Codata (V7): strange memory faults crash the system

[Sam Kendall]

The problem: periodically (lately once or twice a day) the system
decides that there should be lots of memory faults.  Most commands you
type die horrible deaths; eventually your shell dies and you are gone.
Likewise for the other users.  The only solution is to reboot.

The system: Codata 3300 (a 68000 box) running Unisis 3.1.1 (Codata's
UniSoft V7).  Lots of serial I/O (netnews, 2 modems), disks (3 Atasis,
each with several ~10 MB filesystems; and we are frozen forever at 52
system disk buffers, no more), and load (netnews, some large interactive
programs).  All three of these factors have increased recently.  We have
1.3MB of RAM and rarely swap.

Has anyone seen something like this on a Codata, on a UniSoft V7 system,
or on any V7 system?  Maybe some inconsistency in the memory management
(?).  If it were something simple, like this happens iff processes start
swapping--but that doesn't seem to be it.  Any solutions for a
binary-only machine, with no new system releases expected ever?

----
Sam Kendall			     allegra \
Delft Consulting Corp.		seismo!cmcl2  ! delftcc!sam
(212) 243-8700			       ihnp4 /
ARPA: delftcc!sam at nyu.ARPA or @nyu-cmcl2.ARPA