Fwd: Naked Mini Broke

From: Chris Kennedy <chris_at_mainecoon.com>
Date: Sat Feb 3 12:14:31 2001

Iggy Drougge wrote:


> What's wrong with old-arsed computer anyway???

Particularly in space-based applications, where flight qualification for
man-rated hardware is a pangalactic bitch.

> BTW, I read somewhere that the space shuttle actually used core memory,
> apparently due to the bad resistance towards radiation in older IC memory.

I'm sure that's a component -- even contemporary dynamic memory is less
rad hard than you'd probably like, but that's hardly the overriding reason.
My increasingly dim memory suggests that the processor are slightly modified
1750A machines. There was some indication that they were a derivative of the
processor using in the F-16, but I never was able to verify that. Being '70s
designs suggests that core would have been the only real option.

> Could anyone confirm whether this still holds true?

I have no idea if the processors are being swapped out as part of the
flight deck modernization program. If so it can't be too radical a
departure from the existing architecture, since only one orbiter has
completed that modification cycle and the thought of having two
sets of tools for building the code loads for the orbiters staggers the

Oh yeah, that's the other thing. The code load for each orbiter is unique
to the mission, and there's no real executive function -- it's a bunch
of cooperating real-time tasks, such that if one pukes out it probably
takes out the rest. There's been at least one documented case where
the flight code load, during on-the-pad prelaunch simulation, dropped
the ball and the flight deck displays ended up with the shuttle's
answer to the BSOD -- an 'X' drawn through the flight deck displays.

If you think that's odd, you should check out the way that voting works...

Chris Kennedy
PGP fingerprint: 4E99 10B6 7253 B048 6685  6CBC 55E1 20A3 108D AB97
Received on Sat Feb 03 2001 - 12:14:31 GMT

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