🚀 go-pugleaf

We run Ultrix 2.3 on a VAX 8200.  Since upgrading to 2.3 before Christmas,
we've been getting the following type of error on different lines on a dhu11
on our UNIBUS:

----- EVENT INFORMATION SEGMENT -----

EVENT CLASS                             OPERATIONAL EVENT 
OS EVENT TYPE                  250.     ASCII MSG 
SEQUENCE NUMBER                 12.
OPERATING SYSTEM                        ULTRIX 32 
OCCURRED/LOGGED ON                      Sat Mar  4 12:58:57 1989 WET
SYSTEM ID                 x05282B14
OCCURRED ON SYSTEM                      v1 
MESSAGE                                 dhu0,line9 DHU HARDWARE ERROR.  
                                          TX.DMA.START failed 

These occur 2 or 3 times a week and cause the line to hang up for an
indeterminate period.  Field service have replaced the board twice to
no effect.  During these hang-ups, the program "sps" on Ultrix shows
a process trying to write to the terminal line but stuck inside the driver.
(Consequently the process won't kill).   As far as I've seen, the process
has been either a terminating login shell or the getty program.

DEC suspect (without evidence so far) a hardware error further up, eg in the
UNIBUS.  Anyone know of another explanation?
The list of hardware on the UNIBUS is: Camtec DEXPAND x25 board, controller
for EXABYTE tape, DEUNA, TU80 controller, DHU11, DMF32.
-- 
  Robert Evans, Dept of Computing Maths, University of Wales College of Cardiff,
  PO Box 916, Cardiff, Wales, UK, CF2 4YN.  Tel: +44 (0)222 874000 x 5518
  E-mail: R.Evans@computing-maths.cardiff.ac.uk     UUCP: R.Evans@cf-cm.UUCP