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• 



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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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on a US bank. Printed in United States of America. 

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 
CCC, 2 1 Congress St. Salem MA 01 970. Copying done for other than personal or internal reference use without 
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BYTE® is available in microform from University Microfilms International, 300 N Zeeb Rd, DeptPR, Ann 
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Palo Alto CA 94303 



MIDWEST (312) 966-0160 

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Hajar Associates 
3303 Harbor Blvd 
Suite K-4 
Costa Mesa CA 92626 



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 




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PASCAL/Z generates true Z-80 native code - ROMable 
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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, 
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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. 



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Turn your electric typewriter into a low cost, 
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DYNATYPER - Rochester Data's patented* Computer/Typewj 
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o&l||Sta< 
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S 



2 minutes to initially install and 5 seconds to remove *Q|J(ace. 
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Compatible with all power carriage return JApewriters having 
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(17 plungers) is available for a nornjoal fee. 
The Dynatyper is compatible with ^(♦major word processing software. 
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Interfaces available for "WS-80, APPLE, PET/CBM, OSI, Northstar, 
HP-85, H-89. WeigljjMnly 3 lbs. Extremely portable. 
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Tlvfc'is a 



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Timing 



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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. 



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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. 





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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 



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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 



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BYTE April 1981 17 



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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 



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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 



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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 



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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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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 



Circle 25 on inquiry card. 



Circle 26 on inquiry card. 




d 



1 

% 



Hi* 



How to tell if it's a White Computer. 



(Users 2 through 16 — multiuser expansion 
with high performance through distributed 
processing.) 

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. 

And double-density storage is here in a big way. Because now 
you can choose from three different levels of mini-disk systems — 
all double-density rated. 

And get the stojrage that precisely meets your application 
needs. 

Not to mention tlje service and quality that's made Percom the 
industry leader. 



Although rated for double-density operation, all 
levels of Percom drives work equally well in single- 
density applications. 

You can operate these drives in ordinary single- 
density format using TRSDOS* Percom OS-80™ 
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 



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For Texas Instruments 
TM990 Micro 
Modules 




v« 



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ei* 



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• Advanced EXPRESS BASIC 
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round robin clock swapping. Up 
to 32 contiguous or non- 
contiguous files can be simultane- 
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modes. Large or small floppy 
disks, bubble memory, hard disks 



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are enthused by the product. . ." 

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Assistant Research Professor 

Desert Research Institute 



and extended memory capabilities 
of up to 256k bytes are handled by 
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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. 
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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 



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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: 




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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 



Circle 33 on inquiry card. 



Solution \s6 J lii-shun\ n[ME,f r.MF,£r.L solution-] 
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WORKING SPACE 



DISPLAY FILE 



SPARE 



STACK 



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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. 



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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: 



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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 



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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. 



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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. 



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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- 
cant), editing, tracing, user-definable keys, 255-character 
string arrays, floating point 9-digit accuracy, and even 
machine language routines. 

Priced at Only $599, the TRS-80 Extended Color BASIC 
Computer is useful, entertaining and educational. Yet using 
it can be as simple as plugging in one of Radio Shack's 
instant-loading Program Paks. Come in and see what's 
already available. The computer attaches to your TV, or our 
own $399 TRS-80 Color Video Receiver. For just $24.95, 
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 
below) offers Color Computer owners quick, affordable 
access to many kinds of information and data services. For 
example, our exclusive agreement with CompuServe i? 
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news, weather and sports from 1 1 area newspapers and the 
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other users; and much more! You'll also access Dow Jones 
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more. 

Only $29.95 Buys You VIDEOTEX Software including a free 
hour on both CompuServe and Dow Jones, plus operator's 
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programs and accessories, at one of our 6000 outlets today! 




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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needs and make it your own. It has the flexibility and 
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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 
Research, Inc. Apple 11 is a registered trademark of Apple 
Computer, Inc. SoftCard is a trademark of Microsoft. 



North Star • Heath H8/H89 
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• Most other CP/M R Systems with CRT or Memory Mapped Displays 



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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. 



SYNCHRO-SOUND 



The ORIGINAL Computer People 

who KNOW Computers 

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CLOCK 






il 
















B-BIT CPU 




1024 X8 

PROGRAM 

MEMORY 




64X8 

DATA 

MEMORY 




8-BIT 
TIMER/COUNTER 
















































































8-BIT 
DATA BUS 
INPUT REGISTER 




8-BIT 
DATA BUS 
OUTPUT REGISTER 




8-BIT 

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 
screen. 

Use the DS-65 for: Precision Security Systems 
• Computer Portraiture • Robotics • Fast to 
Slow Scan Conversion • Moving Target Indi 
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NEW SOFTWARE FOR THE DS-65 IS NOW AVAILABLE 
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— Portrait System Software: This program includes 
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— Picture Scanner: Provides a variety of differ- 
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Write or call for more information! 



THE 



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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. . . 

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"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 




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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- 
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print 

(1410. 1420, 1500, 1520, 1552) 
Call COMPUMART Now for our 
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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- 
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operation $355.00 

Application Modules 

$29.95 

NEW SUPER 41-C Systems with 
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memory onboard leaves slots 
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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- 
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face, and Power Supply $1,299 
Call or write lor our complete 
Microflex 65 brochure 



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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 
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lor EXP-lOO $25. 




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1250 North Main Street 
Ann Arbor, Michigan 



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Our AIM system includes 4K AM 
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NEW FROM SANYO-Four Great 

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Prices Sanyo's new line ol CRT 
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HP83 VIRGO Has the same com- 
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CALL FOR COMPLETE DETAILS 8c 
SPECS. 



COMPUMART exclusive ATARI 

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8CO operators Manual 16K Rany 

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Box 

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Atari 410 Program Recorder 

$89.95 

Atari 810 Disk Drive 

(SlOO off with purchase) $699.95 

NEW Dual Disk double density 

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825 Printer (Centronics 737) 

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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. 



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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.. 
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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 
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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 

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FROM PERSONAL software 

Visicalc $149 

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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 
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From Microsoft 




16K RAM Board 


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FORTRAN 


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COBOL 


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$49.95 



HARDWARE ACCESSORIES FOR 
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Silentype Printer w/x face $635 
Super Sound Generator (mono) 
$159 (stereo) $259 
Light Pen $249 
X-IO Controller (plugs into pad- 
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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 



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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. 

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ABTs Numeric Key Plan $UO 
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Keyboard $195 

Apple m is in stock— CALL! 



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until 6-30-81. 



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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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Call us for more information on products, 
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We have a staff of highly knowledgeable 
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— iA* 



SYSTEMS, 

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In Mass. Call 617-491-2700 



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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- 
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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 
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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™-; **« 

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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- 
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Use it with Apple II™ , TRS-80 Level II ™ , PET ™ or other 
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The HIPAD's™ built-in RS-232C and parallel 8 bit interfaces make it all 
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For complete information contact Houston Instrument, One Houston Square, Austin, Texas 78753. 
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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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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. 



^&^ S-100 

PROGRAMS MOST 
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• ACCEPTS 1K/2K/4K 
OR 8K EPROMS! 

• EXTENDED DEVICE OPTION 

• PHANTOM SLAVE OPTION 

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Put your frequently used 
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"CLUGE CATO 

SIMPLIFY YOUR 

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Bare board $39.95 

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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 



When You Have To Face A Deadline 




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NOW! THE PACKAGE INCLUDES OUR EXCLUSIVE PASCAL ORIENTED SCREEN EDITOR. 

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INTERFACE CARDS 

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Symtec Light Pen 214 

Versa-Writer Digitizer 

Drawing System 209 

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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. 

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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 



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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 



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Please list system with which you plan to use 
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90 April 1981 © BYTE Publications Inc 



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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. ■ 



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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. 




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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 




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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 



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dotasouth announces. • • 

THE TOTAL PRINTER PACKAGE! 



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With so many matrix printers on the market today, it may seem 
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flexibility and still others the forms handling capability. But no 
printer offers all the features you need... until now. 

The DS180 matrix printer provides the total package of perfor- 
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competitive units. 

High Speed Printing-Bidirectional, logic-seeking printing at 
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Non-volatile Format Retention -a unique programming keypad 
featuring a non-volatile memory allows the user to configure the 
DS180 for virtually any application. Top of form, horizontal and 
vertical tabs, perforation skipover, communications parameters 



and many other features may be programmed and stored from the 
keypad.When your system is powered down, the format is retained 
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rate, etc.... it's all stored in the memory. If you need to recon- 
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Communications Versatility -The DS180 offers three interfaces 
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Forms Handling Flexibility -Adjustable tractors accommodate 
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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 
them, check the directory for the resulting sizes, and 
repeat the process again. Finally, you can write a pro- 
gram that counts the lines in a CP/M file and tells you 
how many tracks and sectors the IBM disk will require. 

In summary, if you have access to an IBM or an IBM- 
compatible computer system and you want your file- and 
data-transfer problems solved, Reformatter is probably 
what you've been looking for. 

If you have a TRS-80 or access to DEC machines, 
Microtech Exports has another version for you.H 



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DOMESTIC subscription rate: 

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96 April 1981 © BYTE Publications Inc 





1.1 


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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 
a Vector 3 terminal, a 5%" floppy, and a 5K" Winchester 
rigid disk drive that provides 5 megabytes of storage 
is quite a responsibility. It used to take 20 floppies to give 
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 
errors, and almost completely eliminates data loss on 
disks due to dirt, wear, or damage. 

"All this makes us pretty awesome, all right. But there's 
more. When coupled with Vector's MEM0RITE III and 
EXECUPLAN software packages, we give you a 30,000 
word dictionary, the ability to create your own phrase 
library, a teaching manual right on the screen, pass word 
security, plus a host of other word processing capabili- 
ties as well as financial planning, forecasting and 
basic accounting. 

"And we're reliable. Our powers won't diminish, our abili- 
ties won't fade, and dedication to mankind won't weaken. 

"For more information and your nearest dealer, call 
Vector at 800-423-5857. In California, call 800-382-3367. 
Or write to them at 31364 Via Colinas, Westlake Village, 
CA 91362. 

"Thank you all for coming today. And I hope we'll have 
the chance to do business together in the future!' 




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 



C ^Pascal 

Efficiency^rortability 
Flexibility^otrong Typing 

Now you don't have to compromise! 

Whitesmiths Ltd. now offers portable language development systems for four 
families of computers. Approximately one thousand installations use our 
software. 

We support complete versions of both C and Pascal, as compilers and cross- 
compilers. You get C automatically when you license Pascal, and you get 
native support with each cross-compiler. Test the software on your VAX 
before burning PROMs for your 68000 or 8080. 

Whitesmiths Ltd. offers a variety of licensing arrangements, the simplest 
being a binary license for use on a single CPU. The full source code is avail- 
able with internal documentation. Maintenance, training and sublicensing 
rights may also be obtained. 

Call or write for more information. 



Source 

Operating 

Systems 


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# 


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C: $1130 
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* 


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Idris is a trademark of Whitesmiths, Ltd, ■ Unix is a trademark of Bull Laboratories ■ CP/M is a trademark of Digital Research Company ■ VMS, 
RSX-ll/M, RSTS/E, LSI-ll, VAX, arc trademarks of Digital Equipment Corporation ■ VERSAdos is a trademark of Motorola Corporation 



* Special Order 

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\\r Tl investment. ♦ 1 y t 

Whitesmiths, Ltd 

RO.Box 1132 Ansonia Station New York, NX10023 
(212) 7994200 



Circle 67 on inquiry card. 



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 



"We regret to 
inform you that 
we can no 
longer supply 
replacement 
parts for your 
system." 

NOP 



"It was in ac- 
cumulator A." 



"Looks like 
you're getting 
a hard-copy 
memory 
dump." 



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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 



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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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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 
operating system available for microprocessors. 
Designed for the 6809 and 68000, it offers its 
users a very friendly computing environment. 
After a user 'logs-in' with his user name and 
password, any of the system programs may be 
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 
system and device independent I/O, allows the 
creation of a variety of complex support 
programs. There is currently a wide variety of 
software available and under development. 
Included in this list is a Text Processing System 
for word processing functions, BASIC interpreter 
and precompiler for general programming and 
educational use, native C and Pascal 
compilers for more advanced programming, 
sort/merge for business applications, and a 
variety of debug packages. The standard 
system includes a text editor, assembler, and 
about forty utility programs. UniFLEX for 6809 is 
sold with a single CPU license and one years 
maintenance for $450.00. Additional yearly 
maintenance is available for $100.00. OEM 
licenses are also available. 



FLEX 



Multi-Tasking 



UniFLEX is a true multi-tasking operating system. 
Not only may several users run different 
programs, but one user may run several 
programs at a time. For example, a 
compilation of one file could be initiated while 
simultaneously making changes to another file 
using the text editor. New tasks are generated 
in the system by the 'fork' operation. Tasks may 
be run in the background or 'locked' in main 
memory to assist critical response times. Inter- 
task communication is also supported through 
the 'pipe' mechanism. 



UniFLEX is offered for the advanced 
microprocessor systems. FLEX, the industry 
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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. 



"If your database system 

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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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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 

MICROCOMPUTER 

PERFORM LIKEA 



MAINF 



Now, you can use a microcomputer for 
sophisticated business applications 
. . .because now there's CIS COBOL. 
Micro Focus developed this COBOL so 
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programs as a minicomputer or a 
mainframe. 

CIS COBOL is Micro Focus' Compact, 
Interactive, Standard COBOL which 
offers the advantages of COBOL . . . 
powerful data structure features, English- 
like language, existing programmer 
expertise ... to provide you with a full 
commercial language. You won't be 
restricted by size either: a 64K byte 
microcomputer will compile up to 8000 
lines of COBOL, more if the program's 
split into dynamically loaded modules. 

Choose a Compact Compiler. 

The Compact compiler runs on 32K byte 
microcomputer systems. Its powerful 
subset includes full support for random, 
indexed and sequential files. 

Or choose the 
Standard Compiler. 

The Standard CIS COBOL compiler 
requires a minimum 48K of user RAM. 
A super- set of the Compact compiler, 
implementing ANSI 74 COBOL to 
Federal Low-intermediate Level. 



The same CIS COBOL 
extensions for conversational 
working, screen control, interactive 
debugging, and special peripheral sup 
port are in both compilers. And there are 
more reasons to consider CIS COBOL: 

• It conforms fully to the ANSI 74 stand- 
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• Its interactive features enable main- 
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Forms 

The FORMS utility lets you build a 
screen layout online at the CRT. Then 
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Forms -2 

A superset of FORMS, it eliminates the 
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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 



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(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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116 BYTE April 1981 



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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 



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124 BYTE April 1981 



Relational Query System For Management 



By Ken German & Toby Zweifach 



DATABASES: You've Heard The Hype Before... 
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SOURCE'" 



DATABASE SELECTION— 

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• Query output can be routed to disk, CRT 
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ONLY $225 



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Superkram (see below) and: Commodore Pet 
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SUPERKRAM 



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by Ken Germann 



Since KRAM™ was introduced in 1 979 it has fast become known as the quickest 
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defined keys for the file (Automatic Upgrade) 

• KRAM 2.0 files are totally compatible with SUPER KRAM 



a UNITED 
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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 



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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 




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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 
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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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PRINT USING, CHAIN and COM- 
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More languages. With SoftCard and 
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/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 



. - . .. 



•• t 






""• mil 



■ 
01 



■ 




SBfc" 



Unretouched CAT 400 display. 242x256k 16 bits per pixel 128K byte imaae buffer Partial picture shown here to highlight detail quality Imao 
Analysis Systems, Inc . 999 McMillan St . N W . Atlanta. Ca 



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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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TERMS: WE ACCEPT CASH, CHECK, OR MONEY ORDERS. CALIFORNIA RESIDENTS ADD 6% SALES TAX 



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 
for Apple, Atari, Commodore, Ohio 
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Minimum hardware requirements are: 48 K 
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80-column printer (optional). 



The FINANCIAL PARTNER™ is available from your 
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THE DENVER SOFTWARE COMPANY 

MANUFACTURERS OF MICROCOMPUTER SOFTWARE 




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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- 
turing over 50 Million Dollars worth of software and hard- 
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You'll see computers costing $150 to $250,000 including 
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electronic typewriters, peripheral equipment, supplies and com- 
puter services. 

All the major names are there including; IBM, Wang, DEC, 
Xerox, Burroughs, Data General, Qantel, Nixdorf, NEC, Radio 
Shack, Heathkit, Apple, RCA, Vector Graphic, and Commo- 
dore Pet. Plus, computerized video games, robots, com- 
\puter art, electronic gadgetry, and computer music to 
entertain, enthrall and educate kids, spouses and peo- 
ple who don't know a program from a memory disk. 
Don't miss the Coming Of The New Computers- 
J, Show Up For The Show that mixes business with 
pleasure. Admission is $5 for adults and $2 for chil- 
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- 
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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 
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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. 

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TV^WSSPORT 
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Soundchaser is a trademark of Passport Designs. Inc. 
Apple is a registered trademark of Apple Computer, Inc. 



Marketing: 
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134 April 1981 © BYTE Publications Inc 



Circle 91 on inquiry card. 



Circle 92 on inquiry card. 



MULTIUSER 



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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- 
cated system that links an Apple* or an 
RS-232 interfacing computer with a 
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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 
improving their audiovisual training 
and testing with the new technology 
pioneered by Cavri. 



Training, of course, is only one appli- 
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Tell us your application, and we can 
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guidance on programming and video- 
tape or videodisc production. 



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interactive video 

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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 



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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 



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138 April 1981 © BYTE Publications Inc 



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from OSBORNE/McGraw-Hill 



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covers the Machine Language 
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PET/CBM Personal Computer Guide Second Edition by Adam Osborne and Carroll Donahue #55-1. $15. □ 

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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 



IS 



Address . 



City/State/Zip 

Plus n.75/item 4th class a$1.25/item UPS a$2.50/item Air Mail n$4.00/item Overseas 
(California residents add applicable lax ) □ Please send me your free catalog. 

Total amount enclosed $ 

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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 


4E 




LDA 


B TPC 


0019 


CB 


20 




ADD 


B # $20 


001B 


D7 


4E 




STA 


B TPC 


001D 


DE 


4D 


ENDR 


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 


06 




BRA 


ENDD 


003F 


6A 


02 


DEC1 


DEC 


$02, X 


0041 


28 


02 




BVC 


ENDD 


0043 


6A 


00 




DEC 


$00, X 


0045 


C4 


IF 


ENDD 


AND 


B # $1F 


0047 


E7 


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. 



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Program names and computer names are 
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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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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 



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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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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. 



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From the Software Evaluation Group: 
A Review of the Configurable Busi- 
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Authors. 

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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$3.60 for each back issue: all other countries. 

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must be in U.S. $, drawn on a U.S. bank. Or use your 
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'SBASIC is a trademark of Topaz Programming 
* CP/M is a trademark of Digital Research, Inc. 
The CP/M Users Group is not affiliated with Digital Research, Inc. 



■^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 



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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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BYTE April 1981 153 



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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 



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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 



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has all of the advanced features of the 
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including our low cost MIRROR back- 
up and multi-user CONSTELLATION 
network that allows up to 64 computers to 
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such as printers. 

Want the full story? Contact your local computer 
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2029 OToole Avenue 
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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 • 


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• APPLE 2 • ATARI • SCORCERER 


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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. 




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Here's the nucleus of a truly exceptional S-100 system: 



1. 16 bit/8 bit Dual Processor (w/6 MHz 8088) 

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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 

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DON'T MISS OUT! 

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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- 
tems installed throughout the world, SD Systems offers 
you both proven and state-of-the-art products! We pro- 
vide you with a complete family of kits for all your sys- 
tems needs — 

SBC 100/200 — A 2.5/4 megahertz range of single 
board computers which are effective standing alone or 
combined with the complete SD board range. 

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 
Z-80 controller that adds display capabilities to your 
system. 

Z-80 Starter Kit — A low-cost entry into the world of 
microcomputers designed primarily for education and 
experimentation. 

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 



y <*\ ':■■■ ■-' 



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YOU CAN SAVE $50 

when you purchase any two SD Systems board kits from 
participating DEALERS and present coupons included in 
any two kits to participating DEALERS listed below. 
Coupons must be presented to participating DEALERS 
by 10-15-81. 



A.S.A.P. COMPUTER 
PRODUCTS 

SlqnalHill, Ca. 213-595-6431 



Q. T. COMPUTER SYSTEMS, 
INC. 

I awndale, Ca, 213-970-0952 



f COMPUTERS, ETC 

i Dallas, Texas 214-644-5030 

v JADE COMPUTER PRODUCTS 

Hawthorne, Ca. 800-421-5500 

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Swansea, England, U.K. 
44-792-460023 

ARCON ELECTRONICS LTD 
Toronto, Ontario, Canada 
416-868-1315 



RATIONAL SYSTEMS 



Buckinghamshire, U.K. 
0908-61 1349 

ALPHA BYTE STORES 

Calabasas, Ca. 213-883-8594 

ARISIA MICRO SYSTEMS 
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. 



GgGgGgGgGgGgGgGgGg 

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 



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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- 
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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 



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. 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 
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} 



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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 
For Model 1 Operation 




Jl 



MODEL 488-80C 
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 

microcomputer system ... 

under $ 4,000.0O* 



Having so much disk capacity as standard in a low cost 
microcomputer system is reason enough to make the 
900 Series your logical choice — but the fact is, it's only 
one of the reasons why this system offers the best 
price/performance value of any now on the market. 
There's also a simple modular design, a reliable single 
board computer, dual flexible disk drives, a versatile 
disk operating system, plenty of room for expansion, 
and attractive quantity discounts — plus a lot more. 

Just check out these standard features and expan- 
sion capabilities. 
STANDARD ON THE 900 SERIES: 

□ Single board microcomputer: Z80 based; 4 MHz. 
operation; DMA controlled disk access. 

□ Dual eight inch flexible disk drives: on-line formatted 
capacity of 2.5 megabytes expandable to 5 Mb: access 
time of 3 milliseconds track-to-track; 8000 hour MTBF 
reliability rating. 

□ IBM 3740 format compatible 

□ 48 kilobytes of dynamic RAM, 
expandable to 65 Kb. 

D CP/M" Disk Operating System 
with assembler, editor and debug 
subsystems. 

□ RS232 or TTY serial port for system 
console. 

□ Parallel line printer port 
(Centronics-compatible). 



DESIGNED FOR 
OPTIMUM RELIABILITY 
AND EASY SERVICING 

Single board design 
Quad-density flexible disk drives 
Turn-key operation and security 
Expansion capabilities 
Industrial quality construction 



'In OEM/Dealer quantities, please contact 

factory for pricing detail. 
CP M " is a registered trademark of Digital Research 




OPTIONS FOR THE 900 SERIES: 

□ Disk expansion: up to 5 Mb formatted capacity. 

□ Serial I/O expansion: two additional RS232 ports 
(serial printer, modem, etc.) 

□ S100 bus adaptor for system expansion. 

□ Multi-user operation 

□ Hard disk subsystem □ OASIS operating system 

AVAILABLE SOFTWARE FOR THE 900 SERIES: 

□ High level languages include: BASIC, FORTRAN, 
COBOL and PASCAL. 

□ Application packages include: Inventory, Word 
Processing, GL, AR, AP and Payroll. 

the Quay 900 Microcomputer System offers the 
most complete package for the money 




QUA3 

CORPORATION 

P.O. Box 386, Freehold, New Jersey 07728 ■ (201 ) 681 -8700 
Factory: Route 34, Wall Township, New Jersey 0771 9 

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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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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• ASSEMBLY LANGUAGE FOR BEGINNERS 

• DISK FILES 

• MOD-III REVIEW 

• KEYBOARD THUNDER AND LIGHTING EXPLAINED 

• DOS COMMANDS IN LEVEL II 

• PROBABILITY CURVE GENERATOR 

• CALCULATOR SIMULATIONS 

• THE MEGABYTE GAP 

• STOCKS AND BONDS 

• BUDGET ANALYSIS (FOR BUSINESS AND HOME) 

• NEWDOS/80 REVIEW 

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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 
OTHERS 



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I Calculate odds on HORSE RACES with ANY COMPU 
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I SCIENTIFICALLY DERIVED SYSTEM really works. TV 
Station WLKY of Louisville. Kentucky used this sytem 
to predict the odds of the 1980 Kentucky Derby See 
the Wall Street Journal (June 6. 1980) article on 
Horse-Handicapping. This system was written and 
used by computer experts and is now being made available to home computer owners. This 
method is based on storing data from a large number of races on a high speed, large scale 
computer 23 factors taken from the "Daily Racing Form" were then analyzed by the 
computer to see how they influenced race results. From these 23 factors, ten were found to 
be the most vital in determining winners NUMERICAL PROBABILITIES ol each of these 10 
factors were then computed and this forms the basis of this REVOLUTIONARY NEW 
PROGRAM 

I SIMPLE TO USE: Obtain "Daily Racing Form" the day before the races and answer the 10 
questions about each horse. Run the program and your computer will print out the odds for 
all horses in each race. COMPUTER POWER gives you the advantage! 

I YOU GET: f) TRS-80 (Level II) or Apple Cassette 

2) Listing of BASIC program for use with any computer 

3) Instructions on how to get the needed data from the "Daily Racing Form" 

4) Tips on using the odds generated by the program. 

5) Sample form to simplify entering data for each race 



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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 

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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 



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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 



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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 

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each account with month and year-to-date totals create a suspense file to remind you of 

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(14) SMART TERMINAL (Howe Software) enables your TRS-80 to be used as a remote terminal 

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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 

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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 

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(21) DOSORT (Racet Computes) includes GSF (above) extends the in memory sort to sorts 

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(22) COPSYS (Racet Computes) allows the user to make copies of machines language cassettes 

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stored in your previous program line many programs together without losing important 

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(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 

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(29) MAIL LIST (Racet Computes) all routines are in machine language allowing for quick 

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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 



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272 pages ■*, 

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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 
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illustrated 



ISBN 0-07-05420 1 -5 



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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; 
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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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TWX: 910-335-1594 



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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(714) 452-0101 



* CP/M trademark of Digital Research, Inc. 
Z80 Softcard trademark of Microsoft, Inc. 



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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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Explorer/85's Level "A" system features the advanced 
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PC Board: Glass epoxy, plated through holes with 
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System Monitor (Terminal Version): 2k bytes of 
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change all registers . . . single step with register display 
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out channel so that monitor can communicate with I/O 
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System Monitor (Hex Keypad/Display Version): 
Tape load with labeling . . . tape dump with labeling 
. . . examine/change contents of memory . . . insert data 
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Level "A" 
With Hex 
Keypad/Display. 



single step with register display at each break point . . . 
go to execution address. Level 'A" in this version 
makes a perfect controller for industrial applications, 
and is programmed using the Netronics Hex Keypad/ 
Display. It is low cost, perfect for beginners. 
HEX KEYPAD/DISPLAY SPECIFICATIONS 
Calculator type keypad with 24 system-r'efined and 16 
user-defined keys. Six digit calculator-type display, 
that displays full address plus data as well as register 
and status information. 
LEVEL "B" SPECIFICATIONS 
Level "B" provides the S-100 signals plus buffers/ 
drivers to support up to six S-100 bus boards, and in- 
cludes: address decoding for onboard 4k RAM expan- 
sion selectable in 4k blocks . . . address decoding for 
onboard 8k EPROM expansion selectable in 8k blocks 
. . . address and data bus drivers for onboard expansion 
. . , wait stalegenerator(jumperselectable). to allow the 
use of slower memories . . . two separate 5 volt regula- 
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LEVEL "C" SPECIFICATIONS 
Level "C" expands Explorer/85's motherboard with a 
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thai plugs into the motherboard, 
number of S-100 connectors. 



Just add required 




LEVEL "D" SPECIFICATIONS 

Level "D" provides 4k of RAM, power supply regula- 
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LEVEL "E" SPECIFICATIONS 
Level "E" adds sockets for 8k of EPROM to use the 
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RAM IC's (allowing for up lo 12k of onboard RAM). 
DISK DRIVE SPECIFICATIONS 

• 8" CONTROL DATA CORP. • Data capacity: 401.016 bytes 
professional drive. (SD). 802,032 bytes (DD). 

• LSI controller. unformatted. 

• Write protect. • Access time: 25ms (one 

• Singleordoubledensity. track). 

DISK CONTROLLER/ I/O BOARD 
SPECIFICATIONS 



• Cont. , olsuptofour8"drives. 

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Please send the items checked below: 

□ F,xplorer/85 Level "A" kit (Terminal Version). . . SI29.95plus 
$3 post. & insur. 

□ Explorer/65 Level "A" kit ( Hex Keypad/Display Version) . . . 
$129.95 plus $3 post. & insur. 

D 8k Microsoft BASIC on cassette tape. $84.95 postpaid. 
D 8k Microsoft BASIC In ROM kit (requires Levels "B", "D" and 
E") . . . $99.95 plus $2 post & insur. 

□ Level "B" (S-100) kit . . . $49.95 plus $2 post. & insur. 

D Level "C" (S- 100 (Hard expander) kit $39.95 plus $2 post 

& insur. 
Level "D" (4k RAM) kit . . $69.95 plus S2 post. 8. insur. 
D Level "E" (EPROM/ROM| kit . . . $5.95 plus 50c p&h. 

□ Deluxe Steel Cabinet for Explorer/B5 . . . $49.95 plus $3 post. 
& insur. 

D Fan For Cabinet .. . SI5.00plus $1.50 posl. & insur. 
D ASCII Keyboard/Computer Terminal kit: features a full 128 
character set. u&l case: full cursor control: 75 ohm video 
output: convertible lo Baudot output: selectable baud rale. 
RS232C or 20 ma. I/O, 32 or 64 character by 16 line formats, 
andean be used with either a CRT monitor or a TV sel (if you 
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CALL IS 

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□ Gold Plated S-100 Bus Connectors. $4.85 each, postpaid. 

□ RF Modulator kit (allows you louse your TV set as a monilor) 

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□ 16k RAM kit (S-100 hoard expands lo 64k). . . $199.95 plus $2 
posl. & insur. 

□ 32k RAM kit $299.95 plus $2 posl. 8. insur. 

□ 48k RAM kit $399.95 plus $2 posl. 8, insur. 
D 64k RAM kit. . . $499.95 plus $2 post.* insur. 

□ 16k RAM Expansion kit (lo expand any of Ihe above in 16k 
hlocks up lo 64k) . . . $09.95 plus $2 posl. & insur. each. 

r :■ Intel 8083 cpu Users' Manual . . $7.50posipaid. 

□ 12" Video Monitor (10MHz bandwidth) . . . $139.95 plus $5 
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□ 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: 

O Personal Check D Cashier's Check/Money Order 

D VISA a Master Charge (Bank No ) 

Add, No. Exp. Dale 

Signature 

Print 

Name 

Address 



City- 
Slab 



. Zip_ 



NETRONICS Research & Developmenl Ltd. 
333 Litchfield Road, New Milford, CT 06776 



rig] *1l%Ss I M* J COT, RflDIUS. UfUE fffiDED 

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f|] ^[3]i'((I-«n])'2)«!J-flR[2] !»Z)«B.SMMP 

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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. 




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•#\t r >\ 






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7 






«T 



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-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. 

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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™ 



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division of 



(OjlBB i 

"ELECTRCmI :, 



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on 



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All CompuPro products meet the most demanding mechanical and electrical standards, and are backed with one of the best 
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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 
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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 
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SYSTEM SUPPORT 1 
MULTIFUNCTION BOARD 

$295 Unkit, $395 A/T, $495 CSC 
This multi-purpose S-100 board provides sockets for4K of extended 
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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 
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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 
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and comprehensive manual. Specify Z-80* or 8080/8085 version. $175. 



Most CompuPro products are available in Unklt form, Assembled/Tested, or 
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r\ 



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COMPUTER ENCLOSURE 2 

Introductory price: $795 (specify rack mount or desk top version) 
Includes fused, constant voltage power supply ( + 8V at 25 Amps, 
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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 
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shunts plus TRS-80* conversion instructions. Limited quantity. 

S-100 MEMORIES FROM THE 
MEMORY LEADER 

CompuPro memories feature fully static design to eliminate dynamic 
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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 
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typical! It's fast, too; runs with 6 MHz Z-80®* CPUs, or 10 MHz 
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Morrow disk controllers (the CompuPro disk controller can use 
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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 
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FREE CATALOG : Want more information? Then send for our free catalog. For fast 
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•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! 



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operate . . .. modular maintenance . . . 

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Its highly reliable, industry-standard MFE drive is compact. 
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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- 
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Circle 142 on inquiry card. 



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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 



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Free up critical and expensive backplane space. Saves you 3 dual slots. 

Addressable in 4K increments up to 4 Megabytes. 

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Battery back-up capability. 256KB unit draws less than 300 ma at 5 volts in battery back-up 
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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 









TO GROWTH 



A year ago, the course for Marot 
Software Systems, Inc. was clear. 
We were on our way to becoming 
the world's best source for software. 
And we were going to accomplish 
that by distributing only the operating 
system and the application software 
that brought out the best in micro- 
computers. That was our course... 
and, in all modesty, we were most 
successful. 

That's when something funny 
happened. The dealers, consultants 
and computer users with whom we 
had relationships began asking — 
and then demanding— that we at 
Marot apply our expertise and 
follow-through to the supply of 
reliable, quality-oriented hardware 
and complete computer systems. 
Systems that could solve specific 
problems in data -based manage- 
ment and analysis for business, law, 
medicine, science and government. 



Here's the hardware 
we now distribute: 

ONYX — Extremely powerful and reliable 
5-user Z80-based micro, with 10 or 20 
Mb hard disk and integral tape sub- 
system. Also available: 16 bit Z8000 
operating UNIX™ Version 7, with up to 
1 Mb RAM for as many as 8 users. 10 
or 18 Mb hard disk with integral tape 
subsystem and additional storage 
available. 

ALTOS — Cost-effective floppy disk 
system, 208 K RAM for up to 4 users. 
Expansion to 58 Mb hard disk with tape 
backup available. 






The marketplace told us of the 
need for support, too. Of the gap 
that existed in matching hardware, 
operating systems and software to 
application requirements. And of the 
need for assistance in evaluating 
options available to meet those 
requirements. 

So, we thoroughly searched and 
found the best hardware we could 
distribute. 

As a result, Marot Software 
Systems, Inc. has become Marot 
Systems, Inc. It's the one company 
you can rely on to handle total 
computer needs: from hardware, 
software, operating systems and 
support to total computer solutions. 

If you're a computer dealer or a 
computer consultant, Marot's total 
backup and support could be the 
special something you need to make 
your operation grow. Call or write 
us today. 



Here are the products distributed by 
Marot Systems, Inc. Please check 
items of interest and return this 
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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 



Circle 149 on inquiry card. 



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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 
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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 


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; 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 


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8 


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1 


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56 





Listing 4 continued on page 244 



240 April 1981 © BYTE Publications Inc 



For $ 4,995*you not only 
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Automatic screen prompting 
guides user through operations. 

Familiar, typewriter-like key- 
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Word Processing software is 
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Processing software, with the 
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lure, is only $400. Optional 
Accounting software is avail- 
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puter Stores. 





Communications options let you 
transmit information electron- 
ically. Communicate with other 
computer systems. 
Flexible text editing features, 
easy to learn, easy to use. 
Boilerplate library of commonly 
used text. Abbreviation (or 
short-hand) library. 



Dual 8" floppy disk drive. 
Convenient storage with flex- 
ible diskettes. 



Standard 30 cps draft printer. 
(Select optional Letter Quality 
Printer instead of draft printer 
and system price becomes 
$7295:) 



You also get the 
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At $4,995, Digital's Word Processing has to be the best value in the industry. 

Value which includes immediate delivery. Special discounts on 3 -pack systems. 

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For a personal demonstration, call 800-528-6050, ext. 1276. In Arizona, 800-352-0458. 
For $4,995, you get a lot more than a word processor. 



'Software and destination charges not included. Prices quoted apply in U.S. only. 




We change the way 
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In Canada, call Digital Equipment of Canada Ltd., Kanata, Ontario, Tel. 613-592-5111. In Europe, call Digital Equipment Co. Ltd., Reading, England, Tel. (0734) 85131. 



Into computers? Want to get started? 

What is The Computer Book Club? An exciting new concept that puts 
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iOMPt,rERisrs handy 

DATABOOK DICTIONARY 




242 BYTE April 1981 



List $4.95 

Circle 155 on Inquiry card. 



Take 4 exciting books 

IOr Ip .Uy (values to $70.75) 

. . . and get one FREE! 



1141 
List $12.95 




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7 very good reasons to try 
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• Reduced Member Prices. Save up to 75% on books sure to 
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• Satisfaction Guaranteed. All books returnable within 10 
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• Extra Bonuses. Take advantage of added-value promo- 
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THE COMPUTER BOOK CLUB 
Blue Ridge Summit, PA 17214 

Please accept my Membership in The Computer Book Club 
and send the 4 volumes circled below, plus a free copy of 
Computerist's Handy Databook/Dictionary. I understand 
the cost of the books selected is $1.00 (plus shipping/ 
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1000 
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Circle 155 on Inquiry cara. 



BYTE April 1981 243 



Listing 


i continued 


3 0AD 


02 


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03 


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4100 





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2 ; 


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5660 




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5690 




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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 




M€€T AXIOM'S IMP - 
TH€ ONLV LOUJ COST 
IMPACT PRINTER 
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Three-Way Forms Handling 

IMP is equipped with both friction and adjustable tractor feed (2-1/2 
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and fan fold. 



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Axiom's versatile IMP-APPLE is the 
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IMP prints 80, 96 or 132 columns of crisp hardcopy at a speed of 

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Circle 156 on inquiry card. 



AXIOM CORPORATION 

1014 Griswold Avenue • San Fernando, CA 91340 
Telephone: (213) 365-9521 •TWX: 910-496-1746 




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 
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payment 
to: 

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Attn: 

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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 



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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, 
CA 94043. Or contact us at (415) 969-7600. TWX 910- 
379-5034. We'll introduce you to 
a new assistant that doesn't talk 
back. Except to your computer. 



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 



JfXfivfccf tie KXyicocy 




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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 



NEECO 





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I 



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 
















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RECEIVE 



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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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DEALER INQUIRIES INVITED. 




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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Circle 167 on inquiry card. 



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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that my customer needed. It closed the 
deal for me. Considering its capa- 
bility, FMS-80 is one of the most 
cost-effective application pro- 
grams available today!' 

If you're continuously asked 
to do applications program- 
ming, and you don't have 
the time to do it in Basic, 
consider FMS-80. For 
additional information 
on FMS-80, contact 
Systems Plus, 3975 
East Bayshore, 
Palo Alto, 
CA 94303. 
Phone (415) 969-7047." 





Systems Plus 



I 



Mike Ketcham. Managemenl Information Systems. Belmont, CA 



•TM of Digital Research, Pacific Grove, CA 

°TM of Croniemco, Sunnyvale, CA 



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 



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ALL PRICES CASH DISCOUNTED 

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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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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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NEC PRINTER $2569 
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The Best! $99 
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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