Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site decwrl.UUCP Path: utzoo!watmath!clyde!cbosgd!cbdkc1!desoto!packard!edsel!bentley!hoxna!houxm!mtuxo!mtunh!mtung!mtunf!ariel!vax135!timeinc!phri!pesnta!amd!amdcad!decwrl!dec-rhea!dec-dvinci!fisher From: fisher@dvinci.DEC Newsgroups: net.space Subject: Space Shuttle Computers Message-ID: <2939@decwrl.UUCP> Date: Fri, 28-Jun-85 12:00:09 EDT Article-I.D.: decwrl.2939 Posted: Fri Jun 28 12:00:09 1985 Date-Received: Tue, 2-Jul-85 06:01:04 EDT Sender: daemon@decwrl.UUCP Organization: DEC Engineering Network Lines: 20 <> > ...the fifth one is different from the other 4; it is made by Rockwell... I could be proven wrong, but I am quite sure that all 5 cpus are the same. The fifth one, however, was PROGRAMMED by Rockwell rather than IBM. The quintuple hardware redundancy provides backup for hardware failure. The separate program for #5 provides a backup for the software. BTW, the 5 computers only run as a quintuple redundant set during critical phases of the mission (ascent and decent, and perhaps during some of the prelaunch activities). At other times, they are decoupled and given separate tasks, with only double or triple redundancy for such things as orbital calculations, environment management, and running the arm. Burns UUCP: ... {decvax|allegra|ucbvax}!decwrl!rhea!dvinci!fisher ARPA: fisher%dvinci.dec@decwrl.ARPA