Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site mordor.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!philabs!cmcl2!seismo!umcp-cs!gymble!lll-crg!dual!mordor!@S1-A.ARPA,@MIT-MC.ARPA:cdl@cmu-cs-k.arpa From: @S1-A.ARPA,@MIT-MC.ARPA:cdl@cmu-cs-k.arpa Newsgroups: net.space Subject: Re: Space Shuttle Computers Message-ID: <2362@mordor.UUCP> Date: Fri, 21-Jun-85 15:51:19 EDT Article-I.D.: mordor.2362 Posted: Fri Jun 21 15:51:19 1985 Date-Received: Sat, 29-Jun-85 23:57:46 EDT Sender: daemon@mordor.UUCP Lines: 22 From: Douglass.Locke@CMU-CS-K.ARPA The four (not five) Shuttle computers are indeed IBM AP-101 processors. They are environmentally hardened 32 bit machines which bear NO resemblance to IBM 360's or any other commercial computer, either in architecture or in construction. Although all the processors are identical, one contains a different software package written by Rockwell to avoid the potential of a single software problem stopping all the computers simultaneously. Before one criticizes the packaging, or the memory technology chosen, it would perhaps be appropriate to investigate the difficulties of handling an environment with potential extremes of temperature, vibration, shock, EMI, and radiation, with acceptable reliability, and in a vehicle which is totally dependent on the equipment. When NASA was specifying the equipment, it was in the mid-70's and there was no applicable experience with the actual shuttle environment, so a conservative approach was certainly justified. The IBM AP-101 is one of an extensive line of machines for such environments with a variety of speeds, form factors, memory technologies, etc., each designed to cope with different environmental and application requirements. -- Doug Locke