kurt@tc.fluke.COM (Kurt Guntheroth) (07/20/88)
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?
jwatts@hpihoah.HP.COM (Jon Watts) (07/21/88)
mec@ardent.UUCP (Michael Chastain) writes: >I've read that NASA successfully recovered the Challenger core >memories. Talk about a violent "core dump"! This is quite likely true when I was working on core memories for the F-16 we recovered data from several memories that spent two weeks in salt water in the North Sea. The cores don't care only the drive electronics have trouble with it. >sometime in 1987. Ampex makes core memories for, among other things, >shuttles. I may be mistaken but I believe Ampex only makes the cores themselves for the shuttle and not the complete memory assembly. +-------------------------------------------+ |These opinions do not neccessarily reflect | |those of my employer, my country or anyone | -Jon Watts |else if fact they aren't even opinions, in | |fact, they don't even exist, neither do I | |your hallucinating again. Is this Kansas? | +-------------------------------------------+
bms@bdt.UUCP (Chris Rhodin) (07/28/88)
Well all this talk about core memories got me thinking. I have
an old Ampex 16k byte Multibus Core memory card ( circa 1975 ) .
This was bought from a surplus dealer and was used in my first
"computer" which had an Intel 80/10 cpu card. I was the envy of
all my friends, imagine I did not have to use the teletype or
paper tape anymore.
I took the box out of the closet yesterday, dusted it off,
turned it on, low and behold it still had the the same code in
it that I wrote back in 1978! Ten years, seven moves, and no
power. I can see why Nasa likes core.
Vance at Berkeley Microsystems.