Oldest operational computer was Re: cctalk Digest, Vol 54, Issue

Jules Richardson jules.richardson99 at gmail.com
Thu Feb 14 11:28:58 CST 2008

William Donzelli wrote:
> Tubes back then barely worked. When they did work, they barely
> amplified. And you were lucky to get 50 hours out of them. A try
> getting two that were vaguely similar electrically.

... although note that the person who raised the question placed no 
constraints have been placed on reliability, speed, size, power consumption 
etc. - merely whether it could be done.

Tube theory means virtually nothing to me (except that I know that the 
earliest ones weren't exactly paragons of reliability :-)  - but I suspect 
that the answer to "could it be done" is a yes. The end result might not give 
out sane data most of the time, would probably be as big as a house, and 
likely wouldn't run for more than a day or two before everyone gave up in 
disgust - but I suspect it'd be *possible*

 > And then try to find someone that actually knew how the things worked.

That's probably covered by the "modern knowledge" part of the aforementioned 
post, though (although it's not clear how far the rules can be bent in terms 
of making a tube using modern knowledge but materials available in 1900 - 
presumably a lot of what went into tubes of the 50s was known about in 1900, 
but it was the knowledge of how to work with it that was lacking)

> I have thought about how one would make a very early digital machine
> using tubes, and I have concluded that the very late 1920s is perhaps
> a good line to draw in the sand.

See above though - depends how much of a factor the "modern knowledge" part 
is. If people of 1900 knew how a tube worked, but just couldn't make a very 
good one...

> so the only real option for online storage is an acoustic delay loop.

- or something mechanical for R/W store; remember nobody's put constraints on 
speed (or anything else, really).



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