jmc (03/30/83)
We have twice got into a situation where UNIX has consistently bombed out on PDP11s, once on an 11/24, once on an 11/44 at customer sites. In both cases the DEC test software has not revealed any errors in the hardware, but the problem has gone away (or appeared) when processor boards have been changed. I have this theory that the DEC test software does not run the processor with the UNIBUS map enabled, and is written to live in the bottom 256kb or less, and thus if there is some marginal problem involving transfers with the map enabled, it does not show up except under UNIX. I am certain of this with the 11/44, since the crashes occurred almost immediately after the point where the map is enabled. Can anyone confirm this? Can anyone tell me where I can get a version of the test software that checks out the UNIBUS map? Or am I barking completely up the wrong tree? Thanks John Collins, Root Computers Ltd ...!lime!ukc!root44!jmc ...!decvax!mcvax!ukc!root44!jmc