Thank you much for your comments.

>> Does anyone know if serial works reliably in 3.1 with older
>> (PM7x00-class) machines?
>
>No. You can still lock up the console in NetBSD 3 or NetBSD 4 by typing while getting output. That hasn't changed yet.

I have done some pretty lengthy testing of serial on the G4, and it
seems to work flawlessly.  (Obviously, the G4 doesn't have "serial ports".
I tested with the Cyclades 8-port serial card.  I suppose I could
have tried the internal modem, but my G4 doesn't have one.)

I attribute this to the differences in
interrupt HW on the older and newer style boxes.

When you say you can still lock up the console, which machine(s) do
you know to still have this problem?

-dgl-