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CHRISTMAS ISSUE 

T"5 Hiriiinj 

Affordsbl© Quality for th© Timox ComputGr Us6r 

DECEMBER NO. 2 <i;i oc 



PROGRAMMING 
MATRIX/CURSOR INPUT 
USER-FRIENDLINESS 
MEMORY REDUCTION 


APPLICATIONS 
FINANCIAL PROGRAM 

NUMERICAL ANALYSIS 
ZX CASH REGISTER 


us POSTAGE 
PAID 

PERMIT NO. 









Extend your ZX81/TS1000/TS1500: 
Add Memory that won’t Forget! 

^ DESCRIBED IN lUidiO- 
JULWAUGUST 1983 Eteetroaics 


ADD YOUR OWN SYSTEM UTILITIES 

•X BUILD UP A LIBRARY OF MACHINE 
LANGUAGE SUBROUTINES 


UP TO 8K NONVOLATILE RAM 

USE HM6116LP CMOS RAM 
OR 2716/2732 EPROM 

COMPATIBLE WITH 
16K RAM PACKS 


^ READ THE REVIEWS: 

What a super oroduct!...conceived and executed very nicely ..and with quality components 

(SYNTAX QUARTERLY Winter 82) 

8K Nonvolatile memory is a gem! It has so many possible uses. .1 recommend this board most heartily 

(OKLAHOMA S.U.G. Newsletter 1/3) 

We found the documentation to be far superior to that (of) most hardware we’ve received 

(S.U.N. Newsletter Nov/Dec 82) 

For versatility this is even better than an EPROM.. ranks quite high on the list of "must-haves 

(SYNC Magazine Mar/Apr 83) 

Provides the user with instant software, an extremely versatile memory extension. 

(Z-WEST June 83) 



INTRODUCTION . 

This memory board is designed to (ill the transparent 8K block 
of memory (from 8K to 16K) m a ZX81 -ISK system This area of 
memory is an ideal place to store, either permanently or tem¬ 
porarily. machine language routines or data which are to be 
used by the BASIC system 

Sample utilities are included with the kit 

The use of HM6116LP 2K CMOS RAM memory IC s with their 
own reserve power supply means that routines stored m the 
RAM are nonvolatile - the RAM retains its memory even 
when the ZX81 is switched off or reset Moreover, being RAM, 
the routines you store m the memory are easily modified The 
lithium cell supplied with the board will maintain sufficient 
reserve power for almost ten years 


ASSEMBLY 

Complete step-by-step instructions m a 20 page manual 
make assembly of the board easy The kit (pictured above) is 
complete with a siikscreened solder masked printed circuit 
board all capacitors, resistors, transistors, sockets, connec¬ 
tors integrated circuits, and the lithium cell The board is sup¬ 
plied with one 2K CMOS 6116LP 3 RAM - it will accomodate 
three more for a total of 8K 


Complete kit With one 2K 6116LP-3 $32.95 

Additional three 6116LP-3 $18.00 

Bare pc boara & manual $13.05 

Kit tor EPROM use only $22.95 

Assembled & tested with 2K $47.95 

Assembled & tested with 8K $65.95 

Shipping & handling per order $ 1.95 



Send check or money order to the address below 

HUNTER, 1630 FOREST HILLS DRIVE, OKEMOS, Ml 48864 



TSHirkinx 

Affordable Quality lor the Timex Computer User 
2002 SUMMIT ST. PORTSMOUTH OHIO 45662 

TABLE OF CONTENTS 


Introducing the 20^8 

3 

STAFF 


Memory Reduction, by Bill Moreland 

A 



Christmas Gift Guide 

6 

Publ isher/Editor 

Richard Duncan 

Matrix/Cursor Input, by Bill Johnson 

9 

Assistant Editor 

Bill Johnson 

Rule of 1978 

12 

Production Assistant Randall Duncan 

Programming Tips 

14 

Editorial Advisor 

Edwin Simpson 

Hardware Hints 

15 

Technical Advisor 

Tracy Norris 

Kids' Page 

U 

Contibutors 

Wi 11 iam Cline, Jr. 

Numerical Analysis, by K. D. Lewis 

18 


Bill Johnson 

Using the ZX as an Instrument Controller 

19 


Ken Lewis 

Book review 

20 


Jason Setters 

Reset Switch, by Uilliam Cline, Jr. 

22 


Edwin Simpson 

T-S News 

25 


Paul Simpson 

Sinclair-Vision? 

27 



Compattblity 

28 





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Pm 1 




T'SHariiinj 

Dear Readers, 

Our first issue generated quite a lot of interest. The single feature that most people 
wanted to find out about was the announcement of the 8-inch disk drive and interface that 
would be available through T-S HORIZONS from Tracy Norris. At the announced price it seems 
almost too good to be true - tentatively under $200. 

Unfortunately, since the first issue was published, Tracy has become involved in a legal 
dispute concerning copyright restrictions. I was asked not to go into specifics, but Tracy 
has effectively been prohibited by the courts to publish any writings pertaining to any 
Timex-Sinclalr product, until the case is heard in early December. 

Tracy says the system will be made available early next year. Let me assure readers of T-S 
Horizons that the announcement of the disk drive in our premiere issue was not a marketing 
gimmick, but a sincere effort on Tracy's part to offer a useful and greatly needed product 
to TSIOOO and ZX81 users. No one is more disappointed about the delay than I am. (I could 
use a couple of megabytes of cheap mass-storage.) 

Another unfortunate result of Tracy's legal situation is the dearth of hardware features in 
this issue. Tracy had planned to write two to three articles per month for T-S Horizons. 
Since he gave me the "bad news" I have approached several hardware-oriented people for 
material. In the works for the next couple of issues is a simple tone generator, surplus 
keyboard expansion for the TSIOOO, and a simple LOAD/SAVE controller. Sonny Cline, of the 
FUN-2 user group in Indiana, came through at the last min.te with some plans to install a 
reset switch. We really appreciate Sonny and people like him who have been supportive of 
our efforts here at T-S Horizons. 

You know, one thing I've always hated was reading a magazine with a lot of typos. So when I 
finally got a chance to really check out the first issue after I got it from the printers, I 
nearly choked! I thought 1 had checked everything carefully. Well, hopefully typos and 
other errors will be kept to a minimum in this issue. 

Kids Page has the first installment of a special graphics tutorial in this issue. Don't 
pass it over too lightly. The concepts are quite simple, but I've been surprised at how 
many users are unfamiliar with them. 

It looks like Bill Johnson's new article is even better than his previous one. Also his 
"User Friendly?" feature scheduled for last issue has been included in this issue. The 
reader survey mentioned last time has been delayed to a future issue. 

In this and the next few issues we'll be experimenting with new logos and page layouts. But 
to really make T-S Horizons into what we want it to be we need to know what you want it to 
be. Please drop us a line or two and let us know what you think so far. 

Thanks 

r a 

Rick Duncan 



Introducing the 2068 


Fieux 


Think of all the things you like about your 
TS-1000; low cost, one'touch entry of 
keywords, expandability, syntax check, and 
third party vendor and literature support. 

Now think of all the things you dislike 
about your TS-1000: membrane keyboard, slow 
cassette loading, limited graphics, and RAM 
pack wobble. All these problems have been 
corrected in the new Timex Sinclair 2068, 
yet most of the qualities we've come to 
expect from TS-1000 computing have been 
preserved. 

Some of the features that make it even more 
attractive are color and sound, of course, 
and high resolution graphics (512 x 192 
pixels), automatic repeat, an on-off 
switch, a full space bar, upper and lower 
case printing, and a promised library of 
cassettes and EPROM cartridges. 

After a long gestation, Timex appears ready 
to deliver the TS2068. So far the new 
computer has only been seen at computer 
shows. At the second annual Boston Timex 
Sinclair convention, a vendor was selling 
the 2068 (rumor had it that his sister 
works for Timex) and people were literally 
throwing hundred dollar bills at him to get 
one. 


Timex is emphasizing the following applica¬ 
tions: 

- Word Processing - The 2068 has a port for 
a video monitor, and the display has an 
optional 64-character mode. An 80-column 
letter quality printer is promised for 
early 1984 for around $200.00. The 
keyboard is type-writer style with 
automatic repeating. 

Game-playing - The 2068 is equipped with 
an Atari-type joystick port. A unique 
"Command Stick" (TS2090) is to be available 
when the computer is. Timex is touting a 
new flight simulator, a drag race game, and 
space game - all on plug-in cartridges. 

Telecommunications - A modem (TS2050) 
provides access to stock markets, 
home-shopping, electronic mail, and ticket 
reservations. 

The computer is accompanied by a 300 page 
full-color user manual. There is many new 
commands like READ-DATA-RESTORE, DEF FN 
(define function), color commands, DRAW, 
CIRCLE, commands to address mass-storage 
devices, and more. TSIOOO users will be 
Impressed by the new symbols and 
punctuation like underlining , [brackets], 
§braces§, a copyright sign, a /backslash, 
an @, an f , a#, a %, an &, an ', and 
something to really get excited about, an! 



PME 9 













MORELAND'S MEMO 


MEMORY REDUCTION 
By: Bill Moreland 

The Timex computer is a wonderful machine, 
but it does have its limitations. With 
clever programming, some thought about 
alternatives, and a few hours spent "on" 
the computer most of the difficulties can 
be overcome. 

For example, I have all of my accounting 
and cash register functions set up on a 
modified Timex 1000. (The modification is 
a fancy keyboard.) As many of you know, we 
own an entertainment store in Columbus. 
All of our retail transactions are entered 
on the TSIOOO with receipts printed for the 
customer as well as business records. Each 
evening we off-load the program after 
printing the daily receipts, week-, month-, 
and year-to-date totals (long load and save 
times are a pain for us too!) 



Cash register receipt trom 
Magic Castle Uideo. 


Originally, this program was about 39K. 
But after waiting 25+ minutes for loading 
or saving, we decided to shorten and modify 
the program as much as possible. Using the 
tricks described below, the power of the 
program was increased while reducing the 
total memory requirements to less than 8K. 

Let's start with the little appreciated 
fact that the T/S stores numbers different¬ 
ly than it stores characters. The number 
"1" occupies seven bytes, while a char¬ 
acter (even numbers stored as characters) 
are stored as single bytes. 

For example, the expression 

LET A = 1234 

stores the number 1234 in ten (10) bytes in 
the variables area of memory (the number of 
bytes needed to store an integer is the 
number of digits plus six). On tue other 
hand, the expression 

I 

LET A = VAL "1234" 

stores the characters "1234" in four (4) 
bytes. (Formally speaking the leading and 
trailing quotes and the function VAL also 
occupy space--three (3) bytes.) A savings 
of three (3) bytes (including the other 
stored characters) does not sound like 
much, but the savings are cumulative. 

A second technique that saves a lot of 
memory is the use of assignment statements 
to fix values in GOSUB or GOTO transfers. 
For example, using GOSUB 1000 for a 
transfer seems simple and straightforward. 
Yet, if statement 1000 is a major transfer 
point that is used as an entry many times 
: during a program, then a simple LET A = 
I 1000, GOSUB A sequence will save many 
bytes. To estimate how many, multiply the 
number of repetitions times the saving, eg. 
25 (GOSUB calls) * 9 (bytes). = 225 bytes. 














Combining both of the above techniques in 
an example may help. Suppose you want to 
use statement 1000 as an entry point for a 
print routine that is called several ways 
by the main program. (We have forty dif¬ 
ferent ways to get to a print point in our 
cash register program.) Or, suppose you 
want to use statement 1000 as an entry 
point for calculation and storage in a 
large array of data. Whatever the uses of 
these techniques, it looks like the follow¬ 
ing: 

15 LET A = VAL '»1000»' 


95 GOSUB A 


200 GOSUB A 


400 GOTO A 


Since most of us are not mathematicians, 
and are not interested in number theory, I 
won’t go into the details of conversion 
from decimal to octal or hexadecimal or 
base 36. Suffice it to say we chose to use 
the base 256 as our number system because 
the Timex works well as an eight-bit pro¬ 
cessor on this number base. 

Using this method, the Timex can store any 
integer between -32,767 and +32,767 
(decimal) in two (2) bytes. Normally, as 
we saw above, a four-digit integer requires 
ten bytes of memory. So significant memory 
savings occur by using a simple conversion 
routine before storing a number in an 
array. The listing below shows a simple 
input and output procedure that 
incorporates the base 256 conversion. One 
caution: Remember to convert the contents 
of your array back to decimal form before 
operating on or printing the data! 


Each time the variable A is specified in a 
statement within the program instead of the 
four-digit integer, nine (9) bytes of 
precious memory are saved. Total savings 
will, of course, depend upon how many times 
A is used. 

A third technique we use can save an enor¬ 
mous amount of memory when dealing with 
large data arrays. First the theory, then 
I will list a subroutine that may be very 
useful. 

Most of us grew up learning the decimal 
number system (base 10), and we all learned 
that other number systems were possible, 
even desirable, under special 

circumstances. Storing large amounts of 
data in a limited memory is just such a 
circumstance. Since the computer uses a 
binary (base 2) number system, and since 
the computer can operate (translate) with 
other number systems quite easily, why not 
use a number system that maximizes the 
storage capacity of the machine? 


9900 DIM F$(5,25) 

9910 FOR X=1 TO 5 
9920 INPUT ZX 

9930 LET F$(X,24)=CHAR$ INT (ZX/2 
25) 

9940 LET F$(X,25)=CHR$ (ZX-CODE 
F$(X,24)*256) 

9950 NEXT X 


9960 FOR X=1 TO 5 

9970 LET ZX=C0DE F$(X,24)*256 

9980 LET ZX=ZX+C0DE F$(X,25) 

9990 PRINT X,ZX 

9995 NEXT X 



2386 Wellesley Lane 

Lane Ave. Shopping Ctr. 

Columbus, Ohio 43221 

(614) 488-1181 

llon.-Sat. 10 a.iii.-9 p.ni. 

Sunday Noon-O p.ni. 


PAGE 5 






CHRISTMAS GIFT SUGGESTIONS 


CHRISTMAS BUYING GUIDE 

Recently someone suggested that a 
gift-buying guide of Timex-Sinclair-related 
products would be a good idea for the 
December issue. I hesitated at first. 
After all there are literally thousands of 
products that could be considered, and no 
one could cover the whole range adequately. 
I gave it some thought and I consulted the 
Bill Moreland of Magic Castle Video in 
Columbus and a few other people. What 
follows is a list of several products that 
come highly recommended, but please bear in 
mind, that this is not intended to be an 
exhaustive list. 


make a set of stick-on keytops that are 
placed individually over the key locations 
on the Sinclair (or Timex) membrane key¬ 
board, to simulate the feel of a real 
keyboard. Their address is P.O.Box 4068, 
Little Rock, AR 72214. Only $5.95. 

However Bill Moreland recommends the 
Filesixty overlay keyboard. It also comes 
with adhesive backing to stick on the 
membrane keyboard, but it is all one piece. 
The Files ixty keys actually *'give” and 
produce a calculator-type feel. It is 
available from Magic Castle, 2386 Wellesley 
Lane, Columbus, OH 43221, and other deal¬ 
ers, for $19,95. 


COMPUTERS 

Obviously, the first consideration is; does 
the gift recipient have a Timex computer? 

With the introduction of the TS1500, prices 
for the TSIOOO will continue to drop. 
(Don’t be surprised to see the price go 
under $20 if the backlog of TS-1000*s 
continues for a while.) It may then be in 
the price range most people would consider 
as a Christmas gift. 

Actually having seen the new TS1500, I 
really cannot recommend the TSIOOO too 
highly. The 1500 is what the original ZX81 
and Timex 1000 should have been. The 
biggest (and often only) objection many 
people had to the ZX81 was the keyboard (or 
lack thereof). Can you imagine what would 
have happened in 1982 if Timex and Sinclair 
would have come out with the TS1500 for 
around $100? Everyone would have bought 
one! The 1500 is internally identical to 
the 1000. Plus you get 16K RAM, a real 
keyboard, a sturdier case and a cartridge 
slot all for around $80. 

One product for anyone who has a TS-1000 or 
ZX81 without a separate keyboard, (recom¬ 
mended to me by Tracy Norris) is made by 
E.H. Enterprises, in Little Rock. They 


Before I go to other accessories, I recom¬ 
mend the TS-2068 as a more expensive 
Christmas gift (See this issue’s article on 
the 2068). While it is a very powerful 
computer, it also doubles as a video game 
machine at a price not much more than the 
’’pure game machines.” 


#So/ve your LOADing problems\ 
I Duplicate any TS/ZX Cassette 
I ... and morel 

I with 

\ IUINM¥ BOMDII 

■ CRSSem COMPUTER INT€RfFK€ 

, For your 
TS 1000,ZX8H80 

H I I I ^ III I * aclualsiZ0 1 X 1H’ 

• User friendly. Just plug Into 
cassette player and computer 

• Complete directions for 
multiple uses 

_ • Protective case included 

|^$19.95assembled; $14.95kit-add $1.00sh. 

I MasterCard/Visa 1-814-364-1325 

I G. RUSS€U eUCTRONKS 

I ftD 1 • BOX 539 • C€NTfl€ HALL, Pfl 16828 

■ FREE information and list of utilities ^ 

on cassette on request. ARQI 


- on cassette on request. 

•Pa add 6% sales tax 


PAGE 6 





ACCESSORIES 


A nice gift for serious programmers (no 
matter what computer they have, if they use 
cassette storage) is a supply of Loran 
computer*grade tape. They provide superior 
performance and come in 3, 5, 7^, 10-minute 
lengths, with a special over-write pro¬ 
tection. They retail from $1.95 to $3.25. 
Another is the Headmaster Headcleaner, a 
"wet” system for cleaning audio cassette 
players. It is non-abrasive, and 
easy-to-use. (Recommended once per month). 
Retails for $7,95, Both products are 
available from Magic Castle Video and from 
most computer and audio stores. 

The Timex 16K memory pack for the TSIOOO is 
notorious for its tendency to wobble during 
programming (which causes all kinds of 
problems). One solution, called "The 
Solution" is a special rubber ring that 
stabilizes the RAM pack. (Available only 
through Magic Castle Video for $3.95). 

SOFTWARE 

ZX Pro/File written by Thomas Woods is said 
to be perhaps the best program available 
for the TSIOOO, and is highly recommended. 
I recommend it for people who are really 
serious about Timex programming. It comes 
with a 59-page book to guide you through 
the powerful features of this program. 
Available from Robotec, Inc,, 59 C Street, 
Ampoint Industrial Park , Perryburg, OH 
43551, for $14.95 (Cheap.) 

HARDWARE 

A good hardware project for amateur 
solderers is the Hunter Non-Volatile RAM 
Kit, This is an excellent product. With 
the kit you can add from 2K to 8K CMOS RAM, 
in the so called "invisible" 8 to 16K 
region of computer memory. Extremely good 
instructions and materials, easy-to-build, 
and very useful for storing machine code. 
(See inside front cover for details.) 


LET YOUR ZX81/TIMEX 1000 
WORK FOR YOU! 

PERSONAL AND BUSINESS PROGRAMS: 

Are on cassette, are menu driven, run with or without a printer and save 
on tape automatically 

SALES FILE 16K or 64K: 

Holds (150 16K) (600 64K) products w wholesale and retail prices — 
Shows separate wholesale and retail totals and amount of profit m up 
to (25-16K) (too 64K) different accounts — Records inventory automat¬ 
ically or manually — Totals sales tax — Cash register m^e totals, 
identifies, adds sales tax. and keeps records for your bookkeeping. — 
Prints a list of products, accounts, inventory and sales slips with printer 
•**A must for any small business**’. $19 95 

CHECKING 16K or 64K: 

Lists (25 16K) (100 64 k) deposits showing amount and date entered 
— Lists (80 16K) (500 64K) checks and displays check number, date 
and payee — Lists by account total of checks written — Keeps running 
total of checks written and balance left in account. — Adds interest and 
subtracts service charges. — Search for a check by number, name, 
date or amount Print a list of deposits, accounts, and checks with printer. 
*”Great for tax records *”. . $9 95 

INVENTORY 16K or 64K: 

May be used for everything from keeping an accurate inventory for your 
business to your personal record collection. — Holds up to (150 16K) 
(750/64K) items w comments for each. — Comments may be used for 
senal numbers, dates, prices or location. — Lists all items, search for 
single item, change or delete any item — Sort items in alpjliabotical or 
numerical order — Prints a list of items, quantities and comments. 
"’Everyone should have an inventory of household items in case 
of fire or theft *" .$9 95 

MAILING LIST 16K or 64K: 

Holds (100 I6K) (425 64K) names, addresses and telephone numbers 
— Search by name, city, zip code, or phone number — Will sort by 
name city, or zip code m alphabetical or numerical order — Lists all 
names, changes or deletes — Prints list of names or names and 
addresses or address labels if they are available for your printer 
‘"A valuable tool for your home or business***.$9 95 

APPOINTMENT CALENDAR 16K: 

May be used for everything from reminding you of birthdays to business 
appointments — Just enter the date and list up to (8) appointments per 
day for up to (31) days — Lets you change or delete any appointment 
— Print a list of appointments for day or month Save all appointments 
on tape 

’"Keep a permanent record of past appointments’" $9 ,95 

FINANCIAL RECORD KEEPER 16K: 

User can define and use 20 files of income and or expenses which may 
be noted as tax deductible for future reference if applicable. — Informa¬ 
tion may be reviewed in various ways — Includes ability to correct or 
change information already entered without knowledge of computers or 
programming. At end of year you have a complete overview of cash 
flow for the preceding year and a list of tax deductible expenses. — 
Prints all information with a Timex or compatible printer. . $14 95 

FINANCIAL RECORD KEEPER PLUS — 48K: 

Does everything the above 16K version does, plus keeps up to 500 
checking transactions and it automatically reconciles the checkbook with 
the bank statement 

’’’A complete finance package"’.$19 95 

GRADEBOOK 16K to 64K: 

A sophisticated, friendly and flexible grade management program for 
teachers of all levels — Ranks students by weighted or unweighted 
average — An example of the program s capacities with I6K: 50 stu¬ 
dents may have up to 40 exams — GRADEBOOK is limited only by 
memory size. 

"’Written by an instructor at Purdue University’".$9.95 

INVOICE CONTROL: 

A program designed to keep track of and print invoices for the small 
business. — Is self-adjusting to memory size. — Will hold (20 16K) 
(120/64K) invoices of up to (5 16K) (10 64K) lines each. — Review or 
change any invoice, list all invoices, list invoices with an open balance, 
enter additional payments and review invoices written to a particular 
account. Prints your company name and address on each in¬ 
voice..$14.95 

Send for free catalog of personal, business & educational programs such 
as -CASH REGISTER." MULTIPLICATION TABLES, MATH QUIZ and 
FLASH SPELLING at $9 95 each — C-10 blank cassettes packaged in a 
hard plastic box 10 pack $8.50 - 5 25" Diskettes sinqie side/double-density 
soft sectored with hub nngs 10 pack only $1800—add $2 per 10 pack 
shipping for tapes and diskettes 


Any throe $9.95 tapes for $24 95 DEALER INQUIRIES INVITED 

Add $1.00 per tape for shipping. Indiana res add 5% sales tax. Send Certified 
Check, M O , Visa or MasterCard No. with Exp. Date 

NIATH COMPUTER SERVICES 
9S0 East - 52 South 
Qroofitown, IN 46S36 
Phono (317) 62S/3130 











• TV Cll C Inventory Records 

rK\-/”l ILC Personnel Files 
16K $16.95 NOW with 59 page user’s manual. 
The just released, machine code updated 
version of ZX DATA FINDER (below). 

• Instant searches • Printer compatible 

• Multi-word searches "Numeric ordering 

r Z-WRYTER — WORD PROCESSING $12.95 
t PROFIT PLAN — Analyze 5 proposals. 30 
variables each. A MUST for entrepreneurs. 

16K $12.95 

t EZ-HEX — Write, edit, test, and save 
machine code hex programs. 16K $12.95 

» ZX DATA FINDER — Data handling fully 
explained. 28 page tutorial manual. 16K 

"The most useful and economical program dedicated to the 
data handling that I have found yet" SYNC, Jan • Feb., 1983 $14.95 

t METAGRAPHICS — Draw and save any 
graphic pattern with machine code cursor 
control. 16K $14.95 

k CHECKSTUB — Register and Budget.$l2.95 
y r^QAPH I A II — Eouation Grapher $14.95 


^ STOCKING STUFFER SPECIALS 

Offers good through 12-3T-83 

Buy any 3 programs and the least 
expensive selection is absolutely FREE!!! 

-and 

ARCADE GAMES 3-PAC, ONLY $25 

Our 3 best machine code arcade games. 

TIMEBLASTERS • ULTWA-FAST cla««ic space battl* 


TEE • Th« MttlHHite ehaltenae et your 


MAZEBALL • 7 «cr#«w ol frantic action 


$14.95 each or ALL 3 FOR $25 


* TEACHER’S GRADEBOOK — Grade records, 
Statistical analysis, and more. 16K $12.95 

* NFL*****USFL STATISTICAL SUMMARY 

Complete statistics for every team in the 
league. 3 versions, USFL ’83, NFL '81 -’83, 
NFL '82 -’84. NFL covers two seasons. You 
update weekly. 16K $14.95 

* EPHEMERIS V — ASTRONOMERS!! 16K 
Deluxe planet finder and much more. $14.95 


robotec. inc. 

59 C Street 

Ampoint Industrial Park 
Perrysburg, Ohio 43551 
VISA 419-666-2410 MC 

ROBOTEC software is now available 
at your local SOFTWARELAND store. 


Name 


Name 


Addresi 


S&H $1.25-f-ISO for each add'l cassette 
Ohio Residents b''3°a Sales Tax 

FAST DELIVERY 
PHONE ORDERS WELCOME 


Credit 
Card No 


Date _ Signature 


BOOKWARE 

A new book from Wayne Green, Inc., is a 
great resource for any TSIOOO user. **Con- 
verting to Timex Sinclair BASIC” is an 
excellent manual of BASIC commands from 
virtually every BASIC dialect. It makes 
converting BASIC language programs almost a 
mechanical process. It*s the most compre¬ 
hensive treatment of the subject available. 
Wayne Green Books, Peterborough, NH 03458. 
$14.95 plus $1.50 shipping. 

My final recommendation is a product very 
close to my heart - T-S Horizons. There 
are several publications for the TSIOOO, 
some good, some bad, but T-S Horizons 
produces the highest QUALITY material 
available at a price lower than ANY other 
TS/ZX-based magazine! And we do it every 
month. We are determined to make T-S 
Horizons the best magazine for the TSIOOO 
(and 2068) at any price. All that for 
$12.00 a year. That*s what I call a nice 
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FEATURE 


MATRIX/CURSOR INPUT 
By; Bill Johnson 

In any interactive computer program (i.e., 
one that requires the user to supply the 
computer with information at several times 
during program execution), far more time 
will be consumed waiting for the user to 
get the computer information than the user 
waiting for the computer to finish 
manipulating the data. Not only are we 
simply slower than the computers, but since 
the computer must have the correct data in 
order to generate the correct answer, 
inputs must always be checked and then 
re“checked in order to minimize the pos¬ 
sibility of error. This "weak link*', where 
information must pass from computer-to-user 
and user-to-computer, can be addressed in 
two ways. The first is through the use of 
such hardware as touch screens, "mouse" 
controllers, etc. But the. most straight¬ 
forward way to address the problem is 
through software. The user must be able to 
clearly understand what the computer is 
asking. This involves concise, readable 
questions or queries, and responses that 
require only a minimum number of key¬ 
strokes. Error recovery is another impor¬ 
tant partial solution to the problem of 
data input, one that we will deal with 
separately in a later article. But what we 
will address now is the question of how to 
get the most information on the screen, in 
a relatively simple and imageable format, 
in order for the person sitting at the 
computer to have the maximum understanding 
of not only what is being asked of him by 
the computer, but also what information the 
computer already has. 

In most programming applications, data can 
be broken down into repetitive sets, simi¬ 
lar in units of measure and other respects. 
To input each set of data, similar or 
identical sets of questions must be asked 
in order to prompt the inputs. When this 


is the case, the twin problem of requesting 
information in a readable format and then 
displaying the received data in a readable 
format, can be solved by what I call 
Matrix/Cursor Input. 

The idea is to map on the screen a set of 
headings at the top and side that outline 
an empty matrix into which you can input 
information. To prompt inputs, all one 
needs to do is to place a cursor (i.e. a 
question mark or inverse question mark) in 
the location on the screen corresponding to 
the row and column that define the informa¬ 
tion that the computer requires. After 
this information is read in from the key¬ 
board, it can be printed in that same 
location, and the process repeated until 
the entire matrix is filled with informa¬ 
tion. 

For example, in the screen copy below, each 
row holds a different type of information 
and each column holds a set of infDrmation 
describing a particular business trip, 

(PRINT HEADING HERE...) 

BUSINESS TRIP 123 

DESTINATION 

DATE(MO/DY) 

ODOMETER(IST) 

ODOMETER(END) 

GASOLINE($$$) 

GASOLINE(GAL) . 


*TOT.MILEAGE= 

*MILES/GAL. = 

*AVG.$/GAL. = 

Using this concept, the data from three 
business trips can be requested, INPUT^ and 
PRINTED on the screen with a minimum of 
changes in the screen--allowing maximum 
display of inputs in an easily examinable 


PA6E 9 


format. This method makes it possible for 
you to check your entries a second time, 
after all the information has been read in, 
giving you a chance to see discrepancies 
between sets of data. Also, the more 
information you can get onto the screen at 
one time, the more control the user gains 
over the program and its data. 

We will now briefly outline this concept 
and then go on to a detailed description of 
how to incorporate it into your programs. 

OUTLINE OF PROCESS 

1. PRINT a row/column format on the 
screen. 

—Headings and titles: be sure to 
include units of measure and other 
important notes. 

2. PRINT cursor (inverse question mark) 
in the correct row/column of the 
matrix. 


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3. INPUT information (into an array) 

4, PRINT information in its square (over 
the cursor). 

5.PRINT cursor in the next square. 

As a specific example of this format, we 
will now look at the input section of a 
program I have written to analyze the heat 
gain/heat loss of a building. 

This particular portion of the program 
requests information describing the windows 
for a room in the house. Each window has a 
data set which describes its area, orien¬ 
tation, shading, etc. This program accepts 
up to four windows per room, 

(PRINT HEADING HERE) 


GLASS 

1 

2 

3 

4 

AREA(SQFT) 

1024 

572 

544 

750 

DEG.HORIZ. 

90 

90 

75 

90 

DEG.REF.< 

10 

55 

10 

-80 

OVERHANG 

24 

24 

0 

24 

WINDOW HT. 

72 

48 

72 

72 

HEAD TO OH 

8 

8 

0 

8 

NO.GLAZNGS 

2 

2 

2 

2 


The cursor would begin in the upper left 
part of the matrix and continue down the 
column until the first window has been 
fully described. The program will then 
proceed to the second column, and so on. 

Before we go on to a program listing, let's 
look closer at the outline given earlier 
and clarify some programming decisions. 

1. PRINT a row/column format on the 
screen. This involves a decision as to 
what the length of the inputs will be 
(i.e. 0-9999, all integers, requires 

four characters as well as separating 
spaces), and whether the inputs would 
be in a row or column. I placed the 


glass data in a column in this case 
because seven items would not fit in a 
single line. 

2. PRINT a cursor in the correct cell. 
This requires you to set up two print 
position variables (x,y), one to indi¬ 
cate the row and one to specify the 

column. In setting up the glass data, 
we want to print our inputs on the 

fourth line, (row 3 in Sinclair display 
format) and the fourteenth column (#13 
on the Sinclair), We will input seven 
consecutive items in the same column, 
and then proceed to a similar set of 
items five spaces to the right (the 
second column of data). Thus the 
printing locations are as follows (in 

the PRINT AT (row, column) format): 

(3.13) (3,18) (3,23) (3,28) 

(4.13) (4,18) (4,23) (4,28) 


• • • . 

(9,13) (9,18) (9,23) (9,28) 

These are the row/column locations of 
each cell of the matrix that the pro¬ 
gram will have to generate. 

3. INPUT information . This requires 

setting up an array that corresponds to 
the screen matrix that you have settled 
on. For clarity in this example, we 
will INPUT the glass data into a sin¬ 
gle, two-dimensional array of seven 

rows and four columns. But if the 
program were to accommodate several 
rooms (which my full heat loss/heat 
gain program does), it could be 

expanded to a three-dimensional array 
with the third dimension being the 
different rooms. 

4. PRINT information over the cursor. 
Printing the data (using the same print 
position variables as in Step 2) will 
overwrite the cursor and fill the cell 
with data. 

PAGE 11 


Continued on Page 26 





Rule of 1978 - Car Loan Payments 


This program can be used to closely approx¬ 
imate the repayment schedule of a bank 
financed auto loan. Most banks use the 
"Rule of 1978" rather than the simple 
interest formula to calculate loan payments 
for cars. Even though the total amount of 
interest paid is the same in either case, 
in the "Rule of 1978" loan more of the 
interest is paid in the earlier payments 
and less in the latter payments, compared 
to a simple interest loan (i.e., in a 
simple interest loan the interest is 
figured on the unpaid balance). This rule 
was developed due to the rapid depreciation 
of new car values. 


This program allows the option of printing 
to the ZX or TS 2040 printer, using LPRINT 
statements. For any time period over 14 
months, the screen fills up and it is 
necessary to press CONTinue, then ENTER, 
This can be avoided by adding line: 485 IF 
I > 15 THEN SCROLL. 

The last number in the balance column gives 
an indication of the accuracy of the 
calculation. The smaller the absolute 
value of the number, the better the 
calculation. 


Dollar Format Subroutine 

Lines 900 through 990 of the "Rule of 1978" 
program comprise a dollar formatting sub¬ 
routine that can be used in other 
business/financial programs. This routine 
converts the number represented by ZZ into 
the string Z$ which contains exactly two 
decimal places (i.e., 117 is converted to 
117.00 and 456.8352 is converted to 
456.84.) 


X PEM OF 1076**** 

a REH ♦ INTEREST PAYMENT « 

S REM ♦ P.G. SIMP5C3tf4 * 

4 REM ****T~S HORIZONS**** 

190 PRINT "RULE OF 1978“ 

- 'INTEREST PRyMENT"^.. 

RHOONT TO 8E FINANCE 


'YEARLY INT • RATE ( 


110 PRINT 
laO PRINT 
D7“i 

108 INPUT PU 
130 PRINT PU, 

PKPCENDT"; ^ 

138 INPUT Y1 

14.0 PRINT Yl, “NUMBER OF MONTHS7 

14.0 INPUT N 
144 PRINT N 

148 LET PU»XNT (PU*ie&> /‘1©0 

148 LET MX»YZ/100O 

180 LET DsN*(N*l)/'0 

180 LET PM«PU/C Cl-ri*MI) **-N> 

^188 LET 2Z»PM 
170 GOSUB 900 
175 LET D««Z« 

190 LET AP«^N*UAL 
000 LET XC»0 
010 LET IT«AP-PU 
000 LET BL*PU 

080 PRINT “DO YOU UANT A PRINT 
OUT7«Y/N> “ 

060 INPUT A4 

070 IF A4«“Y“ THEN GOTO 310 
080 IF Ai«''N“ THEN GOTO 400 
090 GOTO 060 
300 PAST 

310 LPRINT TAB -9; “g 
3g0 LPniPiT TAB “ *•" 

LPRWr AMOUNT TO 6E PINA 
NCED a“iPU 

“YEARLY INT. RATE (PE 

AGENT> «“;YI 

SB® UPRINT "NUHBER OF MONTHS 

rH? PfiYHENT INTE 

EST® PflVMEW INTER 

410 FOP 1 = 1 TO N 

til LET 

434 GOSUB 900 

hil 14 

440 LET BLsBL-P li*IM 
450 LET Z2=:BL 
460 GOSUB 900 
465 LET 64=Z4 
470 LET IC=rIC*IM 

i I^TflB^a^SS.Tti=N J_PRINT TOB 1 
3^ D4; ; 14; ;B4 

R0C®^EXT X 

ZZ«XC 
510 GOSUB 90? 

814 LET J4»Zf 
816 LET ZZ«AP 
818 GOSUB 900 
820 PRINT ''SUM“;Z4; 

830 IF A4a“Y“ THEN LPRINT “TOTA 

*“5fei*^RINT “DO YOU UXSH TO REPEA 
TT (Y.i^'Ni •' 

560 INPUT A4 

870 IP THEN GOTO 100 

880 IP A4<>“N“ THEN GOTO 550 
600 STOP 

899 REM ROUTINE-PORMRT DOLLARS 

900 LET 2 4*“ *'+STR4 t INT 

( tZZ + .OOS) *100) /100) 

910 FOR Xal TO LEN 2$ 

III 

940 LET 24*24+“-00“ 

950 GOTO 980 

960 IF LEN 24-X=0 THEN LET 24*2 
4+00 

^970 IF LEN Z4-X = l THEN LET Z4«Z 

90® let Z»*2*tUEN Z$-B TO ) 

990 RETURN 



flHOUWT TO BE FINfiWCED =500© 

Y ERRI_V INT- RRXE CPERCENT) =15 


Y*ERRI—V « ■ rT.r-1 I li- ■ 

NUMBER OF MONTHS 
MONTH PRYMENT INTEREST 


1 

S 

3 

4. 

5 

6 

7 

8 

9 

10 
11 
12 
13 
14. 

15 

16 

17 

18 

19 

20 
21 
22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 
5UM 


207.99 

207.99 

207.99 
207.99 
207.99 
207.99 
207.99 
207.99 
207.99 
207.99 
207.99 

207.99 

207.99 

207.99 
207.99 
207.99 
207.99 

207.99 

207.99 

207.99 

207.99 

207.99 

207.99 

207.99 
207.99 
207.99 
207.99 
207.99 
207.99 
2 ©^. 99 
207.99 
207.99 
207.99 
207.99 
207.99 
207.99 

7467.64 


80.41 
78. iS 
75.95 
73.71 
71.48 
69.24 
67.01 
64.78 
62.54 
60.31 
58. ©S 
55.84 
53.61 
51.37 
49.14 
46.91 
44.67 
42.44 
40.21 
37.97 
35.74 
33.51 
31.27 
29.04 
26.80 
24.57 
22.34 
20.10 
17.87 
15. S4 
13.40 
11.17 
8.93 
6.70 
4.47 
2.23 
1437.63 


=36 

BRL.RNCE 

5872,42 

5742.81 
5610.56 
5476.2© 

5339.77 
5201.02 
5060.04 

4916.82 

4771.37 

4623.69 

4473.78 
4321.63 
4167.24 
4010.62 
3851.77 

3690.69 

3527.37 
3361.81 
3194.08 
3024.01 
2851.76 
2677.28 
250©,55 
2321.60 
2140.41 
1956.99 
1771.34 
1583.44 
1393.32 
12©©.97 

1006.38 
809.56 
610.50 
409.20 
205.68 

“.06 


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PReSSfiM 


User-Friendly? have been depressed. If so, the key is 
By: Bill Johnson stored in the proscribed variable and if 

not, the variable remains unchanged. At 
(Editor's Note: This column is intended to any rate, the scan does not wait either for 
present tips on clear, concise, a response, or the ENTER key, as the INPUT 
"user-friendly" programming.) statement does. 


One of the simplest programming tricks that 
can be utilized on the TS lOOO/ZX-81 to 
make your programs "user-friendly" involves 
a BASIC statement that is a powerful one 
yet poorly defined and never thoroughly 
explained in the manual. It is the INKEY$ 
statement, and I doubt whether most ZX-81 
owners have used it outside of game 
programming, if at all. The statement, 
when encountered in a program, scans the 
keyboard momentarily to see if any keys 


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In trying to write programs that are 
user-friendly, the INKEY$ statement can be 
used in two ways; first to eliminate some 
unnecessary keystrokes, and secondly to 
screen out accidental entries. This method 
is particularly appropriate when the number 
of> keystrokes can be cut down to one, such 
as yes or no response ("Y" or "N") or a 
single symbol input. The way to make it 
work is to get the computer -to continue 
scanning the keyboard until a particular 
key is depressed. The following example 
illustrates a yes/no input, with the 
program continuing if yes , branching to 
line 1000 if no, and ignoring all other 
inputs. 

10 REM "INPUT ROUTINE" 

20 LET 1$ = INKEY$ 

30 IF 1$ = "N" THEN GOTO 1000 
40 IF I$<> "Y" THEN GOTO 20 
50 PRINT "YES" 

60 STOP 

lOOO PRINT "NO" 

1010 STOP 

As you can see, the program will continue to 
loop through lines 20, 30 and 40 until one of 
the two required keys is depressed. With a 
little imagination, you can modify the 
program to accept a series of 
single-keystroke entries. 

ERROR CODES - November issue. 

Page 14, column 2, "Patriotic Program" 

Should read "Line 10: 25 grey squares." 

"Line 20: 25 squares - gray 

on top, white on bottom." 






HRRDURR 



REVIEWS FOR THE NON-PROGRAMMER 
A, Gindin 

Sure, we bought the Sinclair because it was 
cheap. Then we read that it could do 
anything a *'real" computer could do if we 
would just write the program in machine 
language. Unfortunately for some of us, 
any foreign language, e.g. German or BASIC, 
is more than we can handle. For us the 
computer should be a device to do things 
faster and better and not an exercise in 
frustration. The problem then is to get a 
configuration (hardware) and program (soft¬ 
ware) to carry out those aims. 

If this is your problem also I would sug¬ 
gest that one of your first purchases be a 
Hunter Board. This is a memory board that 
uses the 8-16K memory addresses and enables 
you to use the fast-load system. (Write 
for it at this address: 1630 Forest Hills 
Drive, Okemos, Michigan, 48864). Another 
item, I would consider is a Z-XLR8*. 
(Ac-cel-er-ate, get it?) This is the fast 
load system that will work together with 
the Hunter board. This combination will 
overcome what I consider to be the worst 
working feature of the Sinclair: the inter¬ 
minable slow loads and saves. Obviously 
another solution would be to buy a Timex 
2068, but you would not get the versatility 
of the Hunter system or the numeric key¬ 
board (to be discussed at a later date). 


of each program. It can be mounted direct¬ 
ly on the Sinclair board, but I prefer not 
to alter the board directly. Some programs 
require you to enter SLOW after entry to 
get the program to run properly. 

• 

The Hunter Board** holds a total of 4 CMOS 
and/or EPROM chips. It comes as a kit, or 
complete if you don't like to solder. It 
is one of the most professionally produced 
electronic kits I have ever seen (of Heath, 
EICO, etc.). Additional CMOS ^ chips are 
available from Hunter or from other suppli¬ 
ers (slightly cheaper). The documentation 
is beautiful. In addition to clear di¬ 
rections for construction there are pro¬ 
grams to save the screen, reload from 
memory, generate a REM statement, merging 
programs, and bytes of free memory. The 
board can also be used as RAM. 

Next month we will deal with crashes, 
printing, and hopefully some useful pro¬ 
grams. 

* From Advanced Interface Designs, Box 
1350, State College, PA 16801. 

HINT: Rubbing a few drops of motor oil 
onto the case of your ZX81 or TSIOOO will 
really make it look glossy. Also a few 
drops of oil on the edge connector will 
prevent the contacts from oxidizing. Fewer 
crashes! 


The EPROM of Z-XLR8 mounts in slot 4 
(14-16K) of the Hunter board and is always 
ready to go. Any software you have for the 
computer (so far I've used it only with 16K 
memory which of course loads into the 16 - 
32K memory area) will load/save in seconds, 
and I rarely ever check now for a good 
save. The Z-XLR8 permits such esoteric 
functions as Graphics Save (of the screen). 
Data Save (of an array in storage), and 
Binary Save (of any number of contiguous 
bytes). It also gives a visible index of 
what's on the tape and the number of bytes 


HINT: A cheap, quick addition to your TV 
monitor is to take a yellow document pro¬ 
tector and a red document protector, put 
them together and tape over your TV screen. 
Viola! A cheap amber monitor. Suggested 
by Sonny Cline of Jasper, Indiana. 



SEND 9.95 FOR CASSEHE 
and manual. Gives 
leasure and helps 
l/our thinking. i6K. 
CIRCLE CHESS, Box 63 
Des Plaines, IL 60017 


PAGE 15 



Timex Computing for Kids 


"Double Feature Adventure" 16K 

- Quest for the Holy Grail 

- The Elusive Mr. Big 

$17.95 from Softsync, Inc. 

This month I want to review "The 
Elusive Mr. Big." For all you 
masterminds out there, you’d better 
be good detectives. This game is a 
lot like "Quest for the Holy Grail" 
(which I reviewed last time) except 
it happens in the city instead of 
the jungle, and you have a shorter 
time limit. 

This is how the game starts. You 
are sitting in your detective 
office and the phone rings. It’s a 
dame. She gives you some informa¬ 
tion about Mr. Big and you have to 
go to New York to catch him. But 
you have to be careful because you 
have to ask people questions and 
they may lie. You can pick up 
certain objects like bandages, 
knives, and a bullet-proof vest to 
protect yourself, but you can only 
carry five things. 

This game has all the same commands 
as "Quest for the Holy Grail" plus 
SEARCH (North, East, South, West) 
for the criminal, STUDY clues, and 
USE FORCE to subdue criminal. 

If you find the criminal you should 
be very careful since he is very 
dangerous and you could be killed. 

See you in the next issue* 

Jason Setters 


HOW TO USE GRAPHICS Part 1 

If you look up the word GRAPHICS in the 
dictionary it says that graphics means 
drawing pictures. When a person uses a 
COMPUTER to draw pictures it is called 
COMPUTER GRAPHICS. Every kind of computer 
has a different way to draw graphics. 

The TSIOOO or ZX81 computer has a special 
way to draw graphics, by using little 
BLOCKS, When you put the blocks together a 
certain way, you can make pictures. The 
key called GRAPHICS (which is the key that 
the number 9 is on), is used to make the 
BLOCKS, 

The easiest way to make a picture with the 
blocks is to line the blocks up in a row 
across the screen. For our first picture, 
let*s try to draw an easy picture of a 
tooth brush, 

10 LET 

20 PRINT A$ 

Here*s how to type in the picture in line 
10, After you type the quote marks (”) 

then press SHIFT and GRAPHICS (on the 
9-key) at the same time. This makes the 
computer ready for the graphics blocks. 
Then press SHIFT and 6, and it will make 

the following block H , Press SHIFT-6 

two more times. Then press SHIFT-F. That 
will make the following block K , Last of 
all press SHIFT-GRAPHICS again (this tells 
the computer to QUIT using the graphics 
blocks). Then type the last quote marks. 
Now anytime you run this program it will 

draw a toothbrush with a black handle. 

Now I admit that a picture of a tooth brush 
isn*t all that great. But that*s just the 
beginning! Another thing we can draw all 
on one line is a snake ! Like in the next 
program. 

30 LET B$=" — » ■=* " 

40 PRINT B$ 



To type in the snake from line 30, press 
SHIFT-GRAPHICS, then press SHIFT-D, SHIFT- 
Q, SHIFT-R, SHIFT-6, SHIFT-E, SHIFT-W, 
SHIFT-6, the letter o (without the SHIFT) 
and then press SHIFT-6 again. Press 
SHIFT-GRAPHICS again to go back to regular 
letters. (Don't forget to put quotes 
around the snake.) 

Some other one-line pictures you can draw 
are a caterpillar MflnHflri 
(SHIFT-GRAPHICS, SHIFT-X, the SHIFT-R five 
times), or a pencil Bl'lll 'l"'TT"fT^ 
(SHIFT-GRAPHICS, SPACE (without SHIFT), 
SHIFT A, SHIFT-L five times, then 
SHIFT-GRAPHICS again and SHIFT-M). 

You don't even need SHIFT-GRAPHICS for some 

pictures, like this arrow >- > . 

To make it just type SHIFT-M, SHIFT-J five 
times, and SHIFT-M again. 


If you use your imagination, you can think 
of other one-line graphics. If you think 
of any good ones, you can send them to 
KIDS* PAGE, 2002 Summit Street, Portsmouth, 
Ohio 45662. Next time we will talk about 
more graphics. Until then here's a program 
to use the snake graphics, called SNEAKY 
SNAKE. Just type in any short message and 
SNEAKY will spell it with his tail. 



XFORTH® 

WRITTEN IN ENGLAND BY 
PROFESSIONAL PROGRAMMERS 
Sinclair ZX-61 ‘Timex T/S 1000* 

• Very full FORTH-79 sub-set 

• On cassette for 16K (or more) 

• Loads in one pass (unlike some versiortt 
which require up to four extra editor 
loads) 

• Compact coding - 10K+ still available for 
user code. 

• Sirx;lair specific look up tables (uses 
Sirclair code instead of ASCII) 

• Extra utilities - CLS, FH.OT ... 

• BASIC call - return to BASIC with simple, 
or^ \Mord inst. 

• Full FORTH restart - No loss of words or 
data 

• Only $25.00/tape ♦ $1.00 P&H. Arkansas 
residents add $1.00 

• F.P. Errhancement - Now available at 
only $15.00 ♦ $1.00 P&H 

HAWO WILD Software“ 

P.a Box 7^ • Little Rock. Arkansas 72217 


SPECIAL $11.00 

Any Mindware, Softsync or 
Timeworks program in stock 

Regular Prices 

Dk'Tronics Keyboard 81.30 

64K RAM 100.00 

16K RAM 40.00 

Graphics Board 44.20 

Toolkit EPROM 17.00 

Q-SAVE 40.00 

Softmagic FORTH CHIP 49.90 


Many other brands of hardware 
and software. FREE CATALOG. 

Send cheque, M/0, or Visa 
with $1.50 P&H/order to 

Integrated Data Systems 
11 Brighton Avenue, 
Department T, 

Toronto, Ontario, 
Canada M4M IP3 
416-466-5571 
(Answer-phone) 





MATRIX INVERSION USING 
GAUSS-JORDAN ELIMINATION 

By; K.D, Lewis 

The inverse of a square matrix C is defined 
by the matrix equation 

cc"^ = c'^ C = 1 

where C ^ is the inverse of C, and I is the 
identity matrix, for example 


1 0 0 | 

I - 0 1 0 

0 0 1 when C is a -3x3 matrix. 

The matrix C ^ exists if and only if C is 
nonsingular, i.e., if the determinant of 
CoC. 

One approach to finding C is to consider 
the matrix equation 

cc'^ = I (1) 


and apply a series of elementary row op¬ 
erations to C on the left hand side of the 
equation and simultaneously to I on the 
right hand side, with the objective of 
transforming the C matrix into I, Ulti¬ 
mately, the left hand side of ^the C matrix 
eqi^ation (1) then becomes IC , or simply 
C . 


These same operations must transform I on 
thj right hand side of equation (1) into 
C in order to preserve the equality. 
Thus equation (1) eventually becomes. 

I C = C (2) 

This is the Gauss Jordan elimination meth¬ 
od. 


The Program 

The program given here uses the ideas 
above, and in addition employs several 
techniques for maximizing pivot elements in 


pivot rows and columns. In order to save 
storage space, the input matrix C js over¬ 
written by the inverted matrix C (i.e., 
the original matrix C is destroyed). The 
program has no error exits, and if a singu¬ 
lar matrix is entered, erroneous results 
are returned. Within the program however a 
’’feasibility index” is computed, and an 
extremely small feasibility index is 
usually indicative of a singularity in 
which case, the matrix has no true inverse. 


To run the program, the user must respond 
to the prompt ’’INPUT DIMENSION N” by enter¬ 
ing N, the dimension of the square matrix C 
to be inverted, and to the prompt ’’INPUT 
C-MATRIX”, by entering the C matrix by 

^ 11 ' ^ 12 ’ ^ 13 * 


Si % Si » ^ • 

In’ 21’ 22’ 


"23*•• 


nn 


Example 

2 . 1 

Invert the matrix C“ 1 2 1/ 

1 .1 .2 

When A is substituted inco equation (1) we 
get 


2 

1 

1 

li 

0 ()! 



-1 

1 

il 

2 

1 C 


I'.'l 

' 1 

1 

2 

0 

0 li 


The program will prompt: ”INPUT DIMENSION 
N.” Since we have a 3x3 matrix, enter ”3”. 
The next prompt is ’’INPUT C.-MATRIX.” Now 
the C-matrix is entered as 2, 1, 1, 1, 2, 
1 , 1 , 1 , 2 . 

The final results are printed out as 
.75000, -.25000, -.25000, -.25000, .75000, 
-.25 000, -.25000, -.25000, .75000. 

(Editor’s note): Ken’s future articles will 
feature: Numerical integration of 
continuous functions using the Trapezoid 
Rule and Simpson’s Rule. 

Statistics package, including mean, mode, 
median and standard deviation computation 
from point input. 

Jacobi Method for simultaneous computation 
of eigenvectors and eigenvalues. 


PAGE 18 



C* XHE^H-S XOH M' * 
-HSTRXX” 


1©© REM MRTINU 

Xa© REM THIS PROGRRH XHvERTS 
REH INPUT HBTRXX C 
ae© DIM Cf.lS.lS) 
as© DIM U C4.©> 

3©@ prxht * irapy 
4^©s XNPLFT M 
5043 HHiNT JNRIJT 

S 2 ? ^^5 ^ 

20© INPUT C i xTJ}^ 

000 NEXT J 
1000 NEXT I 
1100 LET PD=:1 
la00 EGR l_=X TO N 
1500 i_ET DD=:0 
14.00 FOP! K=1 TO N 
1500 OI>=OI>+Cil_ .fCl 0_ .K I 

lt:*00 NEXT K * 

1700 L_ET DD=50R s'DDO 
iS00 EEI PO-POs^DD 
X^mm NEXT l_ 

S000 UET DETM^i 
2100 FOR L=1 TO N 
2200 l_ET UCL.+20X=I_ 

2300 NEXT l_ 

2^4.00 FOR l_=l TO N 
2500 L_FT CC=0 
-2500 1_ET H=4_ 

2700 FOR fC—-L “O 

2S00 IF ( flRBS (CCO -hBS 

=©)) THEM GOTO 31@© 

2Q00 I_ET 

5^0 UET CC=CtL_^K> 

-5100 NEX T H 

3200 IF (U=H) THEM GOTO 4-1©© 

3300 LET K:=^a CM-1.201 

34^00 LET a CH^20> =rU CL4;S0'f 

-3500 LET a ?L f--20> =:K 

3500 FOR K=1 TO N 

3700 LSI f 5=:OrK,L* 

3500 LET C .L‘J ssC jK .Ns 
3900 LET CtK*^M)=S 
4-000 NEXT K 
4-100 LPT P ft l t — 

4^200 LET DETMrrbETiT^Ce 

4-300 FOR H=1 TO N 

4.4.00 LET CTL ».=C €L 

4.508 NEXT M 

4-500 FOR M = 1 TO N 

4-70© IF L=H THEN GOTO 54.00^ 

4.S00 LET C€r=rflfTr.Ll 

J90© IF CCC=0) THEN GOTO 54-0© 

5000 LET CCM^L}=0 

510© FOR K=1 TO N 

iiH tM,K) -CC*C tL,Ki 

54.00 NEXT H 
. 54^10 N^XT L 
55^0 i^OR L=1 TO N 

560© IF €aCL+20}=LJ THEN GOTO 63 

570© LET H=rL 
5300 LET 

590© IF caCM+20J=Lj THEN GOTO 6i 

t?SS CN>H> THEN GOTO 53©© 

5100 LET a CHl 201 =^a 
5200 FOR K = 1 TO N 
6o0@ LET CC=CCL.K) 

CCL..K>icm.K> 
ccH..K}crec ' 

5500 NEXT K 

5700 LET a{L+2©)=L 

5300 NEXT L 

S-iX J>^TT1=rRBS COETHJ 
??S2 E>‘^NRH=DETHxPD 

”THE FEMSXBXLTrv Xr4DX 

7200 FOR I=i TO N 
7300 FOR a=i TO N 
74-©© PR InT C { X . a> 

750© NEXT a 
7500 PPXMT 

7700 HEX“L T 


^SING THE ZX81 AS AN INSTRUMENT CONTROLLER 

A Review By: Ed Simpson and Rick Duncan 

The extent to which the Sinclair computer 
has been utilized as a controller in 
industrial, business and scientific 
applications may surprise some people. One 
of the main reasons for its use is its low 
cost. To. control various instruments and 
appliances, all that is needed is an 
interface device to translate the 
electrical input/output signals of the ZX81 
to the signals used by the device to be 
controlled. 

The February 1983 issue of American 
Laboratory (Vol.. 15, No. 2) features an 
article by Dean Webster, a graduate 
chemistry student at the Virginia 
Polytechnic Institute. Mr. Webster built 
an interface which allows the Sinclair to 
control a Fisher Titrimeter system. The 
result is an inexpensive method to perform 
titrations, which, of course, provides a 
savings in manpower. 

Mr. Webster writes: 

"The Sinclair ZX81, despite its 
deceptively simple appearance offers 
attractive possibilities for use as an 
inexpensive...instrument controller. The 
ZX81 contains a powerful Z80 8-bit 
microprocessor and has a sophisticated 
built-in BASIC. The Z80 bus is also 
conveniently located at the rear of the 
computer." 

Mr. Webster goes on to describe the Fisher 
titration system for which the ZX81 acted as 
a controller. He also presents schematic 
diagrams, flow charts, and "a description of 
the pitfalls encountered (in order to) save 
others time and confusion in constructing" 
such a system. His combined cost including 
a black and white television, ZX81 with 16K 
RAM, and interfacing components came to 
around $350. 

This article may be a valuable reference for 
anyone wanting to use a Sinclair-type 
computer as a controller in other scientific 
and industrial usages. 






By: Rick Duncan 
T]ie.li!lciair_ZX81 
Dilithium Press 
8285 SW Nimbus, Suite 15l| 

Beaverton, OR 97005 
$11.95 ($24.95 with 
cassette) ___ 

‘’The Sinclair ZX81 - Programming for Real 


Applications,” may not be the most recent 
book written for the ZX81 and TSIOOO com¬ 
puters, but it is instructive and 
well-written, and would make a fine addi¬ 
tion to anyone's Timex-Sinclair-related 
library. The book is intended for the new 
user who is ready to go beyond the Sinclair 
manual, yet it has material of interest to 
more experienced programmers as well. The 
author, Randie Hurley, covers a range of 
several practical applications including 
word processing, bulk data storage, test 
scoring and analysis and financial applica¬ 
tions, The program listings are presented 
interspersed with text and are extensively 
documented. All the programs (which are 
available on tape) require 16K RAM. 


The Word Juggler (Chapter 4) is a 
menu-driven mini-word processor, complete 
with cursor controls (on the arrow keys), 
and limited delete, correct, and insert 
capabilities. The program is in BASIC (as 
are all the programs in the book), and 
takes about 3.5K of memory, leaving room 
for approximately 2000 words. There is an 
optional "readability calculator” which 
computes the reading difficulty of the text 
by paragraph. This subroutine is valuable 
for teachers and others who need to gear 
their work to a particular age group or 
intellectual level. The Word Juggler is 
written for use with the 32-column ZX (thus 
TS 2040) printer. 

Chapters 5 through 7 contain programs and 
subroutines for financial applications, 
including a bill payment/checkbook 
balancer, a dollar (or pound) format sub¬ 
routine, and a bank program. The latter is 
a program developed by Mr. Hurley for use 
at a "student bank” in a school where he 
teaches in England, It can handle 200 
accounts and handles various transactions, 
opens and closes accounts, calculates 
earned interest, and does general 
accounting. 


However before presenting the applications. 
Hurley spends two chapters on an excellent 
discussion of programming techniques. 
Chapter 2 begins with a succinct introduc¬ 
tion to flow charting. (All the major 
programs are accompanied by flow charts.) 
The chapter also provides routines for 
input checking, auto start-up and crash 
protection. Program de-bugging and 
a”dry-run” technique are also discussed. 

Chapter 3, Saving Time and Space, begins 
with a comparison of integer, decimal, and 
binary number manipulation as an introduc¬ 
tion to a discussion of memory- saving 
techniques and running and loading time 
saving techniques. 


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(614) 488-1181 




PAGE 20 









Chapter 8 discusses a clever technique for 
the bulk storage of large amounts of data. 

Chapters 9 and 10 have teacher aids like a 
"Rank Order" program to rank students by 
test scores, and a Exam Result Analyzer to 
evaluate test scores by overall 
performance, Individual subjects, random 
samples and other considerations. 

Hardware Modifications, Chapter 11, ,seems 
oddly out-of-place In this programming 
book. Two of the projects are obsolete, 
dealing with the ZX80 and the ZX81 kit. 
The third Is on linking a "normal keyboard" 
to the ZX81, and provides several helpful 
hints for doing so. 

The book does what it is intended to do, 
which is to take the Sinclair user beyond 
the owner's manual, and mostly to offer 
real world applications 
Hurley's eclectic writing 
book a comfortable feel. 


for 

style 


the ZX81. 
gives the 


Partial Pascal 

Bring Tape Under Control 

Partial Pascal makes tape easier and 
more convenient to use. The write state¬ 
ment in your Partial Pascal program 
stores output to tape in buffers in RAM. 
When a buffer is full (or when your pro¬ 
gram indicates it has no more data to 
write). Partial Pascal asks what name 
>mu want to give it and records a header, 
u ® specify and the data from 

the buffer, releasing it to be refilled with 
more data from your program. The head¬ 
er recorded by Partial Pascal, unlike a 
header consisting of silence, allows the 
automatic level control on most cassette 
recorders to stabilize before the name and 
data are recorded, improving reliability 
when the tane^is read. 

Partial Pascal is not fussy at all about 
positioning the tape for input. Anywhere 
before the header of the file to be read in 
will do, inclining in the middle of earlier 
recordings. Partial Pascal keeps you in¬ 
formed of what it’s reading. If it comes to 
a header with a name other than the one 
you ve asked for. Partial Pascal shows 
you th^e name it has found and continues 
searching the tape. This makes it easy 
to rediscover, if necessary, all the names 
you ve used on a tape. If you’ve typed in 
me wrong name, press the space key and 
Partial Pascal will ask you to respecify 
the name. 

The Partial Pascal programminjr 
package includes full-screen editor co- 
resident compiler, run-time interpreter 
utility library, example programs and 
1000^r*T-^ ‘ Timex Sinclair 

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1569 Brittany Court Wheaton, IL 60187 


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MAKE YOUR OWN 'GAME CART.RIDGSS’ 
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IN YOUR TS1000/15C0. WHY WAIT .MINUTES TO 
LOAD FROM TAPES WHEN YOU CAN LOAD FROM 
EPROM IN LESS THAN A SECOND? EACH EPROM 
CHIP CAN HOLD UP TO 4K BYTES OF PROGRAM. 
USE TWO CHIPS TO STORE UP TC £K. SPECIAL 
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BEACON ELECTRONICS 
5002 E. BROADWAY 
TUCSON, AZ S 5711 



CHIRPER modiil# for your ZX81 
or your timex/sinclair 1000. 

The CHIRPER module lets you enter key- 
TOard data fast and accurately. A sound can 
be heard when a key is entered enabling you 
to spot a missed entry or a double entry with¬ 
out looking up at the screen. A buzzy-chirp is 
produced when the key entry routine runs on 
a 1 or a 2K machine. A large program in a RAM 
on key^^*t^* ® continuous tone that changes 

A program can control the sound. Included 
IS a demo program that converts the keys into 
a music keyboard of over two octaves. 

module installs easily inside 
the ZX81 case with only three wires to connect. 
Complete installation instructions are included. 

To order your CHIRPER send a check or 
Canada^^*^^*^ Postage in the USA or 

AniiBn®©iMipjHi (g®o 

3584 Leroy, Ann Arbor, Ml 48103 


SCIOTO 
SOFTWARE 
SYSTEMS. INC. 

Tiine.H Sinclair 1500 
W9.?5 ♦ $2.50 shipping 

TS-2040 Printer 1 

♦S4.95 ♦ $3.50 shipping i 

(Compatibie with TS- 1000 , i 

TS-1500, and TS-2068) 

j 

Ohio residents: j 

Add 5.55C sales tax i 

j 

SCIOTO SOFTWARE SYSTEMS, INC.! 

Rt.l, Box 41 i 

LucasMille, OH 45 ^ 49 ! 


J 


P 1 A 6 E 21 






SIMPLE RESET SWITCH 
By: William Cline, Jr. 

One of the noted short-comings of the 
TIMEX-SINCLAIR TS1000/ZX81 is the lack of 
an "off-on*' switch. I*ve found that adding 
a simple *»reset" switch to the computer 
gives me the same end result as an "off-on" 
line power switch and it has the added 
benefit of less wear and tear on the power 
input jack. 

Adding a **reset" switch is really one of 
the simplest and most inexpensive (read 
cheap) first additions an owner can make to 
his computer. 

In any modifications I give instructions 
for, I usually specify Radio Shack catalog 
numbers simply because Radio Shack outlets 
are accessable to more people than other 
national suppliers. The fact is that there 
are a lot of first-time computer owners 
that will feel more comfortable with spe¬ 
cific part numbers, supply sources, and 
simple instructions. Let's face the fact 
that not everyone who owns a computer can 
make successful hardware modifications 
using "paper clips and alligator clips." I 
will try to make all my instructions as 
"goof-proof" as possible but remember I 
can't be responsible for any damages to 
your machine. 

PROCEDURE 

First disconnect all cables from the unit 
and turn it over. Next remove the three 
rubber pads covering three of the five case 
screws. I usually just stick them to the 
case toward the center so I don't lose 
them. Otherwise they get dirty and won't 
restick. 

Now remove the five screws that you can 
see; be sure to use a good phillips-headed 
screwdriver since you will be removing and 
re-installing these same screws many times 
as you modify your computer. Remove the 


cover and set it aside. I place the re¬ 
moved screws in the turned-up case to keep 
track of them. 

Now while looking at the bottom side of the 
PCB, you will see the raised metal strip 
going diagonally across the PCB. Apply a 
soldering iron to the end nearest the RAM 
expansion edge connector while giving a 
slight upward pull with a pair of 

needle-nose pliers; in a few seconds the 
end will come free. Lift the free end 

gently and brace it up out of the way (I 
used a flat rubber eraser). Now you should 
have a view as in figure 1. Set the unit 
aside and prepare your switch. I used the 
Radio Shack catalog no. 275-1547 which 
comes five to a package. It is a Mini SPST 
NO (normally open) momentary contact with 
solder lugs. Prepare two 2-inch lengths of 
wire (R/S Cat. No. 278-1307-package of 3 
color); it is best to use two different 
colors for later identification. Solder 
the wires to the switch; prepare the wires 
to mount into the PCB. Note at this point 
the more experienced builder will probably 
take out the two PCB screws and carefully 
move the PCB out of the way to drill and 
mount the switch in the rear of the case. 
If you do this be careful to avoid hitting 
any of the PCB components and make sure you 
don't pull out the flat keyboard cables. 
After you have decided on mounting or not 
mounting the switch proceed to the actual 
solder attachment to the PCB. Refer to 
figure 1. Solder one of the wires to the 
indicated point (it doesn't matter which 
wire is used). Be neat and clean. If you 
have used #22 wire it should fit in the PCB 
hole easily. Now remove the rubber eraser 
letting the metal strip again rest on its 
original mounting pad. Place the remaining 
wire lead on the strip and resolder the 
connection. Replace the bottom half of the 
case. Plug in the computer and fire it up. 
A cursor should appear as normal (If it 
doesn * t, remove the bottom and check to see 
if you have loosened the keyboard flat 
cable). Now press the switch. The cursor 


MK 22 



should disappear for a few seconds and 
reappear after the computer has reset all 
the registers to zero and run its intermal 
RAM check routine. There it is: two simple 
solder connections and you have a useful 
addition to your computer. 


-t-5V 



ScHCmat( c 


RA/A COMMdTcToC ,5LoT 



I.o-tT'oaa \/ I £W 


F I 1 


5. PRINT cursor in the next cell. This 
will mean reaching the end of the 

program loop and starting the cycle 
over again. 

The following is a listing of the input 
portion of the heat loss/heat gain program 
that will set-up and read-in the glass data 
in that screen format previously shown. It 
sets up a seven-row, four-column matrix and 
reads information into it. For your infor¬ 
mation, the variables are explained follow¬ 
ing the listing. 


LISTING 

4000 REM MATRIX/CURSOR INPUT 
4050 DIM 1(4,7) 

4060 LET Y=8 

4080 PRINT AT 0,0;"(PRINT HEADING HERE)" 
4090 PRINT AT 2,0;"NO,OF GLASS AREAS?" 
4095 INPUT NO 

4100 IF N0>4 THEN GOTO 4090 
4105 PRINT AT 2,0;" GLASS" 

4110 PRINT AT 4,0; "AREA (SQFT)" 

4115 PRINT "DEG,H0RIZ," 

4120 PRINT "DEG,REF,<" 

4125 PRINT "OVERHANG" 

4130 PRINT "WINDOW HT," 

4135 PRINT "HEAD TO OH" 

4140 PRINT "NO,GLAZNGS" 

4150 FOR N=1 TO NO 
4155 LET Y=Y+5 
4160 PRINT AT 2,Y;N 
4165 FOR X=1 TO 7 
4170 PRINT AT X+3,Y;" " 

4175 PRINT AT X+3,Y;"?" 

4180 INPUT ,I(N,X) 

4182 LET I(N,X)=INT I(N,X) 

4185 IF I(N,X)>=1000 THEN GOTO 4170 
4190 PRINT AT X+3,Y;I(N,X) 

4195 NEXT X 
4200 NEXT N 


VARIABLES 

1(4,7) - array that stores all glass data 
Y - print position variable that 
indicates column 

X - loop variable and print position 
variable that indicates row 


I 




Continued from Page 11 


line 4190 ; print data in its cell. 


NO - no. of glass areas (1-4) 

N - loop variable, indicating which 

column is operating line 4195 : bottom of X loop (7 rows). 



line 4200; bottom of N loop (1-4 columns). 


line 4050 : define the array sufficiently 
large to store all of the requisite 
data. Re-dimensioning will wipe-out 
all existing data and you will have to 
start over. 

line 4060 ; since the print locations that 
we seek are at y=13,18,23 and 28, we 
begin with y=8 and add 5 at the begin¬ 
ning of each loop (line 4155). 

lines 4080-4100 : these lines print a title 
and ask how many glass areas there are 
in order to set up the number of 
columns in the matrix. 


Depending on the requirements imposed by 
your particular set of data, you can fill 
up the screen with a single matrix, or have 
several matrices on the screen at one time. 
And if only a few pieces of data comprise a 
data set, such as in the budget program 
that I discussed in last month’s article on 
files, you could conceivable display 15 to 
20 lines (sets) of data at one time. 

Below is another example of using the 
matrix format) where not all of the data 
columns are applicable to each data set. 

SURFACE TYPE: "BRIC” (1) 


lines*4110-4140 : these statements print 
cryptic headings down the left side of 
the screen to define the type of data 
in each row. 

line 4150 : set up loop to go from column to 
column. 

line 4155 ; increment variable (Y) to the 
correct value. 

line 4160 : print at the top of the column 
the number (1-4) of each glass area. 

line 4165 ; set up loop to go down seven 
rows of data. 

line 4170 ; blank out anything that was in 
the cell (this becomes important in 
conjunction with error recovery). 

line 4175 ; print cursor (?) in the cell to 
indicate data to be input. 

line 4180 ; input data into the 
corresponding cell of the array. 

lines 4182^4185 ; limit inputs to four-digit 
inte gers. 


MATERIAL 

R/IN 

IN THK 

R-VAL 

niTTQTnF ATPFTT.M_ 


0.14 

BRIG 

0.11 

4 

0.44 

PLYWOOD 

1.25 

0.625 

0.78 

STUDS.... 


... 3.5 

0. 

BATT INS 

3.2 

3.5 

11,2 

DRYWALL 

0.85 

0.5 

0.42 

INSIDE AIRFILM.... 


0.68 


NOMINAL R-VALUE= 13.66 
ADJUST.FOR FRAMING= -2,27 
TOTAL R-VALUE= 11.39 








T-S NEWS 


ITEM: The December issue of DISCOVER, and 
presumably other magazines, has an 8-page 
booklet from TIMEX with the comic strip 
character B.C. introducing the TS2068 and 
the following peripherals: TS2040 

32-column thermal printer ($99.95, nothing 
new), TS2050 Modem ($119.95, no mention 
whether it is TSlOOO-compatible), TS2020 
Program Recorder ($49.95, cassette record¬ 
er), TS2090 Command Stick ($14.95 each, 
game controller). Some of the software 
touted in the booklet are an auto mechanic 
program, foreign language teaching, IRA 
interest, flight simulation, drag race, 
spelling, astronomy, solar heating, and 
spelling. The hardware is available from 
Timex Computer Corp., P.O.Box 3138, 
Wallingford, CT 06492. (Add $5.00 
handling; TS2068 price is $199.95.) 



If the following 
pages can’t convince 
you what to do with 
a home computer, 
maybe you belong 
in another age. 


ITEM: The Timex Sinclair Amateur Radio 
Users Group is made up of computer users 
who are interested in putting their Timex 
or Sinclair computers to use in amateur 
radio operations. Most of the members are 
not computer experts, and most but not all 
are licensed by the Federal Communications 
Commission to operate in the amateur radio 
service. 

The group publishes a journal called QZX, 
which is the main benefit of membership. 
It is sent monthly by first class mail to 
all members. Membership is $12 per year 
(with a $7 surcharge for members who live 
outside of the United States, Canada, and 
Mexico). The journal publishes complete 
programs and hardware projects submitted by 
members. The journal also publishes per¬ 
sonal items about the members and informa¬ 
tion about operating events such as nets in 
which the members might be interested. 

Those who wish to join (and they need not 
be licensed amateurs) can do so by sending 
$12 dues to Alex. F. Burr, K5XY; 2025 
O’Donnell Drive; Las Cruces, NM, 88001. 


ITEM: Hawg Wild Software recently an¬ 

nounced a new set of programs for amateur 
radio enthusiasts. The programs are called 
the ”Ham-Hacker” series. The series in¬ 
cludes: 

- Morse code (16K). Code practice with 
built-in audio tone. $14,95 

- MiniMUF 3.5. A maximum usable frequency 
radio propagation program. $17.95 

CE Amp - Common E mitter Amplifier 
design/test program. $19.95 
Prices are discounted 10% until December 
15, 1983. Available from Hawg Wild, 

P.O.Box 7668, Little Rock, AR 72217, 

ITEM: Just got our new 32-page catalog 

from E. Arthur Brown. They sell all the 
Timex hardware, all Memotech products, 
Basicare products, and others. And they 
sell their own line of MKIV peripherals 
including a keyboard (with optional numer¬ 
ical keypad), a modem, keyboard overlays, 
and 16K and 64K memories. They have tried 
to select an assortment of peripherals with 
maximum compatibility with other products. 
The catalog is attractive and informative. 
Available from: E. Arthur Brown Co., 1702 
Oak Knoll Drive, Alexandria, MN 56308. 


PAGE 25 






ITEM: TIMEX has a hotline for Timex users. 
Just dial their toll free number 
1-800-24-TIMEX and (if you can get through) 
the Timex Technical Support Group will 
provide a quick answer to your hardware or 
software questions. Monday thru Friday, 
SAM to 8PM, ET. 

ITEM: TIMEX also has a personal computer 
club. Members receive an official newslet¬ 
ter filled with creative programming ideas 
and early notice of new products. Write to 
Timex Personal Computer Club, Timex Comput¬ 
er Corporation, Waterbury, CT 06725. 


ITEM: In England, Sinclair Research has 

unveiled a compact, continuous loop 
tape-drive and interface for the Spectrum 
called the ZX Microdrive. The approximate¬ 
ly Ih inch-wide tape cartridge has an 85K 
capacity and an average access time of 3^ 
seconds. The tape drive requires a $50.00 
interface unit but the interface can handle 
up to eight drives. (The drives are $75.00 
each.) The interface has an RS-232 port 
and a local-area network port. It is 
expected to bq marketed in the U.S. for 
the Timex 2068. Sinclair Research, Ltd., 
23 Motcomb Street, London, England SWIX 
8LB. 


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How To Get Rich With Your Microcomputer 

Reveals the facts you need to make your microcomputer pay for itself! 


WHAT OTHERS SAY 


Today there are no greater opportunities to make money fast than 
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people have already proved the above statements! You can too! 
Many computer related businesses can be operated from the 
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SECRETS REVEALED 

The computer industry is filled with success stories in which 
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You can apply these same techniques and watch your business ex¬ 
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NO EXPERIENCE NECESSARY 

You do not need to be a computer expert to make money in this in- 
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CONTENTS 

This book is packed with detailed examples of how to make 
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•Word processing service 
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•Computer rental 
•Marketing techr)iques 
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•Plus much mors 

INVEST IN YOUR FUTURE 

You have invested from several hundred to several thousand 
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Here is proof of the value of HOW TO GET RICH WITH YOUR 
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You must be satisfied or return my manual within 90 days for full 
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(H ony). 

Send order to BUSINESS NEWS 

12221 Beaver Pike 
Jackson, Ohio45640 


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♦ALLOWS UP TO 20 PROPERTIES 
♦FILES 15 OPERATING EXPENSES 
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FROM 3 SOURCES OF FINANCING 
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♦ALTERABLE DATA 
♦MENU DRIVEN 

16K cassette & TEXT 

12.95 included) 

George Bezushko 
P.O. BOX 1752 
BINGHAMTON.NY 13902 

(NYS residents add 7^ tax) 


BATTERY 

BACK-UP 

• Uninterruptable power supply 
for ZX80, ZX81, and T/S1000. 

• No memory loss when AC fails. 

• Allows portable computing 

7 hrs normal, hrs with 16K. 

• Completely rechargeable with 
your computer power pack. 

• No wiring, simple plug-ins. 

• Sate, easy to use, economical. 

• Ask tor WITWATT 1000. 

$36.50 plus $3.50 shipping/ 
handling, CA residents add 6% 
sales tax. Send money order or 
check to: WT ASSOCIATES, 

3808 Rosecrans St., #262, San 
Diego, CA 92110. 



PAGE 2d 









Sinclair-Vision? 



If youVe reading this magazine, you’ve 
probably heard of Sir Clive Sinclair, It 
was Sinclair who created the ZX80 and its 
successors the ZX81, TSIOOO, TS1500, Spec¬ 
trum, and TS2048. He made it affordable 
for many people to buy a real computer, and 
a whole industry has sprung up around the 2 
million Sinclair computers sold, You may 
not know that Sir Clive has also been 
working on many other projects through 
Sinclair Research, Ltd., the company he 
founded. 


Ltd., and sells for $120. (Sony's watchman 
is $167 and Casio's mini-TV is $200), It 
is expected to be sold in the U.S. for $99 
in late 1984. The TV's lithium cell 
battery holds a 15-hour charge which is 
several times that of rival mini-TV's. 
Pocket TV's may be as common as pocket 
calculators in a few years. 

What other products can we expect from 
Sinclair Research, Ltd.? Sir Clive is said 
to be very interested in producing electric 
cars. Also in the works: robots, 
telecommunication devices, computer-aided 
design tools, and a new 
business/professional computer using 
"fifth-generation" technology. 


Now Sinclair Research has come out with a 
new pocket-sized television, which Sinclair 
predicts will do for TV what the transistor 
did for radio. The dimensions of the set 
are 5^3^xl^ inches deep, with a 2 inch 
screen. The TV is available only by mail 
order at this time from Sinclair Research, 


Sinclair spends only a few hours a day in 
the office. He says "The office routine is 
an interruption to what I see as my real 
work - which is thinking." 

As for TV-viewing, Clive says he watches it 
only "once in a blue moon." That should 
tell us something! 


Use Your TSIOOO or ZX81 
To Save Money 
*PAY0FF* analyzes Credit 
Card and Charge Accounts 
Do You have an account 
chat will take 10, 20 
years to pay off? Cost 
thousands in interest? 
*PAY0FF* computes: 

- Monthly Finance Charges 

- Minimum Payments 

- Years/Months to pay 

- Total Interest Cost 
AutoStart, AutoSave. 

Gives Printouts, On 
cassette for 16K, $12,95 
ACE S0FT1‘7ARE, 2 E, Oak 
Moorestown, N,J, 08057 


ScreenMate 

Scre«nMate’s Lightpan and InterFace for the Atari * 
Joystick adds versatility to your ZX81 or TS1000. 

• Play Action Games 

• Direct Interaction with 
the TV Screen. 

• Features a “Piggy-back” 

Add On Feedthrough 

'• Draw and Doodle 

• Ideal for Educational 
Programs 

•independent of 

Keyboard > 

$39.95 includes 

• Lightpen with Joystick Interface 

• User Guide • 90 Day Limited Warranty 

• All Postage and Handling 

ScreenMate Program Cassette 
$9.95 includes 

• Draw • Doddle • Math Quiz • Master Mind 

• Tic-Tac-Toe • Word Scramble • Break Out 

• States • Safe Cracker 

Interface Innovations 

4372 Casa Brazilia, Suite 201. St. Louis, Mo 63129 
Check Money Order MasterCard or Visa Accepted 


conuE 

COMPUTINB 

make your computer pay for ITSELF! 

Learn how you can make money with your 
computer. Cottage Computing is a new monthly 
publication which reveals the money-making 
secrets you need. 

SUBSCRIPTION: $12.00 year SAMPLE: $1.00 

Ad rates: $5/inch 

HOME BUSINESS NEWS 
12221 Beaver Pike 
Jackson, Ohio 45640 




COMPATIBILITY 


The original ZX81 and later the TSIOOO have 
been so popular that hundreds of companies 
in the United States, England, and Canada 
have developed literally thousands of 
products that are compatible with the 
Timex-Sinclair computer. This broad 
support opens up a potential that owners of 
some other computers are denied, either due 
to prohibitive expense or non-availability. 

Yet there is a problem. Many Timex users 
have gone to great expense to expand their 
systems only to discover that components 
from different companies are not always 
compatible with each other. 

As an example a recent letter to COMPUTE! 
discribes one ZX81 owner's problem. He has 
a Memopak 32K RAM from Memotech that works 
fine with his ZX81, and a TS-2040 printer 
that works equally well. However he com¬ 
plains that when the printer and the RAM 
are both attached to the computer nothing 
works! In this case the problem seems to 
be an extra circuitry loop that reduces the 
RF emission from the printer. Timex is 
said to have made this modification to meet 
FCC guidelines. While it does not effect 
the Timex 16K RAM, the Memopaks (16K, 32K, 
64K) have subtle differences, and in some 
cases the Memopaks are not compatible 
(although strangely, not always). 


Local stores carrying Timex-related prod¬ 
ucts where you can test new peripherals are 
few and far between, so what's the eager 
TSIOOO owner to do? E. Arthur Brown's 
policy, according to their recent catalog, 
stresses a 10-day trial period for a hard¬ 
ware, during which any item can be returned 
for a full refund or exchange. This re¬ 
moves some of the anxiety about new hard¬ 
ware investments. Also, they try to keep 
tabs on the products they sell and indicate 
in their literature any compatibility 
problems they become aware of. 

Actually, Postal regulations require that 
any item ordered through the mail be eligi¬ 
ble for a full refund, for any reason, if 
the item is returned in essentially the 
same condition as shipped, for a period of 
ten days. (Obviously this excludes any 
attempted hardware kits.) However, when 
buying through the mail an uncooperative 
company can be hard to deal with. It is 
nice that at least one company has made the 
ten day trial period a matter of policy. 

To help our readers with this increasingly 
common problem we will be printing "Com¬ 
patibility Alerts" in the T-S News section 
of T-S Horizons. If you have any com¬ 
patibility-type problems, let us know. In 
the meantime don't forget your right to a 
10-day return period when you order any¬ 
thing by mail. 


TIMEX SINCLAIR 1000 Special 


Budget Master 1000 cassette 11.00 


Reversl 1000 * 11.00 
2K Trek " 9.99 
Sabotage • 10.00 
2K Fun Pack “ 10.00 
Bulper “ 10.00 


Add $2.00 Ship per Order 
Illinois add 57. Sales Tax 

COMPUTER SOFTWARE CO. 

?U S. Center, Dept. T-S, 
Bloomington, 111. 61701 
1-309-828-3251 till 9PM, 7 days 
$99.00 orders ship free 


PLAY CQMPUBflLL 

New for ZX81/TS1000 
16K BASEBALL 

Name your own teams, use any names you 
choose Pit your own team against any op¬ 
posing team you want. 

Continuous and complete display, play o'' 
play report of score. Inning, balls, strikes, 
outs, men on base, runs scored. 

Batting— hold or swing option, 

base stealing option. 
Pitching— fast balls, curves, sliders, 
slow balls. 

Make your own leagues. 

Hold your own playoffs, world Series, 
cassette • *7.95 

N.Y. state residents add 7% sales tax 

Send check or money order to: 
CCJttPUBflll 

P.O. BOX 122 
vestal, NY 13850 


FOR SRLCS PROFE5510NfiL5 


UOULD YOU LIKE TO ORORNIZE YOUR 
time OETTERT 

WOULD YOU LIKE TO KNOW UMERE YOU 
ORE MRKINO YOUR MONEY'’ 

UOULD YOU LIKE TO KNOU UMICH 
CUSTOMERS TO DROP7 

UOULD YOU LIKE TO KNOU EXACTLY 
HOU YOU RRE D0IN07 

IS PREPARING FORECASTS AND 
SCHEDULES NOT EXACTLY YOUR 
TM1N07 


WOULD YOU LIKE TO CO GOLFING OR 
FISHING UITH A CLEAR CONSCIENCE? 

THEN "SALES AID 1" IS FOR YOU. 
tZXOl/TIMEX lose PLUS ISK RAM) 


PROGRAM ON CASSETTE ♦ DETAILED 
USERS INSTRUCTIONS; USS 88.00 

USERS INSTRUCTIONS ALONE, FOR 
INFO AND EXAMINATION: US$ 6.00 
(WILL OE APPLIED AGAINST 
PURCHASE OF PROGRAM.) 


ORDER FROM; 
M.SIEDER 
5710 MILAN 
BROSSARD,OUE. 
w<4.Z 8A9 





Advertising information 


FORMAT 

SIZE* 

IX 

2X 

4X 

Full page 

6-1/4 X 9 

125.00 

118.75 

112.80 

2/3 page 

4-1/2 X 9 

100.00 

95.00 

90.25 

1/2 page 

6-1/4 X 4-1/2 

75.00 

71.25 

67.70 


3x9 




1/3 page 

4-1/2 X 4-1/2 

65.00 

61.75 

58.65 


2x9 




1/4 page 

3 x 4-1/2 

35.00 

33.25 

31.60 

1/6 page 

2 X 4-1/2 

28.50 

27.10 

25.75 

1/9 page 

2x3 

17.10 

16.25 

15.50 

2 inch 

2x2 

11.50 

10.90 

10.25 

1 inch 

2x1 

6.00 

5.75 

5.50 


* No charge for ad reductions. 

INSTRUCTIONS; Print or type clearly. Multiple same-size ads to be run in the same or 
consecutive issues qualify for discount rates. 

AD REDUCTION; Because of the reduced page size of T-S HORIZONS, there is no additional 
charge for reduction or enlargement of ads where necessary. 

TERMS; All advertising is payable in advance until an account is established. Ad agencies 
write for discount information. 

FORMAT: Black and white only at present time. Provided that-" sharp, clean copy is 

available, an ad may be reproduced from an ad in another publication. 

CLOSING DATES: The deadline for all camera-ready advertising is the 15th of the month 
preceding issue date. Example; November 15th is the deadline for the December issue. The 
deadline for noncamera-ready advertising is the 10th. 

PUBLISHING FREQUENCY; MONTHLY. 

Even though most people seemed to agree that the premiere issue of T-S Horizons was a great 
first effort, we received quite a lot of constructive criticism. All of it is greatly 
appreciated. We want T-S Horizons to improve in quality and grow - both in distribution and 

number of pages - and the only way to accomplish that is to serve the needs and interests of 

our readers. 

Some of the criticism we intend to act on. We want to provide more good program listings, and 
not-so-technical hardware articles, as you will see in coming issues. We also plan to improve 
general layout and proof-reading. 

Some people are concerned about the format (newsprint, reduced page-size) of T-S Horizons, but 
most don't seem to be bothered. Our motto is "Affordable Quality for the Timex Computer 
User." The kind of quality we're talking about is not paper stock, but what's on the paper - 
the articles, programs, and information content. 

Another concern expressed by some is one that we can't do anything about - the competition.’ 

It IS true that there are several publications based on the Timex computer, but how many are 

monthly, cover the range of topics we cover, have 32‘ pages, have the same quality (of 
material!), and cost only $1 per issue (by subscription)? I don't know of any. And don't 
forget. The best is yet to come. 

Sincerely, 

Rick Duncan ^ 




BEYOND 64K... 

Would you believe up to ONE MEGABYTE? 

Memory expansion is only the BEGINNING of the possibilities available through BASICare ... the ONLY expandable- 
expansion system for Timex-Sinclair computers. 

This is a unique flexible ‘Building Block’ expansion system that enables you to expand your system in any configuration you 
choose. 


BASICare modules are what is required to turn any Timex 
Sinclair into a serious computer for business, education, 
industrial, and hobby applications. Your system can grow 
gradually as you can add new functions when and as required. 
In order to open the door to this exciting new world of 
expansions you require a Persona module. It simply (and 
firmly) plugs into your computer. No soldering. No 
modifications of any sort! 

BASICare uses a unique 64 way Organic Bus. This bus is the 
pathway to all modules. You have INSTANT access to all 
modules simply and easily through the PEEK and POKE 
commands. 

Memory can be added AS REQUIRED in blocks of 16K or 64K 
up to one MEGABYTE. This is memory that is INSTANTLY 
AVAILABLE. This is unlike any other system available for a 
home computer and compares in capability to multi-tasking 
systems costing thousands of dollars! 

You can grow gradually, adding memory or other functions as 
you need them. Just think of the added power expandable 
memory will provide! 

The PERICON modules add Input Output functions like driving 
relays, LED s or a Centronics type printer. 

The DROM offers a PERFECT alternative to tedious cassette 
saving and loading by holding your programs and data in non¬ 
volatile RAM. 

These, combined with the other BASICare modules, put YOU 
in complete control. 

PERICON a: —A general- 
purpose, user programmable 
device providing 24 lines of 
input output. $ 54.95 
PERICON b: —24 lines ot 
heavy duty output to access 
and control the outside world. 
$ 59.95 


PERSONA: —Interface 
module to enable BASICare to 
grow on your computer $ 59.95 
MINIMAP: —Memory mapping 
to extend the address space 
beyond 64K to 1 Megabyte. 

$ 59.95 

RAM 16: —16K add-on 
memory. $ 54.95 
RAM 64: —a TRUE 64K add¬ 
on memory $ 149.95 
DROM (2K); —Ultra low power 
memory backed by a 
rechargeable battery for non¬ 
volatile storage of programs 
and data. $74.95 
USERFONT: —Provides user 
definable characters for DROM 
and TOOLKIT $17.95 


GROW UP TO REAL COMPUTING. With BASICares Modular 
Expansion System the modules will never become redundant. If you 
eventually change to a bigger, more powerful computer, the chances 
are that we will have a Persona interface to allow you to use your 
modules on the new equipment. 


PERICON c: —To drive an 80 
column printer with Centronics i 

type parallel interface $ 74.95 5 

SONUS: —Three voice music 
sound synthesizer with i 

independent envelope control 
under BASIC commands ; 

$ 59.95 ^ 

TOOLKIT: —An 8K module of 
utilities in EPROM ROM $4<L^| i 


ss 

SSBSSSS^ 




BASICare lOIStiular Expansion Systems can ‘grow’ on Timex Sinclair 

TS1000 microcomputers ZX81 

To order call toll-free 800 “ 833“8400 In New York call (716) 874-5510. 

The phones are open SAM - 10PM (E.S.T.) Monday to Friday. Call or write for further information. 
BASICare is available direct from BLaOSTOnB ELECTRONICS and from selected dealers 


tsaSKeiimore Ave., Buffalo, NY 14217 


Dealer enquiries welcome.