Ok, here is some more information for anyone who might know where to look:

Booting a 1.5BETA kernel from 10/31/00 sources on a VAXStation 3100/M76. 
The kernel boots until it gets to wsdisplay0, which it sets up and then types:
boot device: <unknown>
Stray interrupt: vector 0x2c4, ipl 20
and it repeats the last line infinitely.

Anyone have any clues? Userland is 1.5ALPHA2

--Chuck