OThe
O Boston
O Computer
O Society
SINCLAIR-TIMEX USER GROUP NEWSLETTER
xttiirvTTK* & noaw & Azmwd Q&&Q
LATEST NEWS
The Aug. meeting was quite
lively. Don Weiss, our librarian,
exhibited his word-processing
system, which begins with a
TS1500 + 16K, using a Compusa
disk, drive for mass storage,
feeding a Seikosha 150 printer
driven by a Memotech Centronics
parallel interface. He also has
seperate keyboard with a space¬
bar. Unfortunately a system bug
ft££,Yented his demonstrating
wORD-SINC, a popular program,
but he was able to show other
operations.
Marty Warner, from Games to
Learn By, demonstrated MSCRIPT,
the wordprocessing program which
was to Rave been available for
the TS2068 along with a Mannes-
mann/Talley printer which was
also planned as a TS product.
Marty has alsoe tried TASWORD II
and discussed pros and cons of
both these superior programs.
She offered a copy of MSCRIPT as
a door prize, which was won by
John Kemeny.
Then, as an encore, she ex¬
plained how to make internal
color adjustments on the TS2068.
Watch for details in our next
issue.
Finally, "Things move fast in
the computer industry." Our dir-
e c to r. Sue Mahoney, brought
copies of the Connecticut Com-
puter Spciety News , which among
other items of interest, an¬
nounced her engagement to Todd
Tolhurst, after a brief court¬
ship conducted largely over
CompuServe. Details next issue.
i
I
i
The Absolute Beginner 1 s Guide to
Machine Code Programming on the
ZX81/TS1000/TS1500
by Jack Hodgson
Over the years I've been amazed at
the number of beginner programmers
who are interested in machine lang¬
uage programming. Others might say
that a beginner should avoid this
type of stuff because it's far too
complicated for them but I don't
agree .
DIRECTOR’S COLUMN
Susan Mahoney
News -from Sinclair . . .
Maggie Bruzelius. Executive VP
o-f the U.S. branch of Sinclair
Research, Ltd., resigned on July
20, 1984 to take a position as
marketing director -for Alpha
Software of Burlington, MA.
The search for a replacement
is being handled personally by
Nigel Searle, Managing Director
of Sinclair Research, Ltd.,
Cambridge, England.
Over the years, our group has
always enjoyed and appreciated
the support of Sinclair Research
(Clive Sinclair is a patron mem¬
ber of BCS) . Best of luck to
you Maggie, and thanks for all
of your help.
* * *
Sinclair’s QL (Quantum Leap),
based on Motorola’s 32-bit 68008
microprocessor chip, is still
slated for release in the U.S.
this November. However, since
production of U.S. -bound QL’s
will not Deal? until the first
quarter of 1985, initial quan¬
tities will be limited.
If you’re interested in purch¬
asing a QL, Sinclair Research
will be happy to take your name
and mai 1 you an announcement
when they are ready to take
orders. Write to:
Sinclair Research. Ltd.
50 Stamford Street
Suite 800
Boston. MA 02114
con .
Pg.8
Con. p.9
MERGE
It If
With any luck, most of you
have received the late April
issue of this newsletter. It
seems the Postal Service mis¬
placed a bag or two. We're
planning an extra issue this
fall anyway, for the upcoming
East Coast Computer Faire, which
will be part of our 4th
Birthday” celebration this Fall
Your suggestions and contrib¬
utions will be appreciated.
WJS
MEETINGS
The July main meeting was
attended. Mike Coughlin explain¬
ed the nature of T.V. sets and
their idiosyncracies when hooked
up to a computer. Future
activities were discussed and
programs proposed for future
meetings. The August MC meeting
at Mitre featured as promised a
presentation by Dave Wood on the
secrets of the ZX81's internal
juggling act, whereby it
concurrently processes up to
three signals at once. Just
what's inside the NOP generator
anyway ? Future meetings prob¬
ably won't be so intense; all
those interested in Machine Code
at any level are encouraged to
attend. Next meeting:
September 6, 1984
CALL FOR ADVERTISERS
The next three issues. Sept.,
Celebration, and Oct. will offer
an excellent opportunity to reach
an interested and active section
of the surviving TIMEX/Sinclair
community. Contact either Sue
Mahoney, Group Director or the
editor for special rates for all
three of these issues. Members
wishing to sell off equipment,
offer services or software are
also reminded that classified
ads are available at economy
rates .
This newsletter is produced by
the Sinclair/Timex User Group of
the Boston Computer Society in
addition to regular meetings and
activities. It is mailed free to
members and supporters; back
issues are available for a small
fee.
DIRECTIONS TO MEETING
We meet in the Large Science
Auditorium (Room 8/2/009) on the
Harbor Campus of U/Mass Boston,
which is located 3 miles from
downtown Boston just off
Morrisey Blvd. Follow signs from
the SouthEast Expressway, Exit
17. During reconstruction,
Columbia Road, which comes in
from Dorchester may be a better
connection.
On the MBTA, take the Red
Line (Ashmont) to Columbia Sta.
Use the free University
Shuttlebus from the T parking
lot to get to campus.
The Sinclair TIMEX User Group
Sue Mahoney Director
c/o BCS Office
or 203-755-2699
Will Stackman Editor
210B Summer St.
Somerville MA 02143
617-666-8626
Jack Hodgson Correspondent
P.O.Box 526
Cambridge MA 02238
617-354-7899
John Kemeny
User Group Correspondent
284 Great Rd. Apt. D5
Acton MA 01720
Allan Cohen
Meeting Coordinator
617-961-3453
LIBRARIAN
Don Weiss
27 Mitchell St.
Randolph MA 02368
(617) 986-8449
THEY'RE OUT THERE!
The newsletter exchange con¬
tinues provide us with the
doings of TS Users across the
continent. Triangle Sinclair
User's Group is in hot pursuit
of the 64 column screen and has
published the detailks of an RGB
hook-up designed by John Oliger
of Cumberland, IN. Doug Dewey,
their fearless leader is ready
to market his Chameleon for $60.
Call 919-929-3079 for details
Want an audible keybeep ? ZX
World News Bulletin suggests
POKE 23609, (#from 1 to 255).
What's your favorite ? They are
publishing programs from an
Italian correspondant , Oriani
Massimo.
Fred Nachbaur's Syncware
News is now coming out under the
aegis of our northern friend,
Tom Woods. The magazines' new
address; P.O.Box 64, Jefferson,
N.H. Nov. -Apr. (delayed issue)
had instructions for using a
Votem to make a cassette
controller, a "Caveman" BASIC
Wordprocessor for both TS100 and
TS2068 (the differences are
instructive) , a page of
schematics for small loading
aids, plus some high-powered
math articles. May-June, Fred's
last has an improved monitor
driver, more math, and a Data
Acquisition Development program
for using the Votem or another
V-F circuit board with the 1000.
TUG from Gainesville, Fla. is
getting into the Westridge Modem
and will be on line to talk.
Roger Hunsiker of the group
suggests that green PAPER and
BORDER with black INK makes the
most readable B&W screen for the
2068. Any comments ?
David Hosher, from ATSU in
Central Ohio, gets into the
colored cursor on the 2068 and
uses it to highlight listings
(how about red REM statements ?)
To activate a colored cursor, go
to E mode, then shift the color.
If you shift 8 or 9, which are
"colorless" you can create
flashing statements without
using the FLASH 0/1 commands; 9
for on, 8 for off.
We continue to receive issues
fron the T/S User's of
Vancouver. June/ July reviews Z-
Speak, a simple allophone speech
synthesizer and offers a short
program to compute your pulse
rate.
From issues early this year,
which are beginning to swamp our
faithful correspondent, John
Kemeny, (more about which later)
comes headline sized printing
from New Brunswick.
FROM THE SINCLAIR PRINTER MANUAL
A PROGRAM TO ENLARGE CHARACTERS
DOESN/T SEEM TO WORK FOR TS1000
10 DIM A $ { 4-0 )
20 INPUT A$
30 FOR Y =4-3 TO 4 STEP -1
40 hOR X=0 TO 7
50 LET 5=43-7
50 LET N=X+S* INT (S/S)
70 LlT SCRN=S-8*INT (S/S)
80 LlT P=Pt:EK (76S0+8*CODE h$ (
N+l) +SCRN)
90 FOR 1=7 TO 0 STEP -I
1 0 0 R L OT b X 4-7-1 , Y
110 UNPLOT Q*X+7-I.Y
120 IF P<2**I THEN GOTO 150
130 LET P =P -2 ■+•■+■ I
1 4 0 P L OT 8 ■£ X + 7 - J . Y
158 NEXT I
160 NEXT X
170 NEXT Y
Unfortunately, this doesn't seem
work on the 2040 printer. Anyone
see a fix ?
Finally, from TIMELINEZ , the
newsletter of the Triangle Timex
ser's Group of N.C. a method for
darkening the display file
image on the screen which will
also COPY or LIST to the printer.
See lines 1 through 9.
The rest of program is derived
from several British sources.
For an explanation of this "toy"
see the last few issues of
Creative Computing, the Math and
Art series.
There is a wealth of material
out there. We need help mining
it for the newsletter and for
your use. Volunteers are needed
to compile an index. TS2068
users especially should want to
participate in such a project.
Contact John Kemeny for more
information.
WJS
On the Magazine Scene
One of the most interesting
magazines on the news stands in
Harvard Square is a British pub¬
lication, Your Computer, which
covers all the smaller personal
computers on the English market.
Naturally the ZX81 and the
Spectrum figure prominently on
its pages. Among the tips
published so far this year is
the secret to INPUTing anywhere
on the TS2068 (Spectrum)
screen. Key in;
10 INPUT AT 22,0; AT 1 , 10 : "Promp
t message"; var.
Experienced BASINC users will
recognize this as a variant on
the technique for speeding up
screen displays. The second
screen location can be anywhere
legal. So much for that gripe!
Courtesy of Hubert Surrer from
somewhere in Germany.
Programs range from the
weird to the wonderful. The May
issue, (the latest I've seen)
has a software generated speech
synthesizer! for the ZX81, as a
follow up to an article last
year on the same feature for a
Spectrum, a Quickload for the
latter with a top speed of over
3600 Baud, arcade games for both
machines, and other goodies.
Even the ads are of some
interest. Watch for the Floopy
from 'Phi Mag which uses a loop
of standard sized cassette tape
and a nine-track recording head
(one for error checking) . Claims
an average access time of 3
seconds, data transfer of 10K
bytes per second. Will load 32K
in just over 3 seconds.
Earlier issues this year
contained items of interest such
as "Function Keys" for the
Spectrum (which would require
some address changes for the
TS2068) and definable printer
characters for the ZX81.
Other general interest
British magazines, such as "What
Micro?" support Sinclair
computers, but none to the depth
of "Your Computer"
1
CLEAR
ReM set rairitep
ess
LET s =57736:
REM start addr
3
kLhD Fi
4-
IF Fi =— 1 THEN
GO TO 8: REH d
a t a
f lag
5
POKt: S - Fi
6
LET S=S-I
~7
GO TO 3: REH
POKE next addr
ess
S STOP
S DATA 17,0,221,213, 1,0, 3, 4-2,
34- , 02 , 3b , 12S , 157 , 31 , 132 .13,35,19
, 13 , 32 , 24-b ,15, 24-4- , 225 . 37 , 34- , 54- , 9
2,201,-1
10 RtH iSPYRG— GYRGi
20 BORDER 6: PRPER 0: INK 7
30 LET OV =0 : CI_S : GO TG 150
50 LET 3=0: LET h=0: LET F=0:
LET i=.i: LET hl=0: LET vl=0
100 LET b=— CaiL) sS : LET V=INT i
CCL-SiiSIN Csi-piSIN CfaJJ+.S): L
ET h=INT CCCL-Si^COS (a } -peCOS C
b))*.5>
110 II- f =2 THEN PLGT I2S+hl,8S+
Vl: DRRU h-hl , V-Vl
115 IF f <2 THEN LET f = f+l
120 LET hl=h: LET V 1 =v : LET 3=3
Pi
125 LET 3 * = IN KEY 4 : IF a$=““ THE
N GO TO 10@
130 GO TG 310
150 PAPER 0: INK 6: CLS : PRINT
SPYRQ-GYRG*"
"
1B0 INK 7: PRINT ' 11 This prog
ram drams patterns mhich can
he generated by tso gears shorn
n be i oai-”
170 CIRCLE 60,51,40: CIRCLE 34-,
51,1b: INK 3: PLOT 60.51: DRRU 0
,4-0: PLOT -34-, 51 DRRU 0.16: PRIN
T RT 12 , 7; “L“ ; RT 14 . 10 ; ”s “ : PLOT
94-, 51: DRhU 15,32: PLOT 94-, 51:
DRRU 13.-30
130 INK 6: PRINT RT 11.12: “pen"
190 INK 7: PRINT RT 10 j 16 ; “ Th
e smaller“;RT 11,16; “gear rotate
s " ; RT 12,lb; “around the“;RT 13,1
6; “inside of the“;RT 14,16; "larg
er gear,”
200 PRINT RT IS , 16; "producing a
pen" ; RT 15,16; “trace . “
210 PRINT RT 17,16;“ Input L,s
,and“;RT 13,1b; “pen position“;RT
19,16; “in small circle."
220 PRINT Ri 21.11; “Hit a ley":
^TIU5£ 0 '
225 INPUT “ Load a Pattern from
Tape?ji/n “;x$: IF x$=“y“ THEN I
NPUT ”i-i lename ?" ; f S: CLS : LORD
fSCGDb : PAUSE 0: GO TO 130
227 PRPER 7: INK 0
230 INPUT “Radius L 10-35J^":L-
PRINT L ‘ :
240 INPUT “Radius S 7";s: PRINT
250 INPUT “Pen position inside
B ?“;p: PRINT p
255 INPUT “In SCO lor ?“ ; i c : INK
i S~
i^u i raperco lor ? .pc
300 PnUbt 50: IF ov=0 THEN PRPE
R PC: CLS : GO TO 50
305 GO TO 50
310 INPUT “overprint another pa
item ? y,n“; if qs="y“ then
LET OV =1 : GO TO 230
315 If qf=”y“ THEN GO TO 30
320 INPUT “Print Hard cony
“;q$: L PRINT L;“ “;s;“ ";p
$=”y“ THEN COPY
j.npUT “save Tape copy
“;qs. IF q*=“y“ THEN INPUT
name 7“; y*: SRUE qSSCREENS
340 GO TO lb@
7 y,Ts
XF q
? y .rn
"Fi le
WJS
RfiHDGHiZE UsR 8773b to durteii
POKE 23607,6© to restore
A Comparator to Use on Lad 2068 Cape 3'*.
by Chuck Ludiwsky
aa told to Hike Coughlin
The program loading end saving process
on the 152068 is a great improvement
over the 131000. The signal recorded
a series of square pulses, with ones
shorter than zeros. There is no DC
component and reversing plus and minus
has* no important effect. Square waves
are difficult to record and some tapes
are being sold that may not loaa.
A tape would have to be in re all y
dreadful condition before the point
where the signal changed from plus to
minus was effected. A handy elect¬
ronic circuit known as a comparator
comparator
out
is specially designed to take a tao
scmare wave ana make it into a good
sauare wave. An ordinary op— amp
makes a good comparator for our pur¬
pose. Chile an LF^N was used in
our example, any op-amp that will
work at low voltage is suitable.
A comparator is a very high gain
amplifier whose output is designed
to go from one extreme of the power
supply to the other . Think of it as ^
a constantly overloaded amplifier and
a one Lit A to D converter. The output
is equal to the power supply voltage.
The values of the components are not
critical, so don’ t be afraid to
WANNA GET SOMEBODIES' ATTENTION
Try this on your TS2068 !!!!!!!!
experiment .
USING BOB MASTER'S BOOK
Most TS1000/1500 (ZX81) owners
and not a few TS2068 users have
Psion Ltd . s VU-CALC and VU-FILE
(The Organizer) . But even those
who have applications developed
for these two utility programs
probably do not use either as
much as they might. The in-box
documentation which accompanies
these programs is sketchy at
best, and barely scratches the
surface of their potential
usefulness .
"Getting Serious with Your
TIMEX/SINCLAIR" could end the
under-use of either program.
Expanded from tutorials BOB has
given at S/T Users' Group
meetings, this book walks
through a range of examples
which can yield results of the
sort we usually claim we bought
a computer to get.
The appendix by Mark Fisher
on VU-CALC for the 2068 will
allow those of us with color
computer to benefit from this
book as well. Although this
spreadsheet can be as large as
50x50 (Rows from A to AX,
columns from 01 to 50) , the
templates included with this
book will serve for most
applications. Larger forms can
be created on fullsize
accounting paper.
Both versions of VU-Calc can
be printed out using the 2040
Printer. In vertical format, a
TS100 version can be pasted up
on 8 1/2 x 11 to 6 columns by 26
rows; horizontally, 9 columns by
18 rows. (Six screens in either
case). On the 2068, vertical
yields 8 by 50; horizontal, 12
by 36 .
TS1000 users should also con¬
sider following Fisher's custom¬
izing notes. Carefully entered,
these improvements are worth
adding to most uses of VU-CALC.
The whole secret to getting
the most out of this book is to
sit down and use it. As with
most spread sheets, developing
formulas is really a form of
programming using simple
accounting and the "language" of
the program at hand.
VU-FILE (The Organizer) seems
at first a simpler piece of
software, but may be harder to
use effectively. Bob's sugges¬
tions for formatting are
ingenuous and increase the
usefulness manyfold. His demyst¬
ification of print formatting
procedure is invaluable. Again,
most explanations are clear only
after use.
Anyone seriously expecting to
use VU-FILE will need to study
the formatting templates
supplied. Otherwise you'll spend
(waste) hours trying to get
records the right size. Perhaps
the major lesson of this book is
that effective planning before
using an application program,
applying an old-fashioned pencil
to an appropriate form will
yield maximum results.
Too often, users assume the
computer will do it all. There's
not a little laziness in the
demand for "user-friendly"
software. A good tool may take a
while to learn to use well.
To reiterate a point. If
carefully though-out document¬
ation were supplied with more
software, it would be more often
worth its price. Unfortunately,
many programs are released hot
off the printer. It will be
interesting to see what the
documentation for the software
bundled with the QL is like.
WJS
A BUG IN TS2068 VU-CALC !
Option 2 on the end menu,
which clears the sheet for a new
model crashes the program. GOTO
9000 will not display the error.
Variables have been overwritten.
Repairs are simple. Enter #q
to exit to BASIC. The LIST 3200,
and bring it down to EDIT. Add
the following statement to the
head of the line before the DIMS.
3200 CLEAR 29327;
and leave the DIMs, etc in place.
Return to VU-CALC by entering
GOTO 3200.
Discovered by Gary Szekeres,
T/S Users Group of Cincinnati
i
Reserving Space in a
REM Statement
When storing a machine code
program in a REM statement, the
programmer must have written the
statement with at least as many
bytes as the program requires;
often a tedious and time
consuming task, especially if
the program is large. Assuming
that the first line in BASIC is
the REM statement (1 REM xxx - )
the first addressable byte is at
16514 (hex4082 ) . The following
procedure will simplify loading
MC into 1 REM.
Step 1 : Enter 1 REM; 10 Program
loader .
Step 2 ; Place this short MC
program above Ramtop, at, say,
30000 (hex7530) .
Address HEX Mnem
7530 21 82 40 LDHL 4082
Addr.lst byte
7533 01<st qr > LDBC qrst
No. reserved bytes
7536 CD 9E 09 Call 099E
Make room
7539 C9 Ret
Step 3 : RAND USR 30000 (safe
address above Ramtop)
Step 4 : POKE into 16511 and
16512 the number qrst + 2 (low
byte into 16511, high byte into
16512)
Following Step 4, the machine
code program may by entered by
POKEing the code into addresses
beginning at 16514, using any
standard loading program.
For example, suppose the MC
program uses 1000 bytes. The
number qrst = 03 E8 in hex; the
instruction at address 7533 is
01 E8 03 (note reversal) . After
Step 3, the number 1002 would be
POKEd into addresses 16511 and
16512 in the immediate mode, i.e
POKE 16511,234 <enter>
POKE 16512,3 <enter>
"FUN MATHEMATICS
on your microcomputer"
Czes Kosniowski, from the
Computer Dept, of the University
of Newcastle on Tyne, has
written a maths book for those
who always suspected that
computers probably could be used
as mathematical tools, but that
somehow that wouldn't be
"friendly" .
This moderately advanced text
(at last past freshman year of
highschool) contains very clear
discussions of important
principles which support the
screen display of mathematical
functions .
The accompaning BASIC programs
can be run on most Microsoft-
based home computers including
all Sinclair/Timex models.
Several have been specifically
converted into BASINC, most
require some knowledge of its
idiosyncracies . The polar graphs
which accompany this review show
some of the posibilities
inherent in mathematically based
computer "art".
Published by Cambridge
University Press; ISBN 0 521
27451 6. Available locally under
$10. Get this one into your
library.
/ * *•’
(Note; 3 x 256 + 234 - 1002)
Contributed by Arthur Kant, 139
Woodridge Rd., Wayland MA 01778
T i me;.
Computer Fairs/East . .
News -from
Where. 0, Where are the TS2068
technical manuals? I’ve scoker.
with many people who ordered the
new tech manual -from Little Roc)
in April or May and still have
not received them, while several
ether oar sons have. Why should
this be'-'
It turns out that Timex orig¬
inally produced 200 copies of
the approximately 300-page man¬
ual on a Xerox machine. As the
orders began to outnumber the
manuals, it was decided to send
the manual to the printer
instead.
Three months later, during the
week of July 30, Little Rock
mailed 1,000 tech manuals - bulk
rate. So, it may be near the
end of August before you find a
present from Timex in your
mai lbox .
One final notei Timex is now
putting all new orders for the
manual on "hold" until they have
enough to warrant a second
printing. For those of you who
wish to order, send your request
(along with a check for *25.00)
to:
Timex
P.G. Box 1378
Little Rock, AR 72203
ATTN: Material Sales Div.
And Good Luck!
* * *
Timex has sold its entire
inventory of computer-related
products to wholesalers and
retailers. This means that you
CANNOT purchase any of these
items directly from Timex any¬
more. From this point forward,
it will be very important for
all of us to share information
on the whereabouts of Time;
computer products.
You’ve heard of the West Coast
Computer Faire° Well, it’s
coming East to Boston. The
producers of the three-day show
(October 2-4) are providing a
booth for the Sinclair/Timex
User Group (all those other BCS
groups get a booth too) . What
we need are:
- Ideas. What are we going
do with this opportunity?
- Volunteers. For planning,
staffing, and generally
hanging around the booth.
Since the show will fall near
our third anniversary, let’s try
and make this opportunity into
a showcase and celebration for
our group. Please get in touch
with me if you have ideas, or if
you’d like to help out in the
booth.
(RETurns ) .
Originally, I wanted to show you,
in this first installment, how to
load this program into your compu¬
ter and run it. But I've run out of
room and you have enough to chew on
anyway .
Next time I ' 11 tell you about load¬
ing machine language programs; get¬
ting "letters" from the keyboard,
and the infamous, "Hex numbers".
Machine language is not mysterious.
It is a little more complicated
than some "high-level" languages
because in machine language you
must keep track of many details
yourself. But it can add to the
sophistacation of your programming
and speed up you routines. And
finally many programmers like to
simply "work closer to the mach¬
ine . "
If you got this far you'll love
installment two.
Jack
I was only a beginner when I first
plowed my way through Toni Baker ' s
book. If I learned it, anyone who
wants to can.
The biggest problem I had in learn¬
ing all this was that the Z80 pro¬
cessor chip that's in the Sinclair
is so sophisticated that it had too i
many instructions for me to deal j
with. I didn't know where to start, j
!
What I'm going to do in this series
of articles is to present a simpli¬
fied view of Z80 programming. I
won't show you all the instructions
or make you understand all the
details of how it works. I will
give you enough info to write sim¬
ple, useful machine language pro¬
grams .
This series will deal with the
ZX81/TS1000/TS1500 series of compu¬
ters. Many of the priciniples I
demonstrate will apply to the
TS2068 as well, but some of the
details will have to be adjusted.
Ask me or another machine language
programmer at the meetings about
the differences. If there's enough
interest the editor of this letter
may allow me to write an updated
TS2068 version.
OK let's get started.
A computer is just a collection of
storage places where one puts num¬
bers. The instructions tell the
computer to move numbers from one
place to another, do arithmetic
with them, compare them, and do
things as a result of those compar¬
isons .
First let's look at how these stor¬
age places are set up.
The processor has a bunch of stor¬
age locations built into it. They
are called "registers". There are
alot more storage locations in the
area we all call RAM. The registers
have names that are letters: like
A, B, C, H, and L. The RAM loca¬
tions have names that are numbers :
0 up to 65,535.
The computer understands instruc¬
tions that tell it to move a number
from one location to another, for
example, "move the contents of
16514 to A". That instructions is
actually called "LD A, (16514)".
That means load the A register with
the number that currently in loca¬
tion 16514.
The parentheses tell the computer
to load A with the contents of the
"address" 16514 instead of the
number 16514 itself. If we wanted
to put a particular number into A
we would say "LD A, 16514" without
the parenthesis.
An important note here . The compu¬
ter can only deal with certain
sized numbers. Our second example,
using 16514, would not work because
16514 is too big for the computer
to handle. The computer can only
handle numbers up to 255.
What follows is as complicated this
is going to get. So please take a
deep breath and understand it.
The number "fifteen" can't be un¬
derstood by a desktop calculator
when it's written that way. You
need to divide it into "digits"
between 0-9. We all know that "fif¬
teen", turned into digits is "15"
but understand how that happened.
"15" is "1" times 10 plus "5" times
1. That's called "base ten". Compu¬
ters use "base 256" (Please don't
everyone holler at me. I know
people always says computers use
base two. They do, but you don't
need to know anything about that
here. Just THINK BASE 256).
Converting numbers from base ten to
base 256 is easy. You look it up in
a chart. For the stuff we'll be
doing here I'll supply the conver¬
sions. Next installment I'll show
OVER
OK. Enough of this fooling around.
Let's write a program. Here's a
BASIC program:
10 PRINT "
HELLO WORLD.
If
How would
we do that
in machine
language?
It's really
not too hard.
ADRS
OP CODE
INSTRUCTION
—i
II
H
II
II
II
II
II
II
II
II
64-130
33-144-64
LD HL, 64-144
64-133
126
LD A, (HL)
64-134
254-255
CP 255
64-136
200
RET Z
64-137
205-8-8
CALL 8-8
64-140
35
INC HL
64-141
195-130-64
JP 64-133
64-144
45-42-49-49-
-52-0-
60-52-55-49-
-41-27-255
ADRS is
the RAM location where
these instructions are going to be
stored. OP CODE is the numbers that
the computer understands as instr¬
uctions. The numbers starting at 64-
144 are the code numbers for the
letters "HELLO WORLD."
The first instruction LD HL puts
the starting address of these let¬
ters into the HL register. LD A,
(HL) puts the first "letter" into
A. CP 255 compares whatever ' s in A
to see if it's equal to 255. RET Z
ends the program if the comparison
we just did is equal to 255 (notice
that the last "letter" is 255).
CALL 8-8 tells the computer to
executea routine that is already in
the computer, at address 8-8. That
routine causes the "letter" in the
A register to be printed on the
screen. INC HL causes the HL regis¬
ter to be increased by one so it
now is the address of the next
"letter". JP 64-130 causes the
computer to go back to the LD A,
(HL) and get the next "letter".
It does all this, getting letters
and printing them, until it gets to
the "letter" 255 then it stops
you how to make a chart of your
own .
Anyway, where were we? Oh yah.
16514 is 64-130. That is, 16514 is
"64" times 256 plus "130" times 1.
LD A, 16514 is written for the
computer as LD A, 64-130. LD A,
(16514) is written LD A, (64-130).
Sometimes we want to store numbers
bigger than 255 in a register. We
can do this by combining two regis¬
ters into a bigger one. Some regis¬
ters are set up to be used in
pairs. B&C and H&L are ready to be
combined. They are then called by
their combined name: BC or HL. We
can put numbers in them by using LD
HL, 64-130 or LD BC, 64-130.
Up above we asked to computer to
load A with the number stored at
adresss 64-130. We can also tell it
to load A with the number stored at
the address that's currently in
register HL. For example:
LD HL, 63-130
LD A, (HL)
This does the same thing as
LD A, (63-130) .
Before the computer can execute
these instructions we must convert
them into numbers. The computer
can't understand the letters LD A,
28. It only understand numbers.
The number for the instruction
LD A, 28 is 62-28. The 62 means LD
A and the 28 tells what to load it
with. 62-255 would mean LD A, 255.
When your 're loading a register
pair you have to do something
strange. LD HL, 64-130 becomes 33-
130-64. 33 means LD HL and the
number to be loaded is tacked on in
reverse order. Whenever the compu¬
ter is reading a two section number
like that, it must be given to it
in reverse order.
concl . p.8.
10
T/S 2068 ROM BUGS by John Kemeny
i
Well, the Technical Manual
from Timex finally arrived, and
it has lots of interesting
things in it. Unfortunately, it
is no longer available from
Timex. Since the manual's
audience is software developers
and not consumers, most of the
material concerns arcane machine
code interfaces with the
cartridge system (via LROS and
AROS). Of interest to the BASIC
programmer, however, is Section
Six - "Known 'Bugs' and 'Work-
Arounds'"; here's the list •
1 - Pressing ENTER multiple
times with an invalid LOAD,
SAVE, or other tape command
causes a system reset.
2 - If a non-existent line
number is specified for an
ON ERR GOTO statement, followed
by an error, the system will
hang. In case youte interested
in the details, "the ROM code is
in an endless loop trying to
report the absence of a valid
error handler to the
non-existent error handler ! ! ! "
That's what happens when you do
recursion without defining
initial conditions.
3 - Parameters to the SOUND
command are not fully validated.
This leaves the possibility of
accidentally changing the I/O
ports for reading the joystick.
The remedy is to execute SOUND
7,63 to enable the joystick for
input .
4 - If you respond to the
SCROLL? message using multiple
keys you will get strange
results, e.g., Cap Shift/4
scrolls two pages, Cap Shift/2
dumps ROM data.
5 - When Cap Shift /0 is held
down to delete characters in the
Edit Line, it sometimes outputs
the DELETE keyword instead. "It
should not do this in autorepeat
mode. This is especially
noticeable when the input line
is long."
These are all the
documented bugs. Here's an
extra, undocumented, bug.
6 - The UP-ARROW function
Lor ** on the T/S 1000,) which
for x~y is supposed to give you
x raised to the y power, doesn't
work for negative x's. That is,
-5~2 gives -25 which is okay(
is done before the unary minus).
But (-5)~2 gives an error, and,
as everyone knows, the answer is
(-5)*(-5)=25 . The problem is
that the algorithm computes
EXP (y * LN x) if x is not zero.
LN x is undefined if x is
negative. If x is zero it
returns zero if y is positive; 1
if y is also zero (i.e. ,0**0=1) ;
and overflow error if y is
negative.
That's a suprisingly short list
of bugs for a system as complex
as the 2068. Please let us know
if you find more.
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