What you really need is a PC driver that accepts the
fact it isn't
the highest priority device, and leaves the bus reset line alone.
Don't forget that the MicroVAX 3100 console
also assumes that it is the only master on
the bus. I don't think anyone envisaged doing
this sort of thing at the time that was written.
Later on (sometime during Alpha development)
consoles became a little brighter and a shared
SCSI bus (mainly for OpenVMS clustering) became
possible.
Antonio