25 Sep
2014
25 Sep
'14
2:28 p.m.
On Sep 25, 2014, at 4:40 PM, Brent Hilpert <hilpert at cs.ubc.ca> wrote:
On 2014-Sep-25, at 11:43 AM, Paul Koning wrote:
That?s a good point. If the restore machinery is not working, you can only read once,
after that you?ll see zeroes. A quick check would be to pick some location and read it
several times. If that works, the restore logic is at least somewhat functional.
Still, safest would be to hook to the console. A BeagleBone Black has enough I/O lines to
do that, I think, so it sounds like just some level shifters and a modest amount of
software.
paul
On Sep 25, 2014, at 2:33 PM, Simon Claessen
<simski at dds.nl> wrote:
I can only encourage the latter approach, I did something similar for my HP 2116C 10
years ago when I received it. Once I had a monitor written and loaded I was able to
recover the remaining contents of core. It was enough to show the last thing the machine
had been doing was running a BASIC game, apparently in July of 1983.
http://www.cs.ubc.ca/~hilpert/e/HP21xx/HP2116CSys/index.html#recovery
Due to a hardware fault in the core memory, I (had) had only one opportunity to get a
full dump, which I had missed due to checking memory from the front panel and not knowing
about the fault, so I didn't get the entire contents. In my case hindsight is great,
but it's something to keep in mind if recovering the contents is of some concern.
Hello all,
The pdp8/f we got last week is working now, after forming the capacitors on the lineair
powersupply and testing it with dummyloads. there is a 8kword and a 16kword corepack in
the machine. we would like to dump the contents of the core to serial to preserve the
original contents for later examination while we can to tests with the machine.
is there a way to do this, using a empty part of memory and a M8650 uart?
One way would be to wiggle the console switches under program control, as the CHM PDP-1
team did according to an article from a few years ago.
Another would be to find, or write, a simple memory dump program, and load that in a
small bit of memory that you have previously saved by hand (from the console
switches/lights). I don?t speak PDP-8 assembler, but I imagine such a program wouldn?t be
more than 30-50 instructions total.