6 Sep
2014
6 Sep
'14
12:57 p.m.
Hi all --
The CPU in the 11/05 seems to be behaving nicely as far as I can tell,
now that the Microcode ROMs are no longer filled with bogus data. It
will run small programs I've toggled in without issue, and so I've moved
on to testing the memory.
Basic testing (via the simple address test listed here:
http://www.psych.usyd.edu.au/pdp-11/hints.html) reveals that most of the
8KW of core (H215) and controller is working pretty well, except for a
128 byte range between 012000(8) and 012200(8). Within this range, all
words read back as all zeros regardless of what is written.
Given the nature of the fault, I tend to think that this is not an
addressing problem or an issue with the core drivers -- if it was any of
these I'd expect the fault to repeat across the memory space in a
pattern, rather than being isolated to a single contiguous block of
Maybe, maybe not.
You ahve 8192 words of core IRIC. That's 2^13. An obvious way to address
that is as a128*64 matrix (2^6 by 2^7).
Now, if one of the '64 diriection' drives has fialed, 128 words of core
would be inaccessible. And t may well appear to be a contiguous block, it
depends on how the addressing is done.
I would certainly check the address drvers first, they ara a lot easier
to fix than core planes.
-tony