UBSTO, UBSSYNTO, cp read fault

[stanonik at nprdc]

Recently our vax 780, running 4.2bsd, has suffered several crashes.  
The console log usually indicates "uba error <UBSTO,UBSSYNTO>" followed
by a "machine check: cp read fault", although occasionally it only
indicates the machine check.  The crashes seemed to appear after
installation of 4Mb of National Semiconductor memory, bringing our
memory to 8Mb.  (We have the ms780e memory controller.)  It doesn't
make any sense to us that adding memory could cause uba timeout
problems, but that is the straw we currently grasping at.  Any
similar experences?  Oh yes, the console log indicates that uba1 is
the crasher.  (uba0 only has a uda on it.)

Thanks,

Ron Stanonik
stanonik at nprdc