This info is specific to the 742a but may also cover other Buslogic cards. (Bustek = Buslogic)
There are 2 general ``versions'' of the 742a card. They are hardware revisions A-G, and revisions H - onwards. The revision letter is located after the Assembly number on the edge of the card. The 742a has 2 ROM chips on it, one is the BIOS chip and the other is the Firmware chip. FreeBSD does not care what version of BIOS chip you have but it does care about what version of firmware chip. Buslogic will send upgrade ROMs out if you call their tech support dept. The BIOS and Firmware chips are shipped as a matched pair. You must have the most current Firmware ROM in your adapter card for your hardware revision.
The REV A-G cards can only accept BIOS/Firmware sets up to 2.41/2.21. The REV H- up cards can accept the most current BIOS/Firmware sets of 4.70/3.37. The difference between the firmware sets is that the 3.37 firmware supports ``round robin''.
The Buslogic cards also have a serial number on them. If you have an old hardware revision card you can call the Buslogic RMA department and give them the serial number and attempt to exchange the card for a newer hardware revision. If the card is young enough they will do so.
FreeBSD 2.1 only supports Firmware revisions 2.21 onward. If you have a Firmware revision older than this your card will not be recognized as a Buslogic card. It may be recognized as an Adaptec 1540, however. The early Buslogic firmware contains an AHA1540 ``emulation'' mode. This is not a good thing for an EISA card, however.
If you have an old hardware revision card and you obtain the 2.21 firmware for it, you will need to check the position of jumper W1 to B-C, the default is A-B.