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Serving Timex-Sinclair 
Personal Computers 

A PUBLICATION OF THE HARVARD GROUP 

VOL.3 NO.11 ISSN 0273-2696 NOV., 1982 



IN THIS ISSUE 

8K Programs 

Boolean Demonstration.17 


Dec.-Hex. Conversion...9 

Etching Program.3 

Pie Chart Graph and 

Display.6 

Self-running Programs..4 
Solar Program for Flat 

Plate Collectors.8 

Star Hunter.6 

Two Numbers in 

One Byte.19 

Book Review 

ZX81 BASIC Book.5 

Classified Ads.19 

Dear Editor.12 

Hardware Project 

Switch Box.15 

Hardware Reviews 

Byte-Back Modem.18 

Computer Keyboards Kit 

and Enclosure.16 

QSAVE.4 

Machine Code Programming 
Storing MC Routines 

in REM.10 

News, New Products....1,2 
Software Reviews 

QSAVE.4 

ZX81 Home Computer 

Package.11 

Syntax Errors.2 

Users' Groups.13 

Index of Advertisers 

Byte-Back Co.16 

Cases Inc.11 

Dallas Development.7 

Memotech Corp.14 

Mindware Inc.3 

Rist Computers.17 

Softsync Inc.15 


TIMEX PRINTER AND MODEM INFO 

Timex's 40-column thermal printer will 
be available in Dec.82 for $99.95, says Timex 
VP Danny Ross. Despite its 40-column format, 
it LLISTs in screen format (32-col). The 
printer needs no interface and has its own 
power supply. Printer also uses the keyboard 
print commands. Ross also said Timex's new 
300-baud modem will be ready first quarter of 
'83. Some features: autodial and answer and 
software to let ZX/TS computers communicate 
with other kinds of computers, making commer¬ 
cial data bases accessible to ZX/TS users. 

TS1000 SERVICE CENTER AND COMPUTER HOTLINE 

Timex's repair address: Timex Service 
Center, 7004 Murray St., POB K, Little Rock, 
AR. New hotline number for computer prod¬ 
ucts: 800/248-4639. Call 8am-llpm Mon.- 

Fri.; 9am-9pm Sat. and Sun. 

CAI OFFERS COMPUTER NETWORK PACKAGE 

CAI now offers a network package includ¬ 
ing Lexicon 11 modem, ASCII modem and cable. 
Package (not direct-connect): $149.95+$2.95 

P&H. Separately, network package items are: 
Lexicon modem $129.95, ASCII modem $24.95 and 
cable $9.95. CAI's direct-connect phone 
modem is $149.95. CAI Instruments, P.O. Box 
2032, Midland, MI 48640. 

MACRONICS ANNOUNCES FLOPPY DISK INTERFACE 

Run a 5 1/4" disk drive with your ZX/TS 
and Macronic's new FIZ 1.1 interface. Inter¬ 
face plugs into rear edge connector with an 
expansion bus. FIZ interface, $149, expan¬ 
sion bus $35. Assembled and cased 5 1/4" 
drive with 110V 60Hz supply is $330 extra. 
Prices include airmail postage. Macronics, 

26 Spiers Close, Knowle, Solihull, West 
Midlands B93 9ES UK. 


SECOND ANNIVERSARY ISSUE 


























NEW PRODUCTS 


ADDRESSES (with 16K available) can 
store 133 addresses (90 chars, 
each) or other data. You get 36 
codes for search and listing. En¬ 
tries can be made and changed and 
users familiar with BASIC can modi¬ 
fy this program to suit their own 
needs. ACCR is a payment receipt 
reminder. With 16K it stores 266 
entries of date, name (20 char.) 
and amount. It searches by code, 
month or name. ACCP, companion 
program for ACCR, works similarly 
and is useable for accounts pay¬ 
able. Tapes are $19.95 or 3 for 
$39.90. R.S. Panwar, 2035 Kentland 
Dr., Houston, TX 77067, 713/537- 
8453 (6-9 pm). 

Nonvolatile Memory and I/O Ports 
give 6 parallel I/O ports to inter¬ 
face your ZX/TS to other devices. 

It also has sockets for up to 4 
extra memories, either 2716 EPROMs, 
2Kx8 static RAM or 2Kx8 nonvolatile 
memories or EPROM to store your own 
USR programs. Your Sinclair/Timex 
RAM plugs directly on. $79 kit, 

$99 assembled and tested. EPROM 
Programmer, $79 with hardware and 
software to program 2716 EPROMs. 
Wisconsin Electronics, Box 332, 
Milton, WI 53563. 

SALES-PLUS shows TS1000 selling 
points. It can be factory-custom¬ 
ized to present retailer's name 
with Timex name. $17.95 in quanti¬ 
ty (300) including customization. 
Development Assoc., 1520 S. Lyon, 
Santa Ana, CA 92705, 714/835-9512. 

Z EXTRA, a ZX/TS graphics control 
program (needs SLOW mode, 16K RAM 
min.), provides: keyboard control 
of graphic and display features, 
storage of info into high RAM for 
future reference, revision, or dis¬ 
play; screen storage in "collapsed" 
format so you can store 60-80 
screens in the top 40K of a 64K 
memory, menu-driven screen file 
handling, blinking cursors, repeat¬ 


ing keys, 4 write directions for 
letters or graphics characters, 8 
plot directions for pixel drawing, 
4x4 and 8x8 char, sizes, plus in¬ 
sert, delete, search and other 
editing functions. Z EXTRA is 
user-configurable for 16-64K RAMs 
and can be set to use only part of 
your memory. Tape and instructions 
$19.95 ppd. from Sinware, Box 323, 
Dixon, NM 87501. 

Tape Loader (TL-064) and Heat 
Controller (OP-032) , announced Oct. 
SYNTAX, go up Nov. 1: TL-064 will 

be $22.95 and OP-032 will be 
$15.95. P. Pollack, 6240 Halifax 
St., N.Burnby, BC Canada V5B 2P6. 

Z80 System Reference Card offers 
formulas to calculate your own 
timing with any MHz; condition code 
chart and hex-to-decimal chart; 
undocumented op-codes for some 
chips; instructions in op-code se¬ 
quence for PEEKing, and in mnemonic 
sequence for POKEing with decimal 
equivalents, $4.95. Nanos Systems, 
Bx 24344, Speedway, IN 46224. 

SYNTAX ERRORS: Grading Program, 
Oct.82, indicated line 240 as the 
round-up cut-off routine. Line 210 
is the round-up cut-off routine. 

In Unit Pricer, Oct. 82, line 
84 should read as line 20. Line 
4241 should read as line 145. Add 
line 350 STOP. 

In my Monthly Calendar program. 
Sept.82, the characters "B" in the 
PRINT statements simply mean to 
print a blank space. 

Herb Cohen, Winchester, KY 

In my Hex Math improvement 
(Oct.82), line 530 should read: 

530 LET H(X) + (INT D-INT Q*16)+28 
The line is not elegant in that 
form. This looks better and works: 
520 LET Q+INT (D/16) 

530 LET H(X)=INT (D-Q*16)+28 

Ronald H. Miller, Murrysville, PA 


2 


ETCHING PROGRAM—8K/1K 


This program draws patterns by 
itself. It traces a continuous 
line, starting at the left-hand 
center edge of the screen, bouncing 
off the edges, and stopping only if 
the line leads into one corner. 

ETCH fits in IK RAM. Start 
the program using RUN (ENTER). 

When the cursor appears, enter the 
slope of the line; 0 yields a 
horizontal line; 1, a 45 diagonal 
up; -1, a 45 diagonal down. Values 
may be any number, including deci¬ 
mal or fractional values, but those 
between plus or minus 5 seem to be 
the most productive. 

When an interesting pattern 
appears, type "M" to pause; hit any 
key to resume operation. 

BREAK followed by ENTER will 
stop the program. To restart, just 
press RUN and ENTER again. 

David R. Rowland, Montclair, NJ 


110 

± 2 © 

13© 

14 -® 

16 © 

165 

17© 

13© 

135 

22© 


5 


= 1 
= 2 
= Y + i 
= X + l 


235 
27 © 

23 © 

235 
320 
35© 

«ZT __ . 

tjt »ji L— t 


LET X=© 

LET Y=© 

PLOT X., 
INPUT Z 
LET U = 

LET T = 

LET Y 
LET X 
GQ5UB 5@0 
GOTO 17@ 

LET U — 0 
LET T = 3 
LET Y = Y-i 
LET X = X+l 
GOSUB 30© 
GOTO 2"70 
LET U = 3 
= O 


37© LET Y - Y-f 4 
33© LET X = X*i 
335 GOSUB S3© 

420 GOTO 370 
430 LET U = 2 
455 LET T = 1 

47© LET Y = Y-I 
430 LET X = X-i 
455 GOSUB BO© 

520 GOTO 470 
S00 LET B==20+Z4Y 
005 IP INKEY$ 

1000 © 

310 IP RSS B > 

0-100 *T) 

02© IP PBS X = S4 THEN GOTO 
0-100 *U) 

030 UNPLOT X.-.B 
040 PLOT X j, B 
050 RETURN 
SYNTACTIC SUM: 


= "M 


THEN PAUSE 


43 THEN GOTO C4C 


33943 ,* BK^'SK 


FIRST 
TALK TO 



If you’re writing software for the Timex-Sinclair personal 
computer, you ought to talk first to the software publishing 
company that will do the most for you and your program. Here’s 
six good reasons why good programmers come to us first: 

1. MASS MARKETING CAPABILITIES. 

The Timex-Sinclair computer market is no longer a mail-order, 
hobbyist business. We have the marketing resources to put 
your titles in more than 25,000 retail outlets, including chain 
stores, mass merchandisers, audio centers and PX’s. 

2. VERTICAL MARKETING CAPABILITIES. 

At the same time, we also sell actively to the kind of specialized 
audiences who can’t be reached through mass market outlets. 

If you’ve written the definitive program for machine shop 
estimators, we know where to sell it. 

3. BETTER ROYALTY TERMS. 

Since we expect to buy the best in Timex-Sinclair software, we 
expect to pay the best in royalties. And we pay promptly and 
frequently —a policy that, sadly enough, many other publishers 
seem to feel is unnecessary. 

4. “QUICKLOADING”. 

Every title we sell now incorporates our unique “Quickload” 
algorithm. “Quickload” enables your program to load 
ata rate six times faster than other Timex-Sinclair software. 
That kind of special feature means bigger sales—and 
bigger royalties. 

5. PROFESSIONAL PACKAGING AND PROMOTION. 

We take ourtitles seriously. We’re willing to invest in good 
graphics, good documentation, good advertising. You’ll be 
proud to show off your work, because we are too. 

6. WE’RE NICE TO DEAL WITH. 

Mindware isn’t a big, impersonal corporation with layers of 
bureaucrats to penetrate. We know our leadership in software 
depends on finding the very best authors—and keeping 
them. So we try to respond quickly and honestly, and treat 
you with respect. 

We can’t promise to publish every program you submit. But if 
you’ve got a title you feel is a real winner, our advice is simple: 

FIRST, TALK TO 


15 Tech Circle, Natick, Mass. USA 617-655-3388 




3 




HARDWARE/SOFTWARE REVIEW 

Product: QSAVE 

From: Personal Software Serv¬ 
ices, 112 Oliver St., 
Coventry, U.K. CV6 5FE 
Price: $30 US (includes P&H) 

QSAVE 1 s package consists of a 
small plastic box with four minia¬ 
ture phone jacks labeled A, B, C 
and D, two cables with matching 
plugs, the tape and a manual. 

After briefly scanning the 
manual, I plugged things together, 
put the tape in my recorder, typed 
LOAD "" and watched anxiously while 
nothing happened. I could not find 
the proper-sized screwdriver to 
open the shaper-amplifier so I 
looked more closely at the manual. 
The ear plug from the recorder goes 
to A. One short cable goes from B 
to the computer's ear jack. The 
power plug goes to C. D goes to 
the computer's power jack. 

After I hooked up everything 
properly, QSAVE loaded the first 
time. Almost any tape will load 
with the shaper-amplifier. 

QSAVE automatically moves the 
machine language (contained in two 
REM statements) above RAMTOP when 
it loads. It then prints a short 
menu listing USR addresses for the 
SAVE, VERIFY and LOAD calls. 

When saving with QSAVE, you 
can't save programs by name and you 
can't save self—running programs in 
QSAVE code. But QSAVE's speed 
makes up for these shortcomings. 

VERIFY is especially useful. 
After saving a program in QSAVE 
code, you can play it back to the 
computer with the VERIFY command 
(PRINT USR 32377). The program 
prints V=0 if everything is OK. 
Numbers other than zero indicate an 
improper volume setting or a bad 
recording. You can re-record be¬ 
fore turning off the computer. 

Once QSAVE is loaded (about 45 
seconds), your programs in QSAVE 
code will load in 29 seconds. You 
only need to load QSAVE once per 


computing session—just don't exe¬ 
cute a NEW. When you finish with a 
program, enter the QSAVE Load com¬ 
mand (PRINT USR 32371) to load 
another program in QSAVE code. NEW 
or programs that move machine lan¬ 
guage above RAMTOP will require re¬ 
loading QSAVE. 

It's convenient to copy QSAVE 
at the front of tapes containing 
programs in QSAVE code. To put 
QSAVE onto another tape, don't type 
SAVE. To preserve QSAVE's load and 
execute features, start the record¬ 
er then type RUN ENTER. QSAVE will 
save itself. 

I am very pleased with QSAVE's 
package. The hardware definitely 
aids in loading balky tapes and the 
time saved in loading long programs 
is certainly worthwhile. 

C. Nunnery, Fort Walton Beach, FL 

SELF RUNNING PROGRAMS—8K 

Making a self-running program 
on the ZX81 is very simple. Just 
insert a SAVE statement at the 
place you want the computer to con¬ 
tinue from. The SAVE statement 
acts like a CONTinue statement, 
continuing at the next line with 
the same variables it left off 
with. So a self-running program 
eliminates the need for the user to 
start the program. It also lets 
you put executable statements after 
the SAVE command. 

After entering the example, 
type NEW, LOAD "ZZ" and the screen 
should display the character set 
from your keyboard then pause about 
2 seconds. This program shows that 
the ZX/TS saves the screen content, 
variables and the line the program 
was saved on. 


Chris White, Lake Forest, IL 


1© t* Oh h~ 1 i O hSv> 
2© PRINT CHR$ ; 

'30 NEXT R 
4-0 PfiUSE I@© 

50 SPUE **ZZ“ 

6© PfiUSE 1©© 

5YNTRCTIC SUM * 


4-‘34-£ 8K 


4 



BOOK REVIEW 


Title: ZX81 BASIC Book 

By: Robin Norman 

From: ITT Publishing 

Howard W. Sams 
4300 W.62nd St. 
Indianapolis, IN 46026 
317/298-5400 

Price: $12.95 (softcover, 192 pp.) 

Your ZX81 BASIC Programming 
book supplied with your ZX81 compu¬ 
ter documents the hardware and 
software aspects of the computer, 
but does not give a thorough enough 
introduction to BASIC if your ZX/TS 
is your first computing experience. 

Norman begins at the level of 
the rankest beginner and helps him 
or her "learn to use all the in¬ 
structions in ZX81 BASIC using a 
structured course with a steadily 
increasing tempo." 

Short of teaching someone else, 
the best way to learn is by doing. 
This book is excellent proof of 
that dictum. Chapter by chapter, 
the learner is given examples to 
enter and run, and programs to 
write (with working sample solu¬ 
tions in an appendix). Chapter 
summaries itemize specifically what 
is new in the chapter. I find the 
style acceptable, the content 
interesting and informative, and 
the programs challenging. Begin¬ 
ners should find much of value in 
this book. 

Appendices include a complete 
list of all ZX81 BASIC instructions 
with definitions, a glossary, 14 
varied ZX81 programs, sample an¬ 
swers to program exercises, and 
directions for expanding to 16K 
RAM. A thorough index is included. 

Norman's book suffers minor 
problems. There should have been 
more careful proofreading; mistakes 
in the text are not too troublesome 
but typos in programs cause prob¬ 
lems. Except for "Black Box," 
these fall into two classes: lack 
of clarity and consistency about 
the use of spaces in PRINT strings, 


and occasional incorrect use of 
commas and semicolons. 

I ran a good selection, but 
not all, of the programs listed in 
Appendix 3. They include IK RAM 
programs ranging from "Random Rec¬ 
tangles" and other graphic dis¬ 
plays, and several mathema-tical 
programs like "Moving Averages" and 
"Finding Factors" to interactive 
graphics like "Drawing Pictures" 
and "Cows and Bulls" and games like 
"Electronic Dice" and "Reaction 
Time." There are 16K RAM versions 
of "Drawing Pictures," "Telephone 
List," and "Black Box." In "Black 
Box" the computer hides 4 atoms in 
a 64-box matrix. However, the 
program needs the following correc¬ 
tions to run satisfactorily: 

285, 290, 295, 4230 read 1$ for 1$ 
250 PRINT AT 0,22;"WHAT NOW?"; 

TAB 24;"=END" 

1190 GOTO 2600 
1540 LET Y=Y-1 
2440 LET X=X-1 

Line 250 lets the display work. 
Improve it by adding: 

7 FAST 

190 PAUSE 50 
505 GOSUB 3300 
3650 PRINT AT 5,26;X 
3690 PRINT AT 8,27;4 
3765 GOSUB 3300 

Toward the end of the preface, 
Norman comments to all computer 
users, "You cannot 'read' a book 
like this. Whatever you get out of 
it will be the result of a three-way 
interaction between you, this book, 
and the ZX81. And if you ever find 
yourself thinking, 'What would 
happen if...?' then for goodness 
sake, try it! You won't break the 
ZX81 and you'll probably learn 
something." 

I found this book informative 
and easy to follow. I am happy to 
recommend it to beginners. 

Ronald H. Miller, Murrysville, PA 


5 


STAR HUNTER—8K/1K 


PIE CHART GRAPH AND DISPLAY—8K/16K 


In Star Hunter, you control a 
laser cannon that fires when you 
press "F". The cannon aims upward 
when you hit "D" and downward when 
you hit "C H . You may fire and move 
simultaneously. 

Your ship is stationary on the 
left side of the screen as stars 
move towards you. The object is to 
shoot a star before one of them 
hits the left side of the screen. 
For every star you destroy, you are 
awarded 150 points. When you top 
1500, a faster attack wave starts 
and your score resets to 0. 

To exit, hit break and ENTER. 

Robert L. Nappi, Ashtabula, OH 




1 RRND 

2 LET R=© 

3 LET P=© 

4 LET R=R-M 

5 LET G$ = 
_ 88 


1 

1 


10 LET R = 1I 
23 LET B=© 

30 LET O-INT CRND*2©} *1 

31 LET U =0+5 

3-4 IP O-H >U~R THEN GOTO 3© 

4© GL5 

41 PRINT RT ©,25;P 

42 PRINT PT 0. ; 10.; "hTThCK UftUE 

50 PRINT RT R,B; 

50 PRINT RT R+l.B;*• 

T0 PRINT RT 

50 IP INKEY$ = "D' S THEN LET R=R- 
2© IP XNKEY$ = **e“ THEN LET RsR* 


100 PRINT RT Q , U ; 

110 LET y=y-R 

iii^IF U<2 RND RB5 CR-O)<2 THEN 

113 IP U<2 THEN GOTO 1© 

120 IP XNKEY$ = **F* ! THEN GOTO 150 
14© GOTO 5© 

15© PRINT RT R,B+3;R$ 

151 PRUSE 5 

152 CL5 

130 IF R=D THEN GOTO &&& 

1G0 GOTO 50 

200 PRINT RT 0,U; “SHftSH*' 

210 LET P=P+150 

220 PRUSE 2© 

221 IP P >150© THEN GOTO 3 
24© GOTO 1® 

5YNTRCTIC SUM: 40552., SK ROM 


If you have more than IK RAM, try 
adding Dan Tandberg's Blast Effects 
(Aug.82) or Paul Quail's Screen 
Background (Jun.82) routines.—Ed. 


This program draws a pie chart 
graph with up to 10 sections on 8K 
ROM, 16K RAM machines. 

Enter Pie, then RUN. The com¬ 
puter asks for the number of cate¬ 
gories (segments) you want and then 
each category's name and value. 
Answer each question as it appears, 
pressing ENTER after each. The 
title is limited to 10 characters. 

After your last entry, your 
ZX/TS draws the graph. It also 
lists the categories with their 
percentages of the total. 

To copy the graph and listing 
on a printer, enter Y in response 
to the question printed at line 4. 
Line 947 determines whether to copy 
the screen; if your printer does 
not use the ZX/TS keyboard printer 
commands, modify line 947 to use 
your printer's command to copy the 
screen display. 

Segment resolution is fairly 
good, down to 17% of the total. 

To chart new data, RUN Pie 
again. It stops after each run. 


Ron Oblander, Ann Arbor, MI 


PRQGRRM TO O 
UP TO TEN C fi 


OUTPUT DI 


1 REM PIE 

2 PRINT RT 2©*©; 

RRU R PIE CHRRT FOR 
TEGORIES" 

3 SCROLL 

4 PRINT "IS PRINTED 
SIRED?" 

5 SCROLL 

PRINT “ENTER Y SH - 

INRUT R$t 

HHiNiT R$ 

SCROLL 

PRINT "ENTER NUMBER OF 


6 
V 

S' 

IS 

20 


GORIE5-" 


CSTE 


21 INPUT C 

22 PRINT C 

23 DIM ETC} 

24 DIM C$(C,18) 

25 FOR 0=1 tO C 
2S SCROLL 

27PRIN t "ENTER TITi-E QF CRT EG 

as INPUT 

29 SCROLL 

30 PRINT C$CD} 

36 SCROLL 

GORY ”?D^"--"^ TER URL - UE CRTE 

42 INPUT E CD! 

43 SCROLL 

44 PRINT EfDJ 
i9 NEXT D 

o© LET T=0 
55 FOR F =1 TO C 


6 


37 LET T =T +E ( F5 
53 NEXT F 
tjQ SCROLL 

El PRINT "TOTRL RMQUNT IS “;T 
62 SCROLL 
S3 SCROLL 

Si PRINT “PRESS ENTER TO CONTI 
NUE" 

65 INPUT B$ 

70 FOR G = 1 TO 22 
75 SCROLL 

«fTi WFVT ri 

w w % ; *» % w 

65 CCS 

10© REH CIRCLE 

103 PLOT 31.. 21 

11© LET RRDS=21 

12© FOR P=S TO 3© STEP 2 

13© LET RRDisi=.S17453fP 

14-0 LET R=SIN RRON^RRDS 

150 LET B=COS RRDN*RRD5 

IS© PLOT (31+B5 .. (21*R5 

170 PLOT (32 -B5 .. (21+R5 

IS© PLOT (32-B) .. (21-R5 

130 PLOT (SlfB) .. (21-R5 

20© NEXT P 

21© DIM S(05 

215 DIM Z (05 

22© FOR X=X TO C 

23© LET S (X5 =E (X5 ,'*T 

235 NEXT X 

24-© FOR L=© TO RRDS 

250 PLOT 31.. (21 -fL 5 

263 NEXT L 

270 FOR V = 1 TO C 

2S© LET Z (Y 5 =S (Y 5 *363 *. © 274-53 

230 NEXT Y 

4-0© DIM U(C5 

4-03 LET U ( 15 =Z ( 15 

4-05 FOR Y=2 TO C 

4-1© LET U (Y 5 =Z (Y 5 *U (Y -15 

4-2© NEXT Y 

4-4-0 GOTO 80S 

450 FOR Y=1 TO C-l 

460 IF U(Y5>=© RND U(Y5<=«5 *PI 
THEN GOTO S5Q 

47© IF U(Y5>.5*PI RND U(Y5 C=PI 
THEN GOTO SO© 

4S© IF U(Y5>PX RND U (Y'5 < = 1.5 *PI 
THEN GOTO 55© 

50© LET U(Y 5 =2*PI-U(Y 5 
510 FOR L=s© TO RRDS 

52© PLOT 31-SIN U(Y5 *L,21f€OS W 

(Y 5 *L 

53© NEXT L 

54© GOTO 683 

550 LET U(Y5 =U(Y'5 -PI 


5S3 FOR L =S iO RRDS 

570 PLOT 31-SIN U(Y5*L,21-COS 

CY'3 *L 


5S© NEXT L 
59© GOTO SS© 

600 LET U (Y5 =PI-U (Y'5 

61© FOR L=© TO RRDS 

623 PLOT 31+SXN U(Y) *L.,2i-COS 


U 


(Y 5 *L 

S3© NEXT L 

640 GOTO 683 

65© FOR L =0 TO RRDS 

660 PLOT 31-t-SIN U (Y' 5 *L,2I *005 U 

(Y'5 *L 

67© NEXT L 
680 NEXT Y 
6S5 FOR Y s 1 TO C 

63© IF U(Y'5>=© RND U(Y) < = .5*PI 
THEN GOTO 75© 

635 IF U(Y5 > * 5 *PI RND U(Y5 <=PI 
THEN GOTO 735 

70© IF U(Y'5>PX RND U(Y'5 ( = 1.5*PI 
THEN GOTO 72© 

70S LET U IY 5=2 *P I -U (Y 5 


710 PR 2NT RT 11-COS U(Y 5 *10.15 - 
SIN U(Y'5*1©;Y' 

715 GOTO 752 
720 LET U (Y5 =U (Y'5 -PI 
725 PRINT RT ll+COS U(Y5*1©.15- 
SIN U(Y'5*1©;Y' 

73© GOTO 752 
735 LET U (Y5 =PI-U (Y'5 
740 PRINT RT 11 fCQS U 1Y'5 *10. 15* 
S XN U CY' 5 * 1© ; Y' 

745 GOTO 752 

75© PRINT RT 11-COS U (Y'5 *10.15* 
SIN U(Y'5*10.CY 

752 NEXT Y 

753 PRINT RT 11.15;“*“ 

755 GOTO 90© 

600 REM MRRKING OF SEGMENTS 

SI© DIM U(C5 

62© LET U(15=Z(15/2 

S3© FOR Y =2 TO C 

64© LET U (Y'5 =Z (Y'5 ^2*U (Y-15 

65© NEXT Y' 

66© GOTO 45© 

90© IF R$ = “Y'“ THEN COPY' 

3©4 PRUSE 20© 

9©5 CLS 

91© PR INT “ CRTEGQRY' “ ; TfiB 14 ; “RM 
OUNT" TRB 23; “PERCENT" 

915 PRINT 

92© FOR Y=I TO C 

925 PRINT Y'; " » “ ; C$ (Y 5 ; TRB 15; E 

(Y 5 ; TRB 22; S (Y' 5 *100 
935 NEXT Y' 

94© PRINT TRB 14;"-“ 

945 PRINT TRB 9;“TOTRL";TRB 15; 
T 

347 IF A$="Y'“ THEN COPY' 
q 5 0 STOP 

5YNTRCT XC SUM: 23272.. SKXlBH 


We will pay 

CASH 


for non-exclusive rights to 
manufacture and sell your 
Timex/Sinclair educational and 
entertainment programs. 


DALLAS DEVELOPMENT SYSTEMS 
7410 Stillwater 
Garland, Texas 75042 
(214) 238-1776 


7 






SOLAR PROGRAM FOR 

FLAT PLATE COLLECTORS—3K and up 

If you're using solar techno¬ 
logy to reduce your energy bills, 
a computer can help maximize your 
benefits. SOL will help you orient 
that flat plate collector. 

You need the following informa¬ 
tion: your latitude, vertical tilt 

of the collector, and azimuth (de¬ 
viation from true south)—all in 
decimal degrees. You can adjust 
the tilt to receive minimum heat in 
summer or equalize the tilt (ver¬ 
tical); add 20 percent for months 
of snow cover. Because of screen 
limitations, hourly totals are not 
printed out. They are available 
while the program is running—1(B). 
Changes made to run in the ZX81 
cause slight inaccuracy, but the 
results are within 2% of those 
obtained with a larger computer. 

SOL runs with 3K RAM and up. 

If you omit the graph routine 
(lines 640-890), it should run in 
2K. The program takes about 3.5 
minutes to run—it goes through the 
subroutine 132 times. The graph 
gives an easy-to-interpret picture 
of year-around performance. Remem¬ 
ber that the monthly figures are 
for one day only and that they 
assume no shade. 


Ed Buttenhoff, Grand Rapids, MI 


Based on "Adapting the Sun's 
Energy" by Jerry Berry appearing in 
the June, 1982, issue of BYTE maga¬ 
zine. Copyright (c) 1982 BYTE Publi¬ 
cations, Inc. Used with permission 
of BYTE Publications Inc. 


10 REM 'SuL 
2© GOTO ©22© 

3© REM SUBR TO CALC BTUS 
4-0 FAST 

5© LET 1=4.29* (J + ( . 034#COS 0360 

*N/365*F)>> 

80 LET D =23,4-5+3IN 036©* C234.+M 

>/365*F> 

TO LET DaD*F 

0S 8 ®*COS hI>T in l * sin °*tcos L*C 
i©0 JF M>94.„S76 THEN LET X=0 


11© JF W<=94.976 THEN GOTO 0130 
12© GOTO ©I4-© 

130 LET X —EXP ( -, 

14-0 Lt ! V=tXP ( — « ©9t>*HJ 
150 LET I = X * . 56* (X +Y} 

ISO LET CaSIN D* \ SIH L+CGS T- (C 
OS L*5IN T 4-COS A> > 

170 LET 0=04-005 D*COS HI* * COS L 
*005 T + (SIN L * S IN T * CO S .A j < 


*SIN A*S 


15© LET 0=0+005 D*SXN 
N HI 
19© LET I = X*C 
20© XF X-;© THEN LET I-O 
21© RETURN 
22© DIM X l 12) 

23© DXM G(12) 

24-0 LET U=1 
25© LET K =2© 

26© LET F=PI/i39 
270 5LOU 

'" SOL AR ENERGY , BTUy S8F 


230 PRINT 
T/DRY" 

230 PRINT 
^' r ’TOR ** 

~300 PRXNT 






'FOR FLAT PLAT COLL 
USE DECIMAL DEGREE 


.—i 


310 

32© 


4-20 

4-3© 

idf! 


4-7© 

480 


PR XNT 
INPUT LL 

330 PRINT .,/TXLT ANGLE?" 

34.0 INPUT TT 
350 PRINT , ,"AZIMUTH?" 

360 INPUT AA 
37© LET L=LL*F 
35© LET T-TT *F 
39© LET A =AA *F 
4-00 LET U=© 

4-1© LET N =21 

FOR 0=U TO 12 
LET H =75 
LET R=0 

4-5® FOR B =G TO 11 
4-60 LET HI =H *F 
GO SUB 004-0 
LET X <&> =X 
4.3© LET H=H—15 
50© LET P=P+I*S.* 

51© NEXT B 

52© LET N=N+30.36 

53© LET G O = XNT VR+.E* 

Fly LizT U=U+H 
550 NEXT O 
560 CL5 

570 PRINT TAB 1©;"SOLAR TABLE", 

, , " LAT = ";LL; " TXLT = ";TT; " 

A7 = "’ AA 

55© PRINT ',," MONTH B 

T U yDAY/SOFT" 

59© PRINT 

60© FOR I=U TO 12 

61© PRINT TRB 5-LEN STR$ X; X; TR 
B 25-LEN STR$ Gfl.> ;6fl) 

62© NEXT X 

63© PRINT TOTAL Vi DAYVMCU 

= ”TAB K; XNT <U+.5> 

6 4-0 PRINT , VFOR GRRPH t NJSE 

** "CONT" "> " 

65© POKE 164.15, U 
660 STOP 
670 SLOW 

65© LET A$=" +- + ** 

69© FOR X=U TO K +U+U 
70S PRINT R$ 

710 NEXT J 

72© PRINT AT KU; " 5"; AT IS,U; ” 
1©” ; AT 1©.,U; ”15”; AT 
0 , U;”25" 

730 PRINT AT K,1S;"5";AT 15,15.; 
"IS";AT 1©,15;"15";AT 5,15; "SO"} 
AT ©’, 15; "25" 


8 





74-0 FDR R=U TO 12 

7 S 0 XF D VR) < 376 THEM GOTO 0770 

7 S 0 PLOT R* 2 + 5 , ( (G(R) ) /S 0 ) V 

770 NEXT R 

730 POKE 164-13 , U 

790 PRINT RT U+U*K,©;" 

UflSQND -{MONTH" 

§00 PRINT RT © , K ;"SOLRR RRD" 

P 10 PRINT RT J+J,K; "STU DRY " ; ftT 
0 , 7 ; X 100 

320 PRINT RT 4 -,K;”PER 60 FT" 

330 PRINT RT 6 ,K;"LftT = H :LL 
34-0 PRINT RT 3 ,K; "TILT = " ; TT 
350 PRINT RT IO,K;"RZIH= ";RR 
860 PRINT RT 14 - , K; " i FOR TRBLE , " 
;RT 16 /K;"USE ""CONT""*** 

370 STOP 
38 © FR 6 T 
890 GOTO 0660 

5 YMTRTIC SUM: 64 - 737 ; 3 K ROM 


DECIMAL-HEXADECIMAL 
CONVERSION PROGRAM—8K/16K 

This utility program converts 
values in decimal (base 10) from 
0-65535 to hexadecimal (base 16) 
equivalents. It also takes hexa¬ 
decimal values from 0-FFFF and 
converts them to decimal equiva¬ 
lents. After entering the listing, 
simply RUN—prompts and error mes¬ 
sages will help you along. The 
program can also be listed on a 
printer. Decimal-Hex Conversion 
was developed by Softcrest, New 
Canaan, CT. 

Gytis Adams Kevis, New Canaan, CT 



3—- ■> - ft. J. 

W V—• l*J 

_ _ _ R* _ 

fT—a 

£T h.* 
r*. SH l i 

i ft j— r*. 

a a 5U 

-> y 

t % Ua. • ■ 

■%* * 

W IF- 
« V W • ft 

O 

m mm* m 

tk m m 

o 

REM 

REM 

... CO 

r*. r% 

. . . 'wU 

* 

\ 

REM 

. . . BY 

r 

1.0 

r-. T f-t 

W afta t 1 

H$ { 15 

Lr i«’i 

w w 

D IM 

R$ C4 > 

W ft-X 

r~v -r* a « 

w JL «”• 

D $ (63 

40 

D IM 

B (4-3 

50 

DIM 

T (43 

52 

LET 

T (1 > = 

54 

LET 

T (2) =; 


et 

• r — 

• ft W / — 

V J-N 

« • 

-a— .* -f ft 

i » * - 


t r-~ t 

\ ft f. __ rt 1“ 

W W 

% w 

? t-* ft 

3 = 133 

*1 0 0 

J""\ ill 5 J 

R=23 

i 13 

FOR 

0 = 1 T 

120 

LET 

HS (C3 

13© 

LET 

R=R + 1 

^4*0 

r** j— ft. 
« --ft ft,f» 

HEX 
{—j ^ 

T C 

w «w 

150 

W l^a W 

r% r*^. -r 

f -L 

NT RT 

.~v » ft 
% % \*ftft 

W % 

.—ft \ t-ft r—• 

LrU'w'C. 

ft 


CONNECTICUT. . . 0034-3 
COPYRIGHT, . 2 .362 . . . . 
BY. .G'rTIS. . RC-RrfS . . . 


ITS PRINT RT 11,4-; “ I FOR DE 

CIHRL TO HEX ** 

ITS PRINT RT 13.14-; “OR¬ 
IS© PRINT RT IS!. ©; " 2-> FG 

R HEX TO DECIHfiL ” 

I3S INPUT P 

2©S IF P=1 OR P-2 THEN GOTO 250 
2IS CLS 

22© PRINT RT I©,2; "RE-ENTER CON 
UER5IGM CODE" 

23© PROSE 1©© 

24-© CLS 
2 5 © G OTO 1S© 

2S3 CLS 

2TS GDSUB G jjp 

253 PRINT RT 1S,2,“HOPE CONUERS 

Ions v /n t ** 

29Q INPUT P$ 

3SS IF P$<>"N” THEN GOTO S© 

313 CLS 
323 STOP 


1000 CL.S 

1313 PRINT RT IB . 2 ; “ENTER DECT?-?c 

L vRLUE S -65535" * 

10-23 INPUT P 

1333 LET Z=P 

1332 IF P < >© THEN GOTO 1343 
1334- LET R$ = ** 0” 

1335 GOTO 1175 

134.3 IF P>3 RND P (b5535 THEN GOT 
O 1133 
1050 CLS 

13EG PRINT RT 13.2;**DECIMRL URLU 

E INURLID" 

1373 PRINT RT 11.2;“ RE-ENTER B 
RGUMENT“ 


3S3 

PROS 

E 133 


323 

GO j O 

1333 


133 

FOR 

C = 4 TO 

1 STEP 

110 

LET 

X = I NT 

iP/HCJ 

123 

LET 

Y=X*HC 


ICO 

LET 

R=iP-V 

> *1 

143 

LET 

R$ CC3 = 

H$ (R) 

.153 

LET 

Cr —V* 

% — * *. 


ft . ft »% 

ft—r w 

NEXT 

ft * 
ft—* 


i ^ ft xy 

x-ft <—ft i 

* — ft » “ft « i 

nJ w w w 

S 1223 



11.-5 P'R I NT Pt 1,3; 

***************" 

lies PRINT RT 2,©;“*";TRB 2;“ DE 

CIHRL HEXIDECIMRL * " 

1193 PRINT RT 3.©;"*".TRB 27;" 

1233 PRINT RT 4.3; “ *"; TRB SlZ jTR 

B 12;"=“; TRB i8.;R$;TRB 27;"*“ 
1235 PRINT RT 5,©;”************* 

***************** 

121© RETURN 
1223 FOR C=1 TO 4 

123© IF -i :»"©** THEN GOTO 12E- 

© 

12-4-0 LET VC.* =" " 

V* --"ft *■»-< „i ^ ft, • *•— % .« 1 ■■ ■ .«-k 

a -w —% *.m im r» at i 

lie© RETURN 

»a *—"a. —• < ■ *'•• a 

A Zl / \L' ^ !>** 

’CL. 3 

2© 1© FOR C = 1 TO 4- 
2323 LET B fC) =3 
2333 NEXT C 

H©4© FRIHT RT 18-. 2; "ENTER HEXIC-E 

C.IMBL Y4BLUS Q-FFFF ' 

205© INPUT D S 

2352 LET D$ (S TO S)=" 

2354 GOSUB 2333 

2353 GOSL&B 223© 

237© FOR C = 1 TO 4 

£©S© IF D$ iCJ = ” ** THEN GOTO 211© 

2323 LET P=CODE D$ CCJ —2-3 
213© LET B fC.i =P*T fC> 


9 












2110 NEXT C 
212© LET R=© 

213S FOR C-~S TO 4 
214.0 LET R=R+S tCJ 
2153 NEXT C 
2155 P P INT fiT i , @ > 
***************** 

2I6S PRINT RT 2,0:”*“ ; TPS 2;** HE 
XIDECIHftL DECIHRL * 

2170 PRINT RT 3,0; 27.;"*" 

2150 PRINT RT 4L,«; TWS s; D$; r 

«e 15 ; trb is; r; tss 27; - *" 

2185 PRINT RT 5..©; *************** 
***************** 

2x33 RETURN 
220S LET S = i 

2210 FOR C-S TO 2 STEP -1 

2220 IF 0$ V4.V «>" " THEN COTO 222 

3 

225© LET E-S if ?'5*1/ TO 51 c'5 TO 

C-2) 

2240 LET D* CS» =” " 

2250 LET 5=5+1 
2250 NEXT C 
2233 RETURN 
2300 LET E =0 
2310 FOR C = 1 TO 4- 

2315 IF D$ CCi = ” " THEN GOTO G3SU 

2320 IF CODE £>$ tO 423 OR CODE Iv$ 
vC>’ >4.3 THEN LET E = 1 
2330 NEXT C 

2340 IF E=© THEN GOTO 2333 
235© GOSUB 2480 
2350 GOTO 2303 
2399 RETURN 
240© CL5 

241© PRINT RT 10.2; ** IMURLID 
CHRRRCTER CSi ** 

2420 PRINT RT 11,2:"CHECK RND RE 
-ENTER YOUR UflLUE** 

2430 INPUT D$ 

2435 CLS 

2440 LET D$C5 TO Si =** 

245S RETURN 

3VNTRCTIC SUM: 34.864. . 8K/1SK 


MC PROGRAMMING #11: STORING MC 
SUBROUTINES IN REM 


[All numbers in this article 
refer to the 4K ROM ZX80; for 8K 
ROM (ZX81/TS1000), see "Machine 
Code Programs: Where and How to 
Load Them" in Syntax Quarterly, 
Winter 1982.—EO] 


While you can store machine 
code subroutines anywhere in your 
BASIC program, the best place is 1 
REM (& 2 REM, if you have two 
subroutines) . 

The first address will always 
be 16427. The first BASIC program 
address is 16424 and holds 0 if the 
program line number is less than 
256. The second address, 16425, 
will hold 1 for line 1. 16426 holds 
the code for REM, 254, and the 


first subroutine address will thus 
be 16427. 

Since subroutines use non¬ 
character code numbers, displaying 
MC bytes usually makes the ZX80 
crash. 1 REM is the easiest line 
to keep off-screen since it is at 
the "top" of your program. 

If you store your subroutine 
below other program lines, adding 
or editing program lines above it 
will change subroutine addresses. 

Here is an easy method for 
entering MC subroutines: 

1. Reserve some storage space 
for storing your machine code 
program. Enter "1 REM AAA" etc., 
including as many A's as bytes your 
subroutine requires. Any character 
will do; the idea is just to 
reserve addresses. 

2. A buffer against listing line 1 
is advisable, so enter 2 REM B. 

(This will not protect against line 
1 showing after hitting HOME or 
LIST, however.) 

3. Now, or after entering the 
input loop, POKE 16403,2 to bump 
line 1 off-screen. This trick will 
also work if you accidently LIST 
and the screen is "skewed" but not 
"scrambled". Move the cursor down a 
few lines first, though. 

4. Enter the input loop: 

100 FOR X=16457 TO 16457+(xx-l) 

110 INPUT Y 
120 POKE X,Y 
130 PRINT PEEK X, 

140 NEXT X 

Where xx is the number of bytes in 
your machine code. 

5. GO TO 100 and enter your codes. 
Entering from a 4-column written 
table eases input checking. 

6. SAVE on tape in case your 
subroutine crashes. 

7. Enter LET Q=USR(16427) to test 
your subroutine for a crash. ("Q" 
can be any variable letter.) 

8. Enter the rest of your BASIC 
program. 

Next month: CALLING AND RETURNING 
Jon Bobst, Zeta Software, PO Box 
3522, Greenville, SC 2608-3522 


lO 



SOFTWARE REVIEW 


Product: ZX81 Home Computer 

Package: Etch-A-Screen, 

Music Composer, Checkbook 
Balancer, Billboard 
ROM/RAM required?: 8K/16K 
Printed Listings?: No 
Programs Listable?: No 
Easy to Load?: Yes 
Written in: Machine Code 
Display: Good 

From: Lamo-Lem Laboratories, Box 

2382, La Jolla CA 92038 
Price: $9.95 

Lamo-Lem's Home Computer Pac¬ 
kage of 4 machine code programs 
offer a good variety for a reason¬ 
able $9.95. 

Billboard gives you a continu¬ 
ous left to right scrolling screen- 
size message. The message can be 
up to 250 characters and repeats 
until you enter a new one. You can 
even save your message on tape. 

The graphic display is clear and 
steady and it's the kind of item 
that could be a visual enhancement 
at a convention or store window or 
for simple fun. 

Etch-A-Screen lets you draw a 
picture anywhere in the top 17 
screen rows. The pen moves in all 
directions including diagonally and 
holding down one of the designated 
graphic keys gives you continuous 
line movement. The directions to 
this program were hazy in sections. 
For example, it is unclear in the 
manual that to get the asterisk 
(the drawing pen) to appear, you 
must hold down one of the arrow 
keys while shifting. Also, the 
directions neglect to explain that 
you must press shift A to clear the 
title screen and then shift 9 (gra¬ 
phics mode) to actually draw. These 
problems are minor when stacked 
against the program's merits. 
Lamo-Lem includes a screen display 
sheet if you want to plot out your 
masterpiece before you start. 

Music Composer lets you play 4 
octaves on your computer. The 


sound reproduces poorly through the 
TV, but is better through a radio. 
The directions are clear and 
straightforward and Lamo-Lem pro¬ 
vides you with a color keyboard 
overlay that translates ZX81 keys 
into octave keys, special effects 
keys and edit keys. A music com¬ 
position sheet is included for 
serious composers. 

Checkbook Balancer tabulates 
your checking account and coordi¬ 
nates it with your monthly bank 
statement. It also comes with a 
keyboard overlay that assigns (+), 
(-), CLEAR, VOID, ENTER and SAVE 
functions to keys on your ZX/TS. 

Each program comes with notes 
for advanced programmers, making 
possible such extras as reprogram¬ 
ming Composer to play Sinclair's 
BASIC as if it were music. Refer¬ 
ence cards, which summarize program 
commands, are included for 3 pro¬ 
grams. The ZX81 Home Computer Pac¬ 
kage is a worthy set of programs 
for a good price.—PPW 


PORTABLE COMPUTER POWER 



Protect your Sinclair in o portable, dust free work station. 
6xtra storage space for 6 tapes, connecting cables, power 
and ram pack. 

Removable lid allows in-case operation. 

Non-skid feet prevent desk top scratches. 

Absolutely the most efficient and convenient way to 
protect, store, and transport your computer system. 

Only $54.95 in continental U.S.A. 

Dealer Inquiries LUelcome 

CflS€S INC. P.O. Box 33820 Seattle, UJfl 98133 (206) 365-5210 
VISA MAST6RCRRD 







DEAR EDITOR 


I have a couple of questions 
concerning Sinclair's Spectrum. 

First, will SYNTAX cover the 
Spectrum and its associated hard¬ 
ware? If so, when will there be an 
in-depth review? How about a com¬ 
parison between the Spectrum and 
the VIC-20 or other comparable 
computers? 

Also, what is the Spectrum's 
availability and price? 

Russell L. Gagnon, Oscoda, MI 

For more info see SYNTAX May 82 
p.4, and Sept.82 p.7. We will 
compare Spectrum to other low-cost 
color machines such as the VIC-20 
and the TRS-Color in future issues 
of SYNTAX and SQ. We will expand 
our coverage on Spectrum when it 
becomes available; expect US intro¬ 
duction early 1983. UK pricing for 
the 16K version is 125, and goes 
to 175 for 48K. UK Spectrums work 
only with UK TVs.—KO 


I am having difficulty getting 
my ZX81 to accept line 280 of an 
Annuity Program, Jun.82 p.17. It 
appears as follows: 

280 LET N=(LN (R/(R-S*I))/(LN(l+I)) 
Please advise! 

R.J. VanEstenberg, El Cajon, CA 

LN is a function token meaning 
natural log; type it by pressing 
SHIFT ENTER to get the F function 
cursor, then pressing Z.—EO 


I have a MicroAce with 4K ROM 
and 2K RAM. It runs well with the 
4K ROM but when I put Sinclair's 
new 8K ROM in place it didn't work. 
The TV image was very distorted. I 
tried switching it on and off, 
pressing all the command keys, even 
changing ROMs, but the computer 
still remained distorted. Any 
suggestions? 

Nivio Swami A. Valois, Brazil 


We can't tell from your letter if 
you made the changes described in 
SYNTAX Apr.81. You can't just 
unplug MicroAce's ROM and insert a 
Sinclair ROM—the pinouts differ 
slightly. Once modified for Sin¬ 
clair's 8K ROM, the socket only 
works directly with Sinclair's 4K 
ROM.—KO 


Do you know any way that sound 
can be used with a Sinclair ZX81, 
via a recorder or any other method? 

Carl Bush, Baltimore, MD 

Generate cones in machine code by 
toggling bit 0 of A between execu¬ 
tions of OUT FF instructions. 

Change frequency using time-eating 
loops. Listen with a speaker 
attached to the ear jack of your 
recorder, set up for SAVE. This 
method works only in FAST, perhaps 
why game manufacturers don't use 
it. Quicksilva offers a sound 
board accessory for £ 26.00 or about 
$45. You'll also need OS's mother¬ 
board, §L 12 or about $20.—EO 


I recently came across a good 
deal on a batch of 4116 integrated 
circuits, which are 16Kxl dynamic 
memory chips. Can I build addi¬ 
tional random access memory for my 
ZX81 with these? 

Patrick d'Entermont, NS, Canada 

You can try to duplicate the 16K 
RAM pack, but only do it to gain 
the experience of building it—it's 
not a worthwhile project to save 
money. You'll spend many hours 
trying to duplicate their circuit. 
See Sinclair's 16K RAM schematic in 
SO, Winter 82.—KO 


In machine code programs the 
"RST 28" instruction, (hex EF) 
which causes a jump to the float¬ 
ing arithmetic, is very valuable. 

I am aware of how certain data 
codes following this instruction 
can be used to perform functions on 


12 


the stack. However while happily 
searching through the ROM (8K) for 
"RST 28" instructions, I came upon 
some data codes I was not aware of. 
For example, the code (hex) A0 was 
commonly used. SYNTAX readers 
would benefit from a list of these 
codes and their functions; a lot of 
aspiring machine code programmers 
don't even know about the wonderful 
"RST 28" instruction. 

Referring to the above, I made 
sure that the (hex) EF's were not 
part of another instruction by 
checking for the exit code (34). 

Joseph G. Kuzma, Jackson, MI 

In 8K ROMs, floating point instruc¬ 
tions follow RST 28. The ROM rou¬ 
tine at 0028H interprets these, and 
they are explained in Ian Logan's 
ROM Disassembly Part B, available 
from Gladstone Electronics, 1585 
Kenmore Ave., Buffalo, NY.—EO 


Ross Shuping of Greenville, NC 
asked about a way to merge two or 
more programs (Sept.82 p.12). 

I first POKE one program above 
RAMTOP, thereby protecting it from 
being erased while you load the 
other program in. Then, POKE the 
protected program back into the 
display file immediately above the 
program that you just loaded. You 
can extend this procedure indefi¬ 
nitely, RAM space permitting. 

Send me $2.00 and a SASE I will 
send a detailed explanation of this 
procedure to anyone who needs it. 

Harold Miller, Rt. 2 Box 2330, 

Clayton, GA 30525 

It was interesting to note in 
SYNTAX the complete opposite of the 
problem I am encoutering—horizon¬ 
tal bars on the screen. 

I, too, have the 9.75 VDC 650 
ma power pack. Even with IK memo¬ 
ry, I still get the bar travelling 
up the screen; but, in my case, it 
gradually disappears the longer the 
unit is operating. 


I opened the case and found 
four diodes with no designation on 
them. As Mr. Bosley intimated in 
SYNTAX Aug.82, p.12, it could be 
one or two of the diodes. 

Is there any way I can find out 
what the replacement value is for 
these diodes? 

William Mitchell, Ontario, Canada 
Use lN4002s—KO 

USERS' GROUPS 


Here's our latest list of new ZX/TS 
users' groups. To check for a 
local group not listed, drop us a 
line (with a self-addressed stamped 
envelope) or call. We'll refer you 
to any group we know of. To list 
your group, write or call and we'll 
send interested people to you. 

SYNTAX, RD 2 Box 457, Harvard MA, 
01415, 617/456-3661. 

Franklin County, VA: Gary Preston, 
c/o Irvin, Route 1, Box 21, Glade 
Hill, VA 24092. 

Mechanicsburg, PA: Central PA ZX81 
and TS1000 Users Group, G Antrim 
Dr., Mechanicsburg, PA 17055, 
717/766-8365. 

Montclair, NJ: North Jersey Tirnex- 
Sinclair Users Group, 133 Christo¬ 
pher St., Montclair, NJ 07042. 

Monterey, CA : John Caylor, 698 Van 
Buren, Monterey, CA 93940, 408/372- 
7988. 

Nashua, NH: Nashua Area Radio Club, 
11 Briand Dr., Nashua, NH 03063. 

Send SASE for details. 

Petaluma, CA: Personal Computer 
Services, Northern Calif. Sinclair 
Users Group, 129 Saratoga Ct., 
Petaluma, CA 94952. 

Rockford, IL: Robert Cunningham, 
1602 Midway Dr., Rockford IL 61103, 
815/877-8106. 


13 





BEHIND EVERY 
GOOD SINCLAIR 
IS A MEMOPAK 


If you own a Timex-Sinclair 1000 or 
ZX81 computer, you .should have a 
Memopak behind it. From increased 
memory to high resolution graphics, 
Memotech has a Memopak to boost your 
system’s capabilities. Every Memopak 
peripheral comes in a black anodised 
aluminum case and is designed to fit 
together in “piggy back” fashion to enable 
you to continue to add on and still keep an 
integrated system look. 

^»»f 


Printer Interface-^ Memopak RAM 

High Resolution Graphics 

Order at no risk 

All Memotech products carry our 10 
day money back guarantee. If you’re not 
completely satisfied, return it in ten days 
and we will give you a full refund. 

And every Memotech product comes with a 
six month warranty. Should anything be 
defective with your Memopak, return it to 
us and we will repair or replace it free of 
charge. Dealer inquiries welcome. To order 
any Memotech product call our toll-free 
number 800/662-0949 or use the order 
coupon. 


i'M'ivian 

CORPORATION 

7550 West Yale Avenue 
Denver, Colorado 80227 
(303) 986-1516 
TWX 910-320-2917 



Mail to: Memotech Corporation, 
Code: STX-11 


7550 West Yale Ave., Denver, CO 80227 

•Price Qty. "Ibtal 


1 64K RAM 

$179-95 


j 32K RAM 

109 95 


| 16KRAM 

5995 


Centronics Parallel Printer Interface 

104.95 


j RS232 Printer Interface 

13995 


High Resolution Graphics 

144.95 


I Shipping and handling 

4.95 

$4.95 1 

. * All prices quoted in U.S. dollars 


Tkx** 

• Colorado residents please add sales tax 

J □ Check □ MasterCard □ Visa 


Total 

Account No. 


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■ Address I 

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State Zip 1 


Memopak 64K RAM The 64K RAM extends the 
memory of your Sinclair by 56K to a full 64K. It 
is directly addressable, user transparent, is 
neither switched nor paged and accepts such 
basic command as 10 DIM A (9000). The 
Memopak 64K turns your Sinclair into a 
powerful computer suitable for business, 
recreational and educational use. No additional 
power supply is required. 

Memopak 32K RAM The 32K RAM Memopak 
offers your Sinclair a full 32K of directly 
addressable RAM. Like the 64K Memopak, it is 
neither switched nor paged and enables you to 
execute sophisticated programs and store large 
data bases. It is also fully compatible with 
Sinclair’s or Memotech’s 16K RAM to give you a 
full 48K of RAM. 

Memopak 16K RAM The Memopak l6K RAM 
provides an economical way to increase the 
capabilities of your Sinclair. And at the same 
time, it enables you to continue to add on other 
features with its “piggy back” connectors. It is 
compatible with the Sinclair 16K or a second 
Memopak 16K or Memopak 32K to give 32K or 
48K of RAM respectively. 

Memopak High Resolution Graphics The 
Memopak HRG contains a 2K EPROM monitor 
and is fully programmable for high resolution 
graphics. The HRG provides for up to 192 by 248 
pixel resolution. 

Memopak Printer Interface The memotech 
centronics parallel or RS232 printer interface 
paks enable your Sinclair to use a wide range of 
compatible printers (major manufacturers’ 
printers available through Memotech at 
significant savings). The resident software in the 
units gives the ASCII set of characters. Both 
Memopak printer interfaces provide lower case 
character capabilities. The RS232 Interface is 
also compatible with modems. 

New products coming soon Memotech will 
soon be introducing four new Sinclair 
compatible products: a high quality, direct 
connection keyboard, a digitizing tablet, a 16K 
EPROM and a disk drive. Watch for our future 
advertisements. 


















HARDWARE PROJECT 

This circuit will simplify 
loading and saving programs by 
eliminating ground loop noise 
without the need to pull out the 
earphone plug during saving and the 
microphone plug during loading. A 
separate switch resets. 

Build this circuit with jacks 
on the input (power and cassette) 
side and plugs on the computer 
side. Use a small DPDT switch for 
the cassette switch and a normally 
closed pushbutton switch on the 
"hot" (tip) side of the power 
supply circuit. Use a 12V pilot 
lamp (Radio Shack 272-332) and 
coaxial cables. Be careful to keep 
connections tip to tip and ring to 
ring; mistakes here can be serious. 

To save a program, throw your 
switch so that MIC connects; to 
load, use the other position. 

Reset with the pushbutton. 

Martin Albrecht, Oakland, CA 




APPLICATION...FINANCIAL...EDUCATION... 


K MARKET CALCULATOR 16K 


I Astronomer’s Guide - Two diverse programs geared for Hangman - An educational game featuring; build your Calculates all types of stock investments and options 
[both the amateur and professional. Includes Astromap own library, competitions and five pre-recorded spelling Designed by an experienced stock market executive, 
land Conversions. drills. 

MORE TS 1000 /ZX 81 SOFTWARE FROM 

SOFTSYNC, IIVC. 

14 East 34th St. New York, N.Y. 10016 


( 212 ) 685 - 2080 ' 


M/C & VISA ACCEPTED 


WRITE FOR FREE CATALOG & PROGRAM LISTING 


15 






64K MEMORY 


M-64 $119. 9 k?t 

BYTE-BACK Co. 

m-64 

129.95 WIRED & TESTED 


IN STOCK. SAME DAY SHIPMENT 


All standard features included, plus lower 8K 
of RAM can be disabled in 2K segments to 
allow PROM or peripherals to be added. 




EXPAND YOUR 16K SYSTEM 


95 


If you have a Sinclair 16K RAM module and need 
more memory, expand it to 32K and beyond by usinq 
BYTE-BACK M-16 MEMORY MODULES. 

You can’t connect two Sinclair 16K RAM modules together, 
but you can connect one Sinclair 16 K and one or more BYTE- 
BACK 16K modules to get all the memory you need 

THOUSANDS IN USE WITH PROVEN RELIABILITY 

M-16 $59 • 95 Kit. $69.95 wired and tested. 

IN STOCK. SAME DAY SHIPMENT 


BB -1 Control Module, with 8 relays, 8 leds 

& 8 inputs. $59 Kit. $69 wire and tested. 
IN STOCK! SAME DAY SHIPMENT 


MODEM with RS232 Port. $99. ! 


$119.95 wire 
& tested. 


90-Day Warranty On All Modules. 
10-Day Return Priviledge 
ORDER PHONE 803-532-5812 

Add $4.95 shipping & handling to all orders. 

CHECKS 


BYTE-BACK CO. 

Rt. 3 Box 147 Brodie Rd. 
LEESVILLE, SOUTH CAROLINA 29070 *■ 


HARDWARE REVIEW 


Product: 


From: 


Price: 


Computer Keyboards 
Professional Keyboard Kit 
and Enclosure for ZX81 
Dean Electronics LTD. 
Ascot Birkshire, England 
Gladstone Electronics 
1585 Kenmore Ave. 

Buffalo, NY 14217 
716/874-5510 
Keyboard Kit $119.95 
Enclosure $29.95 


To get full use of this key¬ 
board, I strongly suggest the extra 
investment for the enclosure. It 
allows the ZX/TS printed circuit 
board (PCB) to be housed in the 
same unit with the keyboard. 

Keys are marked with Sinclair 
legends, and the keytops are remov¬ 
able. There are also six extra 
keys for any future use. The kit 
comes with complete instructions 
for removing the ZX/TS PCB and 
remounting it in the enclosure. It 


also details connecting the PCB to 
the keyboard. Two ribbon cables 
are provided for this purpose. The 
completed unit is an attractive 
black aluminum case with a sloped 
front and clear, easy-to-read keys. 
There's plenty of room for adding 
extra circuits. 

Assembly would have only taken 
about 45 minutes if not for several 
unforeseen difficulties. 

Allowances were made in the 
enclosure for the I/O port (for 
printer and RAM pack) and the side 
connectors of the ZX81. These 
enclosures were designed for the 
British ZX81, not the U.S. counter¬ 
part. The result: three needed 
modifications. First, after remov¬ 
ing the ZX's PCB, I removed the 
small metal tab that grounds the 
inside aluminized plastic case of 
the ZX to the PCB. It's not neces¬ 
sary to the computer's function and 
is there to allow the ZX81 to pass 
FCC regulations. In the enclosure 
it could interfere with keyboard 
operation. 

Next, the small switch on the 
PCB used to select the VHF TV chan¬ 
nel (also not on the British ver¬ 
sion) must be moved—it does not 
clear the bottom of the enclosure 
chassis. Simply unsolder the 
switch and resolder it sideways. 

Finally, the hole provided for 
the video modulator output (or TV 
socket) is about 1 1/2" too close 
to the front of the enclosure. The 
easiest solution is to drill a new 
hole in the enclosure, wide enough 
to allow the modulator plug and 
socket to clear the enclosure case. 
I had to drill through the bottom 
chassis of the enclosure as well. 
Don't allow metals outside the plug 
or socket to make contact with the 
enclosure. 

Despite the extra work in¬ 
volved, the ease and joy of using a 
full sized keyboard, without the 
worry of typos, outweighs the need 
to make minor modifications. 

Jim Moyer, Ontario, Canada 


16 



BOOLEAN DEMONSTRATION—8K/1K 


If the ZX81 is your first 
exposure to computers and program¬ 
ming, you may have trouble under¬ 
standing Boolean logic. Initially, 
I was completely confused by the 
explanations and exercises for the 
AND, OR and NOT functions as pro¬ 
vided in ZX81 Basic Progra mm ing . A 
friend showed me a program similar 
to Listing 1, and I began to com¬ 
prehend the mysteries of Boolean 
algebra after running a few values 
for X and Y through it. 

I dressed the program up a 
little and added a replay function. 
If you only have IK RAM, delete 
odd-numbered lines. One note of 
caution! Add a new line 175 STOP. 
This prevents error 7 (no corres¬ 
ponding GOSUB for a RETURN state¬ 
ment) in the shortened version. 

To run the program hit RUN, 
ENTER. You are prompted to key in 
values for X and Y. The results of 
the AND, OR and NOT functions are 
displayed for you. The program 
prompts you with "AGAIN? (Y/N)". 

To rerun, hit Y ENTER; N ENTER lets 
you exit the program. 

Any numeric values can be used 
for X or Y, but zero and one can 
illustrate most of the salient 
points. Try the following values 
for X and Y: 

X Y X Y 


0 

1 

-1 

0 


0 

0 

0 

-1 


0 

1 

-1 

-1 


1 

1 

1 

-1 


Were you surprised at the 
results? Go back and reread Chap¬ 
ter 10 of the ZX81 manual. The 
AND, OR and NOT functions can be 


very useful and powerful program¬ 
ming tools! 


John C. Connell, Middletown, RI 

S REM "BOOLEAN DEMO” 
i© PRINT "ENTER R URLUE FOR X 


4-0 PRINT "ENTER A URLUE FOR Y. 

5© INPUT Y 
5 © PRINT Y 

78 IF X RND V THEN GOSUB 3©Q 
3S IF X OR Y THEN GOSUB 4-00 
00 IF NOT X THEN GOSUB 500 
188 IF NOT Y THEN GOSUB 600 
110 PRINT 

12 @ PRINT "THE URLUE OF X RND Y 

■ »—» ■ a . 

w mm .» 

13© PRINT 
14.0 PRINT 
150 PRINT 

it . 

IS© PRINT 
245 PRINT 

255 PRINT "AGAIN? (Y/Ni" 

255 INPUT fi$ 

275 IF R$=”N" THEN GOTO 1005 
265 IF ft $ = “ Y 
295 GOTO 70 
360 PRINT 
31© PRINT "X 
32S RETURN 


IS 


C X AND Y5 

"THE URLUE OF X OR Y 
IX OR Y 'i 


v 
W V 


4.00 PRINT 
41© PRINT 
42© RETURN 
5©© PRINT 
51© PRINT 
52© RETURN 
60S PRINT 
610 PRINT "NOT Y 
52© RETURN 
70S CLS 
715 GOTO 1© 
i ass r« c. 

1315 PRINT "THE END" 
SYNTRCTXC SUM: 35677 


THEN GOTO 705 
AND Y UAS TRUE." 
OR Y UAS TRUE." 
NOT X UAS TRUE." 

URS TRUE." 


SK / IK 


r 


i® 


HEAR THE POWER OF YOUR 

SINCLAIR 

It’s been said that the future belongs to those who under¬ 
stand computers. If that’s true, what better way to do this 
than by having them talk to you. 

Now you can. Quickly. Simply. Economically. 

Let the power of your Sinclair ZX80/81 ™ or Timex 
Sinclair 1000™ speak for you now. Through R.I.S.T. 
Computer Components, Inc. CHATTERBOX™ — your 
ZX80/81 or TS1000 can speak...clearly, concisely and 
without limit. 

R.I.S.T. has developed a state of the art voice synthesis 
module you plug in. CHATTERBOX utilizes allophone 
concatenation to synthesize speech, with limitless 
vocabulary. Sentences, and any English language word 
can be created. / 

Best of all, CHATTERBOX is affordable. For $69.95, 
your ZX80/81 or TS1000 can give you the t/oice of the 
future...today! 

R.I.S.T. Computer Components, Inc. 

P.O. BOX 499 , Ft. Hamilton Station, Brooklyn, NY 112090499 

My computer is □ ZX80* □ ZX81 □ TS 1000 

Enclosed is $_for_module(s) at $69.95 ea., plus 

$3.00 Shpg ea. (includes complete documentation). 

□ *9V Power Supply (optional) $9.95 ea. (Required for ZX80 or 
expanded system operation). 

For orders outside continental U.S., please send bank draft. 


i 


NAME. 


ADDRESS 
CITY _ 


STATE 


APT. 
ZIP _ 


2S INPUT X 
3© PRINT X 
35 PRINT 


17 








HARDWARE REVIEW 

Product: MD-1 Direct-Connect Modem 

and RS-232 Port 
From: Byte-Back Co., Rt. 3, 

Box 147, Brodie Rd., 
Leesville, SC 29070 
(803) 532-5812 
Price: $99.95 Kit, 

$119.95 Assembled 

Some people just aren't happy 
with the limited world of the 8K 
ROM ZX81. Perhaps they shouldn't 
be. Ads tell you that information 
awaits you at your fingertips. The 
tool you need to access this infor¬ 
mation is a modem. 

Modem stands for modulator- 
demodulator, because it converts 
electronic signals into tones that 
can travel over phone lines. Typi¬ 
cally, modems either connect dir¬ 
ectly to the phone line (called 
direct-connect), or connect to a 
telephone handset through a speaker 
near the mouthpiece and a micro¬ 
phone near the earpiece (called 
acoustically coupled). 

Input to a modem consists of a 
serial bit stream (the number of 
bits per second sent to the modem 
is called the baud rate). Modems 
don't care what bits you send them, 
but they do care what voltages you 
use to represent 1 and 0. Most 
modems use the RS-232C standard. 

But even RS-232C doesn't specify 
the code used to represent differ¬ 
ent characters. 

Most computers (ZX/TS ex¬ 
cluded) use the American Standard 
Code for Information Interchange 
(referred to as ASCII) internally, 
and therefore communicate with 
modems and terminals using ASCII. 
Since ZX/TS machines do not use 
ASCII, software or hardware must 
translate or you will only be able 
to communicate with a limited sub¬ 
set of computers. 

One final definition: modems 
use different frequencies to trans¬ 
mit than they do to receive. Ob¬ 
viously, one modem must transmit on 


one set of frequencies while the 
modem at the other end receives at 
those frequencies. The frequencies 
used by the modem at the calling 
end are the originate frequencies? 
the others are called the answer 
frequencies. Modems that can use 
either set are called originate and 
answer modems. Many modems used by 
personal computers originate only. 

Byte-Back's MD-1 incorporates 
a board to generate RS-232 signals, 
a direct-connect, originate and 
answer modem board to generate 
standard communication tones, and 
cassette software to translate 
ZX/TS code into ASCII and vice- 
versa. You needn't worry about not 
being able to call up your favorite 
computer system with a MD-1—you 
can communicate with virtually any 
kind of computer using the MD-1 
with your ZX/TS computer. 

We did not build the kit, but 
the instructions seem complete and 
clear. Byte-Back also provides 
technical assistance by phone. 

Without modifications, the 
software provided with the MD-1 
runs 300-baud ASCII through the 
modem, sending uppercase and con¬ 
trol characters only, and receiving 
uppercase and lowercase (lowercase 
characters are displayed in reverse 
field). My first attempt at using 
the modem failed because the compu¬ 
ter I called insisted on lowercase 
input. For speed, the software had 
to be written in machine code 
(listing available for $10), and 
requires modification to act as 
more than a "dumb" terminal. Byte- 
Back plans to offer software allow¬ 
ing downloading programs from Com¬ 
puServe (a database system) and 
storing data in memory. On the 
other hand, the software provided 
fits nicely in 2K RAM (but not in 
IK), dispensing with the need to 
carry a RAM pack with you to use 
your TS1000 as a portable terminal. 
Carrying a recorder to load the 
tape is a greater drawback. 

Byte-Back's hardware exempli¬ 
fies good design: careful choice 


18 



CLASSIFIED ADS 


of components to minimize cost; 
quality, neatly laid-out circuit 
board; simple packaging; low cost. 
Their software, on the other hand, 
works with no frills, and, in fact, 
with not all the neccessities. 

Most of the missing features (no 
lowercase input, for example) can 
be avoided easily. But if you 
expect performance like a typical 
$1000 terminal, there is no emula¬ 
tion of cursor positioning, clear 
screen, home, or many of the other 
amenities that have been in term¬ 
inals for years. 

If you don't mind loading a 
program to use your modem, and 
don't need frills (or can add them 
yourself), Byte-Back's MD-1 will 
work for you.—EO 


Reach thousands of ZX80/81, TS1000 
owners! Send your ad, typed 35 
characters/line (including spaces 
and punctuation), with check or 
money order for $9/line. Include 
your telephone number, whether or 
not the number appears in ad copy. 
Ad must arr ive by the 15th of any 
month for the next month's issue. 
Any ad arriving after the 15th will 
appear in the issue following the 
next unless you request its return. 
Ads must be resubmitted for each 
month. No phone orders or credit 
cards. We take no responsiblity 
for advertisers or products 
advertised. SYNTAX Classified Ads, 
RD 2 Box 457, Harvard,MA 01451 


TWO NUMBERS IN ONE BYTE—8K/16K 

Suppose you have a large 
program, lots of data, and not 
enough memory. Is there any way to 
fit more in less? 

If your integer data always 
falls in the range 0 to 15, you can 
store two numbers in each byte 
(character) of a string array 
(since there are 256 different 
character codes) by multiplying the 
first number by 16 and adding it to 
the second. In the accompanying 
program, line 70 stores two numbers 
(N1 and N2) in the Xth character of 
a string, and lines 120 and 130 
read them back. 

Rolf L. Miller, Ventura, CA 


*********************************** 

* SOFTWARE for ZX81 and TS1000 * 

* Games,Business,Utility and more * 

* Send $1 for air new catalog * 

* refunded with first order, to * 

* GREAT LAKES SOFTWARE,201 Burl- * 

* ington Rd,Valparaiso IN 46383 * 

*********************************** 

*ZX80/81 Owners New Filter Network* 
*Cures your interference problems * 
*Fully tested w/60 day warranty. * 
*A11 parts UL-CSA approved. * 

* ONLY $49.95 plus $4 shipping. * 

*(VT,add 4%Tx) Send check or MO to* 

* DYNAMIC CONCEPTS,INC. * 

*6 Eaton Ave. Springfield,VT.05156* 

TRANSPARENT DUST COVERS to fit your 
ZX81/TS+16K $3.49 ea.:MIKE ROBERTS 
1367 E. 12th, Des Moines, la 50316 


IS DIM a £ C 3j_ 

gw t- ytj V = 3_ i Q rj 


o© 

PR IN 

T N2 



70 

v—. .-•v 

J—V, 

LET^ 

NEXT 

fi $(X) =CHR$ 

*. / 

* f .T .. .» j— . •> *.—V X 

iwi* xb twc: ? 

W 0 

*1.0 0 

*-"v 4—k -r“ a * 
W ■ IV* 
z a -- t 

S—\. *— t T* *. t 

K K JL r-4 

• 

» 

"T 



110 

FOR 

X = 1 TO 5 



x£S 

L_cE i 

Nl=INT (CODE 

f X i /16J 

13© 

LET 

N2=COC-E Ri 

(X) 

— i HI IS) 

24-0 

PR IN 

IT HI . M2 



153 

NEXT 

V 




SYNTACTIC SUM; 224-SB, SKy'i&K 


***for TIMEX/SINCLAIR computers*** 

LOST IN SPACE (uses SLOW)-11.95 

UNIVERSAL INVENTORY FILE -16.95 

UNIVERSAL M AILING LIST -10.95 

UNIVERSAL COIN COLLECTION -10.95 

UNIVERSAL STAMP COLLECTION -10.95 


UNIVERSAL COMIC BOOK COLLECT.- 10.95 
UNIVERSAL BASEBALL CARD COLL.- 10.95 
UNIVERSAL RECORD ALBU M COLL.— 10.95 
Each program on cassette + manual. 

(8K R0M,16K RAM) M.C.Hoffman Co. 
P.0. Box 117, Oakland, NJ 07436 


19 







SYNTAX offers a faster way to find 
answers! Laminated Microprocessor 
Instant Ref. Cards Z80, 6502, 8080A 
& 8085A, 8048 & relatives and 
programmers' algorithms ref. card, 
$5.95 ea. Prices include shipping. 

**"EPHEMERIS V" (C) PLANET FINDER** 
Any date,time,place on Earth—Finds 
RA&dec,constell,azimuth&alt for the 
major planets,Sun&Moon! Plus LOCAL 
sidereal time,moon phase&much more! 
16K For amazing cassette send $8.00 
to:EPHEMERIS V 124 Professional Ave 
**P0 Box 261 Winchester, Ky 40391** 

FIND GOLD IN CALIF-16K TAPE $3. 
Free-Sftwr&Hrdwr Cat.-No Tape over 
$3-R0SE 269 DAHLIA I.B.CA. 93032 

** ADD MEMORY THAT WON'T FORGET! ** 
* Kit $31:90 SASE details: HUNTER * 
*1630 Forest Hills OKEMOS MI 48864* 

EDIT, DELETE AND " WITHOUT SHIFTING 
on big keyboards. Schematic: $4.95 
SI/TI 25 Hilltop Ave, Lex MA 02173 

FINANCIAL PLANNING TAPE-Annuities, 
Mortgages and more-for ZX81 $9.95 
SIMEX 25 Hilltop Ave, Lex MA 02173 

MC LINE RENUMBERER(DOES GOTO&GOSUB) 
Utilities $5(SASE for info)TO Brown 
SOFTWARE 53 CLIFF LANE LEV.NY 11756 

ZX81 VIDEO MONITOR AMP. COMPOSITE 
Output. Installs Easily Inside Case, 
Instructions Included $9.95? JDC 
5-14- SENTINEL RD.?DOWNS. ONT.CANADA 

PUT YOUR TIMEX/SINCLAIR COMPUTER TO 
WORK! Maximize your investment with 
the TIM EX/SINCLAIR SOURCEBOOK which 
list programs, hardware and books 
for TS and ZX computers. $6.95+1.25 
P&H TX res add $.35. MDC Dept SY-11 
PO Box 280 Carrollton, TX 75006 

*********************************** 

*CUSTOM ATTACHE CASE Formfit for * 

*ZX80/81,TS 1000 and hardware for * 

*info send SASE COMPUTA-DEK 6009 * 

*Kenwood Dr. Nashville, Tn. 37215 * 
*********************************** 


DRY GULCH. An interactive adventure 
written in the classic style. Over 
100 words of vocabulary. This one 
will take days to solve. Written 
in BASIC, it is listable and may be 
SAVEd in progress. 8K/16K. Send 
$10 for a cassette to: UPSTATE LABS 
27 ELVIRA STREET ROCHESTER,NY 14606 

5 programs on tape 99 Free Details. 
Original Programs,3763 W.Crocus dr. 
Phx,AZ 85023 Stamp Appreciated 

*SLOTMACHINE* 16K-LIST-$3.00.32K/64K’ 
Tape-$5.00.L.Youngberg, 13794 Beach 
Blvd,#433,Westminster,CA 92683 

COMPUSETTE is a C-10 cassette which 
is especially designed for micro¬ 
computer application by TAPEMASTERS 
25 for $20.00 100 for $70.00 

VISA MASTERCARD C.O.D. 

TX 214-349-0081**OTHER 800-527-1227 
10% Discount for Check with Order 
P.0. Bopx 38651*Dallas, Texas 75238 
FREIGHT PREPAID*DEFECTIVES REPLACED 

*** THE DEFINITIVE TAX PROGRAM *** 
Fr 16K ZX81/TS1000. EASY DATA ENTRY 
AUTOMATIC TAX COMPUTATION FOR EACH 
CHANGE, INCLUDING INCOME AVERAGING. 
Info:SASE, Cassette:10.95. ** LQP 

2365 Newcastle,Cardiff,Ca,92007 ** 

**NEW SPORTS PROGRAMS FOR ZX82 16K* 
FOOTBALL-Predicts which pro teams 
will win with amazing accuracy 
GOLF-Shows a hole by hole anylisis 
of your scores to improve your game 
BOWLING-Anylisis of score by frames 
Each program: Tapes $7 Listings $3 
BRONZE STAR SOFTWARE 
PO BOX 265, Chicago Ridge,, IL 60415 

*********************************** 

THE ORIGINAL AND MOST POPULAR!!! 
THE SINCLIAR COMPUTER FAMILY SOURCE 
BOOK (1st Revision) gives detailed 
listings of over 600 programs,books 

6 accessories. 99 pg. only $6.95 + 
$1.25 P&H. VA res. add 4%. Send 
check or money order to ATLANTIC 
COMPUTER PRODUCTS,POB 936 Norfolk, 
VA 23501 

*********************************** 


20 



PROBLEMS? We deal in SOLUTIONS. Our 
professional quality hard/software 
are a step beyond the rest. Send an 
SASE now for a free catalogue to: 
PHOENIX ENGINEERING SYSTEMS, 704 
Washington, Grosse Pte., MI 48230 

$$$FALL SALE ON 16K '81 SOFTWARE$$$ 
ZX-FORTH, ZX-CALC(Spreadsheet) , ZX- 
FILE, Zx-BUDGET, ZX-PLAN(Personal 
Calendar), ZX-INVENTORY. $15 ea. or 
3 for $40 or all 6 for $80. SofTek, 
Box 4232, Santa Fe, NM 87502-4232. 

10 MATH UTILITY PROGRAMS:problem- 
solvers for teachers/students:Quad- 
ratics,determinents,series,statist¬ 
ics,etc.$7.50 cass.THE RANCH SCHOOL 
Rt. 1 Box 150, Laneville,Tx. 75667 

IMPROVED HEATSINK eliminates over¬ 
heating of ZX81/TS1000 4 info:SASE 
B.Sanzone 289 Baxter La.Milford,CT 

BUFFERED BUS KIT$63,BARE BOARD $43. 
UHF MODULATOR rids video noise $15. 
RIBBON CONNECTORS male,female,$8ea. 
Project Book $8. Opcode Program $4 
COMPUTER CONTINUUM 301-16th Ave. 

San Francisco CA.94118.(415)7526294 

ZX81/TS1000 - 16K FINANCE SYSTEM. 

Consists of 5 programs: Annuities, 
IRA Accounts, Trend Analysis, 
Compound Interest, Annuity Due. 
Menu driven, on screen update. 
$19.95 + $1 P/H. K & K Software, 
PO Box 6403, Falls Church, VA 22046 

KROK — AN INTELLIGENT GAME AT A 
thinking man's price. 500 coins are 
scattered randomly in a 135-room 
maze in an ancient Mayan pyramid, 
differently each time of course. 
Bats, snakes, monkey sare a few of 
the graphic obstacles confronting 
you — but the greatest is KROK, 
the relentless pursuing crocodile. 
Maps, keys, magic rings, a sword 
open new doors, including doors in 
your mind. High quality cassette. 

16 K RAM required. Satisfaction or 
refund. $6.95 from Brown Cottage 
Industries, 4386 Bright Hawk Court, 
Columbia, Md., 21045. 


Easy build portable table top cab¬ 
inet holds Timex/Sinclair,recorder, 
TV,wires and more neatly.Plans 2.50 
Gabriel 108 Evans,Tiverton,RI-02878 

CHECKBOOK 16K Written in BASIC 
200-400 checks and more $10 tape or 
info SASE to D Lipinski, 2737 
Susquehanna Rd, Roslyn, Pa 19001 

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ 
$ No-Limit DRAW POKER $ 

$ Challenge any 5 of 10 opponents $ 
$ - each plays differently - $ 

$ ZX81 16K Cass_ZXP11C..$16.95 $ 

$ TS1000 16K Cass..TSP11C..$16.95 $ 

$ $ 

$ BASICALLY SOFTWARE COMPANY $ 

$ PO Box 2987, Syracuse, NY 13220 $ 

$ Postage & Handling.$1.50 $ 

$ NY residents add 7% sales tax $ 

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ 

PAKGUY:Avoid goblins & gobble dots. 
SKYMINES:Move to destroy mines with 
lasers.2 fast thrillers on cassette 
with 16K M.C!-$6.MILL RESEARCH 2307 
Adanac St.Abbotsford,B.C.CAN.V2S4T1 

*********************************** 

AT LAST: REVERSE VIDEO FOR THE ZX81 
WHITE LETTERS ON A BLACK BACKGROUND 
FITS INSIDE CASE-ONLY 4 CONNECTIONS 
send check or money order $15. 

SIGHT AND SOUND ELECTRONICS 
1120 Bailey Hill Rd. #10 

Eugene,OR. 97402 
*********************************** 

***FREE XMAS GIFT FOR ZX/TS USERS. 
Send printed stamped & self add¬ 
ressed envelope to:YAGSEE,POB 155 
,VICKSBURG,MICH,49097************* 

LEARN DATA HANDLING -ZX DATE FINDER: 
for 16K ZX81s. A versatile file 
storage tool w/comprehensive file 
search, display and edit functions. 
1900 words of data capacity. $9.95 
gets you list/complete explanation 
or send for free specs and catalog. 
Tom Woods box 64 Jefferson,NH 03583 

SALE-2K RAM-ZX81.WRITE D.F.ROBERTS 
2138 Salamanca,Port Richey,FL 33568 


21 





ZX PROFESSIONAL PROGRAMMING FORMS 
9xll-ea line,col,pixel numbered Pad 
of 50: 1.99 /5 at 9.25(25 post) 
pTp,7760 N. Hopdown,TucsonAZ 85741 

WOW IK Games on Cassette:JUST $9.00 
AUTO RACER,MINI ARTIST,DEPTH CHARGE 
BLACKJACK, eight more! Send to: H&H 
Electronics,3379 Rt46-6D,Parsippany 
NJ , 07054-P&H 75f-"FREE CAT." SASE!! 

*********** C.R.C. INC. *********** 

* 16K PRACTICAL SOFTWARE FOR THE * 

* HOME, SASE FOR FREE CAT&PR LIST * 

* 2901 Auburn Auburn Hgts Mi 48057* 

**ASTROLOGY 16K-Now you can write a 
complete,professional horoscope.All 
planets/interpretation.$17.L&S, POB 
935 NewPaltz,NY,12561 (914)255-5521 

<*VOTEM*> Analog Interface* Measure 
voltage & temperature with your ZX* 
$39.95/kit-$59.95/asm-$5/doc alone* 
Add $3/USpost* Down East Computers* 
PO Box 3096 , Greenville,NC 27834 * 
*6116 RAM 1K->2K w/soc $9.95 p.p. * 

PLAY "T.V. FUED" ON YOUR ZX MACHINE 
Like the famous T.V. game show 
Requires 8K ROM and 16K RAM-Specify 
ZX80 or 81 version-on cassette tape 
$6.95 plus $1.50 shipping & handle 
DESERT SOFTWARE 212-B North Fifth 
Kingman, Arizona 86401 

Put your ZX81 to work! Stock pkg. 
incl. Stk-Calc & Stk-File, or Bud¬ 
get Planner. Either: $5.95 cass. 
3.00 Xerox to—Mike Putira 5 Farm¬ 
stead Lane, Rockville CT 06066. 

INPUT AT Add this powerful command 
to your ZX81/TS1000.Equivalent to 
PRINT AT,it allows you to input va¬ 
riables from any location on the 
screen.Simply enter into REM's.Ex: 
300 LET K=USR Input-At 
310 REM INPUT AT 5,2,A,V,AT 6,4 C$ 
Resides above RAMTOP(400 bytes).Pro 
vided w/ screen editor (uses * f) 
for simple data entry.Excellent for 
setting up menus.$12 Send check or 
MO to ANDES INT'L 219 S. MILITARY 
Rd Apt B SLIDELL,LA 70458. 


EZRA GROUP II 
EZRA GROUP II 

LOW LOW LOW LOW LOW LOW LOW LOW LOW 


PRICES! 

Biorhythms 8K ROM/lK&up.1.00 

Graphics Billboard 8/lup...1.00 

Horse Race 8/lup.2.00 

Plotting Work Sheet 8/1.3.95 

Plotting Work Sheet 8/16.6.95 

SPINNER TM(like Rubik's) 8/16...2.00 

Improved SLOW PAUSE.1.00 

Linear Regression 8/lup.2.00 

CHEWTER TM(like Pacmn)SLOW/lup.2.95 

Dog Race 8/lup.1.95 

Random MUSICISLOW/1 up.2.00 


TAP WRITER TM (Handicap Aid) 8/1.free 
CHAR. Generator Demos 8/lup....2.95 
ORDER or $1 refundable gets you 
GOODIES Catalog and !FREE! Program 
EZRA GROUP II 
EZRA GROUP II 

POB 5222 San Diego California 92105 

RELIABLE PROGRAM LOADING AT LAST! 

ZX LOADMASTER unit does it right. 
For info send SASE to CINEVISION 
PO Box 546 Montebello Ca 90640 

New game! "LOST IN SPACE" Moving 
graphics. Flicker-free. Steer ship 
past meteors & enemy ships. Land on 
fuel ship for bonus. Status fuel 
monitor $ current score. Auto-run. 
Prompts & more! for TS1000 or ZX81. 
16KRAM. Cassette + Instruct. $11.95 
(dealers wanted) M.C.Hoffman Co. 
P.0. Box 117, Oakland, NJ 07436 

*********C H AS. E. GILL CO.********* 
* * * * *f 0 RMERLY THE FUNWARE CO.****** 
l.LAND THE SPACE SHUTTLE 2.LAND/AIR 
BATTLE 3.SPACE BATTLE 4.HUNTMAN*ALL 
ZX-81/16KRAM ON QUALITY C-20 TAPES. 
EACH GAME $4.95 OR ALL FOUR $16.95. 
PAPER FOR ZX/PRINTER $6.50 PER ROLL 
ALL PRICES INCLUDE SHIPPING/HANDLE. 
7119 Santa Fe Av. Dallas, Tx. 75223 

HAVING PROBLEMS LOADING FROM TAPE? 
AI-1, auto level set, selfcontained 
interface corrects those problems 
for any tape recorder or deck. 
$25.00 pp USA. Send check or MO to: 
JACYN Electronics, PO Box 570, Port 
Orchard, WA, 98366 


22 












SOLVE LOADING PROBLEMS—DIRECT COPY 
ANY ZX/TS CASSETTE w. multi-feature 
WINKY BOARD1 Easy to use. No mods. 
Free info. $18PPD,$12kit. G.Russell 
RD 1 Box 539 Centre Hall PA 16828 

"SUPER DUNGON" This adventure game 
changes ea. time you play it. $20 
($5 charge on all returns) 8K/16K 
CUSTOM COMPUTERS 20927 124 Ave. SE 
Kent, WA 98031 (NO CODs, enc. pay) 


OUR POLICY ON CONTRIBUTED MATERIAL 

SYNTAX invites you to express opinions related to any Sinclair computer or 
peripheral, or the newsletter. We will print, as space allows, letters discussing items 
of general interest. Of course, we reserve the right to edit letters to a suitable length 
and to refuse publication of any material. 

We welcome program listings for all levels of expertise and written in either 
Sinclair BASIC or Z80 machine code. Programs can be for any fun or useful 
purpose. We will test run each one before publishing it, but we will not debug 
programs; please send only workable listings. Programs submitted on cassette can be 
tested more quickly and with less chance of error. 

In return for your listing, we will pay you a token fee of $2.00 per program we 
use. This payment gives us the nonexclusive right to use that program in any form, 
world-wide. This means you can still use it, sell it, or give it away, and so can we. 

We will consider submissions of news and hardware or software reviews. Please 
keep articles short (350-400 words). Again, we reserve the right to edit accepted 
articles to a suitable length. We will pay 7 cents per 6 characters, including spaces 
and punctuation, for accepted articles. 

When you send in programs for possible publication in SYNTAX, please 
include the following information: 

• How to operate the program, including what to input if it does not contain 
prompts. 

• Whether you can run the program over again and how. 

• How to exit the program. 

• The Syntactic Sum (program published in Feb. 81 and Jun. 81; send SASE 
for a free copy). 

• What RAM size program requires. 

• What ROM program uses. 

We pay for this explanatory text at the same rate as for articles in addition to 
payment for the program itself. 

If you want us to return your original program listing or article, please include 
a self-addressed, stamped envelope. Otherwise, we cannot return submitted material. 


ZX ADVENTURE II — Latest "CASTLES 
& CREATURES" (TM) adventure game 
from CINQUEDA SOFTWARE. Challenging 
and enjoyable for beginner and 
advanced.16K RAM. Complete instr. & 
tape. Send$9.95 chk or MO to: 
CINQUEDEA SOFTWARE 214 Indian 
Creek Drive, Pekin, II 61554 

EZ-HEX Read-write-test Z80 machine 
code on your 16k ZX81.Count-move- 
convert between hex&decimal-even 
saves and loads above ramtop-all 
from menu.No more poking around. 
Z-WRYTER Word processor.Write and 
save text using powerful editing 
functions usually found on larger 
machines.$9.95 each on cassette- 
RCO Technical PO BOX 773 St Ann 
MO 630747 

Programs for T/S 1000 -Send $1.00 
for catalog and game: BARLOG S/W 
401 N. GEYER; KIRKWOOD, MO 63122 

ZX81 2K UPGRADE-$14 FOR KIT- $24+ZX 
& I Will Upgrade.Micro Basics, 5768 
ALBANS CIRCLE, LITHONIA, GA 30058. 

FROG-IT! for IK ZX81!! Jump on 
moving blocks. Miss & die! Listing 
$2.50. PANERO SOFTWARE, 3309 Lewis, 
Long Beach, Ca. 90807. Ribbit!! 


SYNTAX is published 

monthly by a wholly-owned 
subsidiary of The Harvard Group. 

Syntax ZX80, Inc. 

RD 2, Box 457, Harvard, MA 01451. 

Telephone 617/456-3661. 

12 issues, $29. Single issue, $4. 

Publisher: Kirtland H. Olson 
Editor: Ann L. Zevnik 
Assistant Editor: Pamela Petrakos- 

Wilson 

Editorial Assistant: Pamela K. Vinal 
Tech. Consultant: Eric Olson 

© Syntax ZX80, Inc., 1982. All 
rights reserved. Photocopying 
prohibited. ISSN 0273-2696 


YES! Please send me 12 issues of SYNTAX for $29. 

□ My check for $29 is enclosed. □ Please charge my □ MasterCard 
Make checks payable to: □ Diner’s Club □ American Express 

SYNTAX ZX80, INC. □ VISA □ Carte Blanche account 

account number_—- 


exp. date_ 

signature_ 

Name_ 

Organization_ 

Address_ 

City_ 

Day PhoneJ_)_ 

I own a □ Sinclair ZX80 


bank number (MC only) 


Title 


_State_Zip__ 

_Evening Phone_i_ l - 

U*St 

□ Sinclair ZX81 Telephone orders call 


617-456-3661 


23 



SYNTAX 


12"B&W video monitor only $89.95. 
Includes free plans and kit of all 
parts needed to add a direct video 
output to your ZX81/TS1000. Direct 
video conversion kit alone is $9.95 
Delux version $18.95 f provides 
switch selectable normalor inverted 
video.Add $8.50- shipping&insurance 
for each monitor,$1.50 for each kit 
Random Access,Box41770S,PHX AZ85080 

SINCLAIR ZX81 TIMER MODULE! 

3 CHANNEL, 5 MODE, TO 18 HOURS. 

2 AMP CONTACTS . Software Control. 
Interval, Delayed Interval, On-Off 

Repeat. $55 Lee Sorrell 3 Bahia 
CIRCLE, LAND O' LAKES FL. 33539 

ZX81 ASSEMBLER in Basic & m.c. (12K) 
stand. Z80, hex/decimal constants, 
outputs anywhere. ZX81 DISASSEMBLER 
also Basic & m.c. (4K), hex or dec. 
output. Both for $15.00 ppd. SERIAL 
PRINTER interface (thru MIC port) 
cheap & easy plans/listing $5.00 
INTEGER BASIC COMPILER avail. Dec. 
22 Keywords,11 functions $22. Bob 
Berch 19 Jaques Rochester NY 14620 

** DIRECTORY ** NAMES/ADDR/ZIP/TELE 
Add/Del/Seek/Sort/Auto-Sav+Run/More 
Listable*16K*Tape*ZX81/TS1000 5$9.95 
NBB, 14 JORDAN RD,BREWSTER,NY 10509 


*********************************** 

Speed it up! Your programming that 
is! Non-Trivial Solutions' ZXPRESS 
Integer Basic Compiler compiles ZX- 
81 source code to machine language. 
This means your programs can be de¬ 
bugged rapidly in ZX-81 BASIC, then 
compiled. The compiled codes are 
stored in REM statements or in 
2000H to 3FFFH address segment, if 
available. The ZXPRESS Compiler 
will make your ZX-81 20 to 50 times 
faster. It's variables are 16 bit 
two's complement integers. The com 
piler allows multiple statements/ 
line. With the ZXPRESS, the source 
code can be located anywhere and 
the position of the compiled code 
can be selected, allowing you to 
write a long program, compile it in 
pieces, then assemble the pieces. 
The ZXPRESS is available from N-TS 
for only $29.95. For mind stimu¬ 
lating recreation, N-TS continues 
to offer the games Letter Raiders 
and Life with Palette for $9.95 
each. NON-TRIVIAL SOLUTIONS, P.0. 
Box 2941, Amarillo, TX 79105, 806/ 

379-5723. Check, MC, Visa welcome. 
*********************************** 

$-WIN CASH PRIZES in ZX WORDGAMES-$ 
Info: SASE Box 505, Carmel CA 93921 


24 


Tl-E 

H\RV\RD 

GROLP 

Bolton Road. Harvard, Mass. 01451 


First Class 


U.S. Postage 
PAID 

Harvard, MA 
Permit No. 8 
01451 


MR WILLIAM TOMLINSON 58 68 

3635 RIVERED6E DR. 

JACKSONVILLE FL 32211