11/34 sanity check

Don North north at alum.mit.edu
Sat Apr 25 01:40:43 CDT 2015

On 4/24/2015 9:32 PM, Josh Dersch wrote:
> While I was waiting for the Ridge's disk to dump over a 9600bps serial port, I 
> finally got a chance to work on my 11/34.  Picked it up last summer and it was 
> in good shape but the power supply was completely dead.  I've rebuilt the 
> supply and last night I worked out the last few kinks.
> So at this point all voltages are spot-on, the AC LO and DC LO signals are 
> high (these are active low, right?) but I can't get the machine to respond at 
> all -- the "DC ON" and "RUN" lights are lit up brightly, and the "SR DISP," 
> "BUS ERR," and "MAINT" lights are glowing dimly.  The status register display 
> is dark.  The system does not respond to any keypresses on the panel.
> I'm getting better with UNIBUS stuff but I wanted to run this past you guys 
> before I whip out the debugging tools and start tracing things.  I've taken it 
> down to a pretty minimal configuration, sans any memory or other stuff.  
> Here's what I have in the main backplane (all others are disconnected for the 
> time being) from right to left:
> Slot 1: M7266 (CPU)
> Slot 2: M7265 (CPU)
> Slot 3: (AB) M9301 (bootstrap terminator) / (CDEF) M7859 (front panel board)
> Slot 4: empty
> Slot 5: empty
> Slot 6: empty
> Slot 7: empty
> Slot 8: empty
> Slot 9: (AB) M9302 (terminator)
> The "empty" slots have Grant Continuity boards installed and the NPG jumpers 
> on CB1-CB2 are all present on the backplane.  I've confirmed that all the 
> right voltages are making it to the backplane (and I've cleaned up those 
> damned Molex connectors as well, just to be sure). Is there anything I'm 
> missing?  Anything I should try?  Does this failure mode sound familiar at all?
> Thanks as always,
> Josh

What is the M9301 configured to do on power up / init? S1-S10 all ON should take 
you to the console emulator.
Which means you need a console TTY interface DL11-W M7856 in one of the empty 
SPC slots.
Without the DL11-W (and no memory either) the CPU (if functional) will  boot and 
then soon die as it tries to access a missing console interface.

Without those probably all you could do it put the KY11-LB programmers console 
into single microstep mode and see the microcode step thru the powerup / init 
flow, step thru a few instruction fetches, and then die with a (probable) double 
bus fault.

So I would check your M9301 switches, get a console, and get a memory board as well.

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