PDP-8/I memory problem (fwd)

From: Robert Krten <root_at_parse.com>
Date: Wed Nov 5 13:07:47 2003

Forwarded message:
> From: jim <jwstephens_at_msm.umr.edu>
>
> Robert Krten wrote:
>
> > If I deposit 7777, I can examine and get 3777. This machine has 8k of
> > core, and the problem is the same in both 4k banks.
> > Cheers,
> > -RK
>
> when you read memory, are here any locations where you get back a 1 bit
> in this position from residual junk data in the core?

Nope, unfortunately. I've been running "junk programs" and it looks like
they scribbled all over memory; I looked through the first thousand or
so memory locations, hoping for a 4000 bit, but no luck :-(

> might be a clue what is wrong with deposit vs rad.
>
> can you examine other registers from the front panel and change that bit, or
> is it just the core?

No other registers are accessible from the front panel -- you're think of the
PDP-11 :-)

> if you can examine the registers, IIRC, can you put a program in there to load
> a constant and deposit it in core? This would exercise a different path to the
> core, though I know that the front panel is probbly doing a step to do the
> deposit.
>
> I may be crossing wires with the pdp11 as far as the registers being
> addressible in
> memory, if so I apologize, it's been a long time, and I have no handy manual to
> verify
> this for you.

No problemo; appreciate any help I can get :-)

Cheers,
-RK

--
Robert Krten, PARSE Software Devices +1 613 599 8316.
Realtime Systems Architecture, Consulting and Training at www.parse.com
Looking for Digital Equipment Corp. PDP-1 through PDP-15 minicomputers!
Received on Wed Nov 05 2003 - 13:07:47 GMT

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