>>>>> Alan Barrett writes:

Alan> Are you sure that the refusal to boot comes from the BIOS,
Alan> rather than from the code in the MBR?

Definitely, at least on one of my machines. It will hang solid during
the BIOS IDE disk probing (!) if I install NetBSD starting at sector 0
on an IDE disk. It never reaches the SCSI probe, or the actual
"booting", I have to hit the reset button. If I put "not installed" in
the BIOS for the offending disk, it will boot ok (from a SCSI
disk). When NetBSD is up I can use the IDE disk without problems.

Leaving the first track free on the IDE disk makes the BIOS happy, and
the disk bootable.

        -- Urban

P.S. this was no more than an anecdote... ;-)