From owner-freebsd-hackers Sat Oct 25 14:37:41 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id OAA24922 for hackers-outgoing; Sat, 25 Oct 1997 14:37:41 -0700 (PDT) (envelope-from owner-freebsd-hackers) Received: from misery.sdf.com (misery.sdf.com [204.244.210.193]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id OAA24917 for ; Sat, 25 Oct 1997 14:37:38 -0700 (PDT) (envelope-from tom@sdf.com) Received: from tom by misery.sdf.com with smtp (Exim 1.73 #1) id 0xPDsG-0006GR-00; Sat, 25 Oct 1997 14:36:00 -0700 Date: Sat, 25 Oct 1997 14:35:56 -0700 (PDT) From: Tom To: Jerry Hicks cc: freebsd-hackers@freebsd.org Subject: Re: Parity Ram In-Reply-To: <34525F3B.1137B612@ix.netcom.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from QUOTED-PRINTABLE to 8bit by hub.freebsd.org id OAA24918 Sender: owner-freebsd-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk On Sat, 25 Oct 1997, Jerry Hicks wrote: > Žoršur Ivarsson wrote: > > > > This has helped me several times when I was suspecting broken memory in > > the old days (90-93) :-) > > > > Thordur Ivarsson > > ECC Memory was marginally useful for this years ago when were using NMOS > RAM. Lately, most memory failures I've seen are catastrophic, taking out > a whole device or better. > > I'm not a hardware specialist; Does 'Parity RAM' employ a conventional > parity scheme, a la asynch serial communications? Most do, except for ECC schemes. > Didn't Richard Hamming show these to -cause- more problems than they > solve? It seems I recall a number like 256K (bits/bytes/words?) as being > the threshold in a proof he presented. Huh? I don't understand. How does it cause problems to determine that a memory location is corrupted? > Jerry Hicks > jerry_hicks@bigfoot.com > > Tom