V C F
The Digital Group
|Mark-8 Minicomputer Documentation
I have been collecting vintage computers and books
for many years now (since they were
cutting edge!), these are a few that I have scanned
into pdf format for posterity. Many of the files here relate to other
8008 CPU based machines such as the Scelbi 8h & 8b, Mod-8, Mike, and
Most of the information here has been
scanned from my own originals, some was scanned by others and sent to
me. There might be a few that were pulled from other web sites, but if they
are here, I have originals somewhere and was just too lazy to duplicate
the work. :) Also here a few of my own software listings.
Most scans were done at 200-600 dpi,
depending mainly on when they were scanned. Some of the pdfs are
searchable, but most are not.
Please Be Kind...
I have limited bandwidth! Download only what you know
you want or need, and take your time--only download what you need right
now, then save what you download so you need not download it again.
Thanks, and enjoy!
Pile O' Mark-8 Docs
Mark 8 construction article:
I have three original copies of the Mark-8 construction
booklet, as well as a photocopied one from Jon Titus. These were among the
first things I ever tried to scan and convert to pdf, I must have scanned
these about a dozen times trying to get the best printable and readable copy.
- 21.8 Meg My scans of the article from a photo copy sent to me by Jon Titus. This
is a very useful scan as it contains a hand drawn backplane diagram from
Jon Titus, not included in the original article. Don't try to make boards
from these scans!
- 39.6 Meg These are NEW scans, 4/07, from my best copy of the construction article,
scanned at the highest dpi my scanner can do, and BONUS - These scans are
searchable! Not a perfect OCR, but better than a finger in the eye, huh? Also,
my scanner did an auto-rotate on a few of the pages... deal with it.
- 12 KB Front panel switch wiring chart, circuit board top connections, and the
layout I used to restore my front panel. Info that was missing, or just plain
hard to figure from the original plans.
- 68 KB This is a list of known Mark-8 bugs, taken from a page of the Micro-8 Newsletter.
- 172 KB Pin outs of Signetics chips used in the Mark-8
Construction details of my 4K Memory Board, with photos and
- 1.9 Meg My board is most likely a Celetron board from Maury Goldberg of
MiniMicroMart. Celetron used the "CF2" logo on their boards,
and the blue material as well. Godbout seems to have bought or borrowed the
design. (Godbout info from Jim Kearney. Thanks Jim!)
- 41 KB in 2006 I added 32K of bank-switched RAM to my Mark-8.
- 22.2 Meg This is my earliest 8008 manual, which was given to me by Jon Titus, very good
- 6.0 Meg Some minor changes, check it out.
12.4 Meg Yet another Version
- 10.6 Meg Manual for the Intel Intellec8 Computer!!
- 5.4 Meg Good stuff...
- 26.2 Meg More good stuff!!
- 4.3 Meg From the net. Any PLM programmers out there?
The Digital Group
The Digital Group was a pre-Altair era company that made
accessories for the Mark-8. This Packet of information showed M8 users how to
expand their I/O ports, add a cassette interface and a video card to their
systems. It also includes listings for all the software needed to operate these
new additions... Really cool! Read about the digital group by clicking the above
- 2.4 Meg The original "Packet #1", These scans are from my original copy,
given to me by the author, Dr. Robert Suding.
- 6.0 Meg Data sheet for the character generator chip used in the DG TV Typewriter. Hard
to find item.
This was a Canadian company that second sourced the 8008, they
went belly up not too long after releasing this applications manual. This manual
has information on the Mod-8 too.
- 25.3 Meg Excellent information, construction information for the MOD-8, great operating
system software that even includes a simple assembler/diassembler!
- 6.1 Meg I think this version was distributed in Canada
6.7 Meg Yet another version. I have not inspected these versions for differences...
they may all be the same inside.
The Mark-8 spawned at least two newsletters, and they
contained a wealth of information. The "Micro-8 (aka, Mark-8)
Newsletter" was mostly a collection of letters from 8008 based
machine builders. There is a bundle of troubleshooting hints and bug
reports for the Mark-8 in here! It also carried some articles for the
then new 8080 and Altair, but the focus was the 8008. "The Computer
Hobbyist" was more professional and contained nicely written
articles of amazing nature, intended for the 8008. Most of these scans
were done by Jim Kearney, I cleaned them up a bit and made pdf files out
of them. Although I have my own originals (seen in the photo), his
scans were already done. Why re-invent the wheel?
The "ECS Magazine" was a very professional
mini-magazine devoted mostly to the 8008. ECS was edited by Carl Helmers,
who was pulled from the newsletter by Wayne Green to become the founding
editor of the then new Byte Magazine. Five issues are included here.
(Also shown in the photo here, but not here, are a couple issues of the
"digital group Clearinghouse". This was Dick Bemis' entry into
newsletters, and was pretty much a flop.)
These two files comprise the first two years of the Micro-8
39.7 Meg The
first few pages look terrible, but they actually look better here than in the
- 18.1 Meg The Micro-8 was probably the most useful of the newsletters available on
The Computer Hobbyist
2.1 Meg Flyer, advertising the new newsletter.
23.8 Meg Well, maybe not ALL issues(?) but all the ones that I have anyway.
- 10.3 Meg Five issues from 1975. From historical data on the origins of Byte Magazine, I
believe this is a complete collection for that year. There was at least one
earlier year, which I do not have. ...do you? :)
Scelbi Computer Consulting
Scelbi was on of the earliest of all computer publishing
companies focusing on microprocessors. For a short time, they also made an 8008
based machine, the Scelbi 8b & 8h. Other than Intel, the first micros made
in the USA.
- 7.4 Meg This is the operating manual for the famous SCELBI 8H.
8008_Monitor_Routines - 15.1 Meg Great for learning how the 8008 can be put to
Language Programming 8008
- 16.2 Meg This is my 8008 Bible for writing software, all the instructions, how they
work, flags they alter, etc..
Language Programming 8008 - 43.7 Meg Newer version--I don't know if there are any
- 6.6 Meg Space Capture, Hexpawn, and Hangman for the 8008/8080
Space Capture Board.pdf
- 7 KB Game play board for Space Capture
Galaxy_Game - 23.1 Meg Star Trek for the 8008/8080!
- 39.2 Meg BASIC on your 8008! (or 8080) (Scans by Kinko's).
- 261 KB Rescan of garbled page, page 12-80
- 677 KB All the add-ons and corrections. Scans from Jack Rubin.
2.2 Meg String handling for SCELBAL, these scans were done by Len Bayles, a little
grainy but readable.
- 1.1 Meg Math functions for SCELBAL, also done by Len Bayles, also a little grainy
My Mark-8 Software
These are a few things I put together to help me program, and a
few of my programs. Careful: They may not be bug free! I have a bad habit of not
documenting all my bug fixes. I usually end up fixing the same problem a couple
times before getting smart enough to write it all down, if only I could
learn...! Most of my software is hand written, so until I get the gumption to
type it into a word processor, it will never show up here! Sorry!
|All of the following files are very small -
Less than 20 KB.
Yes, I know. Some of the descriptions are not 100% accurate. I was
learning by trial and error, but to the best of my knowledge, the code
and mnemonics are correct. Just some of the descriptions are off. (See
self deprecating comment above!)
Ditto, sorted by function.
Ditto again, sorted by mnemonics.
Handy little instruction set reference card. I have redone this from a
drawing in the Micro-8 Newsletter.
This routine saves/restores registers (except D & E, which are
This very short subroutine clears memory until an error is found.
Could be used to determine memory size by looking at H&L on return.
This is my M8 binary paper tape and I/O software for my ASR-33. (The comment
about adding/stripping parity will not work for punching binary tapes - Don't
This is my text output/printing routine, read the comments to see how it
This is my "on-display" software. Unless I am working on my M8,
this is what is running. Also includes a routine for random display on my Digital Group TVT.
This program requires a very simple hardware mod to allow front panel switch
mapping to an input port to work as written, if you don't have the mod, just
load any number instead of reading the front panel data.
Don Lancasters TV Typewriter
- 12.3 Meg Original RE plans. These scans are from photocopies, it was all I had at