Process hanging on AT&T 6386 Sys V R3.2

[Doug]

I'm having a problem with an AT&T 6386 running System V/386 R3.2 using
an AT&T IPC-802 Intelligent Ports Card.  A program has one of the
ports open for reading and writing.  While executing a write(2) system
call of more than one byte (although I'm not sure that matters),
something happens on the line and the process hangs.  It can't be
killed in this state.  A scan of the manuals reveals no useful information.

I guess I don't expect you to be able to tell me what is going wrong,
although it would be nice :-).  However, if someone could tell me how
you go about diagnosing what is causing this problem it would be appreciated.
A pointer to relevant documents or a place to poke around in the system 
would be nice.
-- 
Doug Scofea   Email: nimbus3!djs at cis.ohio-state.edu    Phone:(614) 459-1889