Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!agate!ucbvax!tut.cis.ohio-state.edu!rutgers!att!skep2!slr
From: slr@skep2.ATT.COM (Shelley.L.Rosenbaum.[ho95c])
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle Computer Info?
Message-ID: <594@skep2.ATT.COM>
Date: 9 May 89 17:53:38 GMT
References: <24055@agate.BERKELEY.EDU> <3227@kalliope.rice.edu> <2645@ndsuvax.UUCP> <3234@kalliope.rice.edu>
Reply-To: slr@skep2.UUCP (46321-Shelley.L.Rosenbaum.[ho95c],4M415,x3615,)
Organization: AT&T Bell Labs Center 4632, Holmdel, NJ
Lines: 22

In article <2645@ndsuvax.UUCP> ncoverby@ndsuvax.UUCP (Glen Overby) writes:
>On another subject; I recall reading that the Shuttle's computers were so
>stuffed that to add something, something else had to be removed.  With a
>16MB address space, it would seem that more memory could be added and this
>could be avoided.

One of the things that had to be eliminated from the software during
countdown was the constant update from the IMUs (Inertial Measurement
Units).  During one phase of countdown, the computers would be too
overloaded, so the IMU inputs were ignored.  The IMUs are "recalibrated"
during one of the holds (T-9 minutes comes to mind, but don't hold me
to it).

[Note:  I used to work for Singer-Kearfott, which made the IMUs; my
supervisor had been on the shuttle project, and he gave me the above
info.]

-- 
Shelley L. Rosenbaum, Air Traffic Control Systems, AT&T Bell Laboratories
{allegra, att, arpa}!ho95c!slr     slr@ho95c.att.arpa      (201) 949-3615

"Surrounded by a thin, thin, thin, 16-millimeter shell."