Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!tektronix!sequent!jjb
From: jjb@sequent.UUCP (Jeff Berkowitz)
Newsgroups: sci.space.shuttle
Subject: Re: Shuttle Computer Info?
Message-ID: <15715@sequent.UUCP>
Date: 7 May 89 06:59:23 GMT
References: <24055@agate.BERKELEY.EDU>
Reply-To: jjb@sequent.UUCP (Jeff Berkowitz)
Organization: Sequent Computer Systems, Inc
Lines: 18

In article <24055@agate.BERKELEY.EDU>
  labc-4da@e260-4d.berkeley.edu (Bob Heiney) writes:

>What kind of information can I get on the design, implementation, etc. of
>shuttle software?  Is there someone I should write?

As noted in another posting, the Sept 84 CACM has excellent coverage.
I found the section about the synchronization of the primary computers
particularly fascinating.  The four flight computers don't run in lockstep
at the hardware level; all cross checking is under the control of the
HAL/S code.  Synch points and checks are only as good as the real time
software which implements them.  There is some discussion of the synch
bug which delayed the very first shuttle launch.  The article also goes
into the (excruciating:-) configuration control process used for the
software.  Highly recommended.
-- 
Jeff Berkowitz N6QOM			uunet!sequent!jjb
Sequent Computer Systems		Custom Systems Group