From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 101deb,885dab3998d28a4 X-Google-Attributes: gid101deb,public X-Google-Thread: 103376,885dab3998d28a4 X-Google-Attributes: gid103376,public X-Google-Thread: f74ae,eca28648989efca9 X-Google-Attributes: gidf74ae,public X-Google-Thread: 107079,eca28648989efca9 X-Google-Attributes: gid107079,public From: "Wayne L. Beavers" Subject: Re: Ariane 5 failure Date: 1996/10/01 Message-ID: <52s00v$oj1@beyond-software.com>#1/1 X-Deja-AN: 186536211 nntp-news-admin: newsadmin@beyond-software.com distribution: inet references: <1780FB1E3.KUNNE@frcpn11.in2p3.fr> <324F1157.625C@dynamite.com.au> <52p49m$kug@beyond-software.com> <3251322B.1076@lmtas.lmco.com> content-type: text/plain; charset=us-ascii organization: Beyond Software mime-version: 1.0 newsgroups: sci.astro,sci.math.num-analysis,comp.lang.pl1,comp.lang.ada x-mailer: Mozilla 2.02 (Win95; I) Date: 1996-10-01T00:00:00+00:00 List-Id: Ken Garlington wrote: > That's actually a pretty common rule of thumb for safety-critical systems. > Unfortunately, read-only memory isn't exactly read-only. For example, hardware errors > can cause a random change in the memory. So, it's not a perfect fix. Your right, but the risk and probability of memory failures is pretty low I would think. I have never seen or heard of a memory failure in any of the systems that I have worked on. I don't know what the current technology is but I can remember quite awhile ago that at least one vendor was claiming that ALL double bit memory errors were fully detectable and recoverable, ALL triple bit errors were detectable but only some were correctable. But I also don't work on realtime systems, my experience is with commercial systems. Are you refering to on-board systems for aircraft where weight and vibration are also a factor or are you refering to ground base systems that don't have similar constraints? Does anyone know just how good memory ECC is these days? Wayne L. Beavers wayneb@beyond-software.com Beyond Software, Inc. The Mainframe/Internet Company http://www.beyond-software.com/