New QBone Question

[Dan Schlegel]

Hello everyone!

I'm new to PDP-11's and the QBone, so this is probably user error but I hope someone can help.

A couple years ago I bought what was probably a PDP11/03 chassis out of some industrial machine. It's as a H9270 backplane and power supply. I validated that the power supply is operating properly. I got ahold of a bunch of boards for it, but all in unknown / untested condition. Since this sounds like a debugging nightmare for someone new to the hardware, I bought a QBone figuring I can test boards by emulating other parts of the system.

I just received my QBone the other day and slotted it into position 1 in the backplane. I'm using a VT220 as a terminal and it successfully boots. But, when I try to run the demos, for example:

./rt11v5.5sj_dl1.sh -aw 18

it does the power reset, waits 3 seconds, then says: "Disable memory emulation, size physical memory" and hangs forever.

Does anyone have any idea what my next steps should be?

Thanks!

-Dan

[Dave Plummer]

Does trying again help sometimes?  Or 3-4 times?

I’ve found the memory sizer can do DMA before the bus is ready and will hang in DMA.  I’m not a “PRU guy” but I added a small delay to let the bus go quiescent and that helped.

But in my case, it’s kind of random.  It’ll start sometimes, hang sometimes. This fixes the sometimes, but not sure if its the right fix.

- Dave

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[Jay Jaeger]

Several things occur to me...

1)  You don't mention a CPU card.  If you don't have one then you can only do QBone arbitrated DMA.   The QBone itself can only emulate a PDP-11/20, last I recall - not sure how that emulation would reaction to a QBus backplane.   (PDP/11 03 and 11/23 CPU cards are not hard to find on eBay.  (11/73, too, but more pricey)). 

2)  Is the bus properly terminated?  (Not likely the issue on a short QBus, but worth checking/knowing)

3)  Have you run the diagnostics to check your QBone and some aspects of the bus (I seem to recall this will require changing some switch settings on your QBone.)

JRJ

[Dan Schlegel]

Ah ha! Thank you all! I put in an 11/03 CPU card and all is well! I had some misconceptions about what was a normal initial configuration. Now the fun can begin!! :) 

Thanks again! 

-Dan

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