Award BIOS won't boot option ROM

[luRaichu]

I'm trying to get a VIA VT6421A card bootable on my Biostar MB-8500TTD. It's a Socket 7 board.
I burned the "Memphis" ROM on an EPROM and stuck it on a PCI Ethernet card. Couldn't reflash the VT6421A's onboard EEPROM, sometimes they are fake.
The ROM will boot on a newer ATX box from 2009, but not on the 8500TTD. It has Award BIOS v4.51PG.

 

[GiGaBiTe]

There could be several issues causing that card to not work. First would be that the Socket 7 board uses the old PCI 1.x standard and doesn't support 3.3v PCI cards. PCI cards by spec are required to have a reverse key for 3.3v operation, but there were many cards that didn't conform to the spec that required 3.3v, but used the old 5v keying.

Next would be that maybe the Option ROM uses code that doesn't run properly on a CPU that old. It'd be the same reason why a PCI card Option ROM for a PowerPC or other arch wouldn't work on x86.

Another possibility is that the VIA controller chip isn't wired up properly, or just isn't compatible with such an old chipset. I've seen some reports of VIA controller chips not being wired to the PCI slot properly, and it causes them to not work on older chipsets, or some more modern chipsets.

 

[luRaichu]

I erased the EPROM which previously contained Memphis and wrote a "Digger" option ROM to it instead.
That game booted up just fine on the Ethernet NIC. Which means the Memphis ROM and VIA VT6421A card cannot work on the 430TX chipset.