Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site fortune.UUCP Path: utzoo!watmath!clyde!burl!mgnetp!ihnp4!fortune!wall From: wall@fortune.UUCP (Jim Wall) Newsgroups: net.micro Subject: Re: another *parity* argument Message-ID: <3987@fortune.UUCP> Date: Mon, 13-Aug-84 17:39:38 EDT Article-I.D.: fortune.3987 Posted: Mon Aug 13 17:39:38 1984 Date-Received: Tue, 14-Aug-84 02:14:41 EDT References: <692@sri-arpa.UUCP>, <1217@vax2.fluke.UUCP> Organization: Fortune Systems, Redwood City, CA Lines: 22 Remember that a parity error is telling you that your memory cannot be trusted, at all! Memory parity errors are all hard, once failed, they can never be trusted until rewritten. Usually if one location is bad then other locations will be as well. What most systems do upon a detection of a parity error is jump to a ROM based error routine that sends an error message to the appropriate output device and gracefully brings itself down. It never tries to recover any data or program. I know people will scream over this, but you cannot be sure of the memory anymore, so trying to save portions of it will just cause grief. Remember that memory failures are rarely just one address affected, most are caused by power surges, ESD, and other similar events. EDC is better, but not at all perfect, and for the cost isn't worth it in my book. Now fault tolerence is entirely a different story.... -Jim Wall !amd!fortune!wall