What is the first computer?

From: Philip.Belben_at_powertech.co.uk <(Philip.Belben_at_powertech.co.uk)>
Date: Thu Jun 18 12:27:40 1998

William Donzelli quoted Tony Duell as having written:

>> Agreed. You can understand an ASR33 or similar by turning it by hand and
>> tripping linkages, etc. I did it years ago. Doing the same to a video
>> terminal, even a simple dumb terminal, is a lot harder (Done that as well!)
>
> I have actually done that with a chunk of one of these computers - the
> turn of one gear would cause a hundred others to move.
>
>> The other nice thing is that, with the possible exception of custom cams,
>> it's generally pretty obvious what broken parts should be like. And then
>> it's possible to make them without too much equipment. But a dead custom
>> chip is almost impossible to figure out, and hard to reproduce.
>
> That is very true - a stripped gear is a stripped gear is a stripped gear!

Ooh! Not so fast! Is it straight, helical, worm or hypoid? Or an
eliptical gear even? But yes, a gear is easy to rconstruct from its
wreckage. Some cams and levers, though, have quite tight tolerance
spikes and notches which it is quite difficult to get right from seeing
the bent/broken ones.

> Fixing one of these mechanical computers, however, is completely different
> from the familiar digital ones. In the latter, all problems (except video)
> are go/no go. In the former, problems manifest themselves in the outputs
> giving out-of-spec or erroneous results (except with a catasprophic
> failure!).

Bearing in mind Tony's, Sam's and others' comments on intermittent
faults and the like, yes, up to a point. Video is not the only
exception, though - other things (e.g. disk drives) can suffer
similarly.

And finally, remember digital mechanical computers do exist - I have a
Facit mechanical calculator with some quite sophisticated algorithms
(optimised multiplication, non-restoring division) done digitally,
entirely with mechanical parts. (The only electrical bits are a motor
and a switch.)

Philip.
Received on Thu Jun 18 1998 - 12:27:40 BST