Subject: Alpha memory requirements
To: None <>
From: Joseph Sarkes <>
List: port-alpha
Date: 04/17/1999 12:11:48
No Spam writes:
> One thing that would be nice to know, for the PC164
> currently being discussed as well as other models
> that take 72 pin SIMMs, is whether or not EDO memory
> can be used.
> EDO memory tends to be less expensive than FPM,
> dispite being a newer technology.
> I have read on Micron's web site that some FPM
> systems can use EDO, while others cannot.

I have some parity edo memory that I have occasionally used in
my multia with good results. The parity edo memory that I have
has 12 memory chips of all the same size though, rather than the 9
that would work in an ecc parity application.  Only one bit out of
4 is used in the 4 parity bit chips. Ecc parity needs to access the 
entire 72 bit wide word at once (36 bit simm pair), whereas the typical
pc needs byte addressibility with parity per byte, and ability
to write a single byte without doing a read-modify-write cycle.
I suspect that the edo memory chips are cheaper merely due to the
fact that they are in production and possibly due to a smaller 
process size, from being a newer part. 

> Snoopy
> snoopy percent sopwith dot uucp at qiclab dot scn dot rain dot com

Joseph Sarkes         
P.O. Box 482
Ipswich, MA 01938
(978) 948-5017