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About Me |
| Computer
History 101 |
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Once upon a time in the 1970's, if you wanted to
own a computer, your choices were very limited. A few million
bucks would buy a nice mainframe, or a year or two of an average
salary could get you a cheap mini. Guys like Don Tarbell built
their own from surplus parts, but unless you were a really good
scrounger, or incredibly dedicated, you were just out of luck!
Enter the microprocessor: A chip. Just a chip!
What now? Intel built the Intellec series of computers from the 4004,
4040, and the 8008
processors, but in 1974 dollars, they were priced like a new car.
(I don't know about you, but my wife is not that
understanding!)
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My Fully Restored Mark 8
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Then along came Jon Titus. He designed
the Mark 8 Minicomputer using the Intel 8008 processor and got Radio
Electronics magazine to run a construction article. This was
groundbreaking. Complete plans to build a working computer for
under $500! Amazing! Unheard of!
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The article and the Mark-8 computer lit a fire
in the hobbyist world. Clubs and newsletters were spawned, mostly
to exchange software, hints, and construction tips. When Popular
Electronics caught wind of the growing revolution, they were eager
to trump RE and the Mark 8, and in January of '75 they stole the
crest of the wave with the introduction of the Altair 8800. Bill
Gates saw the Altair on the cover, and we were off and running!
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The Mark 8 & Radio Electronics |
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The Mark-8 Radio Electronics magazine article was interesting but
sparse. If you really wanted to build a Mark-8 computer, you had to order
the real plans from Radio Electronics. The editor sort-of
apologizes for this at the end of the article, and then tries to
play it as a plus, since "interested readers" would get
"full details on the computer in a single package." Mr.
Titus estimated (from tax records) that about 7500 plans were
sold, but only about four hundred PC board sets. It is pretty hard
to imagine that every set of boards sold resulted in someone
building a working computer, and I suspect that most of the plans
sold never went far beyond a good first reading. Some have
estimated the original number built at between 1000-2000. Since I
actually own an aftermarket memory board, I know there was at
least one company out there who thought there was a potential
customer base. But I think those numbers sound very high for two
reasons: When the 8080 based MITS Altair was described in Popular Electronics
just six months later, and offered assembled or as a complete kit,
the Mark 8 was already on the fast track to obsolescence.
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The Mark-8 Minicomputer in RE.
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| The Mark 8 was not offered as a
complete kit; this was a real do-it-yourself project! The only
thing offered was a board set, scrounging of parts was entirely up
to the builder. The Mark 8 also proved too challenging
a project for many builders who ran out of skill before the
computer was completed. It was a very complicated machine from a
hobbyist standpoint, and required of the builder a skillful
ability to read and follow schematics in order to connect all the
boards (this information was not included with the plans!).
Further, the boards did not have plated-though holes on the
circuit boards. This required builders to solder numerous
connections on both sides of each board. Many who have emailed me to tell
their Mark 8 stories, never got their machines
to run. I suspect that a lot of Mark 8 computers were abandoned,
half finished, or cannibalized for parts. Too bad, because the
Mark 8 is a soundly designed and beautiful machine.
Today, the number of Mark 8 computers in existence, working or
not, is no more than a handful. Information on those I am aware of
can be found on my links page.
Only two others are known operational. Do you have
one? Do you know someone who does? Let me know!!
Connections
The Mark-8, besides inspiring the development of the Altair
8800, inspired another computer pioneer, Robert Suding. Dr. Suding
built his Mark 8 Minicomputer in July-August of 1974, and within
days formed the digital group. This new company sold a
packet of plans for improving the Mark 8, along with a plethora of
new software. They soon offered a video interface and also a
cassette interface. For more info, visit my
digital group pages.
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| My Mark 8 |
| I received my Mark 8 Minicomputer in small pieces,
early 1999, as a result of an eBay auction. (See
my restoration details.) It took me about two years to fully
restore to the condition shown in these photos. Today, my Mark 8
computer sets on a display cabinet in my living room, connected to
my digital group video interface,
and hums along nicely 24/7, running various programs. When idle, it simply blinks the front
panel lights randomly, and never fails to attract attention. |
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