On the machines which will accept 128MB 72 pin SIMMs, it works, except in the PM6100. Will the P578 work with a 128MB SIMM? If so, this will probably work.

The problem in the PM6100 seems to be how the RAS lines were paired. There're four of them on a SIMM, and by separating them into groups, the SIMM can have multiple banks on the SIMM. Well, the SIMM has two banks, but it seems to have its RAS lines paired in the opposite manner to what the PM6100 expects, which is really weird because Apple paired them correctly in the Quadra models, and then did them backwards in the PM6100.

I stopped my investigations before I checked to see if the RAS pairing is configurable. There're are four tiny resistors on the SIMMs, which might be used to set the RAS pairing....