PDP-11/45 RSTS/E boot problem
elson at pico-systems.com
Mon Feb 4 21:09:16 CST 2019
On 02/04/2019 11:34 AM, Fritz Mueller via cctalk wrote:
>> 2. Make a copy of ls, and see if the copy also fails
>> (different location on disk would mess with timing just a bit).
> Also done; the copy appears to behave identically to the original.
OK, here's a really complicated thing to try. If you know
the physical memory address of ls when it has the problem,
write a machine language program that loads a copy of ls
into that location and then tries to read it back. You
might be able to do this in Unix, having it start with the
exact code of ls, but then has the tester above that and the
entry point is for the test program.
This would detect a pattern sensitivity in the memory. If
ls, when actually running reads an instruction wrong, it
could then try to read a bad address, and cause the MMU trap.
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