>> My machine can neither send nor receive(!!!).
>
> Well, FWIW, I just upgraded venus here to a 5000/240 that was laying
> around unused, and *neither* of the serial ports coming out the back
> of it function (I use a serial port to control a robot optical disk
> changer).  I suspect, without really knowing, that the two serial
> ports in back are run by one double-channel DUART, which is blown, so
> both my serial ports are gone.

IOASIC DECstation (3MIN and 3MAX+) has two Zilog 85C30s.  Those chip
have two channels each.  Serial ports behind chasis are connected with
B channels of them respectively, while remaining two A channels are
used for LK keyboard and VSXXX mouse.  It might be technically
possible that both of chips are equally dead, but I suspect there is
an unidentified reason for serial port woe.

Tohru Nishimura
Information Technology Centre
Nara Insitute of Science and Technology