> There are evidenly some 4 MB SIMMs that the SLC and ELC can share.
> There may be problems related to refresh timing or something that
> prevent others being shared.

The SLC (IPC) runs with memory as slow as 80ns, the ELC (IPX) wants 
at least 70ns sims (sure works with 60ns sims). I had a case where
a SLC wouldn't work with memory chips previously used in an ELC,
but I never discovered why at that time (that was some years ago...)

Harald.