Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cbmvax!jesup
From: jesup@cbmvax.commodore.com (Randell Jesup)
Newsgroups: comp.sys.amiga.tech
Subject: Re: Parity Checking / ECC RAM on the A3000
Keywords: parity error detection and correction, marketability
Message-ID: <11958@cbmvax.commodore.com>
Date: 30 May 90 07:22:21 GMT
References: <756@bilver.UUCP> <1990May27.101258.24470@zorch.SF-Bay.ORG> <321@tlvx.UUCP> <1990May29.204550.27961@zorch.SF-Bay.ORG>
Reply-To: jesup@cbmvax (Randell Jesup)
Organization: Commodore, West Chester, PA
Lines: 24

In article <1990May29.204550.27961@zorch.SF-Bay.ORG> xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes:
>alpha particles have very limited penetrating power; they do all their
>mischief near their point of origin.
...
>The older memory chips had very little susceptability to alpha radiation
>induced parity errors.
...
>Since dynamic RAM means the memory is refreshed repeatedly by renewing the
>control charges holding the state (0 or 1) of each gate, there is not usually
>time for the charges carried by individual alpha particles to accumulate
>from several events to switch a gate, before the refresh cycle sets the charge
>back to its nominal value.

	All well and true, however advances have been made in reducing
susceptability to alpha errors, I think perhaps enough to offset the reduction
in charge storage.  For example, plastic-packed parts have less alpha
problems, as I remember, due to lower radioactivity rates.  All 1Mb and
higher ram I've seen is plastic, though there could well be some ceramic
out there somewhere.

-- 
Randell Jesup, Keeper of AmigaDos, Commodore Engineering.
{uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com  BIX: rjesup  
Common phrase heard at Amiga Devcon '89: "It's in there!"