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Homebrew Computer Club
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R obert Reiling, E d i t o r □ Po st Of fi ce Box 6 2 6 , M o u n t a i n Vi ew, C A 9 4 0 4 2 □ Joel M ille r, S t a f f Wr it er
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T y p e s e t t i n g , g r a p h i c s a n d e d ito r ia l service s d o n a t e d b y Laurel P u b lic a tio n s, 1 7 2 3 5 L a ure l R d . , Lo s G a t o s , C A 9 5 0 3 0 (4 0 8 ) 3 5 3 - 3 6 0 9
organizers Dr. W. J. Schenker, and R. J. Hendrickson
are to be congratulated.
MORE ON THE S -100-A prii, 1977. The First
West Coast C om puter Faire being held April 15-17,
1977 at the San Francisco Civic A uditorium , N orthern
California’s largest convention facility, will have a con­
ference session on the S-100 bus according to Jim War­
ren, Faire Chairperson. You can participate in this ses­
sion or others scheduled for the Faire. Write or call Jim
Warren, Box 1579, Palo A lto, CA 94302, (415) 8517664 or 323-3111.
LETTER—November, 1976. Samuel H. Daniel,
V andenberg AFB, CA sent a letter asking to be put on
the mailing list and enclosed a donation. He com ­
m ented as follows on his activities, “ I presently have
an 18K Digital Group 8080 System , to which I may
add a pair o f Phi-Decks and a controller. It works as
advertised and w ent from bits and pieces to assembled
and tested in only 14,5 hours. Needless to say, I ’m
pleased w ith and recom m end it.” Thank you for the
p roduct inform ation and for the contribution to the
Newsletter.
CONTRIBUTIONS—The Hom ebrew Com puter
Club New sletter is supported by contributions, both of
articles and m oney. Your articles help keep inform a­
tio n flowing and all of us benefit. In this issue you will
read about w hat others are doing with their com puters.
W hat are you doing? Do you have a favorite software
idea? How about a p roduct evaluation? Send me your
article for the Newsletter.
M oney, of course, is another requirem ent of the
New sletter. Printing and postage are very expensive
and so it follows the N ew sletter costs a reasonable
am ount to produce and distribute. Please keep your
contributions coming in. Mail to Hom ebrew Com puter
Club New sletter, P.O. Box 626, M ountain View, CA
94042 or m eet me at the next Club m eeting. □
RANDOM DATA
By R obert Reiling
MEETING—Nov. 12, 1976. Acapacity crowd was
on hand, estim ated at over 450 people for this m eet­
ing. A nderson Jacobson, Inc, had their term inals and,
as promised, provided an inform ative talk about the
Selectric m achine as used in their term inals. Particular­
ly interesting was the discussion of the way th a t the
type ball is positioned to prin t a character. Also, the
differences in the I/O unit as com pared to the office
u nit were listed. The I/O Selectric is a heavy duty
m achine developed for com puter use and workloads.
The office Selectric does n o t have the heavy duty
features.
M&R Enterprises dem onstrated the Astral 2000
w ith the special version o f BASIC which has been spe­
cifically designed to operate in the Astral system . The
Astral is available in fully assembled, turn-key condi­
tion as a partially assembled kit.T fhe kit saves a lot of
m oney and is easy to p u t together since the m ajority
of the electronics 'áré preassembled, burned in and
tested. Marty Spergel and other .-xepresentitives from
M&R discussed these and other features of this com pu­
ter system . If you missed the pieeting you-m ay obtain
Astral 2000 inform ation by writing M&R Enterprises,
P.O. Box 61011, Sunnyvale, CA 94088.
S-100 SYSTEM SYMPOSIUM—Nov. 20, 1976.
Well over 100 people attended the S-100 System Sym ­
posium held at Diablo Valley College. Three perspec­
tives were given by Dr. Harry Garland, George Morrow
and Lee Felsenstein. It was noted by Lee Felsenstein
th a t a large variety of products are available th a t utilize
this bus. Harry Garland pointed out th a t the bus sys­
tem is basically a good product. George Morrow dis­
cussed the com plex nature of the bus. A panel discus­
sion, m oderated by Jim Warren, brought o u t a num ber
o f opinions b u t the panel generally agreed the S-100
bus system will be used for several years because so
m any products use it. In order to get better definition
of bus signals and electrical requirem ents, it was sug­
gested th a t publishers print m ore bus inform ation and
act as a clearing house for com m ents.
This was the first symposium held covering the
S-100 system. It was very well done and certainly
inform ative to all in attendance. Indeed, it seems
everyone m ust have learned som ething new. The
ONE M A N ’S SYSTE M
B y C harlie P ack
My background is in program ming, including 10
years of experience m ostly on large-scale IBM systems.
I ’ve used IBM 1401 A utocoder, IBM 360 Assembler,
PL/1 and COBOL for m any varied applications, includ­
ing some of my own personal accounting and inven­
tory chores. In 1973 I w ent to w ork for an electronics
1
HCC N ew sletter/V ol. 2, Issue 11-12/D ecem ber 10, 1976
firm which m anufactures intelligent term inals using the
then-new Intel 8008. A lthough I d id n ’t program the
8008, it soon became apparent to me th a t m icropro­
cessors were good for a lot m ore than just form atting
data on a video screen or controlling traffic lights.
In the m eantim e, I had gotten interested in digital
electronic circuitry while building digital clocks and
m eters, and finally I built and got running a RadioElectronics “ TV T ypew riter” (the TVT-1, w ith the
boards th a t are stacked like cordw ood). Then the bug
h it me for sure—I wanted my own com puter. So in
November 1975 I devised a point system and rated all
of the available hobbyist com puters.
I had been renting tim e on an IBM 360/30 ffor $30
per hour, so I w anted the capability to run a high-level
language and later a disk operating system. The clear
w inner was determ ined using my point system and
right after New Y ear’s my A ltair 8080 kit arrived
(when I ordered my A ltair I d id n ’t know ab o u t the
IMSAI com puter).
A t the present tim e I have up and running in my
Altair a Processor Technology m otherboard, 3P+S I/O
interface, tw o 4KRA static mem ories and tw o 4K
dynam ic memories. I use an ASR-33 Teletype m achine
for I/O . MITS BASIC version 3.2 is used for all ac­
counting applications at present.
The aforem entioned hardw are is now being used to
do investm ent portfolio and incom e tax analysis and to
produce a cross-reference index to magazine articles.
The hardw are now being used represents a practical
m inim um for the perform ance p f the applications now
being run.
Assuming th a t the necessary planning and analysis
has been done, com puter inplem entation of m ost sim­
ple business-type applications n o t involving large
am ounts o f data involves four basic needs:
a) Some means of transferring original data from
docum ents to the com puter. For an on-line system
this is done using a suitable keyboard and some
type o f edit/update program.
b) Some means of storing the data outside of com ­
p u ter m em ory.
c) Processing o f data, usually involving data selec­
tion or sorting logic and calculations.
d) R eporting of the desired inform ation to the
user. This is the end p roduct o f th e sytem .
The BASIC line editor itself satisfies the first tw o
needs in my applications. Here is a com plete on-line
data entry program which can add new data, change
existing data and delete data. O f course, the entire data
file is in m em ory, b u t allowing 6K for BASIC and 4K
for a good-sized program (leave o u t com m ents and use
m ultiple statem ents per line to save m em ory space),
leaves 6K bytes rem aining for data.
T h a t’s enough for 100-150 transactions with 3-6
data items per transaction, using DATA statm ents. A
year’s investm ent portfolio transactions are no p rob­
lem! I use line num bers of 10000 and up for DATA
and less than 10000 for program code. The com m and
LIST 10000 stores the updated data file on paper tape.
The latter two needs are satisfied by programs I
write in BASIC and use with the printer on my ASR33. By following set conventions for line num bers
and by using com m on subroutine for READing data, a
HCC Newsletter/Vol. 2, Issue 11- 12/December 10, 1976
program m er may use a DATA file w ith several pro­
grams. To prin t o u t or punch the program code only, I
type LIST and when the last statem ent starts to prin t I
h it control-C a couple o f tim es to stop it.
A lthough my im plem entation of investm ent p o rt­
folio is crude, it illustrates th a t m inim um hobbyisttype equipm ent can be practically utilized for many
small business needs. A video display such as the Pro­
cessor Technology VDM-1 and a tape cassette storage
system could be substitued for—or used in addition
to —the ASR-33. The use of E xtended BASIC would
greatly facilitate separate storage and m anipulation of
data and programs and the display of form atted re­
ports.
My future plans, as far as hardw are is concerned,
include the acquisition of m ore m em ory, a ROM
m onitor which can be used to load BASIC, a video
display, cassette tape interface and hardw are backup
capability. By the tim e this article is in print, I will
have a Processor Technology 8KRA RAM board and a
MITS PROM board up and running, with a system
m onitor in six 1702A PROMs. The latter has loaders
for MITS BASIC (any version) and for softw are in the
Intel hex form at, a block move, full TTY support, and
switchable hexidecim al or octal m ode capability, in
addition to norm al m onitor functions. It will be made
available to hobbyists via the HBCC library and
through the Byte Shop in Santa Clara.
My future plans for software include enhance­
m ent of the m onitor to support tape cassette I/O and
some type of video m onitor display. M emory diagnos­
tics, games and o ther program s will be developed for
use with the run on a cross-assember of my own design
and w ritten in ANSI COBOL for execution on a
medium- or large-scale system . A suitable alternative to
this w ould be a Processor Technology ALS-8 develop­
m ent system and a DECwriter or similar printer, if the
latter could be obtained a t a reasonable cost.
I would be interested to hear from other hobbyists
as to w hat they would like to see in the way of so ft­
ware for the 8080 or Z80. How about a full operating
system for m ultiple cassette tape drives? What features
would you like it to have? Is there an interest in games
(such as Star Trek) in m achine language for smallcapacity systems? I can be reached at 25470 Elena
Rd., Los Altos Hills, CA, 94022. Home phone (415)
941-0495, betw een 7 and 10 p.m . on week-day eve­
nings would be preferred. □
f
(
W I SC O N SI N A R E A
COMPUTER S O C IE T Y
By Robert Reiling
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J
The Wisconsin Area C om puter Society has been
holding m onthly meetings for the last twelve m onths
and has a paid m em bership o f over 80 persons. They
are establishing a good software library, and can com ­
m unicate via Cassette Tape (Tarbell, Digital G roup and
K. C. Standard) and Paper Tape. Recently they pub­
lished their first new sletter. C ontact Don Stevens,
Chairman, Wisconsin Area C om puter Society, P.O. Box
159, Sheboygan Falls, WI 53085. □
2
10 LET A = B + 1 234
11 .
20 GOSUB 100+A
GETTING THE
M O S T OUT OF T I N Y BASIC
T o m P ittm a n
Here, when you type RUN, the program will stop with
the error message,
C o n tin u ed fro m last issue.
Execution Speed
TINY BASIC is actually quite slow in running pro­
grams. T hat is one of the hazards of a two-level inter­
preter approach to a language processor. But there are
some ways to affect the execution speed. One of these
is to use the keyw ord “ L ET” in your assignment state­
m ents. TINY BASIC will accept either of the following
tw o form s of the assignment statem ent and do the
same thing,
•184 AT 11
Now we can PRINT A, B, etc., to see w hat m ight
be wrong, or type in GOTO 20 to resum e, with no loss
to the original program.
As we have seen, there is n o t m uch th at TINY
BASIC cannot do (except m aybe go fast). Sure, it is
som ew hat of a nuisance to write all th a t extra code to
get bigger num bers or strings or arrays, b u t you can
always code up subroutines which can be used in sever­
al different program s like the floating point add above
(line 1000-1250), then save them off on paper tape or
cassette.
Rem em ber, your com puter (w ith TINY BASIC in
it) is lim ited only by your im agination.
R=2 + 3
LET R=2+3
b u t the second form will execute m uch faster because
it is unnecessary for the interpreter to first ascertain
th a t it is n o t a REM, RUN or RETURN statem ent. In
fact, the LET keyw ord is the first tested, so th a t it
becomes the fastest-executing statem ent, whereas the
other form m ust be tested against all twelve keyboards
before it is assumed to be an assignm ent statem ent.
A nother way to speed up program execution de­
pends on the fact th a t constant num bers are converted
to binary each tim e they are used, while variables are
fetched and used directly w ith no conversion. If you
use the same constant over and over and you do not
otherwise use all the variables, assigning th a t num ber
to one of the spare variables will m ake the program
both shorter and faster. You can even m ake the assign­
m ent in an unnum bered line; the variables keep their
values until explicitly changed.
Debugging
Very few programs run perfectly the first tim e.
When your program doesn’t seem to run right there
are several steps you can take to find the problem .
First of all, try to break it up into its com ponent
parts. Use the GOTO com m and and the END state­
m ent to test each p art separately if you can. Add extra
PRINT statem ents along the way to prin t o u t the vari­
ables you are using; som etim es the variables do n o t
have the values in them th a t we expected. Also the
PRINT statem ents will give you an idea as to the flow
o f execution. F or example, in testing the sort of pro­
gram above (lines 500-700) I inserted the following
extra PRINT statem ents:
REFERENCES:
(1) T I N Y BASIC User's Manual. Available from Itty
B itty C om puters, P.O. Box 23189, San Jose, CA 95153.
(2) D octor Dobb's Journal, No. 7, p. 26. Available
from PCC, P.O. Box 310, Menlo Park, CA 94025.
Finally it should be noted th a t GOTOs and GOSUBs always search the program from the beginning
for their respective line num bers. P ut the speed-sensitive
part of the program near the front, and the infrequent­
ly used routines (set-up, error messages, and the like)
at the end. This way the GOTOs have few er line num ­
bers to wade through so they will run faster. □
INE X P E N SIV E GRAPHICS
W orkshop A n n o u n cem en t
_____________
A w orkshop regarding inexpensive graphics is being
planned on the East Coast. It will be held next year
and is sponsored by Sigraph of the A.C.M. Interested
people may co ntact William E tra, 42 E. 23rd Street,
7th Floor, New York, NY 10010. □
ABOUT
RECONNECTING THE IM SAI
POWER T R A N SF O R M E R
525
PR t"x";
r- . r_ _
t
M
545 PR
. ;
555 PR
This gave me an idea where in the sort algorithm I
was, so I could follow the exchanges (the “ x ”s), where
each line represented one pass through the main loop.
Endless loops becom e m ore obvious this way.
If you have not used all the sequential line num ­
bers, you can insert breakpoints in the program in the
form of a line num ber with an illegal statem ent—I like
to use a single period, because it is easy to type and
does n o t take m uch space:
B y D ave K in kade
When I changed the line in p u t connections to my
IMSAI transform er (a Trane 3751), I was chagrined to
learn th a t it did n o t m atch the diagram on the PS-B
schem atic (Rev. 2, 3/3/76).
The term inals are actually: (1) com m on, (2) for
105 V, (3) for 115 V, (4) for 125 V. For exam ple, I
connected to (1) and (4) instead o f . ( l ) and (3) to
lower the o u tp u t voltage and generate less regulator
heat. □
3
H C C N e w sle tte r /V o l. 2, Issue 1 1 -1 2 /D e c e m b e r 10, 1976
v l r í : S 'r
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april, 1977 • san francisco
P .O . Box 1 5 7 9 , Palo A lto , CA
(415) 8 5 1 -7 6 6 4 , 3 2 3 -3 1 1 1
IIIIIIIIIIIM IIIM IM IIIIIIIIIIIIIIIIIM IIIIIIM ^ ^ ^
HOW I BUILT~~
A Í Y F I R S T C O M P U T ER ,
O R F O O L S R U S H I N WHE RE
E N G I N E E R S F E A R TO T R E A D
Building the boards up to o k relatively little tim e.
The largest block of tim e during construction was
devoted to running wire. A total of nearly 1,000 feet
of 26 ga. and 100 feet of 16 ga. was used. C heckout
was prolonged considerably by the unfortunate inser­
tion of the CPU board backwards in the m otherboard.
The snaps, crackles and pops would have done Rice
Krispies up proud. Invaluable assistance by a long suf­
fering friend, G rant Connell, finally got GEORGE up
and running.
The system a t the present tim e consists of the
8080 m icrocom puter with 24K of 2102 RAM, 12K of
1702A EPROMs, a KSR-33 Teletype, a cassette record­
er, I/O boards for the teletype and cassette plus a high
speed paper tape punch. Within the next six weeks,
GEORGE will acquire a high speed paper tape reader
and a VTT 4000B video term inal.
I can tell the m em ory of the pain, sweat and frus­
tration incurred during the construction is beginning to
fade. A few weeks ago, I saw the ad for the Micro Nova
m inicom puter chip set and thought, “ Why, I bet th a t I
can get one of those jewels up and running for alm ost
nothing! ”
By the way, I have a list of parts th a t you have p ro ­
bably got just sitting around gathering d u s t— □
By Norman Walters
A course, “ Introduction to C om puting,” taken
during the fall of 1975 was my first exposure to the
w onderful world of com puters. By m id-term , the itch
to have my own was beginning to be felt. The itch
faded considerably when the prices of the com puter
kits on the m arket was considered. A fter m uch thought,
I decided one could be built at hom e a t a price my
wife w ould n o t be able to use as grounds for divorce.
Naturally, the fact th a t the largest project previously
tackled was a digital clock did n o t cool m y optim ism
a whit.
Ten m onths later my hom e brew com puter is built
and the cost was m uch smaller than if a com m ercial kit
had been purchased, b u t the tim e and effort expended
have been trem endous.
During the construction of GEORGE, every costcutting trick possible was em ployed. N aturally, the
m other board was built from scrap cut-offs bought at
the club, and 80-pin connectors were cut to form 100pin connectors. Every friend I had plus some who had
n o t realized th a t we were even on speaking term s was
presented w ith a list of parts needed and a strong hint
given, “ If you have any of these parts just lying around,
you m ight be able to force me to take them off your
hands if the price is right!” I haunted all the surplus
electronics stores and pored over the Poly Pak catalog
like it was a dirty book. Because o f this approach
(cheap), parts did n o t present a m ajor problem . The
CPU board and control panel board required the lar­
gest outlay of tim e. A fter some initial delays, both
were purchased through the club by group buy.
«»* sue*
ST A T U S
aodress
'XOItci
HCC N ew sletter/ Vol. 2, Issue 11-12/D ecem ber 10, 1976
4
/
V
T I N Y BASIC
OR HOW M Y F A M I L Y
CAME TO L O V E M Y COMPUTER
By Ray Boaz
....... :.r.................... z ^ ^ m
line is given. The com puter can keep score and if the
problem was a “ h a rd ” one, a “ VERY GOOD” is prin­
ted. This is a short and simple program , b u t to a nine
year old girl, it is like magic.
I d id n ’t get off th a t easy, however. A t my side all
the tim e (or was it on top of me) was my son, Chip,
who is only six. Since he is n o t up to m ultiplication
y e t I had to do som ething else. If Tiny BASIC could
m ultiply th a t easy, it m ust be at least as easy to do the
addition facts. So w ith a few chnges in the same
program , another m em ber of the family was into the
com puter.
Well, th a t accounts for tw o o u t of three. What
ab o u t my wife? Glad you ask. She does n o t glare at it
when she walks by and has even started saying some al­
m ost nice things ab o u t it. If this keeps up, I may have
to start on another com puter for myself.
Oh, one other thing. Heidi is busy setting up times
for her friends and m aking arrangem ents to take the
new to y to school. There seems to be no end o f w hat
can happen when your kids can com pute. □
\
I
/
One sure way to get the support of y our family for
all the hours th at you spend w ith your com puter
(only) is to let them get some “ hands o n ” tim e. The
problem is how m any kids, let alone wives, understand
binary, octal, hex or getting a program into the % $& t
thing to do something. So how do you do it? Well I got
Tiny BASIC for my AMI Proto system (by Tom P itt­
man) and it w orked out ju st great.
The first thing I did was write a program for my
nine year old girl, Heidi, to use for her m ultiplication
facts. A fter one m inute she was really into it. The pro ­
gram generates tw o random num bers less than twelve,
prints them (i.e. 9 x l l = ) , waits for the p roduct to be
typed in, and then com pares the entered p ro d u ct to
th e calculated product. If the answer is correct a new
tH 0Q&CG)
F or sale: Cryptographic program th a t will baffle the
codebreakers of the CIA. ENCODE an d /o r DECODE
your private correspondence for m axim um security.
D ocum entation of cypher technique, program listing
and punched paper tape in BASIC for only $6. Jon
Stedm an, 1528 Sum m it Rd., Berkeley, CA 94708.
F or Sale: IMSAI 8080, 8K D utonics m em ory, Poly­
m orphic video term inal interface, Tarbell cassette in­
terface, A ltair 2SIO w ith one port, keyboard and J. C.
Penny audio cassette recorder. Assembled. $1775.
C ontact J. Gill, 497-4715 (days), 321-6289 (evenings).
K leinschm idt 311 printer, 40 char/second, 80 charac­
ters wide, parallel ASCII input, level conversion from
-1 2 V can be tapped from printer pow er supply, full
docum entation, has m odem card, autom atic shut-off
after 60 seconds of no data, good operating condition,
needs cleaning, $300; another 311, has pow er supply,
no other electronics, excellent m echanical condition,
$150; extensive supply of spare parts, $50; all of the
above together, asking $400; Wm J. Schenker, M.D.,
2086 Essenay, W alnut Creek, CA 94596, (415) 9396296.
SOL User G roup now form ing. If you own or have
ordered Processor T echnology’s SOL com puter, please
send your nam e, address, phone num ber and ideas to
Bill Burns, 4190 Maybell Way, Palo A lto, CA 94306.
W anted—Carpool or riders to Fairchild (or Ellis St. area
in M ountain View from the Sum m it Rd. area in the
Santa Cruz m ountains. Must be willing to get going
early as I like to avoid traffic. Joel (415) 962-3372
(days) or (408) 353-2663 (eves).
C om puter store opens in Sunnyvale—recreational Com­
p u ter Centers, 1324 South Mary Ave., Sunnyvale, CA
940S7. Phone 735-7480.
HOW TO GET THE NEWSLETTER
A nyone interested in com puters as a hobby may
receive the Newsletter by sending a request to the
Homebrew Computer Club Newsletter, P.O. Box 626,
M ountain View, CA 94042. The Newsletter is distribu­
ted m onthly at the club m eetings and is also mailed to
individuals w ho are unable to atten d the meetings.
If you have an input to the Newsletter, send it in
and it will be published as quickly as possible. However,
the editors cannot promise th at everything sent will be
published im m ediately. All m anuscripts m ust be typed
and carefully proofed. All listings and diagrams should
be as clear and easy to read as possible.
The Newsletter is m ade possible by yq ur donations.
Please rem em ber th at we m ust pay for postage, labels
and printing. D onations m ay be given to Ray Boaz at
the club meetings or sent to the above address.□
CLUB LIBRARY
Gordon French, club librarian, has lots of interes­
ting m aterial and is able to loan it to anyone w ith a
definite need, b u t . . . please adhere to the following:
☆Limit your telephone calls to the hours of 7PM
to 9PM weekdays only. This is im portant. G ordon’s
phone num ber is (415) 325-4209 in Menlo Park.
☆Be specific w ith your requests and G ordon can
probably help you—he cannot random ly review the
contents o f the library for you.
☆No reproductions will be m ade of any materials.
☆All m aterials loaned m ust be returned so they are
available for others to use in the fu tu re .□
5
HCC Newsletter/Vol. 2, Issue 11-12/December 10, 1976
STAND-ALONE
ADAPTER FOR VDM-1
By Lee Felsentein
VGO
VCC
HR
W LS2
(p*r'.~eE4)ÇojEstop)—
This circuit allows the operation of the Processor
Technology VDM-1 as a stand-alone term inal. It in­
cludes a UART for serial data com m unication with
EIA RS-232 signal levels. All data to the VDM comes
through the UART, so a “ local loopback” connection
is necessary from the D ata O ut term inal to the D ata In
for half duplex operation. Two switchable Baud rates
are available if a SPDT switch is connected to switch
Baud R tn to Baud 1 or Baud 2. The Ready o u tp u t
from the UART allows operation from a generalized
parallel interface at m axim um speed. The Break input
moves the o u tp u t to a space condition and is used as
an escape character in various systems.
The circuit requires a connection to an external
-1 6 V to -1 9 V supply; +5 V pow er is supplied by pin
16 of IC23 from the regulator of the VDM. The cir­
cuit draws very little current since m ost logic is CMOS.
The -1 2 V and +5 V connections shown are for key­
board power.
On power-up, the circuit initializes to a clear screen
w ith a cursor in the lower left corner. N on-control
characters are displayed and rolled up when a 64 char­
acter line is filled. CR will term inate a line and roll it
up. A LF im m ediately following the CR will be ig­
nored, as will a LF following any num ber of DEL (rubout) characters which in turn follow a CR. A second
LF, or one w ithout a CR preceding, will be treated like
a CR-LF com bination. F F will initialize the screen.
BS will be recognized and the cursor will move
back and will erase the last character. A t the left end
of the line the cursor will jum p to the right end and
will cause a roll dow n of the line above. This will n o t
occur if there is n o t te x t on the line above. The cursor
will jum p to the 64th location w hether or n o t it is
visible there. If the previous line was term inated by a
CR, the cursor disappears until backed over the CR.
The circuit m ay be constructed using wire-wrap or
solder; layout is n o t critical except th a t proper supply
bypassing techniques m ust be used for the TTL ICs.
Capacitors (O.lptF) should be connected betw een the
+5 V and GDN pins of these ICs to prevent supply cur­
ren t pulses.
The tw o boards m ay be interconnected with
ribbon cables and DIP headers which plug into the IC
sockets indicated on the drawing.
EPt
RR1
uA pr
(k eoT Y -
T ft 1 T R -,fe 0 2 B
A r - s - f O '3
T P 2.
(n ao 3
29
3«
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10
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y -
ftR q
TR4
TR 5
JZ -
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11
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RR 7
" V )£ >
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-* (3 2 0 .
ilk
THE F O LLO W ING M O D IF IC A T IO N S TO THE VDM
A R E N EC E SSA R Y
«4759
1. C u t trace on solder side fro m pin 4 o f IC 17.
2. C u t trace from pin 13 o f IC 10 o n c o m p o n e n t side.
3. C o n n e c t a ju m p e r from pin 6 of IC 17 t o pin 13 of IC 10.
4. C o n n e c t a ju m p e r fro m pin 7 o f IC 31 t o pin 4 of IC 17.
5. C o n n e c t a ju m p e r from pin 3 o f IC 31 to pin 7 of IC 13.
6. C o n n e c t a ju m p e r from pin 8 o f IC 15 to pin 9 of IC 31.
7. C o n n e c t a ju m p e r fro m pin 3 o f IC 41 to pin 15 of IC 31.
8. R em ove ICs 18, 23, 24, 28, 29, 31, 3 2, 33 , 34, 3 5, 37,
38 , 39 and 40.
9. If n o t y e t installed, resistors R27 th r o u g h R32 and R41
th r o u g h R 48 m ay be o m i tt e d fro m assembly. □
HCC N ew sletter/V ol. 2, Issue 11-12 /D ecem ber 10, 1976
PI
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HCC N ew sletter/V ol. 2, Issue 11- 12/December 10, 1976
SOfiûON F R E N C H ’S CH<»f*-CHOO T R A I N
OR
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0330
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0360
0370
0380
0393
0400
0410
0420
0430
0440
0450
0460
0470
HCC N ew sletter/V ol. 2, Issue 11-12/D ecem ber 10, 1976
HiHiiHiMiiiiiiiiiiiiijiiiijM
THAI iM
EMPTY
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OUT
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CALL
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MVI
CALL
LXI
MVI
CALL
LXI
MVI
CALL
LXI
MVI
CALL
JMP
S-ÎO 1
S MO 2
DAD
MVI
INX
DCR
J NZ
RET
8
A
ONCE UPON A TI ME»
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IN A CURI OUS L I T T L E
H » SHED
PLACE THERE WAS . . A TI NY TRAIN
B »2 0 4 5
M» 20H
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H
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B
• . t h a t was a l l e m p t y
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EMPTY
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35
01
05
FF
05
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CC
01
33
00
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0430 •
0 4 9 0 ENGINE
0500
0510
0520
0530
0540
0550
3560
3570
0530
0590
0600
0610
0620
0 6 30
0640
0650
0660
0670
0680
0690
0730
07 10
07?0
0730
0740
0750
0760
0770
0730
0790
0800
0 3 10
0820
0330
0340
0850
0860
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0830 RAILS
0890
0900
0910
0920
0930
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0950
0960
0970 FIRE
0930
0990
10 0 0
10 10
10 2 0
10 3 0
1040
1050
1060
1070
LXI
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LXI
MV I
LXI
MVI
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
SHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LHLD
SHLD
LXI
LXI
MVI
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I NX
XR A
XRA
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XCHG
LXI
MO V
IN X
H*SHED*322H
A T I N Y L O C OMO T I V E
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WI TH A L I T T L E SMOKESTAK
H»SHED*325H
AND A L I T T L E BELL
M»07H
H »SHED*327H
. . A N D A T I N Y DOME
M*6EH
« • AND A CAB
CABl
S H E D * 3 2 A H WI T H WI NDOWS
* . SO THAT YOU COULD
CAB2
S H E D * 32CH SEE I N T O WHERE THE
CAB 3
. • E N G I N E E R AND THE
S H E D * 3 2 EH F I R E M A N S A T *
SOI 1
» * I T HAD A B E A U T I F U L
SHED* 361 H POLI SHED
BO I 2
• . BRASS
S HED* 36 3H BOILER
BO I 3
* • WI T H
S H E O * 3 6 5 H THE NUMBER
S H E D * 3 6 7 H " 9 9 " ON THE
BOI4
« • S I D E OF
S H E D * 3 6 9 H THE CAB
BO I 5
. * BUT YOU C O U L D N ' T
S H E D * 3 6 8 H SEE E I T H E R THE
# . E N G I N E E R OR THE
BO I 6
S H E D * 36DH F I R E M A N
FRA 1
« • THE L I T T L E E N G I N E
S H E D * 3A 0H ALSO
* . HAD A COWCATCHER
F RA2
S H E D * 3 A 2 H AND LOTS OF FUNNY
S H E D * 3 A 4 H WHEELS AND THE
S H E D * 3A6H T H I N G S THAT CONNECTED
• « AND TWO VERY T I N Y
FRA 3
S H E D * 3 A 8 H WHEELS AT THE VERY
FRA4
♦ • VERY BACK
S H E D * 3 a AH ALTOGETHER I T LOOKED
FRA5
* * Q U I T E LONEL Y AND YET
S H E D * 3ACH I T a p p e a r e d v e r y
B » **2 1 H
» FUNNY J US T S I T T I N G
H » S H £ D * 3DEH THERE ON THE
M# 19H
» . RAILS
B
# * WI T H N OT H I N G AT ALL
H
• • EVER
A
« • TO DO
B
. .
W E L L !
RAILS
* . L E T ’ S RUN I T J U S T FOR
FUN
HtRRY
GET T R A I N Ol)T OF SHED
•
MOVE I T FROM SHED
H * SHED
A »M
LIGHT FIRE
H
xchg
MOV
I NX
MOV
XCHG
GPI
JNE
CALL
JMP
9
M »A
H
A *H
. • MOVE
0D0H
FIRE
END OF YARD?
NO* MAKE MORE STEAM!
GO TAKE T R I P
NO ROUND T R I P S * J U S T
A GAI N
travl
HOSTLE
IT
DO
H CC N ew sletter/V ol. 2, Issue 1 1- 12/December 10, 1976
0020
00ED
00F0
00F1
00F4
00F7
00F8
00 F9
00F A
00pB
00FE
00 FF
002 F
0 10O
0 104
0 J 05
0106
0107
01 0 8
01 0 9
010 4
0 1 OB
0 10E
01 0F
01 0F
01
4?
C5
CD F F
CD 0 F
Cl
08
AF
A8
C2 F 0
C9
21
0E
7E
2B
77
23
01
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03
00
01
00
CC
23
7C
B9
C2 0 4
C9
21
0 1 1 2 7E
0 11 3 23
0 1 1 4 FF
0116 02
01 19 2 3
01 1 A 7E
01 IB FE
01 ID C2
0 I 20
11
0123
0 123 06
01 0 5 7 ?
0 12 6 05
0 1 2 7 CA
012.4 2 3
012P 73
0 1 2C 2 3
0 120 05
0 1°E C ?
0131
0 1 3 1 FE
01 3 3 C ?
0106 1 1
0 1 39 C*
0 1 0C 2 F
0 13F 0 2
0141
11
0 1 A4 0 3
0 147 FE
01 4 9 C2
01 40 1 1
0 14F C 3
01 5 2
0 1 5 ? 01
0 1
(70 CC
06
12
01
11
31 0 1
7E 1 4
1030
1090
•
TRAVL
1100
1110
1120
1100
1140
1130
1160
1170
1180
1190
1200
1210
1220
1230
1240
1230
1260
1270
1230
CHOO
5?
25
14
3C
20
23
13
47
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23
1?
1A
20
23
pa
01
01
01
13
01
01
lp
01
01
11
01
08
COAL
1200
1300
1310
1320
1330
1340
1350
1360
1370
1332
1390
1400
1410
1420
07
*
STROK
LXI
MAKE
TRIP
13
C H U F F ONCE
MAKE F ORWARD
TURN WH E E L S
MILES
POSH
CALL
CALL
POP
OCX
XRA
XRA
JN3
RET
B
STROK
TURN
B
B
A
B
CHOO
LXI
MVI
MOV
OCX
MOV
I NK
I NX
MOV
CMP
H * 0 C C >3 1 H MOVE DOWN THE T R A C K
C *0D0H
A ♦M
ADD MORE COAL
H
M# A
H
H
A »H
C
E NOUGH C O A L ?
COAL
NO» P U T MORE ON !
J ( nJ2
CLICK
MO T I O N
OD OME T E R
13 MI L E S
NO
DO N E X T
YET?
TRIP
RE T
•
TURN
HISS
F O UN D
AXL E
LXI
MOV
I NK
CPI
JN3
I NX
MOV
CPI
JN3
LXI
H * 0 C C MF H T URN WH E E L S
A *M
H
6
F I N D C OWC G T C H E R
HISS
LOOK A G A I N
H
A «M
11H
WHAT Q U A R T E R T U R N ?
NKT1
D » 1 4 7 EH N E X T Q U A R T E R TURN
MVI
MOV
OCR
J?
I NK
MOV
B 17
M#T)
3
WORK
H
M* E
H
3
AXL2
*
1430
1440
1450
1460
1470
1430
A XL 1
A XL2
14 20
INK
1500
1510
15 2 0
1530
1540
1550
1560
1570
1580
1590
1600
16 10
1620
1630
16 4 0
1650
1660
OCR
JN 7
HCC Newsletter/Vol. 2, Issue 11- 12/December 10, 1976
B » 6 4 * 13
DO 4 A X L E S
WH E E L S MOVED H E R E
L A S T WHEEL?
I ' V E BEEN W O R K I N * . . .
. . O N T HE R A I L R O A D . .
( S I D E R O DS MOVED H E R E )
. . A L L THE L I V E . .
. . L O N G D A Y ................
*
N XT 1
NXT2
MXT 3
CPI
JN 3
LXI
JMP
CP I
JN7
LXI
J MP
CPI
JN3
LXI
J M°
14H
QUARTER
NXT2
D * 132DH
A XL 1
13H
QUARTER
LXI
B ♦3000
10
TURN
NXT3
Di 1 25 FH
AXL1
12H
QUARTER
AXLE
D * 1 1 2 QH
A XL 1
*
WORK
TURN
TURN
5 55 03
rt <86 np
r* 5H F 6
P! 5A
0 5D
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1 800 RRY
18 10 SiOKE
18 2 0 C A3 1
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6 FH
1830
1840
1850
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1870
1 880
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19 0 0
19 10
1920
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du
10 4 0
19 5 0
1963
1970
1980
1990
2^00
NO SQUEEKS» PLEASE!
A JUMP TO WHEREVER YOU NEED TO RETURN
IN THE N EX T
..YOUR RETURN LINK GOES
AL 33
JMP
HERE
1780 •
1790 PDA
CAB2
C4B3
BOI l
BOÏ °
BOI 0
BOI 4
3015
B9I6
89A 1
F 2A 2
F 4A3
FRA4
F7A5
TIFF
SHED
CLOUD
#
DID THE CONDUCTOR
..FLAG US DOWN?
QUITTIN' TIME
NO * THEN HIGHBALL
DU
nw
DW
DW
DV
DU
DW
DU
DU
DW
DW
DU
DU
NOP
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PUT YOUR DATA READY FLAG
HERE
0CCO0H
10 01 H
5D 1OH
207 EH
0 A 28 H
19 0 A H
0A0AH
5 3 0 AH
3939H
205DH
?0 06 H
2D 1 1H
2 0 1 1H
PD 6 FH
206FH
191 OH
SMOKE CHARACTER
CAB DESCRIPTION
ft
ft
ft
ft
BOILER DESCRIPTION
ft
ft
ft
ft
ft
f*
ft
ft
ft
ft
FRAME DESCRIPTION
ft
ft
ft
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TIES DESCRIPTION
THIS IS SHED AREA
3*0172H
BEGINNING OF CLOUD
•
*
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î 1A00630'3?A6601?5?AS04?A6301?.?B0042A6A0 l2"32042A6C0122E5C42A6E09
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: 1API15003 1011172140Ç077200CA520123732305C22501FE14C23C01112D5C
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11
HCC Newsletter/Vol. 2, Issue Il-12/D ecem ber 10, 1976
T A B L E OF CONTENTS
PAGE
HOM EBREW COMPUTER CLUB M EETING S
R andom D ata, R obert R eiling..................................1
One M an’s System , Charlie P a c k ............................. 1
Wisconsin Area Com puter
Society, R obert Reiling............................................. 2
G etting The Most O ut Of Tiny BASIC,
T om P ittm a n .................................................................3
Inexpensive Graphics, W orkshop.............................3
A bout Reconnecting the IMSAI Power
Transform er, Dave K inkade.......................................3
How I Built My First C om puter,
Norman Walters............................................................4
Tiny BASIC Or How My Fam ily Came To
Love My Com puter, Ray B o a z ............................... 5
Bulletin B oard ........................................................... 5
Stand-A lone A dapter F or VDM-1,
Lee Felsensteiri..............
. 6
G ordon French’s Choo-Choo T ra in ........................ 8
Where & When
The H om ebrew C om puter Club m eets a 7
p.m . at the Stanford Linear A ccelerator Center
Auditorium . Dates scheduled for the rem ainder of
this year are D ecem ber 10 and 22. The date and
location are subject to change. If a change does
occur, every effort will be m ade to provide ad­
vance notice in the New sletter.
s £ R r a
f r e e w a y <280 )
> C L Æ IU L IB E R 7 V
HOMEBREW COMPUTER CLUB
NEWSLETTER
P.O. Box 626
M ountain View, CA 94042
L M BAKER
DPT OF BIO. SCIENCE
STANFORD UNIVERSITY
STANFORD, CA
94305
C\AsS
HCC N ew sletter/V ol. 2, Issue 11-12/D ecem ber 10, 1976
12