Time to unsolder the part. I think I'm going to install a DIP socket and officially declare this particular motherboard my sacrificial system. :-)
Well the system is sacrificed and I got quite far with a 28F001 DIP part in a ZIF zocket. Unfortunately I connected +15 to the wrong pin (off by one errors in hardware are often more damaging than in software) last night and fried something. I had RAM initialized properly now (I think) and ramtest was executing the load part. Unfortunately the SuperIO (SMC FDC37N958FR) seems to have a watchdog in the internal 8051 core and the 8051 firmware does not follow SMSC's recommended mailbox protocols so I can't shut it off directly. <grrrrr>
Does anyone have a P5-class ICE I can borrow? :-) Bochs doesn't get far enough running the original BIOS to see how the mailbox registers are accessed. I had hacked it to spit out any I/O accesses but I have to do a lot of work in getting the tx chipset more fully emuated before the original BIOS will get to the part where it talks to the 8051 core. :-(
Regards, Anderw