On 16 Sep 2005 05:58:47 -0700, "WM" <[EMAIL PROTECTED]> wrote:
>When I worked at JSC way back, the CPUs were IBM AP-101s from, I think, >Owego. Had a subset of the S/360 instruction set I recall. I'm sure >this is on the net or someone will chip in who did more work than I, >but my recollection is that there were three CPUs running the same >software during critical phases (i.e., launch and re-entry) and if they >all agreed, you're good. If two agreed, go with that answer and take >the 3rd offline (and auto hot swap in a spare? Don't recall.) > >In addition (and very smartly, I must say), there was an extra CPU with >completely different software from another vendor for critical phases >that could be reverted to in case of some common mode error in the >primaries. Current practice (in say, an Airbus) to use a different >hardware platform for this as well. Don't recall what the STS did. Your recollections are pretty good! The "General Purpose Computers" are, indeed, AP-101 (but five systems, not four). In the mid 90's, the original computers were replaced by updated models, AP-101S. Some details: http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/avionics/dps/gpc.html http://www-03.ibm.com/ibm/history/exhibits/space/space_shuttle.html Eric -- Eric Chevalier E-mail: [EMAIL PROTECTED] Web: www.tulsagrammer.com Is that call really worth your child's life? HANG UP AND DRIVE! ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
