12 Sep
2015
12 Sep
'15
10:08 a.m.
So, either something is corrupting the bus, or the
memory is bad.
Correct me if I'm wrong, but if I got this right, you wrote the boot
code by hand into memory, single-stepped it, and after a while, you had
bad contents in memory.
Now, execution here would only be reading from memory, and not writing
to it. Furthermore, this is MOS, so it does not get rewritten on reads.
That would, to me, suggest that the memory board is the problem.
Do you have any other memory board around?
Johnny
I mistyped while doing many things at once.
(It appears that the memory does NOT change while single stepping through it
by hand. Fortunately.)
See my update - reseating the ROMs fixed the boot corruption problem.
I am not sure if the 32K SRAM board actually reads and rewrites - it does
not do so internally, it's just SRAM and a couple of bus buffers.
Whether the 8/A memory cycle does rewrite each time or not, I don't know.
Now I've got yet another RL02 (maybe) problem to chase down...
-Charles