problem with dz and 4.2

[James J. Roche]

We are having a strange problem with a dz on our 780. We brought up
4.2 on one of our 780's to do some preliminary work before converting
the system. As we were working, the system began crashing repeatedly with
trap type 9 (Protection faults).  After some investigation we found
that anytime we started outputting to any 2 ports at the same time
on the dz the system would crash. The pc at the time of the crash
shows that we are in the dzxint routine.

When we were finished we brought up 4.1 again and started output
to all 8 dz ports, but the system wouldn't crash.

Thinking then that maybe it was a 4.2 problem we went to our other
780 that has been running 4.2 for about 4 months and started dumping
output to all 24 dz ports, but again the system wouldn't crash.

We are now stumped. The 4.2 software works fine on one system, and the
dz works fine on the system when we run 4.1. The only difference between
the configurations is that one system has 1 dz and the other has 3 dz's.
Does anyone have any suggestions as to where the problem might be?
Any help would be greatly appreciated. Thanks
-- 

		Jim Roche
		Computer Consoles Inc.
		ccieng5:jim (CCI Central Engineering systems only)
		{rochester!ritcv, ccivax, rayssd, rlgvax}!ccieng5!jim (UUCP)