Subject: Re: parity RAM in Macs
Date: Wed, 28 Oct 98 20:04:56 -0500
From: Adam Powers <apowers@lightlink.com>
To: "Classic Posts" <classic-post@hitznet.com>

The moderator wrote:
>     There are mixed reports as to whether parity SIMMS work in normal
>Macs (which are non-parity.)

And there definitely are mixed results when trying to use parity SIMMs
in Macs.  I now have a few interloping PCs in my mostly-Apple
computer stash, and I've had some interesting experiences with 30-pin
SIMMs.  The obvious holds true: eight-chip (or two, or four) non-parity
SIMMs will not work at all in PCs that require parity RAM; but most
(NOT all) parity RAM works just fine in Macs.  I have some three-chip
1 MB SIMMs that work properly in a Gateway 386sx, but show up as blanks
in a IIsi - no sad Mac, but only the 1MB on the motherboard appears in
the "About this Macintosh" window!  I also have some PC SIMMs which
generate Sad Mac RAM errors if and only if they are paired together -
that is, if I use one of these SIMMs with a regular non-parity Mac SIMM,
it works; if I use two (or more) in a bank of four, I get a Sad Mac.
All the nine-chip 1MB 30-pin SIMMs I tried worked fine.  I remember
hearing something about "fake parity" SIMMs in the PC world a while
back, about the time that the low-chip count SIMMs were hitting the
market, perhaps that's the problem?  I also recall warnings about
using low chip-count SIMMs in the SE and Plus as well.  At least all
my computers are old enough that I needn't worry about 3.3v vs. 5v!

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