Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!ames!skipper!shafer From: shafer@skipper.dfrf.nasa.gov (Mary Shafer) Newsgroups: sci.space.shuttle Subject: Re: New Shuttle Computers Message-ID: Date: 9 Mar 91 18:30:52 GMT References: <1991Mar4.202334.22118@casbah.acns.nwu.edu> <1991Mar5.013344.7971@umiami.ir.miami.edu> <1991Mar06.063034.12021@nowhere.uucp> <1991Mar7.010752.10632@agate.berkeley.edu> <1991Mar9.044834.27802@cimage.com> Sender: shafer@skipper.dfrf.nasa.gov Organization: NASA Dryden, Edwards, Cal. Lines: 26 In-reply-to: gregc@cimage.com's message of 9 Mar 91 04:48:34 GMT In article <1991Mar9.044834.27802@cimage.com> gregc@cimage.com (Greg Cronau) writes: > The bottom line is that harddrives are only useful in situations where >you will be *writing* alot of new data. The control program for the >shuttle is only *read* during flight, never written. A read only tape drive >can be made much more rugged than a hard drive. Well, then, hard drives are in a lot of trouble and will probably never fly. We were using a read-only tape drive in the F-15 HIDEC (Highly Integrated Digital Engine Control) when we were doing one phase of a trajectory control program. We ended up aborting a lot of trajectory guidance flights when the miserable tape drive died as we tried to load the trajectory guidance code and checkpoints shortly after takeoff. We weren't doing anything like high-g maneuvering, either. Just taxi, takeoff, and try to load on climbout. Fortunately we had contingency flight cards and could do other test points. The Shuttle flight control system is another matter entirely. -- Mary Shafer shafer@skipper.dfrf.nasa.gov ames!skipper.dfrf.nasa.gov!shafer NASA Ames Dryden Flight Research Facility, Edwards, CA Of course I don't speak for NASA "A MiG at your six is better than no MiG at all"--Unknown US fighter pilot