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From: xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Parity Checking / ECC RAM on the A3000
Summary: clarification
Keywords: parity error detection and correction, marketability
Message-ID: <1990May29.192558.27129@zorch.SF-Bay.ORG>
Date: 29 May 90 19:25:58 GMT
Article-I.D.: zorch.1990May29.192558.27129
References: <1641@lpami.wimsey.bc.ca>
Organization: SF Bay Public-Access Unix
Lines: 39

In article <1641@lpami.wimsey.bc.ca> lphillips@lpami.wimsey.bc.ca (Larry Phillips) writes:
>In <1990May27.101258.24470@zorch.SF-Bay.ORG>, xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes:
>>
[you already saw my part twice]
>
>Right.. ECC is not parity, and vice versa.

Sort of.  Error Correcting Circuitry always (?) contains Error
Detecting Circuitry, which is an extension of the parity error
detection concept to more complex errors.

>Parity checking is totally, completely, and utterly useless.

I disagree!

That depends on what you're trying to accomplish.  Even parity
checking that does nothing more than crash the machine with a
"parity fault at 0Xnnnnnnnn", which at least tells you that you
there is a problem, beats all hollow having a bit flipped in a
critical datum, and receiving no warning at all, potentially
until after you have made a costly (and wrong) decision based
on the erroneous result.  Since parity checking is so well
known a part of the state of the hardware engineering art, it
is not clear to me that a company could escape unscathed from
a lawsuit for consequential damages if it were omitted from
a computer design of a machine offered for commercial use in
this day and age.  Most of the losers in those suits were the
folks who thought it was safe to ignore Best Engineering
Practice.

>>But then, what do I know after 29 years in the field [...]
>
>Geez... out-yeared me by 3. :-)

I started at 17, young in those days for a beginning programmer,
over the hill today. ;-)

Kent, the man from xanth.
(xanthian@zorch.sf-bay.org)