The Timex-Sinclair Family
Of Personal Computers
A PUBLICATION OF THE HARVARD GROUP
VOL. 3 NO.IO ISSN 0273-2696 OCT, 1982
IN THIS ISSUE
When Your Computer
Loading with Syntactic
Machine Code Programming
ZX81 Logic Signals.13
Index of Advertisers
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
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.
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
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 $4
(S&H). E-Z Key, Suite 75, 711
Southern Artery, Quincy MA, 02169.
"The Writing Instructor", a quar¬
terly journal on computers and
writing instruction is looking for
authors. R. Adams, Univ. of S. CA,
Los Angeles, CA 90089-1219.
SYNTAX ERRORS: Machine Code Screen
Fill (Aug.82 p.6) contains two
errors. In the description of the
REM line, "inverse H" should say
"graphic H". The assembly listing
comment for location 16522 should
read "C<>0". For location 16526 it
should read "BO0".
Our latest list of new users'
groups is is presented below. To
check for a group in your area not
listed here, drop us a line (please
include a self-addressed stamped
envelope) or give us a call and
we'll refer you to any group we
know of. To list your group, write
us or give us a ring and we'll
refer interested people to you.
SYNTAX, RD 2 Box 457, Harvard MA
Des Plaines, IL: Circle Chess
Group, A.F. Stanonis, P.0. Box 63,
Des Plaines, IL 60017.
Detriot, MI: Timex-Sinclair Users
Group, P.0. Box 552, Warren, MI,
48090. Send SASE for details.
Indiana, S. Illinois, S.W. Ohio,
N.W. Kentucky: The FUN-Z, P.0. Box
914, Jasper, IN 47546, contact W.
Long with SASE.
Iowa City, IA: Jim Carroll, 1218
William St., Iowa City, IA 52240.
Joplin, MO: Carlos T. Colon, 1228
Picher, Joplin, MO 64801, 417/781-
New Albany, IN: G. Richard Becht,
2308 Beeler St., New Albany, IN,
Phoenix, AZ: Randy Saxton, 4827 N.
63rd Dr., Phoenix, AZ 85033,
Plattsburgh, NY: Upstate New York
ZX81 Users, Vern Olson, 13 Dennis
Ave., Plattsburgh, NY, 12901.
Research Triangle Park, NC: John
Drummond, P.0. Box 12546, Research
Triangle Park, NC 27709.
Washington, D.C.: Washington Area
Users Group, Box 6239, Washington,
DC, 20015, 703/920-7310.
Mark Freitas' Sine Name (Aug.82)
raises the question: can I make
the message snake up the screen
letter by letter? My solution:
LET J = LEN R$ „„ _
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, can the message be made to
oscillate about a horizontal and
diagonal line? Without using
machine language, the answer is not
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
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
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
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.
IK RAM 1024 Bytes
Sys Var 125
Display File 25
Var End 80H 1
GOSUB Stack 3
Mach Stack 14
More Bytes Remaining
Routine = 821 Bytes
1 REM... +20
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
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
rReview pgs. 128,134 of
;Push address(STRKEND) to
rPop address(STKEND) off
stack and store in regis¬
21 00 00
Load register HL with
?Add the address stored
in the SP register to the
Subtract the address
(STKEND) stored in BC
from the address(SP)
stored in HL. The
;stored back in HL.
rPush the results stored
;in HL to the stack.
; Pop the results off
:stack and store in BC
:Return to Basic and
;Print value in
:BC. The number
displayed is the number
: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
2 FOR X=1 TO 25
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
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
3) ENTER may cause a line to
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
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
uses less space than:
IF X<=5 THEN ....
Try these suggestions when you
need those few extra bytes.—PPW
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
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
Robert Ryan, Gladstone, OR
yu i O 9900.
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
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 <(
; * v
£ Ux33 js *33) )
< ( \
+ 1 >
) *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
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«"
P , 151
3S02 PRINT "PLRY RGRI
3004. INPUT R$
3006 IF R$="N" THEN S
3330 LET P=URL
56 J-PEEK 1539?"
9902 DIM * R £ URL "4.* 1 )
3936 FOR I=SGN PI TO
9912 LET fi (I) = ! JRL "4-3
t256fPEEK 1639?" 4-1 NT
( RND *5 + 1) *33
C RND *S) +JNT
9914. NEXT I
99IS FOR I=5GN PI TO URL "3"
99 IS FOR «J=SGN PI TO URL ''20"
9919 LET R$ = “
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
9937 LET D=URL "PEEK 16395+256*P
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.
GREENVILLE SC 29608
“ 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,
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.
Master Charge & Visa Accepted
KOPAK Creations, Inc. Dept. SX1 448 West 55th Street, New York, NY 10019 (212) 757-8698
Product: VOTEM interface board
From: Down East Computers, P.0.
Box 3096, Greenville, NC
$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
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¬
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
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
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 $4.00/UNIT
DELIVERY 4 - 6 WEEKS. QUANTITY DISCOUNTS. WE
WILL ACCEPT MC/VISA. PLEASE INCLUDE #'S, EXP.
DATE AND SIGNATURE. FOR MORE INFORMATION
SEND SASE. SEND INQUIRIES, CHECK OR MONEY
ORDER TO: ggy
711 SOUTHERN ARTERY
QUINCY, MA 02169
This grading program includes
37 student names—enough to satis¬
fy most classroom situations.
To enter the program, follow
the 4-line pattern in lines 500-
509. Use as many modules, incre¬
mented by 10, as you need to list
all student names (up to line 880).
The line after the last module must
read GOTO 1300 (line 890 in this
After entering the program
press RUN and ENTER. You get a
prompt "CLASS?" Enter the name
of the class (eg.,Algebra 9). You
get a prompt "Grading Period Num-
oer?" Enter the grading period
eg.,1) and ENTER. It prints the
grading period number and gives
you another prompt "PRESS NL TO CLS
AND CALL UP FIRST STUDENT NAME"
Press ENTER and the first student
name appears. Type each numerical
grade, pressing ENTER after each
entry. After the last numerical
grade, enter any numoer greater
than 100 and press ENTER. The
average and letter grade appears
next to the student name. (This
makes use of the PRINT AT command.)
Press ENTER to see the next student
name. Follow the same pattern.
To exit the program before you
have finished, enter a negative
number following the student name
and hit ENTER. Line 240 is a
round-up cut-off routine. You may
wish to edit this to suit your
Lines 220-330 determine the
grading scale. Edit this to suit
your own grade scale.
Robert Demunbrun, Rushville, IN
PEH GRADING PERIOD GRRDE
REM RUERRGE RND LETTER GRRD
REM WITH STUDENT NRME5
REM BY R.M.DEMUNBRUN
PRINT "GRRDING PERIOD NUMBE
PRINT "PRESS NL. TO CLS RND
UP 1ST STUDENT NAME”
LET X =500
LET G ± =3
LET Z$ = " ,l
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
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©
r.3§ GO I O 80
310 P PINT “ hNSQH .. H ;
Bi'3 LET X =»ly
520 PRINT "ANSON,R“
B23 LET X —X 4l©
529 GOTO 3©
530 PR INT " BAKER , S “
533. LET X=X+i©
539 GOTO 30
O ji 30;
0 * 3©;
20; Rl; RT
1,20; Rl; RT
O; 20; Rl; RT
© j 30 j
@ ji 20; Rl; RT
© * 30;
©2@; Rl; RT
GOT O 53
0. 5 28; fil.
0.. £0; fil
GO J G 53
8 .= 28; Hi
8,, 28; 81
8., 28; 81
1250 GOTO 53 ^ „ __ „ - - ,
1265 PRINT Hi 0 8 .« u8 ; H4-
1250 GOTO 53
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
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
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
SYNTfiCTIC SUM: 3272» 5K
These comments correspond to the
9990 Point to Syntactic Sum area.
9991 If 'ss' is in storage get
9992 Save program with Checksum
9993 'ss' is not in storage,
9994 Get loaded Checksum value.
9995 Checksum at LOAD time is the
same as at SAVE time; ok to
9996 Inform operator of error.
9997 Wait for operator reply.
9998 Ignore error, continue to
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/
Word Match - Alien Bomber - Spelling
Flash Master - Educational Alien
Bomber - Educational Dark Star
Make check payable to BREM Systems
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
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-
To prevent poor contact between
the computer and the power supply
or tape recorder, I arrived at the
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
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
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
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
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:
Program: ZETAPAK #3:
Price: $9.95 + $2.50 (S&H)
ROM/RAM required?: 8K/1K
Printed listings?: Yes
Programs listable?: Yes
Easy to Load?: Yes
From: Zeta Software, P.0. Box 3522
Greenville, SC, 29608
For $9.95 you get 6 games on
tape and an instruction oook with
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
GENERAL SYSTEMS CONSULTING
2312 Rolling Rock Drive
Conley, Georgia 30027
SINCLAIR ZXS1 SOFTWARE
16K minimum configuration
Designed to help monitor your finances.
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 ...
TAPE LEVEL INDICATOR
Lots of people have trouole
loading programs. This loading
level indicator may help. This
circuit does not reduce the
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
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
PINS 10-18 OF 3914
CONNECT TO PINS 11-19
OF DISPLAY, IN SEQUENCE
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
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 =
Blase Sanzone, Milford, CT
1© PRINT RT 0,10;
15 PRINT "YOU CRN CRLCULRTE TH
25 PRINT "---
”2 URTT5 "
"5 CURRENT "
‘SELECT BY ENTERING ft
SO PRU5E 4-0000
70 LET Ki = INKEY $
8© IF K* <”I” OR K$>”3”
O© GOTO URL K$*I©0
1©5 PRINT “THE FORMULA FOR CRLC
ULRTING RESISTRNCE IS: R=E^X
115 PRINT "E=WOLTAGE DROPCRURIL
ABLE-NEEDED) "I*CURRENT <IN RHP
12© PRINT ” *^**^*«^*^*-«.*^*3.***^
* * * * * * * * * * ”
125 PRINT “ENTER UOLTRGE DROP"
130 INPUT E
135 PRINT RT 5,2©;E
14.0 PRINT “ENTER CURRENT IN RHP
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
Idt? uuTO SO©
r n jl* t
ii} QTTKir - CRLC
ULHTING WATTAGE iS: P=X*-¥2*R
* n.r> x|n|T*
owuHHtD , R *REs XSTANCE IN OHMS
IIP vKiilT 1ENTER the CURRENT-
SinTEh KE5 XSTmNCE IN
235 PRINT RT 6.18;!
240b PRINT ,: FnTFD
243 INPUT P
§30 PRINT RT 7,25;ft
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
3©5 PRINT "THE FORMULR FOR CRLC
ULRTING CURRENT IS: I=E/R"
315 PRINT “E=UOLTRGE DROP" , . "R =
RESISTANCE IN OHMS"
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
380 GOTO 500
4-00 LET X — < INT ( 10* <X + < . 05) ) ) j ✓
405 RETURN _
500 PRINT RT 15,0;"DO YOU WANT
TO CONTINUE Y/N"
505 PRUSE 1000© ... tmcn gqto 5
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,
When you want to terminate tne
program, Enter STOP (shift A) and
the screen will blank. To play
Fifceen Puzzle again, just hit RUN,
Jon T. Passier, Beverly, MA
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
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.
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
90-Day Warranty On All Modules.
10-Day Return Priviledge
ORDER PHONE 803-532-5812
Add $4.95 ehipplng A handling to all order*.
Rt. 3 Box 147 Brodie Rd.
LEESVILLE, SOUTH CAROLINA 29070
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.
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
7550 West Yale Avenue
Denver, Colorado 80227
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
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
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.
ADDRESS DECIMAL=MNEMONIC COMMENT
4 0 JR Z
/ “ f
/ ^ f
56 JR C
are limited to
addresses and 126 backward ad¬
dresses, enough leeway for most MC
subroutines held in REM lines.
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., ($12.95)
it contains programs in the graphic,
home, business, education and games
areas. In addition to the programs
it offers, I found it co be a very
good resource oook and I recommend
it to any ZX/TS user.
Stephen Zachev, Muskegon, MI
i0 PRINT" "THIS PROGRAM COHDODP
*PRl8i yCTS * flND » bSmd ora??
(GOTO Page 20)
FROM INTERCOMPUTER, INC.
A full line of software in the
areas of business, education, &
entertainment, for your Sinclair
ZX81 or Timex 1000.
Please send me a FREE program and
Intercomputer: P.O. Box 90
Inc. Prudential Center
Boston, MA 02199
Jon Bobst, Zeta Software, PO Box
3522, Greenville, SC 29608-3522
Is PRINT* = " FIRST PR0DUCT "
co |®„ p «INT "HOU MUCH DOES
HOW HftNY UNITS IN PR
35 INPUT fl
4-© INPUT B
LET 5$ = ”SECOND PRODUCT"
C»D hhjlNT "HOU- HUGH DOES " j & jj
SO INPUT C
70 INPUT D
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
14-0 PRINT B$; F; ” CENTS PER
150 IF E<F THEN GOTO 300
ISO IF E=F THEN GOTO 4-00
170 PRINT B$; ” IS 0 ^gT TER ?UY
ACCORDING TO UNIT PkIlE
3®1 PRINTER*;" IS w BETTER BUY
3304- / . 8K
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
TACTILE FEEDBACK OVERLAY,feel your
keys,touch type, $3.95 P.Hargrave,
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 !!!
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.
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
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
♦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
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
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.
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
• 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.
12 issues, $29. Single issue, $4.
Publisher: Kirtland H. Olson
Editor: Ann L. Zevnik
Assistant Editor: Pamela Petrakos-
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
exp. date_bank number (MC only)_
Day Phone A _ 1 _Evening Phone J_)_
I own a □ Sinclair ZX80 □ Sinclair ZX81 Telephone orders call
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*
I Bolton Road. Harvard. Mass. 01451
EZRA GROUP II
EZRA GROUP II
LOW LOW LOW LOW LOW LOW LOW LOW LOW
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
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
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
First Class Permit No. 8