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From: pf@diab.UUCP (Per Fogelstrom)
Newsgroups: comp.arch
Subject: Re: Double-bit errors and ECC memory
Message-ID: <336@ma.diab.UUCP>
Date: Thu, 15-Oct-87 06:36:19 EDT
Article-I.D.: ma.336
Posted: Thu Oct 15 06:36:19 1987
Date-Received: Sun, 18-Oct-87 08:46:41 EDT
References: <686@obiwan.UUCP> <8637@utzoo.UUCP> <8638@utzoo.UUCP> <870@alaska.cray.com> <8724@utzoo.UUCP> <8739@utzoo.UUCP>
Reply-To: pf@ma.UUCP (Per Fogelstrom)
Organization: Diab Data AB, Taby, Sweden
Lines: 16

In article <8739@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes:
>> ... However, if you mean actually decoding the syndrome 
>> bits to determine which bit has been flipped, this seems impractical.  What
>> happens if the error is in the code that corrects errors?
>
>Greg Noel has pointed out that I responded to one of two possible meanings
>of this question; does "code" mean the error-correction software or the
>extra bits on the failing memory word?  In the latter case, which may have
> [ removed discussion about how to take care of correction bits ]

If there is an error in the LOGIC that corrects errors, then you are in trouble,
however there must be a way to locate such faults with software. Anyway, a
fault correction logic tends to signal errors more than missing them.

If the error is in the syndrome bits itself, correction will take care of that.
Even the correction bits are covered by itself !