VAX 750 tbuf machine checks

[Don Speck]

>   550 rsanders at usgs2-multics.arpa... User unknown
Sigh, have to post to everybody.

    Make sure that you are actually getting tbuf errors.
There are about a dozen problems that are printed out under
a "cp tbuf par flt" banner.  If the cache err register is
non-zero, then you actually have a cache error, etc.  Get
out your VAX hardware handbook.
    One of our 750's got cache errors about every 15 minutes
of non-idle time.  Yes, it was a Rev. 7 cpu, and yes, I had
the patch to correctly recognize tbuf par faults - neither of
which helped, because it wasn't the tbuf.  Swapping the L0003
board was the cure.  We went 'round and 'round with DEC Field
Circus, with them continually asserting "it's your software",
before we got them to consent to at least try swapping the
board.
	Don Speck	speck at cit-vax.arpa