Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!uunet!philmtl!philabs!ttidca!hollombe From: hollombe@ttidca.TTI.COM (The Polymath) Newsgroups: sci.space.shuttle Subject: Re: Shuttle Computer Info? Message-ID: <4452@ttidca.TTI.COM> Date: 17 May 89 19:12:06 GMT References: <26.UUL1.3#5131@mvac23.UUCP> Reply-To: hollombe@ttidcb.tti.com (The Polymath) Organization: The Cat Factory Lines: 39 In article <26.UUL1.3#5131@mvac23.UUCP> mvac23!thomas@udel.edu writes: }Obviously, the AP101's are fairly small, but how do they fit in with the }rest of what IBM produces. Is it a mini-mainframe, a specialized design- }to-spec. machine, or what? From foggy memory: The principles of operation of the AP-101 are (is?) similar to the System 370. The major exception is the AP-101 has two sets of 8 general purpose registers instead of the 370's one set of 16. (This is based on my experience with their respective assembler's). Physically, each AP-101 consists of two metal boxes (very) roughly 1' x 1.5' x 3', each and weighing about 90 lbs, each. My memory gets much foggier here, but I recall one box is the CPU and the other is sort of a giant math co-processor. The boxes are connected by a 2" diameter cable. Memory is non-volatile (a source of much confusion to novices [i.e.: Me] and much amusement to old hands at Rockwell's Avionics Development Lab). Mass data storage is provided by the Main Memory Unit (MMU), a mag-tape based device that would put Rube Goldberg to shame. Each program the Shuttle computers need to run is stored on the MMU in triplicate. IBM expended a _lot_ of effort (and NASA's money) to insure that each and every AP-101 is as near exactly like each and every other AP-101 as possible. Disclaimer: The above is what I remember from working in the ADL over 6 years ago. My memory is probably a bit degraded and some things may have changed since then. -- The Polymath (aka: Jerry Hollombe, hollombe@ttidca.tti.com) Illegitimati Nil Citicorp(+)TTI Carborundum 3100 Ocean Park Blvd. (213) 452-9191, x2483 Santa Monica, CA 90405 {csun|philabs|psivax}!ttidca!hollombe