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Date: Mon, 14 Jul 1997 08:25:21 -0400
From: "Donald J. Maddox" <root@scsn.net>
To: Nadav Eiron <nadav@barcode.co.il>
Cc: dmaddox@scsn.net, Wes Peters - Softweyr LLC <softweyr@xmission.com>,
        Nick Johnson <spatula@gulf.net>, questions@FreeBSD.ORG
Subject: Re: A few solutions
Reply-To: dmaddox@scsn.net
References: <Pine.BSI.3.96.970713130431.16120A-100000@pompano.pcola.gulf.net> <199707140404.WAA07219@xmission.xmission.com> <19970714072626.64852@scsn.net> <33CA1547.AD3@barcode.co.il>
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In-Reply-To: <33CA1547.AD3@barcode.co.il>; from Nadav Eiron on Mon, Jul 14, 1997 at 03:02:15PM +0300
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On Mon, Jul 14, 1997 at 03:02:15PM +0300, Nadav Eiron wrote:
> Donald J. Maddox wrote:
> > 
> > On Sun, Jul 13, 1997 at 10:04:27PM -0600, Wes Peters - Softweyr LLC wrote:
> > >
> > > Parity RAM won't prevent errors from happening, it will just tell you
> > > when they do.  The system will respond by rebooting, which really
> > > doesn't get you much.  You probably just ended up with better (or faster)
> > > RAM than what you had before.
> > >
> > > High-end UNIX workstations are often equipped with ECC RAM, which can
> > > actually "fix" one-bit errors in memory accesses.  This is yet another
> > > area in which garden-variety PCs don't stack up to workstations, either
> > > in performance or cost.  ;^)
> > >
> > > Buy good quality RAM, parity or not, and be happy.
> > 
> > Feel free to correct me if I'm mistaken here, but I believe that there is
> > no such thing as "ECC RAM".  ECC is a function of the motherboard, no?  If
> > your motherboard supports ECC _and_ you have parity RAM, you can use ECC.
> 
> No. What you need is ECC motherboard and ECC RAM. To be able to correct
> memeory errors you need more bits than what's available on a parity
> SIMM. Some ECC implementation (the one I have in mind is the AlphaServer
> 1000, don't know if Pentium MBs have this too) use standard RAM, but in
> greater quantity. The AlphaServer 1000 has banks of 5 standard SIMMs,
> instead of the 4 that would otherwise be required for its 128 bit memory
> bus. It uses the extra memory to implement ECC. Later models used 4 ECC
> SIMMs instead.
> 
> Nadav

Well, all I can say is that according to the User's Manual for my
ASUS P/I-P55T2P4 mainboard, all I need for ECC is parity RAM, and
ECC enabled.

I notice, however, that the ECC supported by this MB only supports
1-bit error correction...  Maybe the ECC RAM you two are speaking of
allows for more sophisticated error correction?