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=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 107079,eca28648989efca9 X-Google-Attributes: gid107079,public X-Google-Thread: f74ae,eca28648989efca9 X-Google-Attributes: gidf74ae,public X-Google-Thread: 103376,885dab3998d28a4 X-Google-Attributes: gid103376,public X-Google-Thread: 101deb,885dab3998d28a4 X-Google-Attributes: gid101deb,public From: Alan Brain Subject: Re: Ariane 5 failure Date: 1996/09/27 Message-ID: <324C8405.F8B@dynamite.com.au>#1/1 X-Deja-AN: 185615871 references: <52a572$9kk@goanna.cs.rmit.edu.au> <52bm1c$gvn@rational.rational.com> <1780E8471.KUNNE@frcpn11.in2p3.fr> content-type: text/plain; charset=us-ascii organization: @Home mime-version: 1.0 reply-to: aebrain@dynamite.com.au newsgroups: sci.astro,sci.math.num-analysis,comp.lang.pl1,comp.lang.ada x-mailer: Mozilla 3.0 (Win16; I) Date: 1996-09-27T00:00:00+00:00 List-Id: Ronald Kunne wrote: > The problem of constructing bug-free real-time software seems to me > a trade-off between safety and speed of execution (and maybe available > memory?). In other words: including tests on array boundaries might > make the code saver, but also slower. > > Comments? Bug-free software is not a reasonable criterion for success in a safety-critical system, IMHO. A good program should meet the requirements for safety etc despite bugs. Also despite hardware failures, soft failures, and so on. A really good safety-critical program should be remarkably difficult to de-bug, as the only way you know it's got a major problem is by examining the error log, and calculating that it's performance is below theoretical expectations. And if it runs too slow, many times in the real-world you can spend 2 years of development time and many megabucks kludging the software, or wait 12 months and get the new 400 Mhz chip instead of your current 133. ---------------------- <> <> How doth the little Crocodile | Alan & Carmel Brain| xxxxx Improve his shining tail? | Canberra Australia | xxxxxHxHxxxxxx _MMMMMMMMM_MMMMMMMMM ---------------------- o OO*O^^^^O*OO o oo oo oo oo By pulling Maerklin Wagons, in 1/220 Scale