
ENIAC Operating Manual (1946) [pdf] - segfaultbuserr
https://archive.org/details/bitsavers_univOfPennperatingManualJun46_7248165
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andrewstuart
The thing that people might find hard to understand these days is that
computers - particularly mainframe or minicomputers - were really unreliable.
The hardware was often/always custom built and it would often just stop and
the manufacturer had to come in to work out what was wrong, and fix it which
typically involved replacing boards until the problem went away.

I should note that I'm basing this experience of being involved with company
in the late 1980's - not the 1940's which is the topic of this post. Although
I can imagine that back then the machines would only run for a matter of hours
at best before breaking down and needing debugging.

It was the same with networking which was particularly unreliable when it ran
over coaxial cables like RG58 which had an array of problems that would lead
to the whole company network going down and taking all the connected PCs with
it.

Modern computing is incredibly reliable.

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tyingq
_" Modern computing is incredibly reliable"_

I sort of agree with that, though I'd say there was a peak that passed by
somewhere in the 90's. There was a time when the most important compute was on
high end mainframes. They were more reliable than what we have now.

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copperx
That raises the question, what are the most unreliable components of a
computer nowadays, beside the HDD?

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Stratoscope
What HDD?

I think the most unreliable part of most computers today is the screen that
cracks when you drop it.

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Mxtetris
See also this work-in-progress ENIAC simulator:
[https://www.cs.drexel.edu/~bls96/eniac/](https://www.cs.drexel.edu/~bls96/eniac/)

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segfaultbuserr
An interesting fact of ENIAC is, although it was originally programmed by
plugboards in 1946, it was soon retrofitted to a stored-program computer in
1948 to simplify programming, using its spare function table units as ROM, and
its extra accumulators as a program counter and a pointer. I wonder if there's
any project to recreate an ENIAC simulation in stored-program mode.

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hcs
For anyone interested in this period, there's a book on the stored-program
ENIAC: [http://eniacinaction.com/](http://eniacinaction.com/)

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patkai
I just read von Neumann's biography recently. He wanted to call the ENIAC the
MANIAC - because of its unreliability - but his colleagues refused.

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segfaultbuserr
The name "MANIAC" ( _Mathematical Analyzer, Numerical Integrator, and Computer
or Mathematical Analyzer, Numerator, Integrator, and Computer_ ,
[https://en.wikipedia.org/wiki/MANIAC_I](https://en.wikipedia.org/wiki/MANIAC_I))
was eventually picked up by physicist Nicholas Metropolis to name a computer
designed under his leadership, as an attempt to ridicule and stop the rash of
silly acronyms for machine names, such as ENIAC, EDVAC, UNIVAC, etc.

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mistrial9
a programmer from Huntsville, Alabama started in 1963, and later worked on
Burroughs equipment, and much later on MP/M, then Apple. Quite a clever
fellow, many great stories.. hardware would certainly be down from time-to-
time.

