11/23 CPU problems

[utzoo!decvax!ucbvax!ucsfcgl!sdcarl!sdcatta!sdcsvax!wallen]

I've been helping some people bring up Unix on a couple
of 11/23 systems (the "50 patches" V6 version).  They have
had some hard failures of 11/23 CPUs.  For instance, on
a configuration which runs both RT-11 and diagnostics,
booting up Unix causes the system to hang.  The run light
goes out, but the system does not go into ODT.  The solution
was to swap in a new 11/23 CPU; then everything was okay.

This has happened several times.  They send the CPU back, who
sends them a new one.  Sometimes the replacement works, sometimes
it doesn't.  Has this happened to anyone else?

Mark Wallen
(wallen at nprdc or ucbvax!sdcsvax!wallen)