Before Apple's 15-Feb-93 Macintosh release, most Macs used 30-pin SIMMs. The new Mac spec sheets tout 72-pin SIMMs as "Industry Standard," causing us to wonder if we've been hallucinating when thinking about SIMMs for the last five years. From several reports we gather that recent NeXT machines, such as the NeXTstation Color Turbo and various recent PC clones from IBM, Compaq, and others do use these 72-pin SIMMs. Since many memory vendors serve more than the Macintosh market, it makes sense that these vendors should have 72-pin SIMMs in equal quantities soon. Although it may take a bit for prices to equalize in the Macintosh world, we shouldn't see too great a spike. Of course, since most Macs in the known universe still take 30-pin SIMMs, there's no need to worry about a shortage of those any time soon.
Perhaps the most important thing to keep in mind is that the old 30-pin SIMMs do not work in the new 72-pin sockets. So, as unfortunate as it sounds, that memory you just popped in your Mac will stay there. In all likelihood Apple will never ship another machine that uses those SIMMs, so you won't be able to migrate them to newer Mac.
Information from:
Geordie Korper -- gwkiv@univ.com