3b2-310 lost characters

[James R. Van Artsdalen]

We recently upgraded our 3b2-300 to a 3b2-310.  We were running System V.2.0
and upgraded to 2.0.4 at the same time we did the hardware upgrade.  We have
one serial board, and 1 megabyte of RAM.  We had been running the console and
three of the serial ports on the serial board at 19.2Kbps (the other two
serial ports were run at 2400bps and 1200bps).  With the -300 motherboard and
V.2.0, this worked fine.

After the upgrade, we began having trouble with the serial lines.  Every so
often the system would get into a mode wherein it would lose characters on
the serial ports.  When printing mail it would print some of the mail and
stop: almost as though the character output buffers were being lost.  Once the
system began this there was no way to recover without rebooting.  This
apparently did not affect operation of the CPU itself: the system would run
fine indefinitely after this started.

On the basis of some rumors I've upped the NCLIST value to 200 from 80 and
dropped the baud rate on the terminals to 9600bps from 19.2Kbps.  The problem
has not occurred in two weeks (previous frequency was about twice a week).
Rumor also suggests that the problem can be fixed without rebooting by
re-pumping the serial card.  I have not tried this.

The problem has been seen on a -310 with System V.2.1.  It has not been seen
on a -300 to my knowledge.  The -310 running V.2.1 has only seen the problem
once in a month of operation.

Has anyone else seen this problem, and does anyone know what the true cause
is?  I am not confident that I have solved it with either change.  I would
like to solve this.  With our -300 we ran the computer for months between
reboots, but now we're restarting every couple of weeks.
-- 
James R. Van Artsdalen    ...!decvax!dartvax!osi3b2!james    Live Free or Die