>> That is, could a person swap a 32 MB 72 pin SIMM out of
>>a PC and put it in a Mac that uses 72 pin SIMMs (like the Q630 ;-)) Is
>>there a rule of thumb as to what SIMMs will work with what sort of
>>machine?
>Ryan,
>    Yes, I know of no problem with any of them that use the 72 pin SIMM.
>And here, I've done it myself.  Like in either my Q605, a PC, or my 6116
>or 7100/80.  I don't know of any "special requirement" for those 72 pin
>types.  However, I have also had the opposite experience with older Mac's
>that use 30 pin SIMMs; some are in some way quite unique, such as the 3
>chip variety won't work in certain Mac's but will in others.  Things like
>that.  Some 30 pin's that are parity SIMMs (9 chip) will work in some Macs
>but give the tone of death on powerup on others.  Some Mac's, for whatever
>reason, are sensitive to the actual chip organization used on the memory
>array (the SIMMs matrix--ie, the row & column strategy used by the chip
>matrix), I think it is, as the Apple TroubleShooting guide for some of
>the older Mac's (I have one that ends with the IIvi I think it is) and
>they even point out SIMMs from certain vendors (and even date codes) that
>simply won't work in certain Mac's, or give really strange addressing
>errors and so forth.  These are all 30 pin devices as I recall.  But, get
>this, some of those that are troublesome in one Mac may actually work in
>another model!  Those 3 chip SIMMs for example, may not work in a IIci
>but will run just peachy keen in an old SE30!!!  I know, I've experienced
>that one right here myself!

There are some very known "special requirements" on certain machines. For
instance, the Mac IIx needs 30 pin SIMMs, but must use a special one,
designated as "PAL" *JUST* for SIMMs of 4 MB size. The rest are normal. As
you mentioned, the IIci is particular....but only *SOME* IIci's are. The
IIci actually had 2 motherboard designs. One used Parity SIMMs, the other
didn't. Aparently, you have one of the parity logic boards. To my knowlege,
the IIci was the only parity-requiring Mac. You must also pay attention to
the speed of the SIMM. If your Mac requires a 70 ns SIMM, then you'll
likely have problems if you try to use an 80 ns SIMM. You can ALWAYS use a
lower # (faster SIMM) but you shouldn't try a slower SIMM. One other thing
to look for is the "refresh rate". These come in 2 flavors, 2 ms & 4 ms.
Finally, the Quadra 840 AV & 660 AV are not allowed to use composite SIMMs.
These are similar electrically to using a SIMMdoubler or SIMMstacker...& it
intrduces just enough timing problems to kill the AV Macs.

Hope this helps,
Mike

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