If an ISA card was configured to respond to the address range of the system's BIOS (and the BIOS chips removed), could you boot from it in the same way as the system's default BIOS?
Specifically, I'm wondering if something like this could be modified to load the contents at 0xF0000
(the address that I understand the IBM AT and IBM XT 286 puts the system BIOS). I'm interested in replacing the ROM chips with EEPROMs or flash, since they're easier to program and still being made (making a ROM socket adapter of some kind being plan B).