EDO (Extended Data Out)  SIMMs require matched SIMMS sets, and Pentium
class boards that supported EDO often required matched sets of whatever
SIMMs were being used...i.e. FPM or EDO. However FPM (Fast Page Mode) never
required in itself, matched sets nor did any 486 using FPM 72 PIN SIMMs. In
fact I would guess that most 486s with 72 pin SIMMs were sold with a single
4 meg SIMM. Of course 30 pin SIMMs which were common in early 486 boards
required matched sets of four.

I still have the original manual for the AST and it does indeed require
that you use the same size SIMMs in one to four SIMMs. AST was one of the
first to use proprietary motherboards with special cases to support them.
These boards also came with integrated IDE controllers and video which were
unique for the time.This was all in reaction to the popularity (circa 1993)
of Apple computers which are well known for integrated proprietary components.


Rode
The NOSPIN Group

At 12:34 PM 7/10/2001 -0400, you wrote:
>Entering this string a little late, but my $.02 is that many older pc's
>required
>72 pin simm's to be matched pairs - you could mix 2 - 8 mb chips with 2 -
>32's,
>etc. but 1 8 and 1 - 32 would not work.  I'm a little surprised that the AST
>seems to require 4 of the same -  did you ever try a mix of pairs?
>
>Mark Rode wrote:
>
> > >I've never heard of any issues about size mixing.  I've never read a user
> > >manual that says use only certain sizes together. It would be a
> surprise if
> > >your system has a problem with this mixture, unless it doesn't support
> a 256
> > >Mb DIMM.

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