Case designs (was: New Definiton REQUIRED)

From: Allison J Parent <allisonp_at_world.std.com>
Date: Wed Nov 19 08:51:32 1997

<They're still going. Their modern stuff is not _as good_, but it's still
<very well built. Oh, and the electronic design is up to the same high
<standards.

there is some truth and a fair amount of fiction. Some of the older
stuff was overbuilt and it cost. The Barco had everything out front
for a reason, when was the last time you have to converge a new monitor?
Some of the older stuff that was a fairly common adjustment. Alos how
much of the stuff made before say 1983/4 would pass FCC/DOC/TUV RF
radiation requiments.

Some of those new cases that come off easy are even RF tight, no small
trick. Years ago it was box in box construction to get that. Some things
in racks are still expensive as the racks and the system then support
collectively have to be RF tight without being airtight.

In addition you pay for weight, in shipping, cost of materials and
sometimes time to produce.

Now for a reality check. The last generation of transistor computers were
fairly small. PDP-8, PDP12 being examples. All that quality. Well one
of the itelms in that are a plastic/ceramic packaged transistor used in
heaping piles. Electrically a decent enough device for the time and cheap
too. One little problem, the transistor die is glued to a ceramic pad
then wire bonds from the leads to the die and a drop of epoxy to enclose
the component. Problem, epoxy is not hermetic and the bonds go from the
affixed die to lead posts via they epoxy and as things heat and cool
sometimes the forces are great enough to lift the lead right off the die.
The result is transistors that work when cool and quit when warm. Needless
to say that case design would disappear after a few years. Why use it to
build a computer? Well in the 60s it would take say 10,000 of them and
the same part in a metal case was several times the price as in $0.25 VS
more than $1.00. It was the best option at that time.

An aside for the crazies like me. If a straight-8 were built using modern
surface mount transistors and components to the same electronic printset
and current multilayer board and packaging techniques it would shrink by a
factor of 5-10 without resorting to ICs not available at that time. The
only challenge would be the core memory (the raw cores would be hard to
find and expensive to assemble). Electronic packaging and construction
has undergone considerable advancement and is more than wrapping metal or
plastic around it.

Some items like the cheap screws were also common with a few altair kits
when MITS was having trouble. Or some of the other near vapor machines.

I may add that I can buy a minitower box with PS these days for well under
$100 but at the time of the altair the RAW cabinate from the vendor like
that one was well over $100 and you still had to cut holes in it and fill
it. I may add the Altair (8800) box was actually pretty flimsy compared
to IMSAI or the later Horizon, Vector MX or CompuPro boxes.

Allison
Received on Wed Nov 19 1997 - 08:51:32 GMT

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