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=-0.3 required=5.0 tests=BAYES_00,FREEMAIL_FROM, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f849b,b8d52151b7b306d2 X-Google-Attributes: gidf849b,public X-Google-Thread: 103376,a00006d3c4735d70 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-12-27 17:00:14 PST Path: archiver1.google.com!news2.google.com!news.maxwell.syr.edu!feed1.news.rcn.net!rcn!wn13feed!worldnet.att.net!bgtnsc05-news.ops.worldnet.att.net.POSTED!not-for-mail Message-ID: <3FEDDD73.C0CFAE19@yahoo.com> From: CBFalconer Reply-To: cbfalconer@worldnet.att.net Organization: Ched Research X-Mailer: Mozilla 4.75 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: comp.arch.embedded,comp.lang.ada Subject: Re: Certified C compilers for safety-critical embedded systems References: <3fe00b82.90228601@News.CIS.DFN.DE> <3FE026A8.3CD6A3A@yahoo.com> <$km9afA3DB7$EAYO@phaedsys.demon.co.uk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Date: Sun, 28 Dec 2003 01:00:13 GMT NNTP-Posting-Host: 12.76.131.128 X-Complaints-To: abuse@worldnet.att.net X-Trace: bgtnsc05-news.ops.worldnet.att.net 1072573213 12.76.131.128 (Sun, 28 Dec 2003 01:00:13 GMT) NNTP-Posting-Date: Sun, 28 Dec 2003 01:00:13 GMT Xref: archiver1.google.com comp.arch.embedded:6197 comp.lang.ada:3866 Date: 2003-12-28T01:00:13+00:00 List-Id: James Rogers wrote: > ... snip ... > > When reliability engineers encounter a system relying upon human > actions the commonly accepted error rate, assuming properly trained > humans, is 1 in 1000. Such an error rate is unacceptably low for > most safety critical systems. An error rate of 1 in 1000 is a > reliability rate of 0.999. Safety critical systems commonly > require reliability rates on the order of 0.999999. This is > three orders of magnitude higher than can be achieved through > reliance on human correctness. And even then, 1000 such 6 nines reliable systems together can be expected to have a combined reliability of 0.999. Now consider the count of individual transistors in a moderately complex processor. There are two basic methods of improving the end product reliability: Improve the component reliability, and reduce the number of components. This argues heavily against using a Pentium when a PIC will do. -- Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net) Available for consulting/temporary embedded and systems. USE worldnet address!