The StrongARM can support 4 banks of EDO DRAM. The models are:

Mk1: 8MB fitted (2 banks of 4MB, 2 chips per bank). Easy to go to 16MB as there are pads on the underside of the board for another 4 chips (2 banks). Needs kernel mod to enable the memory, but this can almost certainly be done within the existing kernel as the kernel sits at the base of physical memory.

Mk2: 12MB fitted (3 banks of 4MB, 2 chips per bank). No spare pads. You could piggyback on one of the banks and get 16MB, adding bank 4.

Mk2a: 16MB fitted (one bank of 16MB, 2 chips per bank). You could piggyback up to 3 sets of chips (given enough vertical space; HDD interference might be a problem) to give you up to 64MB of RAM.

The Mk1/Mk2 chips are 1M x 16. I have shedloads of these (at least 1000 pcs), though you need to run the RAM test on them as maybe 1 in 50 seem to be bad. TSOP-42, with a gap in the pinning at the middle. I doubt you can buy these anymore. Incidentally, you could also use these to get 8Mbytes on a Rio Receiver.

Mk2a are 4M x 16. I have some of these (maybe 100pcs). TSOP-50 package. I think you can still find these about - micron list them as obsolete though. You need the 4k refresh variant (it can't support 8k refresh chips) - they're the same chips as used in the original TiVO memory upgrade, and so are available from http://www.9thtee.com/tivomemory.htm - this is probably the easiest place to get them, and they don't charge the earth for them either ($20). I may try and get some of these chips to someone who might want to do this sort of upgrade (maczrool?) but can't really just send them out individually as it'd take up a bit of time packaging them, as they're in a tray, not on tape.

Note! I've NOT tried this myself yet, but I don't see why it wouldn't work. The only change required is setting the necessary bits at the bottom of MDCNFG (bit 0=bank 0, bit 1=bank 1, etc).

Hugo