On Tue, Sep 21, 2021 at 12:05 PM Aaron Jackson via cctalk <
cctalk at classiccmp.org> wrote:
My PDP-11/73 has started misbehaving after several years of being very
stable. It is showing symptoms similar to when I've forgotten to enable
the LTC in the past, except this time, it is enable.
Power supply seems good - +5V, +12V, all seems there and appears to be
stable. I've probed the LTC going onto the backplane and I'm getting
50Hz. It looks a tad noisy, not sure if this is a problem. I will see if
I can get a picture of it, but it has very distinct rises and falls, so
hopefully that's ok. Looks to be about 50% duty cycle.
I've attempted several builds of the kernel, including the
out-of-the-box build from 2.11BSD distribution. I've also compiled a
shrunk down kernel without a bunch of devices I don't have, but it still
fails to work. I am using a SCSI2SD so it's easy for me to copy images
and test them in SIMH - they all boot fine in SIMH with a similar setup
(mscp, tmscp, 11/73, 1MB-ish RAM).
Does anyone have any ideas what might be causing this? I've run out of
ideas unfortunately. I'll stick a dump of the boot below, with debug
flag passed showing output from autoconfig.
I've also tried it without the tmscp card - just CPU, RAM and Emulex
UC07 in MSCP mode for scsi disk. I have tried it with less memory, and
I've tried removing the halt jumper from the 11/73 board (W5 if I
BOOT> DU 0
73Boot from ra(0,0,0) at 0172150
: ra(0,0,0)unix -D
Boot: bootdev=02400 bootcsr=0172150
2.11 BSD UNIX #116: Wed Dec 31 18:01:57 CST 1969
root at localhost.2bsd.com:/usr/src/sys/GENERIC
ra0: Ver 5 mod 13
ra0: RA81 size=1216601
phys mem = 1179648
This is an interesting amount of physical memory to report (1152K). What
memory board(s) do you have installed?
Other than that, this output looks sane to me. I'd suggest booting XXDP
and running CPU, memory diagnostics from there.