Is there a driver for DigiBoard
   PC/4?  This board has four serial ports which share one interrupt line.

Is this one of the `smart' boards, or one of the `dumb' ones?  My
recollection is that you can treat the `dumb' boards just like four
`com' devices.  We don't yet have support for the `smart' boards,
but we'd like to (hint, hint).