On 5 Jun 2017 16:12 +0200, from w.f.j.mueller(a)retro11.de (Walter F.J. Mueller): I'm curious whether the same thing happens if you try that in some other shell? (Not sure how widely here documents were supported back then, but I'm asking anyway.) The PC value in the panic report ("pc 161324") strikes me as high, but 161324 octal is 58068 decimal, so it's not excessively so, and perhaps in line with what one might expect to see with a kernel pinned near top of memory. Are the offsets in the backtrace constant, i.e. does it always crash on the same code? Not knowing what cpuerr 20 is specifically doesn't help, and at least http://www.retro11.de/ouxr/29bsd/usr/src/sys/sys/trap.c.html#n:112 (which doesn't seem to be too far from what you are running) isn't terribly enlightening; CPUERR is simply a pointer into a memory-mapped register of some kind, as seen at http://www.retro11.de/ouxr/29bsd/usr/include/sys/iopage.h.html#m:CPUERR, and at least pdp11_cpumod.c from the simh source code at http://simh.trailing-edge.com/interim/pdp11_cpumod.c wasn't terribly enlightening, though of course I could be looking in entirely the wrong place. -- Michael Kjörling • https://michael.kjorling.se • michael(a)kjorling.se “People who think they know everything really annoy those of us who know we don’t.” (Bjarne Stroustrup)