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Build attempt for PDP-11 from spare boards - will they work together?

C

ccureau

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Sep 28, 2019
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Location
Louisiana
Hi everyone!

I've finally scored a working BA23 and power supply (which I recapped), and now I'm hoping to start my physical PDP-11 journey!

I've got a few different options to build from, but what I'd really like to do is the 11/83 CPU. To that end, I have a couple of M8637 boards, but I think at least one of them is an older revision and won't work with the QBUS. So, I guess that's question one...will these work?

1. MSV11-JB - I think this one is the older revision according to the field guide.
2. MSV-11-JE - This one should work, but the CPU reports an error at test 47 (Memory Parity/ECC)

I also have a M7608, which appears to be a 4MB board for the MicroVAX. I know it isn't PMI, but could this be used with the 11/83?

Secondly, I have a DHV-11 with the single bulkhead port, but sadly no cable to split it into individual ports. I've been unable to find any sort of diagrams online for wiring this up without the mux...does anyone have some knowledge to share?
 
I would suggest reading this manual: http://www.bitsavers.org/pdf/dec/qbus/EK-MSV1J-UG_001_May85.pdf page 1-3.

The -JB is for an 11/84 only.

The -JE should work on an 11/83.

For error 47 I would check the backplane you have installed in the chassis. Is it a 22-bit QBUS backplane - or an 18-bit?

I had a fault on my 11/83 CPU card where one of the address lines was faulty. This resulted in exactly the same error as you are reporting. When I installed a much smaller QBUS memory card, I found it appearing in two (2) memory locations with the same CSR.

Dave
 
The backplane is definitely marked as H9278-A. Good callout though...
I can try installing a smaller memory module I have, though I'm unsure that it works. I guess we'll see.

Update: Seems all I have are some 18-bit memory modules...I don't think they'll work in a 22-bit system.
 
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If you are really stuck with the DHV11 cabling and bulkhead connector I may have one at work that I could provide the pinout for.

However, I am sure I have seen this documented somewhere... Almost certainly Bitsavers :).

Dave
 
You can use 18 bit only boards for up to 256KB memory TOTAL - it will work for testing and a small memory system...
 
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