Nordisk Computer Services (Portland 503-598-0111, Seattle
206-242-7777) is reputed to have memory for use on AIX platforms.
5xx & 9xx machines have 8 memory slots, 3x0s have 2, and 3x5s have
only one. You need to add memory in pairs for the 5xx & 9xx machines
excepting the 520.
Some highend 5xx's & 9xx's get memory as 2, 4, 4+4 cards.
RS/6000 Models M20, 220, 230 and 250 can use "PS/2" style SIMM memory.
All have 8 SIMM sockets. 60ns or better is needed for the 250, 70ns
should be OK in the M20, 220 and 230. The M20, 220 and 230 are limited
to 64MB of memory, the 250 is limited to 256MB.
40P, C10, C20, 41T and 42T also user SIMM memory.
G30 & G40 have two memory slots.
J30, J40, J50, R30, R40, R50 have four memory slots.
These eight models have cards populated with DIMM-like memory.
7248 (Old 43P's) and 7043 (New 43P's) use DIMM-like memory.
F40, F50 & H50 use have two memory slots.
S70, S7A & S80 get memory "books".
Still unidentified: E20, E30, F30, B50, H70
Caveat: Do not mix manufacturers or batches in the same memory card/bank.
PS: [Ed's notice] I say DIMM-like memory because it won't even fit on
my PC's DIMM slots.