KDJ11-B PDP 11/73 getting stuck in Exit standalone mode diag #56

[Mark G Thomas]

Hi,

I picked up an empty 4x8 Q-bus chassis at VCF-East this year. It's 
labelled "USDC CSS-823 Processor System" on the outside. It's not a DEC 
backplane, but the chassis is light aluminum, smaller and in some ways 
nicer than my pile of BA23s. It includes a switching power supply, 
LTC and q-bus termination, and I confirmed it's wired for Q22. I was 
hoping to transplant an 11/83 into it, since it will fit more comfortably 
in my work area. It has lit DCON/RUN/LTC/HALT buttons on the front pane.
The etching on the backplane says something like "MDB Systems, Inc.
East Orange, CA 92665"

Unfortunately, I discovered slots are all wired Q22/Q22, no top ABCD 
(Q22/CD) PMI slots like a BA23. So, not good for an 11/83 CPU wired 
for PMI on slots C-D.

So, I was hoping I could get my KDJ11-B (quad-wide 11/73) running in it.
Upon power up or reset I get "Testing in progress. Please wait" on
the serial console, and the LEDs get stuck on test 56. CTRL-C doesn't do 
anything yet, and my only options seem to be to hit reset, or if I hit the 
run/stop toggle, I can reset to the ODT prompt. This is with either just 
the KDJ11-B in the top slot, or with the addition of a suitably configured 
MSV11-QA in the next slot. If I turn off the LTC on the front panel,
I get the expected Error 61 M8190 clock error, PC and register values,
and options to re-run once or loop on test, so I know the LTC is working.

I confirmed the KDJ11-B works fine in a BA23, getting past test 56. I also 
tried an 11/53 CPU here in the ABAB backplane and that gets past the self 
tests into dialog mode, but I really would like to get the KDJ11-B working
in this chassis. I do see that a couple traces to the KDJ11-B C-D slots
besides the Grant Continuity connections. I assume since the KDJ11-B
has those Grant Continuity connections on slots C-D, it can run in a
qbus/qbus Q22/Q22 quad Q-bus slot.

I noticed the FP "RUN" lamp never comes on (and is not burned out), but maybe
that's normal -- monitoring something on the bus that doesn't happen during
power on self test.

Does anyone here have suggestions about next steps in diagnosing this?

https://archive.org/stream/bitsavers_decpdp1111aintNov86_5833755/EK-1184A-MG-001_1184maint_Nov86_djvu.txt
-----------------------------------------------------------------------------
4.10.18 Exit Standalone Mode (Test 56) 

In the 22-bit mode, the exit standalone mode is checked by using the 
guaranteed timeout address of 17 760 000 to verify that the timeout 
logic works without hanging up the CPU. 
-----------------------------------------------------------------------------

-- 
Mark G. Thomas (Mark at Misty.com), KC3DRE