What is the first computer?

From: Philip.Belben_at_powertech.co.uk <(Philip.Belben_at_powertech.co.uk)>
Date: Fri Jun 19 11:16:44 1998

>> 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.
>
> Well, obviously one replaces with the correct type of gear!
>
>> 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.
>
> Impossible, sometimes. What if a special "hump" on a cam is so worn down
> that one cannot reconstruct its shape? Some of the correct "shape" could
> exist as aluminum powder.

That's what I meant. Tony was saying - and rightly so - that while you
can often see what a failed mechanical part was meant to be like by
studying the failed component, and can then cut a new gear (the
assumption was the gear isn't a standard part) / lever / cam or
whatever, you can't possibly tell what a dead chip was meant to do just
by looking at it. Likewise you can't tell what the value of that
charred resistor used to be...

I merely pointed out that with some tight tolerance cams and levers, you
have a similar problem - you can't tell by looking. "Difficult" in my
line above was a euphemism for "no hope"

>> 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.
>
> No, not disk drives. Sure, some analog circuitry in a drive might go sour,
> but those faults would result in bad data. With a working drive, you want
> correct data, and if you do not get it, something is wrong. There is no
> tolerance. With an analog system, you have to expect that the output data
> will not be perfect. For example (also a magnetic recording medium),
> playing back a signal will never be the same as what was recorded, due to
> noise and distortion.

True, every word. But if you draw the distinction there - digital vs.
analogue circuitry - the comment to which I was replying deserves your
reply as well. The previous poster (wasn't you, William, was it?) drew
the distinction at a higher level, and said something like "a digital
_machine_ either works or it doesn't. Apart from video, the results are
either right or wrong. With analogue/mechanical, things can be slightly
out but the machine will go on working" Video is another analogue
subsystem in a digital machine, just like a disk drive, and all that
that implies...

BTW, video may not make the change from digital to analogue until
actually in the monitor, but the same applies - that which you see on
the display is (at the digital level) either right or wrong. It is only
when you get to the analogue bit that it is merely fuzzy.

Philip.
Received on Fri Jun 19 1998 - 11:16:44 BST