Looking for info on serial line device drivers

[Strider]

I am trying to solve a problem which occurs on the IBM RT when it runs
ACIS (BSD 4.3). The problem is as follows: the normal serial ports are
either on an async/printer card or on what is called a 4 port adapter.
The async card has no buffering and the 4 port card has 16 bytes of
buffering. The problem is as follows: when one is trying to use a serial
line at more than about 2400 BPS or sometimes even at slower speeds if
other processes are running, the RT begins to have real problems. Basically,
the interupts from the port don't get serviced often enough, the buffer
overflows and ... anyway, this leads to UUCP problems, and the occasional
crash. The question I have is whether there is a way of fixing this short
of rewriting the device driver properly or getting a different card with
substantially more buffering. I have heard that early versions of BSD 
running on the Vax had similar problems and that they were solved without
writing a totally new driver or changing devices. I'm looking for helpful
suggestions. Thanks.
				Bill Moran
uunet!bywater!acheron!archet!aragorn  or  moran-william at cs.yale.edu