Ah, I see the pads. Must use 16 bit wide DRAM, which has got to be hard to come by. It suggests an interesting hack, though. The data lines and address lines are going to be common from DIMM to DIMM to soldered-down-RAM. The only distinct signals are going to be amongst the RAS, CAS and/or Bank(0) signal.
So, if I sort that out, install a 128 MB DIMM in one of the DIMM sockets, cut the distinct traces to one bank of 64MB on the DIMM and wire those traces to the corresponding signals on the soldered-down-RAM pads, then, in theory, one should get at least another 32 MB of memory and maybe another...
Oh, I need to go read the Hardware Developer Note again. That may not work at all, at all. I think the machine already does two banked RAM but just won't address more than 32 MB per bank. So that would shoot down my clever idea.
On another front, when you buy stuff on Ebay, don't wait four months to open it. I finally unpacked my PM6500/300 tonight. It's a 250MHz. Stinkin' Ebay sellers.
In his defense, I think it was careless ignorance, rather than intentional fraud, but the fellow had it listed as 330MHz at first. I emailed him, pointed out that didn't exist, he changed it to 300MHz. The jerk could have just plugged the machine in with a monitor attached. Or pulled the logic board. There's a label right there. Sigh. I guess 50MHz is not that big a difference, and I didn't pay a lot for the thing, but it's irritating.
Time to see if it's too late to leave feedback....