On 2009-04-29, Karl Townsend wrote:
I now have four metal mangling machines that need the venerable ISA slot to
operate... These computers are not available new anymore and the new parts
route is about gone too.

I'm settling around one motherboard, CPU, memory, video card combination.
Makes it much easier to maintain. I can do an entire computer swap in
minutes if trouble happens. Or test one component at a time in a spare test
computer.

That makes sense.

lets say I'd like to run these machines another 20 years. How many spares am
I likely to need? I'd like to buy them up now. (Note: I don't think I need
to do hard and floppy drives yet - still a lot of these around)

Floppy drives are becoming quite rare already. I'm amazed that
my Sun Blade 2000 still has one -- not all of them do.

Hard drives keep getting bigger, and older BIOS chips and
motherboards have limits on the largest disk drive which they can boot
from and use in their entirity. I would suggest stocking drives of the
maximum size that the motherboard is happy with *now*.

If the power supply used by the motherboards is the ATX style,
you may be able to get them for a while yet. If the older style used by
the PC, XT and AT -- get them *now* at hamfests and flea markets -- or
be prepared to troubleshoot switching mode power supplies *without*
schematics. (I have yet to find a set of schematics for a PC power
supply.)

Get at least two CPU fan/heat-sinks for each system board. The
fans in those tend to fail sooner than most other parts. (And they
*can* take out the CPU too, if you don't spot it in time.)

Make sure that you use the same size memory in all systems, and
you should be able to mix and match to keep enough working sets from a
full set for each working motherboard and spare motherboard.

You can probably use current production graphics cards for a
while at least. Probably you can stock up from discarded cards as the
gamers keep upgrading to faster and hotter cards.

But you know, of course, that the thing most likely to fail will
be the special cards which are forcing you to need the ISA bus to start
with. And those are the most expensive parts too, I'll bet.

For power supplies, and motherboards, you might be able to keep
things running with spare capacitors. (Remember that for a period a lot
of things were made using capacitors with an electrolyte built from a
stolen (and bad) formula, so the filter caps may be the most likely
non-mechanical part to fail.) If you can replace filter caps on the
motherboards and the power supplies, you might be able to keep them
going longer.

Good Luck,
DoN.

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