The 3Com 3C905B-TX is a bus-mastering 100Mbps PCI network card.
- 3Com 3C905B-TX underside.jpg
This card's boot ROM socket will take a standard 32-pin EEPROM/Flash chip. The high address lines are not connected however, so only chips 128kB and under can be used. If chips larger than 128kB are used, their upper address lines will be left floating, causing unpredictable results (the bytes may change randomly as the address changes unexpectedly.
The card's DOS drivers come with a configuration program (3C90XCFG.EXE) that can be used to enable the ROM socket. The base address cannot be adjusted as this is controlled by the BIOS as part of the PCI device configuration process.