4 Feb
2019
4 Feb
'19
3:18 p.m.
On Feb 4, 2019, at 5:47 PM, Ethan Dicks
<ethan.dicks at gmail.com> wrote:
On Mon, Feb 4, 2019 at 3:15 PM Paul Koning via cctalk
<cctalk at classiccmp.org> wrote:
At the board level, yes. Deeper, it could be bad memory bits or bad
memory decode.
A simple ones-and-zeros test can identify bad DRAMs. It's not as
likely to find bad decoding, which could result in the same chips
tested more than once and other chips not tested at all. I've found
both problems in real MS11-L boards I have for my stack of 11/04 and
11/34s I'm testing.
ISTR in the DEC world, they were good about that. I have multiple
papertapes for the PDP-8, that I think were literally called "ones and
zeros" and "memory address" tests. I would think XXDP has something
similar in terms of progressive tests that expect the previous stage
passed.
Yes, one of the standard early PDP-11 memory tests is the "no duplicate address
test".
paul
On Feb 4,
2019, at 3:43 PM, Noel Chiappa via cctalk <cctalk at classiccmp.org> wrote:
That translates into "the problem depends on the physical address of the code being
executed".
The obvious answer is bad memory.