From: Dale_Adams@gateway.qm.apple.com (Dale Adams)
Subject: Re: Q800 Video RAM Questions
Distribution: na
Organization: Apple Computer, Inc.,  Cupertino, CA
Lines: 45

In article <1993Apr5.192833.19102@cbnews.cb.att.com> 
jbr0@cbnews.cb.att.com (joseph.a.brownlee) writes:
> Could someone post a *definitive* answer about the VRAM configuration 
> for the
> Q800 (and presumably the C610 and C650 as well).  There seems to be a 
> lot of
> confusion about this issue.  I'd like to know:
> 
>     .   What kind of SIMMs are the VRAM SIMMs (i.e. 30-pin, etc.)?

There's only one physical size for VRAM SIMMs (unlike DRAM SIMMs which 
come in many, many sizes and pinouts), although they do come with 
differing amounts of VRAM on them.  The ones you need are 256KB SIMMs, are 
organized as 128K x 16, and have two 128K x 8 VRAM chips on them.  This is 
the only size which the Quadra and Centris machines can use.

>     .   How many VRAM SIMM slots are there?

Two.

>     .   What rules (if any) must be followed in filling the slots (e.g in
>                 pairs, sizes must match, etc.)?

Both SIMM slots must be filled; putting a SIMM in only one slot does 
nothing for you.

>     .   How fast must they be?

80 ns for the Q800 and C650, 100 ns for the C610.

>     .   Is there any other relevant information?

There are certain VRAM chip manufacturers whose parts are not compatible 
with the Quadra and Centris video hardware.  Make sure that the source you 
get them from guarantees compatiblity.  In general, if it works in a Q950,
it will work in a Q800.

> Please don't reply unless you have the *correct* information.  Many 
> thanks in
> advance for helping to eliminate some noise from this group.

Trust me.  ;-)

- Dale Adams
  Apple Computer, Inc.
