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Serving 

The Timex-Sinclair Family 
Of Personal Computers 

A PUBLICATION OF THE HARVARD GROUP 


VOL. 3 NO.IO ISSN 0273-2696 OCT, 1982 



i 





r 


IN THIS ISSUE 


8K Programs 

Fifteen Puzzle.17 

Grading Program.10 

Monsters.7 

Ohm's Law.16 

Unit Pricer.19 

Beginning Programming 
When Your Computer 

Gets Full.6 

Classified Ads.20 

Dear Editor.12 

Hardware Project 
Tape Level 

Indicator.14 

Hardware Review 

Votem.9 

Loading with Syntactic 

Sum.11 

Machine Code Programming 

Jumping Around.19 

News/New Products...1,2,3 

Program Corrections.3 

Program Improvements....4 
Software Review 

ZETAPAK.13 

Subscription Info.23 

Users' Groups.3 

ZX81 Logic Signals.13 

Index of Advertisers 

Brem Systems.11 

Byte-Back.17 

E-Z Key.9 

General Systems.14 

Intercomputer.19 

Kopak.8 

Memotech.18 

Sof tsync.15 

Zeta Software.7 


SQ, SYNTAX QUARTERLY, is 
comming next month! All 
SYNTAX suoscribers get 
the first issue free. 


ASCII PROGRAM FOR ZX/TS COMPUTER 

CAI just announced an ASCII program to 
let the ZX/TS computers equipped with CAI/O 
boards operate as a standard ASCII CRT ter¬ 
minal. The program is on an EPROM that goes 
on the I/O board and is priced au $24.95 
(plus $1.95 S&H). Contact CAI Instruments, 
P.O. Box 2032, Midland, MI 48640. 

QUICK TAPE LOADING AND SAVING BY MINDWARE 

Mindware revolutionizes tape loading 
with 20 new QUICKLOAD software packages 
for TS1000S and ZX81s. QUICKLOAD software 
loads/saves 6x faster than current ZX/TS 
software and verifies whether the program 
loaded properly. Prices range from $9.95- 
$24.95. QUICKLOAD software includes game, 
programming aid, ousiness and engineering 
programs. Mindware will start mass market 
distrioution Nov.l and plans to be in 10,000 
stores Jan 1. 

EDUCATION WORKSHOP SERIES EXPANDED 

Technical Education Research Centers, 

Inc. (TERC) is expanding its workshop series. 
Microcomputers in Education, to 14 national 
sites this year. Workshops are designed for 
professional development for educators (ele¬ 
mentary through college) emphasizing hands-on 
experience with micros including ZX/TS com¬ 
puters. Evening symposia will address micro¬ 
computer applications in education. Sharon 
Woodruff, TERC, 8 Eliot St., Cambridge, MA 
02138, 617/547-3890. 

LONDON MICROFAIR SHOW GUIDES AVAILABLE AGAIN 

We now have a limited supply of show 
guides from the last London ZX Microfair. 
Guides list British ZX suppliers and 
products, $3.50, first class mail. SYNTAX, 

RD 2 Box 457, Harvard, MA 01451. 


1 





























NEW PRODUCTS AND SERVICES 

ZX DATA FINDER, a high capacity 
text/file manager, gives pro¬ 
grammers interested in file and 
data storage techniques on ZX/TS 
computers an advanced course 
on the subject and a versatile 
catalog/index/reference tool. 

The program requires at least 
16K RAM. Price for the listing 
with a detailed explanation of all 
edit, search and display routines 
is $9.95. Free info. Tom Woods, 
Box 64, Jefferson, NH 03583. 

Hunter just announced an 8K non¬ 
volatile RAM board filling an un¬ 
used 8K block of memory (8K-16K) in 
the 16K ZX/TS system. A sample 
rapid display routine, procedures 
for storing utilities on tape and 
a 14-page manual come with the kit. 
A board, sockets, resistors and all 
components are included. It also 
comes with lithium cell (which 
maintains sufficient reserve power 
for about 10 months for 2K or for 
about 2 months for a fully popu¬ 
lated board). A 2K CMOS 6116P-3 
RAM is also supplied. A connector 
is available for an alternative 
external supply. $29.95 by check 
or MO to Hunter, 1630 Forest Hills 
Drive, Okemos, MI 48864. Circuit 
board and instructions are avail¬ 
able separately for $15 ppd. 

1981-82 NFL Statistical Summary for 
the ZX81 with 16K is available from 
Miller-Zamis, Inc., 251 First St., 
Willis Day Industrial Park, Perrys- 
burg, OH 43551, 419/666-2410. 

Zamis Engineering is also involved 
in developing a robot which uses 
the ZX81 as the main control unit. 
After finishing the project they 
may sell both plans and kits. 

KRAKIT, from International Pub¬ 
lishing and Software, is a trea¬ 
sure hunt game that has 12 clues 
and offers a bounty of $2#*000 to 
the first entrant to solve all the 
clues successfully. The game is on 


cassette for the ZX81 and TS1000 
with 16K RAM and will not be of¬ 
ficially released until Oct. 15. 

To keep entrants informed on the 
status of the contest, a 24-hour 
answer line will be in operation 
when the contest is underway. 

KRAKIT will be sold in retail 
stores, or order direct from Inter¬ 
national Publishing and Software 
Inc., Box 1654, Buffalo, NY, $19.95 
plus $1.50 S&H. Address dealer 
and distributor inquiries to: 
International Publishing and Soft¬ 
ware 5952 Chesswood Dr, Downsview, 
ONT, Canada, M3J 2W6. In the U.S., 
Ms. Kearns in NY at 212/490-7957. 

The Home Clock Family Bulletins 
Program gives date, update of the 
time, display of your bulletins, 
and an alarm display area. When 
returning to menu from clock screen 
you don't need to reset the time. 
$20 check or MO for documentation 
and tape. King Software, 85 Myrtle 
St., Lowell, MA 01850. 

Hamrich International is sponsor¬ 
ing a game for ZX80/81 users with a 
$50 cash award to the winner. For 
information on the ZX80 Word Game, 
contact Hamrich International, P.O. 
Box 505, Carmel CA, 93921, 408/624- 
7737. Get entries in by Oct. 15. 

A. &P. Electronics offer every¬ 
thing in stock at close out 
prices. For additional informa¬ 
tion, call them at 916/483-8772. 

Have problems loading tapes and 
overheating in your ZX80? The TL- 
064 module ($19.50, Canadian) and 
and the OP-032 module ($14.95, 
Canadian) may help. P. Poliak, 

6240 Halifax St., North Burnaby, 

B. C., Canada V5B 2P6. 

A directory of educational comput¬ 
ing has just been published by the 
staff of "Classroom Computer News." 
It gives over a 1000 listings, a 
one-year calendar of national and 
regional events and conferences. 


guidelines for selecting hardware 
and software for the classroom and 
a yellow pages listing computer 
services and products. The 
Directory is available in book¬ 
stores and computer stores for 
$14.95/softcover and $29.95/hard¬ 
cover. For info on the upcoming 
Directory or the bimonthly magazine, 
"Classroom Computer News", write 
or call CCN, 341 Mt. Auburn St., 
Watertown, MA 02172, 617/923-8595. 

The National Association For The 
Cottage Industry will hold its 
first regional conference on Oct. 

23 at the Americana-Congress Hotel 
in Chicago from 9:00am to 4:00pm. 
Some workshops topics are: "How to 
Make Money in the Craft Industry", 
and "Rural America and the At-Home 
Industry." Send a $15 check to 
attend; add $15 if you want to 
have "Luncheon with the Experts." 

The National Association For the 
Cottage Industry, P.0. Box 14460, 
Chicago, IL 60614, 312/472-8116. 

The E-Z Key keyboard for ZX81/1000 
has 60 keys, including 8 special 
keys with electronic control. 

Single key functions are: DELETE, 
EDIT, Single and Double Quotes, 
Colon, Semi-colon, STOP and 
Function. Comes with cables and 
instructions. Can be adapted to 
ZX80 or MicroAce. $70 plus $4 
(S&H). E-Z Key, Suite 75, 711 
Southern Artery, Quincy MA, 02169. 

"The Writing Instructor", a quar¬ 
terly journal on computers and 
writing instruction is looking for 
authors. R. Adams, Univ. of S. CA, 
Los Angeles, CA 90089-1219. 

SYNTAX ERRORS: Machine Code Screen 
Fill (Aug.82 p.6) contains two 
errors. In the description of the 
REM line, "inverse H" should say 
"graphic H". The assembly listing 
comment for location 16522 should 
read "C<>0". For location 16526 it 
should read "BO0". 


USERS' GROUPS 

Our latest list of new users' 
groups is is presented below. To 
check for a group in your area not 
listed here, drop us a line (please 
include a self-addressed stamped 
envelope) or give us a call and 
we'll refer you to any group we 
know of. To list your group, write 
us or give us a ring and we'll 
refer interested people to you. 
SYNTAX, RD 2 Box 457, Harvard MA 
01415, 617/456-3661. 

Des Plaines, IL: Circle Chess 
Group, A.F. Stanonis, P.0. Box 63, 
Des Plaines, IL 60017. 

Detriot, MI: Timex-Sinclair Users 
Group, P.0. Box 552, Warren, MI, 
48090. Send SASE for details. 

Indiana, S. Illinois, S.W. Ohio, 
N.W. Kentucky: The FUN-Z, P.0. Box 
914, Jasper, IN 47546, contact W. 
Long with SASE. 

Iowa City, IA: Jim Carroll, 1218 
William St., Iowa City, IA 52240. 
319/351-8031. 

Joplin, MO: Carlos T. Colon, 1228 
Picher, Joplin, MO 64801, 417/781- 
7758. 

New Albany, IN: G. Richard Becht, 
2308 Beeler St., New Albany, IN, 
47150. 

t 

Phoenix, AZ: Randy Saxton, 4827 N. 
63rd Dr., Phoenix, AZ 85033, 
602/846-2882. 

Plattsburgh, NY: Upstate New York 
ZX81 Users, Vern Olson, 13 Dennis 
Ave., Plattsburgh, NY, 12901. 

Research Triangle Park, NC: John 
Drummond, P.0. Box 12546, Research 
Triangle Park, NC 27709. 

Washington, D.C.: Washington Area 
Users Group, Box 6239, Washington, 
DC, 20015, 703/920-7310. 


3 


PROGRAM IMPROVEMENTS/REFINEMENTS 


Mark Freitas' Sine Name (Aug.82) 
raises the question: can I make 
the message snake up the screen 
letter by letter? My solution: 


Ltf N=x 
INPUT Rs 

LET J = LEN R$ „„ _ 

FOR R=0 TO 6*3 &TEP *S 
LET Y =5 XN H 

PR I NT RT C ±0 *Y+10 > R $ (N > 

XF R N=h+i THEN LET H=1 
NEXT H 
GOTO 4^0 

r5UH: i 


10 
20 
30 
4-0 
50 
60 
T© 

90 
100 
110 
5YNT 

Next, can the message be made to 
oscillate about a horizontal and 
diagonal line? Without using 
machine language, the answer is not 
readily apparent. 


f t 


Frederic D. Bogar, Key West, FL 


When using Larry Lockwood's MC line 
renumbering program (Jun.82), if 
your new starting line number (X) 
and/or step size (Y) are greater 
than 255, then 

POKE 16518,X-INT (X/256) 

POKE 16519,INT (X/256) 

POKE 16534,Y-INT (Y/256) 

POKE 16535,INT (Y/256) 

These statements work for any value 
of X and Y. 

The last byte in the MC 
program, EB, isn't the Exchange in¬ 
struction. It is the second byte 
of the 2-byte JR instruction. 

The MC program occupies only 
27 bytes of RAM, so why is it 
listed as 16K? If you use his 
BASIC program to POKE the MC pro¬ 
gram above RAMTOP, you must change 
the values in lines 90, 130 and 140 
accordingly, eg., for 2K RAM: 

90 FOR X=18405 TO 18431 
130 POKE 16388,229 
140 POKE 16389,71 

Harold Miller, Clarkesville, GA 


Some added changes for Hexadecimal 
Math given by Leo Morgan (3/82). 

v'} * -* ;'» ; ,» 

390 LET Y$=¥$ ^2 TO ) 

510 FOR X = i TO 4- 

530 LET H(X)= l INT 0*15)+GS 


You can simplify the parentheses: 

560 PRINT CHR$ H(4* ; CHR$ HC21;G 
HR$ HC1) 

The decimal to hexidecimal con¬ 
version routine was always re¬ 
turning 0000 because the formula 
used for 4K integer math gives a 
different answer with 8K floating 
point math. It will be interest¬ 
ing to see how that comes up in 
other programs. 

Ron Miller, Murrysville, PA 

Here's an improvement to Ian 
Logan's Bytes Remaining—8K 
(Dec.81) which I think more 
accurately represents of the num¬ 
ber of available bytes for a BASIC 
program. As you will note in the 
disassembly listing, the actual 
stack pointer address is subtracted 
from STKEND. 

As in Dr. Logan's program enter 
the following line as the first 
line of a BASIC program: 

i REM E0RND FhST RT 5 T GD3U 
S PX FRST RT TRN 

Again start by entering, 

GOSUB PI FAST AT TAN 
and then backspace to add 1 REM 
etc. Note the two spaces between 
5 and T. Call the routine in the 
immediate mode (no line #s) by 
PRINT USR 16514. On a IK machine 
and just line 1, the display should 
give 821 bytes free. 

I could have saved 2 bytes with 
LD BC,(NN) but 4B hex is not a 
character on the ZX81. 

Max.Bytes Remaining 

IK RAM 1024 Bytes 

Sys Var 125 

Display File 25 
Var End 80H 1 

GOSUB Stack 3 

Mach Stack 14 


856 

More Bytes Remaining 

Routine = 821 Bytes 

1 REM... +20 


841 


4 




There is 'a difference of 15 have to dig up a disassembly of the 

bytes. As fat as I can tell there 8K ROM to be sure, 

are about 14 bytes in the machine 

stack after initialization. I'll William Wentz, Rio Rancho, NM 

Hex Z80 

Character Code Hex Format Mnemonic Comment 

/ 

E 42 2A 2A 1C 40 LD HL,(401C) ;Load the address at the 


;end of the Calculator 
?stack, held at (STKEND)= 
;401C hex=16412 dec, into 


0 

28 

1C 



HL register 

RND 

64 

40 



rReview pgs. 128,134 of 






ZX81 Manual 

FAST 

229 

E5 

E5 

PUSH HL 

;Push address(STRKEND) to 






stack 

AT 

193 

Cl 

Cl 

POP BC 

rPop address(STKEND) off 






stack and store in regis¬ 






ter BC 

5 

33 

21 

21 00 00 

LD HL,0000 

Load register HL with 






-all zeros. 

sp 

0 

00 




sp 

0 

00 




T 

57 

39 

39 

ADD HL,SP 

?Add the address stored 
in the SP register to the 
HL register. 

GOSUB 

237 

ED 

ED 42 

SBC HL,BC 

Subtract the address 
(STKEND) stored in BC 
from the address(SP) 
stored in HL. The 
results are— 

PI 

66 

42 



;stored back in HL. 

FAST 

229 

E5 

E5 

PUSH HL 

rPush the results stored 
;in HL to the stack. 

AT 

193 

Cl 

Cl 

POP BC 

; Pop the results off 
:stack and store in BC 

TAN 

201 

C9 

C9 

RET 

:Return to Basic and 
;Print value in 
:BC. The number 
displayed is the number 

The 

address 

of the 

1st byte 

is 16514. 

:of bytes remaining. 


Jon Passler's Bar Chart (Jan.82 
and improved in Feo.), has a prob¬ 
lem. It can't accomodate a data 
entry of 0 an important data point. 
The program stops with the first 

1 DIM 

2 FOR X=1 TO 25 

3 INPUT 

4 NEXT X 

20 FOR ft=11 TO 21 

3© PRINT ftT ft.. 1; 

40 NEXT ft 

5© PRINT RT ll,@;"£";ftT 16,0; 

1" ; ftT £1,0; ,, 0** 


ruK H = 2 TO 15 

P = 1 TO CUftL + 

® ® PLOT ft *2+3 , P 
0© NEXT p 
100 NEXT ft 

SYNTACTIC SUH: 16066, SR 

empty data point in the array B$(A) 
and generates a run report C/70. A 
0 is accepted as a data point and a 
line is saved. Like Jon's program, 
a GOTO lets you run it again. 


Frederic D. Bogar, Key West, FL 


5 



WHEN YOUR COMPUTER GETS FULL 

Because your computer has 
limited storage space, a time will 
come when you run out—inevitably 
in the midst of your brillant first 
program. Remain calm. You can get 
the space you need. 

Here are some signs that you are 
running out of space: 

1) The listing starts short¬ 
ening. Normally, you can put 22 
lines of program on the screen. 

The line you're entering can use 
the bottom 2 lines. When memory 
gets tight, you get fewer than 22 
lines of program display and the 
working space moves to mid-screen. 

2) After typing in a line, you 
press ENTER, yet ENTER seems to have 
no effect. 

3) ENTER may cause a line to 
disappear altogether. 

4) When you're really low on 
memory, characters you type simply 
will not appear on the screen. 

This is because the computer has no 
room to both store and display your 
input. It chooses to store it. So 
your program line is in the com¬ 
puter, but you cannot see it. 

First get rid of those lines 
that are not crucial to the run¬ 
ning of the program. Try deleting 
some of your REMark statements. 

Next, you can shorten strings 
(which, remember, are within 
quotes) by making shorter state¬ 
ments. For example, change 

30 PRINT "ENTER PLAYER" to 

30 PRINT "ENTER PLY" 

Also, keystrokes take up one 
byte as opposed to spelling the 
command out. For example, "TO" 
spelled'out takes up two bytes. 

Shift 4 (TO) uses only one. 

Constants, numbers with values 
that are stored within the program, 
also take up extra space. 

If you use a constant, say 0, 
often, define it as a variable. 
Instead of using LET A=0, set 
another variable equal to 0: LET 
X=0. Then LET A=X. X takes one 
byte each time you use it. 0 takes 


six. Though you spend some memory 
to set X equal to 0, if your pro¬ 
gram uses 0 many times, you save in 
the long run. 

You can also shorten variable 
names. But remember when compact¬ 
ing a program you sacrifice read¬ 
ability to a certain degree. For 
example: 

80 LET PLAYER=P 

80 LET PLY=P 

Get familiar with the hierachy 
of algebraic functions to gain ex-* 
tra space by using fewer paren¬ 
theses. For example: (4*3)+2 
can be rewritten as 4*3+2. But, 
(4+2)*3 can't be rewritten as 4 + 2 
*3 because the computer multiplies : 
first giving a different answer. 

Eliminate STOP statements at 
the end; your program stops when 
it runs out of lines. 

If you have a display in your 
program, gain space by compressing 
it into the left corner. The same 
lines displayed on the right side 
of the screen take more memory. 

By writing a program in modules 
that don't pass variables between 
one another, you can also save 
yourself some space. But remember 
to include a CLEAR statement at the 
beginning or end of each module. 

For example, a user-friendly intro 
at the start of your program may 
ask the user's name and store it in 
a string variable. If you never 
use that variable in the rest of 
the program, insert a CLEAR 
statement after that intro routine 
to free the space that string 
variable used. And finally, FOR- 
NEXT loops are more efficient in 
memory than programmed loops des¬ 
pite the fact that they use 18 
bytes (1 byte for character/token, 

5 bytes for number, 1 btye at end). 

FOR X=1 TO 5 

NEXT X 

uses less space than: 

X=1 

LET X=X+1 

IF X<=5 THEN .... 

Try these suggestions when you 
need those few extra bytes.—PPW 


6 



MONSTERS—8K/16K 


In this game you (represented 
oy a 0) try to avoid four monsters 
(represented by Xs). You must go 
through a randomly generated maze, 
get to the other side and land on 
a black bar without being caught by 
a monster. 

To move, hit a key from 1 to 8. 
Hitting 1 allows you to move to the 
upper left and hitting 4 allows you 
to move to the upper right. Keys 5 
through 8 allow you to move in the 
direction of the arrow on that key. 

To play again, just hit ENTER. 
To end the game, hit the N key and 
ENTER. If you can't get through 
the maze you may exit the program 
by hitting BREAK. You can rerun 
the program by hitting RUN and 
ENTER. 

Robert Ryan, Gladstone, OR 


yu i O 9900. 
LET J=P 



.*0 


GO f u -3000 


4. LET P=P+ (PEEK P = 118) 

6 IF NOT P=«J THEN POKE U 

7 IF PEEK P=S OP PEEK P=6I 
EN LET P=U 

0 IF PEEK P=5 THEN 
9 POKE P.. 39 

10 RETURN 

11 FOR 1 = 1 TO 4* 

12 GOSUB 2 
14- LET J=R (T) -D 
IS LET K =P -D 

iX ^“iX i-=XNT iK^33> 

19 LET K=K-L*33 
P0 LET J=J-SGN <( 


TH 


X KI- 


; * v 


£ Ux33 js *33) ) 


-L) 

-K) 


< ( \ 

+ 1 > 
f.Q* 


(I) 61 


) *33-6GN £ £ (U-INT 
22 POKE fi(I) 

IF (PEEK (D+U)<>113 RND 
(D+U)=3) AND INT (RND*9) 

l \ OR. PEEK. =0 QP PEEK 

Jl=52 THEN LET A(I)=D+U 

IF PEEK R Cl) =32 THEN GOTO 

000 
26 
2^ 

30 

O000 
6001 

SELF TO BE SUPERIOR * 

ETONS YOU WERE PITTED 
6002 GOTO 9002 

9000 POKE R (I) .. ISO 

9001 PRINT "YOU HRUED PROUED TO 
BE INFERIOR TO THE SKELETONS YOU 
WERE PITTED AGAINST. YOUR RRCE W 
ILL BE ELIMINATED FROM SOCIETY«" 


POKE 
NEXT 
GOTO 
POKE 
PRINT 


R 

I 

II 

P , 151 
"YOU 


HR 


UE 


E>* 


JUED 
HE 


YOUR 

SKEL 


RGRINST." 


3S02 PRINT "PLRY RGRI 
3004. INPUT R$ 

3006 IF R$="N" THEN S 
333S CLS 
3330 LET P=URL 
56 J-PEEK 1539?" 

9901 FRST 

9902 DIM * R £ URL "4.* 1 ) 
3936 FOR I=SGN PI TO 
9912 LET fi (I) = ! JRL "4-3 
t256fPEEK 1639?" 4-1 NT 

( RND *5 + 1) *33 


NT(Y/N) 


TOP 

BEK 16395*2 


URL "4." 

3-PEEK 15396 
C RND *S) +JNT 


9914. NEXT I 

99IS FOR I=5GN PI TO URL "3" 

99 IS FOR «J=SGN PI TO URL ''20" 

9919 LET R$ = “ 

9923 IF*URL "1=1 OR 1=3" THEN LE 
T Ri = n »" 

9921 PRINT A$£URL "INT (RND-fcS)*! 
> 5 " +SGN PI) .* 

9922 NEXT U* 


9924- PRINT "§ " 

9925 NEXT I 
9923 SLOW 

9937 LET D=URL "PEEK 16395+256*P 
EEK 16397*1" 


9933 POKE P.CODE "O" 

934-0 GOTO URL "11" 

SYNTACTIC SUM: 5731, SK/15K 


Chief Editor, Ann Zevnik, will be 
taking a 2 week leave of absence 
from SYNTAX to get married. Ann is 
returning to her home town Peoria, 
IL, for the big day on Oct. 9. 


SCOUT F* I GHTER 
w -J o v s x i o k x 



Yep. $2.50 (postpaid) gets you UPDATE, 
a booklet that guides you thru the easy 
steps of hooking up a joystick to a ZX81. 

Besides listing all possible keys your 
joystick can "enter", UPDATE gives you 
the addresses and codes for poking SCOUT 
into one of the best games around. 

If you want to order SCOUT AND UPDATE, 
send $19.95 which includes $2.50 S&H. 

If you want a catalog, just ask. If you 
live in Europe, ask DELTASOFT, Osterfeld 
str. 79D, D-2000 Hamburg 54 Germany. 

Zeta Software 

P.O.BOX 3522 
GREENVILLE SC 29608 


7 




“ Touch - A - Mat ic ”, Power 
At Your Finger Tips! 



KOPAK'S TOUCH-A-MATIC™ gives you the power to type more accurately 
and much faster. It requires no wires, no soldering. Comes with complete 
instructions. It's as easy as removing adhesive backing and pressing into 
position. Positioning is easy. Once in position, you are ready for touch¬ 
typing with ease. 

Our unique vinyl-key-hold creation will guide your fingers to the correct 
keys. Finally, touch-typing now possible with your Sinclair* or Micro-Ace*. 

This remarkable product, as well as other KOPAK items, are now available. 

Call now to order through MC/Visa or send check/M.0. to Kopak Creations, 
Inc. 

TM Trademark of KOPAK Creations, Inc. 

Sinclair* is a trademark of Sinclair* Research LTD. 

MicroAce* is a trademark of MicroAce* 


$1.50 Handling Charge 


KOPAK CREATIONS, INC. 
(212) 757-8698 

Master Charge & Visa Accepted 


KOPAK Creations, Inc. Dept. SX1 448 West 55th Street, New York, NY 10019 (212) 757-8698 


















HARDWARE REVIEW 

Product: VOTEM interface board 

From: Down East Computers, P.0. 

Box 3096, Greenville, NC 
27834. 

Price:$39.95 Kit 

$59.95 Assembled & Tested 

VOTEM stands for voltage and 
temperature, and that's what this 
new interface from Down East 
Computers is all about. It comes 
with all the necessary components 
to measure temperatures with a 
resolution of 0.04 degrees C and 
voltages with a resolution of 50 
microvolts. 

I assembled the kit version in 
about 2 hours. Despite a few con¬ 
fusing moments, the instructions 
were very good. When you're all 
finished, you have something you 
can really admire: the board is 
slickly sandwiched between two flat 
black panels for a very profes¬ 
sional look. 

VOTEM measures analog signals 
(voltage and temperature) by con¬ 
verting them into a frequency, and 
then measuring the frequency using 
a machine language program. This 
technique makes the hardware in¬ 
expensive and the sampling speed 
slow, so this interface is not 
suited to applications where speed 
is important. Calibration is done 
entirely in software, which leads 
me to be wary of very high 
precision applications. 

The software (in the form of 
listings) that accompanies the 
VOTEM is enough to get you started 
and working on your own, but don't 
expect it to turn your ZX/TS 
computer into a multimeter. The 
manual describes how to set up the 
interface to measure larger volt¬ 
ages (the stock interface measures 
between 0 and 1 volt), a resistance 
thermometer probe (more accurate 
than the stock probe), a game 
paddle, and a light detector. 

As a convenience, the VOTEM 
includes facilities to route the 


cassette output through the on¬ 
board comparator, which cleans up 
the signal and can read tapes not 
otherwise readable. In addition, 
an earphone jack is provided to 
monitor the loading process, and an 
LED blinks to the program. (Hint: 
Remove capacitor C2 and replace it 
with a short. This will make the 
LED brighter, but it disables 
protection against plugging the 
power into the VOTEM output jack.) 

I have only two complaints. 
First, VOTEM's jack arrangement is 
inconvenient, forcing me to route 
wires awkwardly. Second, the unit 
radiates a fair amount of inter¬ 
ference, which can make your tele¬ 
vision picture unviewable* if it is 
already bad. If you do not already 
have interference, the VOTEM should 
not cause problems. 

Down East has brought a good 
idea into the marketplace: for 
low-speed, high-precision, single 
channel analog to digital conver¬ 
sion the VOTEM is a bargain.—EO 


ITS HERE!! 

The keyboard you have 
been waiting for! 


A LARGE 60 KEY TACTILE FEEL KEYBOARD 
(MEASURES 10" x 4") THAT PLUGS INTO THE SAME 
CONNECTORS AS EXISTING KEYBOARD ON YOUR 
ZX81 OR TIMEX SINCLAIR 1000. IT HAS ALL 
SILKSCREENED LEGENDS IN 3 COLORS ON THE 
BASE; MOLDED LEGENDS & GRAPHICS ON KEY TOPS; 
8 AUTOMATIC SHIFT KEYS (NO SHIFTING REQUIRED) 
FOR EDIT, DELETE, SINGLE & DOUBLE QUOTES, 
COLON, SEMI-COLON, FUNCTION & STOP; 5" SPACE 
BAR; 2 SHIFT KEYS; NUMERIC KEY PAD. 


ONLY $ 70. 00 


MASS. RESIDENTS ADD 5% SALES TAX 
SHIPPING & HANDLING $4.00/UNIT 

DELIVERY 4 - 6 WEEKS. QUANTITY DISCOUNTS. WE 
WILL ACCEPT MC/VISA. PLEASE INCLUDE #'S, EXP. 
DATE AND SIGNATURE. FOR MORE INFORMATION 
SEND SASE. SEND INQUIRIES, CHECK OR MONEY 
ORDER TO: ggy 

SUITE 75 

711 SOUTHERN ARTERY 
QUINCY, MA 02169 


9 




GRADING PROGRAM—8K/16K 


This grading program includes 
37 student names—enough to satis¬ 
fy most classroom situations. 

To enter the program, follow 
the 4-line pattern in lines 500- 
509. Use as many modules, incre¬ 
mented by 10, as you need to list 
all student names (up to line 880). 
The line after the last module must 
read GOTO 1300 (line 890 in this 
listing). 

After entering the program 
press RUN and ENTER. You get a 
prompt "CLASS?" Enter the name 
of the class (eg.,Algebra 9). You 
get a prompt "Grading Period Num- 
oer?" Enter the grading period 
eg.,1) and ENTER. It prints the 
grading period number and gives 
you another prompt "PRESS NL TO CLS 
AND CALL UP FIRST STUDENT NAME" 
Press ENTER and the first student 
name appears. Type each numerical 
grade, pressing ENTER after each 
entry. After the last numerical 
grade, enter any numoer greater 
than 100 and press ENTER. The 
average and letter grade appears 
next to the student name. (This 
makes use of the PRINT AT command.) 
Press ENTER to see the next student 
name. Follow the same pattern. 

To exit the program before you 
have finished, enter a negative 
number following the student name 
and hit ENTER. Line 240 is a 
round-up cut-off routine. You may 
wish to edit this to suit your 
needs. 

Lines 220-330 determine the 
grading scale. Edit this to suit 
your own grade scale. 

Robert Demunbrun, Rushville, IN 


JL 

2 


E 


3 

4. 

10 

2© 


OCT 

30 

33 


Rl 


«» 


PEH GRADING PERIOD GRRDE 
REM RUERRGE RND LETTER GRRD 

REM WITH STUDENT NRME5 
REM BY R.M.DEMUNBRUN 
PRINT "CLASS” 

INPUT C$ 

PRINT C* 

PRINT 

PRINT "GRRDING PERIOD NUMBE 


•»c, 

4-0 

4-2 

CALL 

50 

S3 

53 S 
57 

S3 

59 


INPUT G$ 

PRINT G$ 

PRINT 

PRINT "PRESS NL. TO CLS RND 
UP 1ST STUDENT NAME” 

LET X =500 
LET N=0 
LET G ± =3 
LET Z$ = " ,l 
INPUT Zt 
CLS 


5 Ki i t l I ^ 

100 IE G> 18© THEM GOTO GOO 
ii^ IF G<© THEN GOTO 1300 
12© LET N=N+1 
IS© LET G1=G1+G 

14-0 PRINT TAB 2;"GRRDE”;TRB 27; 

15© GOTO GO 
200 LET H=6i/N 

210 LcT RI = XNT \ (INT ( i©0 * C R + » 5 
>)>/I®0) 

220 Ir Ri <7© !HlN GO s O 90S 
230 IF PI <73 THEN GOTO 9-35 
24-0 IF Hi <75 THEN GOTO 955 
25© IF fil<3© THEN GOTO 995 
250 IF R1<03 THEN GOTO 1025 
270 IF Rl <90 THEN GOTCT 1 055 
280 IF Rl<90 THEN GOTO 1085 
290 IF Rl <92 THEN GOTO 1115 
295 IF Rl <94- THEN GOTO 114-5 
3@0 IF Rl <95 THEN GOTO 1175 
31© IF Rl <95 THEN GOTO 1205 
32© IF Rl<98 THEN GOTO 1235 
330 IF Rl< =10© THEN GOTO 1255 
500 PRINT ”RKER5.,U” 

503 LET X=X+1© 

555 PRINT 


r.3§ GO I O 80 

310 P PINT “ hNSQH .. H ; 

Bi'3 LET X =»ly 

515 PRINT 

==1*10 nnrn 

520 PRINT "ANSON,R“ 

B23 LET X —X 4l© 

529 GOTO 3© 

530 PR INT " BAKER , S “ 
533. LET X=X+i© 

535; PRt^T 

539 GOTO 30 


S9@ 

GOTO 1300 



905 

PRINT RT 

0,20;Hi;RT 

O ji 30; 

**F 

910 

PRINT 




920 

GOTO 5:-* 




935 

PRINT RT 

0,20;Rl;RT 

0 * 3©; 

*’D 

94-0 

PRINT 



» 

y58 

GOTO 53 




965 

5.*. 

PRINT RT 

20; Rl; RT 

O 38; 

“D 

970 

PRINT 





GOTO 53 




995 

PRINT RT 

1,20; Rl; RT 

©.. 30; 

”D 

1008 

PRINT 




1010 

GOTO 53 




1025 

u 

PRINT RT 

O; 20; Rl; RT 

© j 30 j 

**C 

103O 

PRINT 




i 04.0 
1©55 

GOTO 53 
PRINT RT 

@ ji 20; Rl; RT 

©..SO; 

"G 

lOS© 

PRINT 




1O70 

GOTO Ss 


© * 30; 

**c 

1035 

PRINT RT 

©2@; Rl; RT 


lO 




1030 

1100 

1115 

PRXNT 

GOT O 53 
PRINT RT 

0. 5 28; fil. 

1120 
1130 
114-5 

PRINT 
GOTO 53 
PRXNT HT 

0.. £0; fil 

1150 

ll50 

1175 

PRINT 

GO J G 53 
PRINT HT 

8 .= 28; Hi 

1188 

1198 

1205 

;; 

PRINT 
GOTO 53 
PRXNT Hi 

8,, 28; 81 

121© 

1220 

1235 

PRXNT 
GOTO 53 
PRINT RT 

8., 28; 81 


124-0 PRINT 

1250 GOTO 53 ^ „ __ „ - - , 

1265 PRINT Hi 0 8 .« u8 ; H4- 

n 

1278 PRINT 
1250 GOTO 53 
1300 STOP* 

SYNTACTIC SUM: 2334-8.= 8K,*16K 


1© LET P=555100 
2 s p" ***■ *—i* ^0 i 0 o -i ^ -L 
3© LET P =P-PEEK X 
4-0 NEXT X 

5S IF P=0 THEN PRINT "ROM OK” 
New 8K ROM test — good ROMs give OK. 


LOADING WITH SYNTACTIC SUM 

Loading with the Syntactic Sum 
is a simple way to guarantee that 
programs loaded by the 8K ROM don't 
run if they suffer from parity 
problems. 

The following program utilizes 
a technique from SYNTAX'S Syntac¬ 
tic Sum program. First, LOAD the 
Syntactic Sum program and another 
program. When you SAVE the second 
program on tape, the Syntactic Sum 
program is called. The value 
returned is saved in variable B. 
Next, the program and the variable 
are saved to tape. 

The next time you LOAD your 
program, the Syntactic Sum will be 
called and compared to the value 
obtained when you saved your pro¬ 
gram. If the two values do not 
match, a parity error has occured 
and the program stops before execu¬ 
ting. The address 18400 in 9990 is 
the location of the Syntactic Sum 
program for a 2K RAM and must be 
adjusted for other RAM sizes. 


3930 LET U-lS4.ee 

3391 XF PEEK U=33 THEN LET B=USR 

U 

3392 SPUE "PROG" 

3333 XF PEEK U < > 33 THEN RUN 
9334- LET R=U5R U 
3395 XF R=B THEN RUN 

3995 PRXNT "ERROR 5/S = ” ; R .. **UflNT 

ed=";b 

3397' STOP 
9395 RUN 

SYNTfiCTIC SUM: 3272» 5K 

These comments correspond to the 
preceding program: 

9990 Point to Syntactic Sum area. 

9991 If 'ss' is in storage get 
checksum value. 

9992 Save program with Checksum 
Variable. 

9993 'ss' is not in storage, 
ignore. 

9994 Get loaded Checksum value. 

9995 Checksum at LOAD time is the 
same as at SAVE time; ok to 
execute. 

9996 Inform operator of error. 

9997 Wait for operator reply. 

9998 Ignore error, continue to 
execute. 

Allen M. Brosco, Carson, CA 

sfc BREM SYSTEMS ^ 

4 P. 0. Box 992 
^ Toledo, OH 43697-0992 

LIMITED INTRODUCTORY OFFER 

For the one low package price of 
$10.00, which includes postage and 
handling, you will receive all of 
the programs listed below. (This 
is a $55.00 value.) 

Programs Include : 

Home Budget Projector - Interest 
Projector - Loan Projector - 
Small Business Accounts Schedule/ 
Receivable 

Educational/Games 

Word Match - Alien Bomber - Spelling 
Flash Master - Educational Alien 
Bomber - Educational Dark Star 

Make check payable to BREM Systems 



DEAR EDITOR 


To establish a feel for my ZX81 
keyboard, I placed a spot of white 
glue on the center of each key. I 
used white glue because it is 
transparent when dry. This worked 
beautifully for a while but then 
peeled off. I was back at square 
one with another solution—Epoxy. 

I mixed a small quantity of 
Epoxy, picked up a little on the 
end of a toothpick and placed it in 
the center of each key. It dries 
as a small transparent dome and 
stays put. I have oeen using it 
now for a month and have developed 
a feel for the keyboard which was 
not possible before. 

H.S. Wake, San Diego, CA 


I nad a problem saving and 
loading programs on the ZX81. The 
problem was the noise level of the 
recorder when it was first turned 
on. By starting the recorder and 
allowing it to settle down (mon¬ 
itored via the led on the recorder) 
and then saving the program, it 
worked very well. I noticed that 
if I allowed the ZX81 to warm up 
before attempting to load the 
program, my success rate was almost 
100%. If I attempted to load 
immediately I did experience errors 
in loading. Saving a second copy 
of a program back-to-back is also a 
good suggestion. 

Gil Grabowski, Hanson, MA 

SYNTAX recommends a 15 sec. delay 
when saving programs. Type SAVE 
"name", start your recorder, wait 
15 sec., then press ENTER. When 
the screen clears, let the recorder 
run, type SAVE "name", ENTER 
again. Now you have the program 
saved twice—use these programs to 
find the proper volume setting on 
your recorder. Also use a short 
tape (C-30 or shorter) for better 
loading and saving. (We use C- 
10s).—KO 


To prevent poor contact between 
the computer and the power supply 
or tape recorder, I arrived at the 
following solution. 

For the power supply, I care¬ 
fully removed the insulation around 
the tip of the plug so I could 
identify each of the leads. I 
soldered these leads to the proper 
contacts of the socket inside the 
computer. I cut the lead to the 
power supply, leaving about a 6- 
inch length of wire outside the 
case. I installed a $.99 Radio 
Shack polarized plug to complete 
the circuit. 

I used the short leads supplied 
with the ZX81 in the same way for 
the tape recorder. This solution 
seems safer to me because discon¬ 
necting the computer after using it 
puts no strain on the weak contacts 
within the ZX81. 

Stewart B. Crooks, Jensen Beach, FL 


When I bought my ZX81 I was 
more interested in using published 
software than programming. However, 
I do need to know the use of all the 
BASIC commands and some of them 
aren't very clear in my instruc¬ 
tion book. Here's an example of my 
problems (Basic Manual, chap. 14, 

#6): After typing in the 35 state¬ 

ments, and trying to run it, I got 
error report 2/2000. According to 
the report listed in the manual, a 
variable was used before it was 
assigned to a LET statement. By 
pressing ENTER, I could call up the 
first half of the listing and check 
it, which was okay. What I need to 
know is: How do I get the second 
half of the listing so that I can 
check it? 

G.I. Loodell, Estes Park, CO 

To see program lines off the 
screen, press LIST, line number and 
ENTER. That line will appear at 
the top of the screen and you will 
be able to read those lines that 
follow.—AZ 


1 2 


ZX81 LOGIC SIGNALS 

We probed a working ZX81 and a 
TS1000 with two Radio Shack digital 
logic probes, one was rated at 
10MHz (part no. 22-301) and one was 
rated at 1.5MHz (22-300). Although 
the 1.5MHz prooe is really too slow 
to be accurate on these signals, 
the information ic provides may 
still be useful. H, L, and P 
indicate the High, Low, and Pulse 
lights on, respectively. Don't 
worry about the differences in the 
L&H lights if the P light is on. 
This may be caused by differences 
in logic probes (even the two 
probes we used gave different 
answers) . 

If your ZX/TS doesn't work, 
probe the bus and compare the 
readings on your logic probe with 
the ones in the chart. This will 
tell you what parts of your system 
aren't behaving correctly, which 
you may then investigate further. 
Here are our results: 



10 MHz 


1.5 MHz 


Pin 

Top 

Bottom 

Top 

Bottom 

1 

HLP 

H 

HLP 

H 

2 

HP 

H 

HLP 

H 

3 

Slot 


Slot 


4 

LP 

L 

LP 

L 

5 

HP 

L 

HLP 

L 

6 

HP 

P 

HLP 

L 

7 

HP 

HP 

HLP 

HLP 

8 

HP 

HP 

HLP 

HLP 

9 

HP 

P 

HLP 

HLP 

10 

HP 

HLP 

HLP 

HLP 

11 

HP 

LP 

HLP 

LP 

12 

HP 

LP 

HP 

HLP 

13 

HLP 

LP 

HLP 

LP 

14 

P 

P 

LP 

LP 

15 

HP 

P 

HP 

LP 

16 

HP 

HP 

HLP 

HLP 

17 

HP 

HP 

HP 

HLP 

18 

H 

LP 

H 

HLP 

19 

HP 

HP 

HP 

HLP 

20 

H 

HP 

H 

HLP 

21 

H 

HLP 

H 

HLP 

22 

HP 

HLP 

HLP 

HLP 

23 

HP 

HP 

HLP 

HLP 


SOFTWARE REVIEW 

Program: ZETAPAK #3: 

SciFi Fantasy 

Price: $9.95 + $2.50 (S&H) 

ROM/RAM required?: 8K/1K 
Printed listings?: Yes 
Programs listable?: Yes 
Easy to Load?: Yes 
Challenge?: Fair 

Display?: Good 

From: Zeta Software, P.0. Box 3522 
Greenville, SC, 29608 

For $9.95 you get 6 games on 
tape and an instruction oook with 
game listings. 

PLANETFALL is a form of the 
game Lunar Lander. Because you 
don't have much control over your 
spaceship, it isn't my favorite. 

HYPERSPACE DISPLAY, involves an 
asterisk (*) "going into hyper¬ 
space." Because all you can do is 
watch in this game, I didn't like 
it. (It's important to remember to 
type in GOTO 1 or the variable array 
A will be erased.) 

In STARCATCHER, you move your 
craft (represented by an inverse 
C) up and down the screen trying 
to catch four stars. Yet, nothing 
happens when you catch a star. 

In WORMHOLE, you imagine your¬ 
self drifting in space. Suddenly, 
you are trapped in a hole trying to 
avoid asteroids. Yet, hitting an 
asteroid has no results. 

In TURRET LASER, you move your 
ship onto a spot where a number is 
climbing rapidly. If a bomb hits 
your ship, it explodes. If you reach 
the number and drop the bomb first, 
you get points. 

ARCADE INVADERS is a version of 
Space Invaders. When your aimed 
missiles should hit the approaching 
invaders, they miss. This fault 
made it #2 on my list. 

These games are not challenging 
because of limited memory, but you 
can easily improve them. 

Christopher Fabbro, S. Pasadena, CA 


1 3 







GENERAL SYSTEMS CONSULTING 
2312 Rolling Rock Drive 
Conley, Georgia 30027 

SINCLAIR ZXS1 SOFTWARE 
16K minimum configuration 

Designed to help monitor your finances. 

1. Amortizations.9.95 

2. Bar Charts.9.95 

3. Annuity Evaluation. 9.95 

4. File Manager. 9.95 

5. Bank Statement Balaricer.9.95 

6. Checkbook Simulator.9.95 

7. Depreciation Straight Line.9.95 

8. Depreciation Declining Balance.9.95 

9. Depreciation (ACRS).9.95 

10. Diet Plan.9.95 

11. Home Budget .9.95 

12. Home Inventory.9.95 

13. Home Payables.9.95 

14. Home Equity Evaluation.9.95 

15. Real Estate Investing.9.95 

16. Savings/Investments Analysis.9.95 

17. IRS 1010 (Long Form).9.95 

18. IRS 1040A (Short Form).9.96 

19. Income Tax Protections.9.96 

Circle selections and fai out form below: 

1 2 3 4 5 6 7 8 

11 12 13 14 15 16 17 

Number of Hems selected __ # 9.96 ... 

Pbstage/Harxftng 1.50.. 

Total 

NAME__ 

ADDRESS 


9 10 

18 19 


CITY/STATE/21P. 


TAPE LEVEL INDICATOR 


Lots of people have trouole 
loading programs. This loading 
level indicator may help. This 
circuit does not reduce the 
recorder's output. 

We chose to build an electronic 
level meter with LED oar-graph 
display using parts available at 
Radio Shack scores and many other 
distrioutors. This indicator plugs 
in-line between your computer and 
che power and ear cables. In use, 
the position and orightness of the 
LEDs show the output amplitude of 
your tape recorder. 

All zero-volt (ground) connect¬ 
ions for ooth power and signal 
should run individually to a tie 
point capaole of accepting eight 
wires (one is a spare). Every lead 
must travel individually to this 
tie point—do not use shared wires 
to make any zero-volt connections. 
Attach leads from pins 2 & 4 of the 
LM3914N to this tie point. One end 


of R2 must connect here as well as 
the 4 zero-volt leads from jacks. 

Brightness of the LED display 
depends on Rl. Current in the LEDs 
equals 12.5/R1 units where Rl is in 
kOhms. We used the standard 10 mA 
drive and thus set Rl=1.2kOhm. A 
quarter-watt resister will suffice. 

Sensitivity depends on both Rl 
and R2. But with Rl chosen, R2 
alone determines the extra signal 
needed to light the next LED. Use 
the formula V=1.25 (1+R2/R1) to 
calculate the voltage at which the 
10th LED just lights. We want this 
to equal 5.0 volts, but we likewise 
want to employ standard resistor 
values. Our choices are: (1) use 
precision resistors of 1.2k & 3.6k; 

(2) use standard resistors of the 
same values and run uncalibrated; 

(3) use standard resistors of 1.2k 
& 3.9k and trim the 3.9k value for 
calibration. We used standard 
resistors and read relative levels. 

If you want to calibrate your 
indicator, disconnect the ear 
caole. Apply a 5.0 volt signal 
(available at pin IB of the ZX/TS 
ous) to the input lead (pin 5 of 
the LM3914N) and try resistors 
parallel to the 3.9k. Start with 
27k and work upward, substituting 
standard resistors in sequence 
until the 10th LED goes out. Use 
che last resistor that lights the 
10th LED. (This procedure also 
works for a 3.6k resistor in the 
upper half of the 5% tolerance 
permitted. It fails for resistors 
of 3.9k at the low-tolerance edge, 
but you can substitute another. 

It's unlikely to be as low-valued.) 

You can also do this trimming 
with a known good tape connected to 
the computer, and trim R2 until the 
9th segment gives a bright, steady 
display during the program portion 
of the tape. 

We used the following major 
parts from our local RS: LED 
display driver, LM3914N, RS276- 
1707; bar graph display, MV50164, 
RS276-081; and Experimenter's dual 
IC ooard, RS276-159. When using a 


14 

























different ooard, get one that 
accepts 20-pin, 0.3" wide ICs— 
they'll hold the 20 pin graph 
display. In operation, the 
computer clips the tape recorder 
output so the maximum amplitude is 
fixed. As you raise the volume, 
you'll see the bright dot climb to 
the segment corresponding to 
clipping, stop moving, and get 
brighter. As you decrease volume, 
the brightness of this segment 
drops and then the dot moves down. 

During the quiet spot of a good 
tape, you probably won't see any 
segment light, or the lowest ones 
will flicker. During loading, the 
pattern quickly becomes obvious. 
The uppermost segment flickering 
off signifies dropouts, where the 
tape signal briefly dips below the 
clipping threshold. Such tapes may 
fail to load correctly, or at all. 

Noisy tapes may give different 
intensity patterns on this monitor, 
but ooserving the TV screen often 
gives more insight.—KO 




EEING IS BELIEVING 




WRITE FOR FREE CATALOG & PROGRAM LISTING 


15 


(TYPICAL) _1 

PINS 10-18 OF 3914 

CONNECT TO PINS 11-19 

OF DISPLAY, IN SEQUENCE 





OHM'S LAW—8K/16K 


Ohm's Law is a useful formula 
for electronics hobbyists. Using 
this formula you can calculate the 
value of a resistor (Ohms), its 
wattage and the amount of current a 
circuit will draw. Knowing two 
pieces of information will allow 
you to calculate the third. 

For example: Your computer and 
printer need 9VDC at 1.2 amps and 
you have a 12VDC power supply rated 
at 1.5 amps. How many Ohms and 
what wattage rating are needed for 
the resistor? 

Enter the program as listed, 
RUN. First, the program displays 
the formula menu. Select the for¬ 
mula you wish to use by entering 
its number. The computer then 
displays the formula with an ex¬ 
planation of the variables used. 
Answer the prompts by entering a 
value for each variable in the 
proper unit of measurement. The 
computer calculates the third 
variable and asks if you want to 
continue. Yes gets you back to the 
menu; No ends the program 

Let's work through our example. 
Select the formula for calculating 
resistance. Input the voltage drop 
(12-9=3) and the current rating of 
the device, computer and printer 
(1.2 amps). You see that you need 
a 2.5 Ohm resistor to drop the 
voltage from the 12VDC available to 
the 9VDC needed. You next need to 
calculate the wattage for this 
resistor. Select formula 2 from 
the menu and enter the required 
variables (2.5 Ohms & 1.2 amps). 

You now know that you need a 2.5 
Ohm resistor rated at least 3.6 
watts in series with the power 
supply to safely run your computer 
and printer. (Remember: Voltage 
drop is the difference between 
available voltage and needed vol¬ 
tage. Express current in terms of 
amps., for example, 650 millamps = 
0.65 amps.) 

Blase Sanzone, Milford, CT 


5 CLs 

1© PRINT RT 0,10; 
e PRINT 

15 PRINT "YOU CRN CRLCULRTE TH 
FOLLOWING: " 

25 PRINT "--- 


"I RESISTANCE 
”2 URTT5 " 


COHHS) " 
"5 CURRENT " 

‘SELECT BY ENTERING ft 


THEN GO 


3® PRINT 

3b PRINT 

4® PRINT 
4-5 PRINT 
5© PRINT 
NUMBER” 

SO PRU5E 4-0000 
70 LET Ki = INKEY $ 

8© IF K* <”I” OR K$>”3” 

TO 7© 

O© GOTO URL K$*I©0 
i©0 CL5 

1©5 PRINT “THE FORMULA FOR CRLC 
ULRTING RESISTRNCE IS: R=E^X 

n 

110 PRINT 

115 PRINT "E=WOLTAGE DROPCRURIL 
ABLE-NEEDED) "I*CURRENT <IN RHP 
S) " 

12© PRINT ” *^**^*«^*^*-«.*^*3.***^ 
* * * * * * * * * * ” 

125 PRINT “ENTER UOLTRGE DROP" 

130 INPUT E 

135 PRINT RT 5,2©;E 

14.0 PRINT “ENTER CURRENT IN RHP 

3 ** 

14-5 INPUT I 

150 PRINT RT 7,23/1 

155 LET R=E/I 

It'S Lu i X=R 

153 GOSUB 4©0 

17© LET R=X 

175 PRlN? RT 1© #0; “R “;R;" OHM 
RESISTOR IS NEEDED TO” , “REDUCE T 
HE RURILRBLE UOLTRGE BY”. E;” UOL 
TC5> TO ft DEUICE DRAWING” I; ” ah 
P ” 

Idt? uuTO SO© 

CLS 


TJviT It 

r n jl* t 


ii} QTTKir - CRLC 

ULHTING WATTAGE iS: P=X*-¥2*R 


* n.r> x|n|T* 


4 V 


* r\ 


."l*5|j9yRRENT,IN fiMPS 
owuHHtD , R *REs XSTANCE IN OHMS 


0 


*ttl*£*******‘ ***»****.**** 

IIP vKiilT 1ENTER the CURRENT- 


SinTEh KE5 XSTmNCE IN 


INPUT 

235 PRINT RT 6.18;! 

240b PRINT ,: FnTFD 
OHMS" 

243 INPUT P 

§30 PRINT RT 7,25;ft 

t§§ p*i**a*R 

LET X =P 
2*5 GOSUB 40© 

-S'IS LET. P-X 

M /b FK IN 5 RT 10,0 : "Q >> - n • » nuu 
RESISTOR_ RATED AT ” t p; ” ‘URTTS H IS 

A ** •' lc e ORfty INC •* : 

580 GOTO SCO 
300 CLS 

3©5 PRINT "THE FORMULR FOR CRLC 
ULRTING CURRENT IS: I=E/R" 

310 PRINT 

315 PRINT “E=UOLTRGE DROP" , . "R = 
RESISTANCE IN OHMS" 

320 PRINT 


16 






Q ^fr e PRINT "tNTER THE UGLTRGE DR 

330 INPUT E 
2?5 PRINT RT 6,23,E 
OHMS" ^ " ENTER RESISTANCE IN 

34*5 INPUT R 
3|g PRINT RT 7,25;R 
356 LET I=E/R 
' 360 LET X = I 
365 GOSUB 4-00 
370 LET I=X 

375 PRINT RT 10,0;"THE MRXIMUM 
CURRENT IS "; I; " AHPS" , "USING R 
;R; " OHM RESISTOR TO","DROP THE 
AUAIABLE UOLTRGE BY ",E," UOLTS 


<1 


380 GOTO 500 

4-00 LET X — < INT ( 10* <X + < . 05) ) ) j ✓ 
1© 

405 RETURN _ 

500 PRINT RT 15,0;"DO YOU WANT 
TO CONTINUE Y/N" 

505 PRUSE 1000© ... tmcn gqto 5 



FIFTEEN PUZZLE—8K/1K 

This 8K/1K version of Fifteen 
Puzzle retains most features of the 
4K version (Apr.82). 

Invented oy Sam Loyd in 1878, 
it consists of 15 numoered clocks 
and 1 space in a 4x4 matrix. 

The oojeccive is co order the 
matrix oy moving the twin dashes 
horizontally or vertically with the 
the fewest moves. 

12 3 4 

5 6 7 8 

9 10 11 12 
13 14 15 — 

In line 4, B$ first five cnarac- 
cers are shift graphics 2, 4, 5, E, 
and S. 

When you want to terminate tne 
program, Enter STOP (shift A) and 
the screen will blank. To play 
Fifceen Puzzle again, just hit RUN, 
and ENTER. 

Jon T. Passier, Beverly, MA 

2 RAND 

4 LET 6 $ = " % I " 

6 LET 5=0 

3 DIM A$(16) 

13 FOR 1=1 TO 16 
12 LET R=RND*16+.5 

14 IF A $ i R)<>“ " THEN GOTO 12 

15 LET_A*-CHP* I 

16 NcX• x 

23 FOR 1=1 TO 15 


22 IF I<9 THEN IF A*(CODE B$tX 
) ) =" (" THEN LET 6=5^1 
24 FOR U-X+l TO 16 
26 IF A*(X)>A$(J) THEN LET S»S 

28 NEXT U 
30 NEXT I 

32 IF INT i 5/2) *2< >5 THEN GOTO 
6 34 CLS 

36 FOR 1=1 TO 16 

33 LET 5=CODE A* (I) 

40 IF 6<10 THEN PRINT " 

42 IF S <16 THEN PRINT S;" ”; 

44 IF 5=16 THEN PRINT "— 

46 IF INT (1/4)*4=1 THEN PRINT 


48 NEXT I 
50 INPUT 6 
52 FOR 1=1 TO 16 

54 IF A*(I)=CHR* S THEN LET J= 


53 NEXT I ’ * THEN LET R * 

60 IF RBS (U-R)<>1 RND RBS 
R) 04 THEN GOTO 50 


62 LET A*(R)=R*(J) 

64 LET A*(J)="(” 

66 GOTO 34 

SYNTACTIC SUM: 38182, 8K 


X 

CJ- 


Bob Cutter of Arlington, MA reports 
that Poly Paks, Inc. offers a 9 volt 
adjustable 3 amp regulated power 
supply for $19.92. 800/343-3046. 

In MA or outside US, 617/245-3828. 


64K MEMORY 
M-64 $119. 9 ^, 

129.95 WIRED & TESTED 
INSTOCK SAME DAY SHIPMENT 
All standard features included. plu$ lower 8K 
of RAM can be disabled in 2K segments to 
allow PROM or peripherals to be added 


EXPAND YOUR 16K SYSTEM $59.95 

If you have a Sinclair 16K RAM module and need 
more memory, expand it to 32K and beyond by usma 
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. 

_»N 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 ehipplng A handling to all order*. 

CHECKS 


BYTE-BACK CO. 

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


17 




BEHIND EVERY 
GOOD SINCLAIR 


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. 




Printer Interface 


Efface ^ 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. Tb order 
any Memotech product call our toll-free 
number 800/662-0949 or use the order 
coupon. 




CORPORATION 

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


IS A MEMOPAK 



Memopak 64K RAM The 64K RAM extends the 
memory of your Sinclair by 56K to a hall 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 l6K RAM to give you a 
full 48K of RAM. 

Memopak 16K RAM The Memopak 16K 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. 


















MC PROGRAMMING—#9 : JUMPING AROUND 


Most of the machine code 
subroutines held in REM will be 
be short around 100 instructions 
and data. Consequently, you won't 
need the "JP nn" instruction. 

The Jump Relatives you use in¬ 
stead are harder to use correctly 
oecause of calculation-error for 
the offset ("e" as in JR e). But 
using JR makes the code relocataole 
in memory. JP NN specifies an ao- 
solute address, which changes if 
you store the program in a newzero 
place. JR e works anywhere because 
the location of the instruction 
remains unchanged when you relocate 
the program. JP nn is simple; con¬ 
trol transfers to the address "nn" 
(nl+(n2*256)). Conditional JPs are 
available and are 3 bytes long. 

JR e and conditionals are 2 
bytes long, but the 2nd oyte is 
added to the Program Counter +2 to 
transfer control to an unspecified 
relative address. Pointing "e" 
value to the right address is hard. 
IB FOWARD 

ADDRESS DECIMAL=MNEMONIC COMMENT 


x02 

4 0 JR Z 

; X45-X02 
; =43 

x03 

41 e 

; 43-2=41=e 

x04 


;To test 

. •»£!»« 

/ “ f 

x45 


;x02+43=x45 

ilfi 

BACKWARD 


X059 


:xl26-x059= 


67 

255-67=188 


=e 


xl24 


r — 

;To test 

/ ^ f 

xl25 

56 JR C 

; 255-188=67 

xl26 

188 e 

;xl26-67= 

; x059 

JRs 

are limited to 

129 toward 


addresses and 126 backward ad¬ 
dresses, enough leeway for most MC 
subroutines held in REM lines. 


UNIT PRICER—8K/2K 

This 8K/2K program calculates 
the unit price of two similar pro¬ 
ducts. To run the program, just 
follow the directions rememoering 
that units are ounces, grams, etc. 

If you want to exit the program 
early, enter XX. 

The idea for this program came 
from William Scott Watson's book 
entitled £2 Ready-To-Run Programs 
In Basic , written for TRS-80 Level 
1 BASIC. Offered oy Tao Books Inc. 
of Blue Ridge Summit PA., ($12.95) 
it contains programs in the graphic, 
home, business, education and games 
areas. In addition to the programs 
it offers, I found it co be a very 
good resource oook and I recommend 
it to any ZX/TS user. 

Stephen Zachev, Muskegon, MI 


i0 PRINT" "THIS PROGRAM COHDODP 

*PRl8i yCTS * flND » bSmd ora?? 


(GOTO Page 20) 


NEW!!! 

FROM INTERCOMPUTER, INC. 

A full line of software in the 
areas of business, education, & 
entertainment, for your Sinclair 
ZX81 or Timex 1000. 

Please send me a FREE program and 
catalogue. 

Name. 

Address 


Intercomputer: P.O. Box 90 

Inc. Prudential Center 

Boston, MA 02199 


Jon Bobst, Zeta Software, PO Box 
3522, Greenville, SC 29608-3522 


19 






Is PRINT* = " FIRST PR0DUCT " 


co |®„ p «INT "HOU MUCH DOES 

! 

HOW HftNY UNITS IN PR 


35 INPUT fl 

36 PRINT 

37 PRINT 
OOCT ft" 

4-© INPUT B 

LET 5$ = ”SECOND PRODUCT" 

C»D hhjlNT "HOU- HUGH DOES " j & jj 
COST” 

SO INPUT C 
S2 PRINT 
65 PRINT 
ODUCT 3" 

70 INPUT D 
80 Cl 


HOU HflNY UNITS IN PR 


98 Lti• E — h/B 
lOO LET F =C sD 
HO LET E=E*IOO 
120 LET r=F*iOO 

130 PRINT CENTS PER 

UNIT” 

135 PRINT 

14-0 PRINT B$; F; ” CENTS PER 

UNIT” 

4-24-1 PRINT 

150 IF E<F THEN GOTO 300 
ISO IF E=F THEN GOTO 4-00 
170 PRINT B$; ” IS 0 ^gT TER ?UY 
ACCORDING TO UNIT PkIlE 

3®1 PRINTER*;" IS w BETTER BUY 

"Sgg^^-BO^P^UCTS ESUHLL 
Y PRICED” 


4-50 STOP 
;trc-~ 


5YNTOGTIC SUM: 


3304- / . 8K 


CLASSIFIED ADS 


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
Join the ZX80/81 USERS' LIBRARY and 
share software expertise. Benefit 
from input of beginners and pros to 
enhance your horizons. Yearly sub¬ 
scription $25, outside USA add $7. 
Address: Suite 434r 4614 Kilauea 

hZ & s* Honolulu/ HI 96816 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 

Fight 30 types of monsters in DUNG¬ 
EON OF DOOM while on a quest for * 
treasure.In INTERGALACTIC TRADER, * 
roam a deadly galaxy&try to survive 
ZX81-16K.Both for $7.95—M.Br letic* 
1072 N.Sunset,Reedley,CA.93654 **** 

- TEACHERS - 

Gradebook for 34 Pupils, 26 Scores. 
Qtr,Final Grades(Weighting Opt)Full 
Stats,Graph.Send $1 (appl to $19.95 
Purchase) for Specs to: TF Brennan 
RD #1 Box 53, Spring City, PA 19475 

PRICE CUT! Ultimate dungeon game!!! 
For 16K ZX81/TS1000. Multilevel gra 
phics-text adventure maps what you 
see. Treasure, monsters etc, like D 
&D. $15US: JLK Software, 6 Dufferin 
PI, St. John's Nfld, Canada A1A 2V1 


Reach thousands of ZX80/81, TS1000 
owners! Send your ad, typed 35 
cnar/line (inc. spaces and punctu¬ 
ation) , with check ($9/line). 
Include tel. numoer, wnether or 
not numoer appears in ad copy. Ad 
must arriv e oy the 15th of any 
montn for the next month's issue. 
Ads arriving after the 15th appear 
in the issue following the next 
unless you request its return. Ads 
must oe resuomitted for each month. 
No phone orders or credit cards. 

We take no responsioility for ad¬ 
vertisers. SYNTAX Classified Ads, 
RD 2 Box 457, Harvard, MA 01451 

BUILD YOUR OWN HARDWARE FOR YOUR ZX 
80/81-T/S 1000. Add music, memory 
speech and more. Learn while doing. 
THE EXPANDABLE ZX-80 AND ZX-81 is 
$9.95 + $1.25 p&h. To: COMPUTER 
ENGINEERING SERVICES. P.O. Box 1222 
Show Low, Az. 85901. Az res add 6%. 


DRY GULCH. An interactive adventure 
written in the classic sytle. 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 

********** 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 

DO YOU HAVE PROGRAMS, HARDWARE, 
LEARNING AIDS OR MANUALS YOU WOULD 
LIKE TO SEE PUBLISHED OR MARKETED? 
For details write or phone COMPUTER 
ENGINEERING SERVICES. P.O. Box 1222 
Show Low Az. 85901 (602) 537-7522 


20 





TACTILE FEEDBACK OVERLAY,feel your 
keys,touch type, $3.95 P.Hargrave, 
SiteV,RR4,Nanaimo,BC,V9R5X9,Canada 

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. Bob 
Berch 19 Jaques Rochester NY 14620 
Next month: Integer Basic compiler 

FIFTY NIFTY: PROGRAMS FOR YOUR ZX8H 
Book has 50 Top Quality 1R Programs 
GREAT GAMES, ACTIVITIES , AND PLENTY: 
OF GRAPHICS **Hours of Fun!** Also, 
same great 50 programs upgraded for 
a 2K TIMEX-SINCLAIR 1000 (very user 
friendly). ONLY$9.95 EACH. JENN 

PRODUCTS BOX 246 HARRISON, ME 04040 

IMPROVED HEAT SINK ELIMINATES OVER- 
heating of ZX81/tsl000 4 inforsase 
B.Sanzone 289 Baxter La Milford, Ct 

ZYX INVADERS-New program similar to 
well-known invasion game, for 16K 
ZX81, using fast action ML. Money 
back guarantee. Listing $3. DIPCO, 
Box 39274, Detroit, MI 48239-0274. 

AT LAST ! VINYL ZX BUMPER STICKERS 
Specify 80/81 $1 MLB,Inc. 3738 
PIPERS FIELD SAN ANTONIO TX 78251 

WHERE TO FIND IT !!! 

Hardware,Software,Books,User Groups 
for TIMEX/SINCLAIR 1000 & ZX80/81 
160 US Sources Listed. Send $3.00 
G.E.TOPP,Box 585,Klamath CA 95548 

SOFTWARE: HOME/BUSINESS APPLICATIONS 

1. RENT OR BUY A HOME ANALYSIS-$5.95 
16K;Worksheet;16 Inputs;Gain / Loss 

2. MORTGAGE,INCOME AV,LOAN,IRA-$5.95 
2K Program. Send ck payable-J.PYRYT 
95 Union Avenue, Garfield, NJ 07026 

256 x 192 HIGH RESOLUTION GRAPHICS 
for ZX80/81. Bit mapped pixels thru 
ZX modulator? Hi-res memory resides 
between 8-14K. Complete plans $5.00 
ADVANCED INTERFACE DESIGNS 
P.0. BOX 1350 
STATE COLLEGE, PA 16801 


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 214-349-9981**OTHER 800-527-1227 
10% Discount for check with Order 
P. 0. Box 38651*Dallas, Texas 75238 
FREIGHT PREPAID*DEFECTIVE REPLACED 

STOCK MARKET TECHNICAL ANALYSIS for 
ZX81 or TIMEX (16K): Prints GRAPHS 
of price, moving aves., and volume 
indicator? prints ANALYSIS of tech, 
condition of stock (6 indicators). 
Send $30 for tape and book to: 
NOOTER STOCK PROGRAM, 320 E. 25 St. 
NYC, 10010 (NY res. add $2.48 tax). 

BUFFERED BUS:$43 BARE BOARD,$68 KIT 
UHF Modulator, solves video noise 
prooiems:$15. Connectors, repairs, 
programs, plans. Ask for details. 
COMPUTER CONTINUUM 301-16th Ave. 

San Francisco,CA.94118.(415)7526294 

FARM PROGRAM: Cost of ownership and 
operation. Compares expenses vs 
anticipated income from any crop. 
User friendly. Cassette $10. B.C. 
Supply Inc., Rt. 3, Enid, OK 73701 

Put your Timex/Sinclair computer 
to work! The TIMEX/SINCLAIR 
SOURCEBOOK lists software, hardware 
and books for your computer from a 
wide variety of sources. Only $4.95 
+1.25 P&H to MDC Box 280 Carrollton 
TX 75006 Sendfor free listing form. 

***for TIMEX/SINCLAIR computers*** 


UNIVERSAL INVENTOR Y FILE—-: -16.95 

UNIVERSAL MAILING LIST- 4 - 10.95 

COIN COLLECTION/INVESTMENT -10.95 

STAMP COLLECTION/INVESTMENT -10.95 


COMIC BOOK COLLECTION/INVEST —10.95 
BASEBALL CARD CQLLECTIQN/INV— 10.95 

RECORD ALBUM COLLECTION/INV -10.95 

Each program on cassette + manual. 
For 8KR0M, 16KRAM. M.C.Hoffman Co. 
P.O. Box 117, Oakland, NJ 07436 

Minefield, Satans Maze? two new ga¬ 
mes (on tape) for your IK ZX81. 

Both for $5. L. Harmon, 4909 Clear- 
lake, Metairie, La. 70002 


21 




FOR ZX-81 - 32K RAM with 4 parallel 
ports; I/O UNIT with 4 ports, EPROM 
sockets, accepts SINCLAIR 16K RAM; 
EPROM PROGRAMMER, requires 3 ports. 
WISCONSINC BOX 332 MILTON WI 53563 

GRAPHICAL*INVISO-MAZE* for the ZX81 
w/16KRam-Full Screen graphical dis¬ 
play.Moving Graphics.4 mazes on 
one Tape:$4.00+1.50 P/H TO:RP soft¬ 
ware,502 Spring St.PO Box 131 
Weston,MO.64098 

♦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* 
*6 Eaton Ave. Springfield,VT.05156* 

TS1000 Owners & lk Games-list $2.00 
SASE for Ctlg. Chris White, 789 S. 
Green Bay Rd., Lake Forest,II.60045 

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 

* PROGRAM CONSOLIDATION * A BLANKET 

Program that indexes 16 Subprograms 
of you choice for singular loading 
(8K/16K) Tape-$6.00, Listing-$3.00 

*TAPE C/W 16 Subprograms for-$15.00 
*K/B Foil Connector for ZX81-$15.00 
R.HARDER, 995 SHAKESPEARE AVE,N.VAN. 
B.C. V7K 1E7(PROMPT RETURN MAILING) 

DOMINO GAME: 1 to 4 players, enjoy 
exciting new game for the 16K ZX-81 
Send $9.95 MO/check to:PHOTOLAB, 

Box 21124, Kennedy Space Center, 

FL. 32815. For free info send SASE. 

HAVING PROBLEMS LOADING FROM TAPE? 
AI-1 auto level set, self contained 
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 


** PICK'EM LIKE THE PRO'S, With: ** 
** PRO-PICKER -An UPDATEABLE pro-** 
** football predictor for 8k/lkUP** 
** ZX80/81 & TS-1000 (Specify). ** 
** $2 Cash or M/O: Benson-Ware: ** 
** 11215 Oakleaf Dr, Apt #220 ** 

** Silver Spring, MD 20901 ** 

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

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 & SOUND ELECTRONICS 
1120 Bailey Hill Rd. #10 
Eugene,OR. 97402 

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

ZX-80 8K ROM USERS . At last a video 
upgrade kit which allows use of 
FAST & SLOW with flicker free video 
Complete kit $32.50 + $1.25 p&h. To 
COMPUTER ENGINEERING SERVICES P.O. 
Box 1222 Show Low, Az. 85901 

"EPHEMERIS V" (c) for the 16K ZX-81 

6 TS-1000 *PLANET FINDER* The five 
principle planets PLUS Sun and Moon 
RA & dec., azimuth & alt., compass 
points, graphic display in constell 
Moon's phs & LOCAL "star" time!!! 
For cassette & instruc, send $8 to: 
Ephemeris V, 124 Professional Ave. 
P.O. Box 261, Winchester, KY 40391 

7 GAME CASSETTE-1K $7.95,*16K $9.95 
Mastermind,Doublemind,Slot Machine, 
Craps,TicTacToe*vs ZX81,Sub Rescue, 
WhiteHotNumber*vs ZX81. NEW ENGLAND 
SOFTWARE, Box 691, Hyannis,MA 02601 

**NEW SPORTS PROGRAMS FOR ZX81 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 
BRONZE STAR SOFTWARE 
PO BOX 265, Chicago Ridge IL, 60415 

♦♦♦ARITHMETIC & ALGEBRA TEACHER**** 
*Pre thru secondary school levels * 
♦lessons are graded CASSETTE $9.95* 
♦FREE catalog of over 60 programs * 
*UAS Box 612 Haddonfield,N.J.08033* 


16K- n ZX81 MONOPOLY", "TRADER JACK",- 
"10 GREAT GRAPHIC GAMES" 

TRADER JACK sails the Pacific Isles 
10 GGG is a great game for kids. 
MONOPOLY versions-Spanish,American 

or British Language and locations. 
$14.95 eacn cassette - Specify 
SAVAGE SOFTWARE - SW IMPORTERS 
P.O. Box 441 Titusville,FL.32780 

ZX81 SOFTWARE;Send SASE-J. Anunti 
3309 20th St.San Francisco,CA 94110 

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. 


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

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 3FFRH address segment, if 
availaole. 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 tne compiled code 
can be selected, allowing you to 
write a long program, compile it in i 
pieces, then assemble the pieces. 

The ZXPRESS is availaole 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.O. 
Box 2941, Amarillo, TX 79105, 806/ 

376-5723. Check, MC, Visa welcome. 

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

ZX81 16-64K Prgms on Cass SASE 
Brittanysoft64K Bx8385BoiseID 83707 


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


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 


□ My check for $29 is enclosed. 
Make checks payable to: 
SYNTAX ZX80, INC. 


□ Please charge my □ MasterCard 

□ Diner’s Club □ American Express 

□ VISA □ Carte Blanche account 


account number__ 

exp. date_bank number (MC only)_ 

signature_ 

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Day Phone A _ 1 _Evening Phone J_)_ 

10 82 

I own a □ Sinclair ZX80 □ Sinclair ZX81 Telephone orders call 

617-456-3661 






SOLVE YOUR LOADING PROBLEMS! AND 
DIRECT COPY ANY ZX OR TS CASSETTE! 
With multi-feature **WINKY BOARD** 
Easy to use.No modifications needed 
Freeinfo. $18PPD,$12 kit. G.Russell 
RD 1 Box 539 Centre Hall,PA 16828 
PA residents add 6%.Overseas add $2 

Tired of lost programs and glitches 
due to over-heating?Replace your un 
dersized heat-sink for a cooler op¬ 
eration.Only $5.95 for the kit with 
detailed instructions. ZXcessories 
5631 Bobolink, Houston Texas 77017 

SYNTAX offers a faster way to find 
answers! Laminated Microprocessor 
Ref. Cards Z80,6502, 808A & 8085A, 
80408 & relatives, and programmers' 
algorithms ref. card, $5.95 each. 
Prices include shipping. SYNTAX RD 
2 Box 457, Harvard, MA 01451. 

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 for a sharp, 
high definition display. Add $8.50 
for shipping, handling & Ins.Random 
Access Box 41770S Phoenix,AZ 85080 

* MERGE PROGRAMS — FAST GRAPHICS * 

** ADD MEMORY THAT WON'T FQRG ST1 ** 

* kit $31:90 SASE details: HUNTER * 
*1630 Forest Hills OKEMOS MI 48864* 


v 

/s H\R\ARD 

GROLP 

I Bolton Road. Harvard. Mass. 01451 



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 

TAP WRITER TM(Handicap Aid)8/1.FREE 

Horse Race 8/lup.2.00 

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

Improved SLOW PAUSE.1.00 

Linear Regression 8/lup.2.00 

CHAR. Generator Demos 8/lup....2.95 

Plotting Work Sheet 8/1.3.95 

Plotting Work Sheet SLOW/16....6.95 

SPLIT-A-STACK TM SLOW/1up.2.00 

CHEWTER TM(like PACMN)SLOW/16..2.95 

ISLAND SQUARES TM SL0W/2up.2.00 

Random MUSIC!SL0W/lup.2.00 

BASIC Keyword Demos 8/1....from .50 
ORDER,SASE,reSASE gets you GOO¬ 
DIES Catalog and !!FREE!! Program 
EZRA GROUP II 
EZRA GROUP II 

POB 5222San Diego California 92105 

"1981-83 NFL STATISTICAL SUMMARY" 
Two seasons of NFL stats. Program 
computes ranks.averages. MUCH more! 
Keeps '82 stats current with weekly 
entry. Schedules,records,division 

standings, much too much to list!! 
ALL you need to pick the winners! 
1982 stats updated to week of sale. 
16K, ZX81 $9.95' ZAMIS ENGINEERING 
251 First St.,'Perrysburg, OH 43551 
24 


U.S. Postage 
PAID 

First Class Permit No. 8 

01451