*** Ideas needed for developing interactive displays....

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Fri Sep 10 18:08:40 2004

> > Incidentally, it always impresses me how many clock museums
> > keep their exhibits running (in most cases about 70% of the clocks are
> > still running in my experience). And they're not faked!
> This is good, but a clock usually costs less to run than
> a computer (and a lot less to run than an *old* computer).

Possibly... On the other hand PCs aren't _free_ to run either,

> There are also many more people willing and/or able to
> sit down and understand a clock than there seem to be
> who are willing/able to do the same for electronics.

This I don't understnad. Classic computers (at least not any one I've
worked on) are not that hard to understand. And if I can do it, anyone
can! Problem is that nobody seems to _want_ to understand electronics any
more (and this worries me a lot!).

> My clock experience is limited to one modern mechanical
> alarm clock and one electro-mechanical clock/radio/alarm
> thing. Both had mechanical problems, both came apart
> (given a little time and effort) and both went back
> together and worked. Plus there was not much difference
> between them (at least in principle, at least to the
> depth that mattered in getting them functional again).

OK, let's see how you'd get on doing jobs like

Bushing a plate hole (this is suprisinging difficult the first time, the
wear on the hole is uneven in general so the centre of a worn hole is
_not_ where the centre of the bush should go).

Calulating the number of teeth on a wheel and pinion if one of the arbors
is missing.

Re-pivoting an arbor

Cutting a wheel (that's a gear for the non-horologists, I mean using a
dividing head to cut the teeth), then crossing it out (cutting the metal
out between the spokes)

Determining the correct dimensions, then making, a set of pallets.

And so on. There are simple clock repairs, there are difficult ones. Much
like computer repairs.

> Computers seem to vary much more in design and have
> evloved quite considerably. There is also plenty that,
> potentially at least, you cannot tell just by looking.
> (PALs, ASICs, custom parts, parts for which you
> have no datasheet etc.).

Depends on the machine, of course. And as I've said many times, the time
to start thinking about repairs is when the machine is still operational.
That's when you pull all the PALs and ROMs and dump them (even
copy-protected PALs can be reverse-engineered, FPGAs are almost
impossible, though!). If a data sheet once existed (i.e. it's not a true
custom part) then it's likely _somebody_ still has it...

> So it is certainly impressive that a clock museum
> can keep many clock operational; but I doubt that
> any sort of computer museum would have the resources
> available to do that for old computers. It is possible
> to build your own valves, but is it possible to
> build a replacement valve for a specific (but now
> unobtainable) valve for some old mainframe?

I couldn't do it, but I don't think it's impossible!

Received on Fri Sep 10 2004 - 18:08:40 BST

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