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From: dbm@icarus.jsc.nasa.gov (Brad Mears)
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle computers break down during glide tests
Message-ID: <1991Apr26.180717.22402@aio.jsc.nasa.gov>
Date: 26 Apr 91 18:07:17 GMT
Article-I.D.: aio.1991Apr26.180717.22402
References: <1593@philtis.cft.philips.nl> <1991Apr26.111139.1@vf.jsc.nasa.gov>
Sender: dbm@gothamcity.jsc.nasa.gov (Brad Mears)
Distribution: sci.space.sghhuttle
Organization: Barrios Technology @ NASA/JSC; Houston
Lines: 26

In article <1991Apr26.111139.1@vf.jsc.nasa.gov>, kent@vf.jsc.nasa.gov writes:
|> In article <1593@philtis.cft.philips.nl>, munk@cft.philips.nl (Harm Munk) writes:
|> > My question: what happened with the computers during that first (?)
|> > glide test.
|> 
|> I will give this one a shot, One General Purpose Computer (GPC)
|> failed and the others quit listening to its inputs ( as they are programed to
|> do).  Three GPC's all run the same software and compare results to assure one
|> is not sick. 

Actually, there are 5 GPCs installed and running on the shuttle (a sixth is
available for on-orbit replacement).  Of these 5, 4 of them are running identical
software.  These 4 share duties equally and monitor each other for disagreements.
The 5th is running an entirely different piece of flight software.  If the commander
thinks the first 4 are completely fouled up, he can disable them and let the 5th
one take over.

-- 
Brad Mears
dbm@icarus.jsc.nasa.gov

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