Subject: Re: Memory: Parity vs ECC?
To: None <>
From: Carl Lowenstein <>
List: port-alpha
Date: 12/28/2002 16:05:06
> From: "Nathan J. Williams" <>
> Date: 27 Dec 2002 22:01:44 -0500
> Matt Thomas <> writes:
> > At 02:35 PM 12/27/2002, wrote:
> > >Say, if I'm trying to buy ECC memory for my AlphaStation 200, will any
> > >1234x36 SIMM work? (Well, 64MB or smaller I guess.)
> > >
> > >I thought non-parity was FOOx32, parity FOOx33, and ECC FOOx36. Is
> > >that not correct? It's pretty easy to find "parity" FOOx36 memory,
> > >but I really want ECC. What's the scoop?
> > 
> > You want x36 FPM since the AS200 uses two bank as once so each 64bit
> > access has 8bits of parity which the APECS chipsets uses for ECC.
> My manuals are at home and I'm behind a slow net connection, but I'm
> reasonably certain that the AS200 memory system does *not* need or use
> ECC; I think it only needs 33-bit memory. The documentation of the
> machine check errors generated on that system is full of notations
> like: "37: ECC error. Cannot happen, hardware does not have ECC
> support."

In any case, it is a lot easier to get x36 memory SIMMs than x33.
High-end PC's greatly outnumbered Sun workstations of that vintage.

    carl lowenstein         marine physical lab     u.c. san diego