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From: kurt@tc.fluke.COM (Kurt Guntheroth)
Newsgroups: comp.misc
Subject: Core memory and the Shuttle
Message-ID: <4513@fluke.COM>
Date: 20 Jul 88 15:57:53 GMT
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I believe the memories on the shuttle are plated wire memories, which are
like core memories in function but are made with a somewhat more modern
mechanical process.

Core memories are intrinsically rad hard and nonvolatile, which is quite
useful in space, but the real reason they are used instead of some semi-
conductor memory is that the core memories and the ancient computers that
contain them are already rated for manned space flight.  The paperwork for
certifying a more modern device is so byzantine that it is simply not worth
the effort.

Let me give you an example of what I mean.  My brother worked for Rockewll
on the space shuttle.  They had a rule that it was worth $10,000 a pound to
remove a pound of weight from the shuttle.  For instnace, the walls of the
crew cabin were some sort of exotic alloy sheet about as thin as TV dinner
trays, and stamped into a waffle pattern for structural strength.  Onto
this wall was bolted a fire extingusher on a soft iron bracket(!).
My brother pointed immediately to the bracket and said, "Let me whip out an
aluminum bracket for this sucker."  Well, it turns out that the fire
extinguisher had been rated WITH the bracket, and would not qualify without
it.  The cost of re-rating the extinguisher alone was many times $10,000, so
the idea had to be abandoned.

So, you won't see semiconductor memories or modern computers in space unless
the added power and capacity becomes mission critical.  By the way, this
same sort of silliness goes on in the military, which is what leads to $500
hammers and so forth.  The contractor knows a $4 hammer would be cheaper,
but is constrained from buying it.  And then when the government tries to
lessen the regulation, the contractor generally goes out and buys a $.50
hammer that breaks on the first nail.  Makes you proud to be an American, huh?