PDP 11/35 troubleshooting

Ashley Carder wacarder at usit.net
Mon Mar 7 21:18:05 CST 2005

Ok, since everyone seems to be in ancient PDP-11 
troubleshooting mode, I decided to get out my 11/35
and see what I can do with it.

I've double checked all the processor options and
the CPU boards all seem to have the jumpers set 
correctly.  The only questionable jumpers are the
two jumpers that indicate parity memory is present,
but since the system seems to have some problems,
I've disconnected the M981 from the MF11-LP core
backplane and replaced it temporarily with an
M9302.  There is also an M7800 console card in
the SPC slot.

I've checked all the voltages and they look ok.

When I power the system on, it comes up with the
following lights lit:

Address: 000026 (octal)
Data   : 000002 (octal)

The PROC, BUS, and CONSOLE lights are also lit.

If I press HALT and then press START, all the
DATA lights come on.  The RUN light also comes
on, along with the PROC, BUS, and CONSOLE lights.

The load address, deposit, and examine switches
don't seem to do anything, although I know they
are functional.

Ideas?  Does anyone know what the ADDR 000026 and
DATA 000002 lights indicate when the system is 
powered on?


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