Check out the following URL:
It claims to be a GZIP, but it's not. It's actually just a straight ISO for a BIOS flash. I'm not sure what version it is, but I know that later versions of the BIOS had the multiplier locked and NIC was providing an earlier version without the multiplier lock, but I'm not sure if this is it.
While you're there, you might want to look at the parent directory at:
It contains an ISO for Version 3.0 of the NIC OS, the packages they used to make it, and an NFS kernel.
Let me know if you still need info about the BIOS in my machine and I'll try to get it for you.