Well, I have since figured out that it's not NetBSD, but rather the
f***ing motherboard that is causing the boot up problem, as it
wouldn't boot the evil DOS either (I feel so dirty now).

This is the Micronics M54Pi Pentium-90 Motherboard with Phoenix BIOS
version 4.04. I am still trying to determine the exact problem, but I
suspect the problem will require replacement for a fix.

In investigating this problem I found out from Micronics that the
CFS420A from Conner (a 420M IDE disk) is apparently incompatible with
the onboard IDE controller. This must take some doing since the drive
happily reports the correct geometry to the autoconfiguration routine
in the BIOS, and can in fact be mounted and read and written to.
Whatever.

Caveat Emptor.
--
Hacksaw