aOat al

eau

F902

Ac i aCsr?

equ

F933

Ac 1 aOat a 2

equ

OV5P

SayeOpc

equ

("051

Aci aSt at e

equ

ansa

S re Arjdr

equ

0056

DestAddr

equ

0058

BvteCnt

equ

0(?«5B

n inVal

eau

a 050

KbPt r

eau

01 rt S F

KbBuif f

equ

3362

KbF.nd

eau

00.63

ChkSun.

eau

;i?6^>

ReedChk

eau

0-lbA

KbState

equ

6 B

RecdAc k

eau

i!06C

Xmi t Ack

eau

03 6

X m i t F i 1 e

eau

006F

W a i t F 1 a q

eau

H ; "6F

Bl ockKb

equ

7V-7S

SaveSu"

equ

(.''17 7

XChkSum

eau

fl?79

Address

eau

$9ti

$83

$82

7

M«

6

6

$d

S 18

$f 900

$f901

Sf9P2

$f 903

$50

S51

$5U

$"5b

$S8

$5h

$5d

ISf

$62

$b3

$b5

th.i

$bb

$bC

$bd

$6e

*6<

$75

$77

$79

die c^ar

et x char

9 1 x char

belt char

control X

control F

backspace

c a r r i age return

I/O Interrupt vector

Ac 1 a to terminal

A c 1 a to modem

place to save ope

state of ac 1 a fsm

ftp sou ret address

ftp destination addr

ftp byte count

place to save number

ot r into KbBuf f

U char buffer

end of hu f f er

xmit checksum, recv side

reed checksum, recv side

state of kh handl e r

f 1 aq - reed ac k

flag - send ac k

f 1 aq - send file

flag - wait for ack/nack

flag • blocks kb ac t i v

olace to save checksum

i« i 1 1 ed checksum

r e c v store address

100

org

I 1 (J 3

* Entry point

1000
1 PIP?

1005
1008
10PA
1000

1010

1013
1015
1018
101A
101C
101r-
1021
1022
1023
1025
1028
102A
1028

8b
B7
B7
86
B7
H7
CE
OF
CE
DF
Bb
CE
bF
!)8
4 4
26
CE
DF
01
HE

03

F90tf

F902

96

F q

F902

lien
51

IIP?

18
06

0^6A
P0

FA

005F

5D

Start

i n i ) o o o

Ida
s t a
st a
Ida
st a
s t a
Idx

St X

1 dx
stx
Ida
idx
cl r
i nx
dec
bne
idx
stx
nop
cl i

«3

Aci aCs r 1

Ac * aCsr2

»$9b

Ac i aCsr 1

Ac i aCsr2

*InzAci a

Aci aState

•IOInt

IOPtr

*6

SKbSt ate

x

i n? 1 oop
#KbBuf f

KbPtr

reset Acia's

/6U, 8 bits, interr

set up ac i a2 entry

clear
start

the f 1 ags
of area

in* the buffer ptr

* Background routine

checks event entries

1P2C
102E
1030
1033
1035

9b
2b
CE
9b
2b

6D

2A

l?b7

6C

PF

Xm 1 t I oop

1037 D6 6ft

1 da a

bne
Idx
1 da a
bne
1 da b

Xmi tF 1 1 e
I nzAddr
*Nac kr r«
Xm1 t Ack
GoAc k
RecdAck

xmlt file event?

ptr to Nack frame
xmit ack/nack event?

reed ack/nack event?

Listing 1 continued on page 272

270 April 1981 © BYTE Publications Inc

r

v

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Save 5% Off wirh Purchase of MOD III System or Disk Drive

New low cost internal disk kit avail-
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With this kit, now, you may expand
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The kit includes one 40 track disk
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• PHONE (714) 979-9923 • TELEX #678401 TAD IRIN

*Uses MTI Memory, Disk Drives & Components

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^ OF TANDY CORPORATION

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ALL PRICES CASH DISCOUNTED

FREIGHT FOB FACTORY

ASK FOR FREE CATALOG

Circle 171 on inquiry card.

BYTE April 1981 271

Listing 1 continued:

039

03B

030
03F
0<J 1
0'JU

?a5

0U8

piaB

cion

0«F

05?
(*$3

pis y

056
058

H5*
050

061
063
0frU
066
068
06A
06C
06F

070

072

073
07U

076
077
079
?7B

07C
07E
080
082

08 a

085
087
088
,*8A
08C
08E
090
091
092
09U

096
097
098
09*
09C
09E
M> 1
0A4
0A7
0A9
AAA
0AC
0AF

27
97
96

27
7F
1 7
39

2B
CE
C6
A6
BO
28
5A
2b
D7
20

6B
6E
FB
0C6ET

3

126,1
07
0F

i tie 4

F7
6C
D2

306D
58

7F
DE
27 51
C6 83
37

C6 30
80 52
96 56
80 73
96 57
80 6F
80 59

33

to

2R 33

37

C6 31
80 3F
5F

96 58
26 3?
06 59
OF 5'J
37

A b g p
33

80 55

81 9.i
26 02
8D «F
»8

5A

26 F0
80 35

33

00
2B
96
27
7A
7C
7C
2*1
5A
26
CE
BD

0F
58
1<I

00 58
cn56
0P5O

Hi

H7
126E

1 IB?

hea
st a
Ida
bea
Cl r
tba
rt s

Xm i t Loop
WecdAck
^ a i t F 1 a g
Xmi t Loop

Wa i t F 1 aq

clear the event

clear the flag

reg a is ack/nack f 1 ag

return to waiting routine

* Routine for sending Ack/Nack ipame

GoAc k

Skpldx
F rmLooP

F i n4

bmi
Idx
1 da
1 da
Isr
inx
dec
bne
st a
bra

Skpldx

*AckF rn>

#7

x

SendC har

F rmLoop
Xmi t Ack
Xm i t Loop

send nac k?
send ac k 1
frame bvte count
get bvte
send out

clear the pvent

* Routine for sending Address frame

I nz Add r

GoAddr

* there

c! r
ldx
beg
Ida b
psh b
Ida b
bsr
1 da a
bsr
1 da a
bsr
bsr
is a wait
pul b
t st a
bmi

Xmi tF i le
Byt eCnt
LastB! k
#3

clear

c hec k

flag
for null

i ndex

ret ransm i ss i on
save i t
opcode byte
send dl e, st x, ope
send out addr bytes

*»0

SendHdr

Dest Addr

UpdtChk

Oest Addr* 1

UpdtChk

SendTl send d1e,etx,cc - wait
for ac k/nac k he re

get ret pans i ndex
check ack/nack flag

RetryBlk branch if ack

* Routine

G o F i l e

Skipl.d
SendBy t es

F i n o U n

there

RetryBlk

F r ror

for
PSh

Ida
bsr
Cl r b
1 da a
bne
Ida b
Idx
psh h
1 da a
pu 1 b
bsr
cmp a
bne
bs r
i nx
dec b
bne
bsr
is a wait
pu 1 b
t st a
hm i
Ida a
beg
dec
i nc
i nc
bra
dec b
bne
1 dx
Isr

sending block of data
b

b

SendHdr

By t eCnt
SkipLd
Byt eCnt+1
S rcAddr

UpdtChk
#dle
FinOoub
UpdtChk

save retrans index

opcode

send dl e, st x, opc

in* byte count index

chk upper hyte

< 256 bytes left

save i t

get byte

restore

update checksum, send

check for die

update checksum, send

check byte count

SendBy t es

SendTl send dle,etx,cc ■ wait
tor ack/nack here

get ret rang i ndex
check ack/nack flag
check for failure
check for done

Ret rvBl k

ByteCnt

LastBl k

ByteCnt

Oes t Addr

SrcAddr

InzAddr

decrease
i nc rease
i nc rease

bv

by
by

256
256
256

bytes
bytes
byt es

GoAddr

*Error M sg print error msq

u t T e x t

Listing 1 continued on page 274

272 April 1981 © BYTE Publications Inc

LOWEST PRICE - BEST QUALITY

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Factory assem. & tested
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FACTORY ASSEMBLED & TESTED LIST ONLY

HORIZON-1-32K-DOUBLE DEN $2695 $1980

HORIZON-2-32K-QUAD DENSITY 3595 2674

HORIZON-2-64K-QUAD + HARD DISK 9329 7149

HORIZON RAM ASSM 16K=$389. 32K = $579

HORIZON RAM KIT SALE! 16K = $314 32K = $469

HORIZON DISK DRIVE SALE DOUB DEN SAVE! 315

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PASCAL-PLUS 14,1 8 OR 36 DIGIT PRECISION 249

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Z-89 48K
List $2895 only $2299

TERMINALS Z-1 9 $725

INTERTUBEIII om y $725

DIP-81 PRINTER om y $395

MICROTEK $675

NEC PRINTER $2569
TRACTOR, THIMBLE, RIBBON

InterSystems

ITHACA INTERSYSTEMS 2A

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TARBELL DISK CONTROLLER DD $445
ECONORAM2A8KASSM $179

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NORTHWORD 294 MAILMAN 234
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TARBELL COMPUTER-PHONE

RCA-COSMAC VP-1 1 1 99 RCA-COSMAC
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EZ-80 Machine Language Tutor $25
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CP/M is a registered trademark of Digital Research, Inc.

Circle 172 on inquiry card.

BYTE April 1981 273

Listing I continued:

10B2 fi6 P7 LastBlk Ida a «beH ring the bell

10BU 80 H\ nsr SendTerm send bell to term

10B6 07 6F sta b BlockKb unlock the kh

1 WBfl 20 9E F4n2 bra Fin4 end of file xfer

* Subroutine which sends out dle.stx, unci in? checksum
10BA 86 90 SendHdr Ida a *dle die char

108C 80 2C bsr SendChar send die

lPlRE IF c 1 r a

10BF 97 77 sta a XChkSum In? checksum

10C1 97 78 sta a XChkSum+1

1BC3 86 8? 1 da a * s t x

10C5 8D 18 bsf UpdtChk send stx

10C7 17 tba

10C8 80 IS bsr UpdtChk send opcode

10CA 39 rts

* Subroutine whi c K sends out dle,etx»ccl#ce2

* and sets up wait for ack/nack
10CB 8b 9a SendTl Ida a «dle

1 C 9 7 6 (-. sta a wgitHaq indicate waiting ack/nack

10CF 80 0£ bsr UpdtChk send out die

1001 86 83 Ida a «etx

1003 80 IS bsr SendChar send out etx

1005 96 77 Ida a XChkSum

1007 80 11 bar SendChar send high bytp

10D9 96 78 Ida a XChkSum+1

10DB 80 00 bsr SendChar send low byte

10DO ?£' 09 bra Fin2 go to idle 1 non

10OF 56 UpdtChk PSh a

10E!l 9B 78 add a XChkSgm+1

10E2 2 4 «3 bec SkpH

1 E 4 7CP; , 77 in C XChkSum

I WE 7 97 78 SkpH sta a XChkSum+1
10F9 3? pul a

10EA 37 SendChar psh r> save it

10FB F6 F90? Ida b AciaCsr2 aet status

10tE C a ? 2 and h a 2 tent for ««it reaOV

10F0 27 F9 beg SendChar+1

10F2 H7 F9B3 sta a AciaData?

10F5 33 Pul b restore req

10F6 39 rts

10F7 r 6 F 9 1- 1 SendTerrr Ida b AciaCsrl aet status

10FA C4 02 a"d b «2 test for transmit rn v

10FC 27 F9 bea Send Term wait for readv

10FF 87 F901 sta a AciaDatal

1101 39 rts

* Entry Doint for the I/C interrupt

1102 &6 F902 IOInt Ida a AcieCsr2 aet status

1105 2A 07 bpl Kblnt chk for ac i a interr

1107 B6 F903 Acia2Int Ida a AciaData2 get l|ne data

110A DE 51 ldx AciaStete

110C 6E 00 j mp x go to ACIA routine

110E 86 F90) Kblnt Ida a AciaDatal get kb data

1111 By 7F and a #$7f kill parity bit

1113 D6 6F Ida b BlockKb Chk if sending file

1115 27 05 beg ChkCl i

1117 86 07 OutBell Ida a «bell

1119 80 0C OutTerm bsr SendTerm send char to term
1 1 1 B 3B rti return

111C D6 6A ChkCli Ida b KbState

I I IE 26 13 bne CI I

1120 81 06 emp 3 #*F
1122 27 05 bea StartCl i

1124 8D 01 bsr SendTerm send char to term

1126 8D C2 bsr SendChar

1128 3B rti return

1129 CE 1278 StartCl i Idx #SrcT x t output S? Listing 1 continued on page 276

274 April 1981 © BYTE Publications Inc

32K Board Pictured Above

Why Not the Best?

From The Dynamic RAM Company.

2MHz

4MHz

16K— $249

$259

32K— $375

$395

48K— $500

$530

64K— $625

$665

We have now been shipping
our 2MHz dynamic RAM boards
for over two years. Hundreds of
4MHz boards have been going
out every month since early
1979. Our reliability is proven in
the thousands of systems which
contain our board. Many quality-
minded systems houses across
the country and overseas are
using our boards for their
equipment.

Our prices still beat all.
Despite rising 1 6K memory chip
prices (at least from reputable
suppliers), Central Data continues
to give you the best buy in
memory today. Nobody offers a
board with a capacity of 64K,
assembled, tested, and guaranteed
for a full year at the price we do.

Circle 173 on inquiry card.

Deselect around PROMs. Our

boards have the important deselect
feature which lets you overlap any
fixed memory in your system with
no interference.

Our features make the board
easily used and expanded. You
address our boards on 1 6K
boundaries with mini-jumps (small
shorting plugs that slide over wire-
wrap pins) near the top of the
board for easy access. If you want
to expand your board after you
have purchased it, all that you
need to do is add memory. We
can supply you with expansion
packages ($1 50-2MHz,
$160-4MHz) which include eight
RAMs that you can depend on as
well as two mini-jumps for
addressing. And of course, our
board never generates wait states.

Low power consumption keeps
your computer running cool and
reliable. The total power
consumption of our 16K board is
typically less than 4 watts ( + 8V @
300ma, + 1 6V @ 1 50ma and

-16V @ 20ma). Boards with
additional memory typically
increase power consumption only
1 watt per 1 6K!

Standard S-100 Interface. Our
board is designed to interface with
any standard S-1 00 CPU. All of
the timing of the board is
independent of the processor chip,
and the board is set up for
different processors by changing
two plugs on the board.

Call or write us today. That will
guarantee a fast response with
more information on the board. Or
make an order — you'll probably
have the board in two weeks! If
you're interested, also ask for a
catalog on our Z8000 16-bit
processor board designed for the
MULTIBUS. All of these products
are available to your local dealer,
also.

Central Data Corporation, 713
Edgebrook Drive, PO Box 2530,
Station A, Champaign, IL 61820.
(217) 359-8010

Central Data

BYTE April 1981 275

Listing 1

J12C
11 2F
1132
1133
1135
1137
1139
1 13B
1130
113F
11UC?
1142
1 t«4
1116
11^8
111A
1 14C
llflE
115?
1152
115a

1157
1159
1156
H5C
115F
H5F
1161
1 162
1 16«
1167
1169
U6B

continued:

8D HB2

7C «P»6A

3B

81

27

81

27

81

27

36

8tf

2B

fl!

2F

81

2B

81

2E

ea

Dfc"
8C
27
A7
08
OF
32
20
32
20
CE
8D
97
CE

0D
46
18
29

32

ID

HA

31

15

36

11

27

5D

51063

H8

(53

5D

BS

B3

1275
49
6A

005F

CI i

CharDK

BadChar

Cancel

InzPt r

i nc

pti

emp
beq

Cffp

bea

emp
bea
pen.
sub
bm1
Cmp

ble

emp
bml
cup
bgt

sub

ldx

CPU

bea
st a
1 nx
stx
pul
bra
pul
bra
ldx
bsr
st a
ldx

OutText
KbState

#CP

Convert

**X

Cancel
tfbs
BackUp

*$30

BadChar

«9

CharOK

tt$31

BadChar

»$36

BadChar

#$27

KbPtr

#KbEnd+l

BadChar

x

KbPt r

Out Term

OutBel 1
*CRLF
OutText
KbState
SKbBuf f

return
check for CR

Check for ctrl x
check for backspace

save for display

check for valid hex char

check for overf 1 ow

qet original char
echo