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DEC units on ebay

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The RD-52's might be of some interest for anyone wishing to upgrade a floppy-only (RX-50) DECmate II.
Hopefully at least one of them is in a useable state.
 
I purchased one of the M8190-AE boards that were on eBay last week, along with an -09 DCJ-11 CPU module (from a different vendor). It is nominally working: Passes the POST diagnostic and boots into 2.11BSD with my QBone supplying 4MB of memory and emulated MSCP hard disk storage. So, a lot has to be ok. Problem is that the OKDAG0.BIC diagnostic throws a number of errors. When the test starts, I see a message 'BCSR<12> DOES NOT DISABLE LKS TEST 000037 PC 117676'. Then it strobes the LEDs on the CPU board. When I hit a key to continue it throws about a dozen errors in the form 'UNEXPECTED TRAP TO 4 TEST 000340 ERROR PC 123736' (shows PC = 0 on the last few then hangs with RUN LED off). I'm thinking the first error is due to the fact that I'm running it in a BA13 enclosure that's been extended to 22-bits on the Q slots. The final cascade is more concerning. I cannot find a test '340' in the sources or documentation so it's unclear what's being flagged. Something in the back of my head suggests this is a basic setup or system configuration problem but I could use some input from more experienced folks.
 
No, I do not have parity memory installed. Using the Qbone to supply all 4 MB. Wonder if I'm missing an important SWR setting?
 
Turns out to be some sort of incompatibility in the QBone memory emulation. If I plug in a 256k CMOS memory board and turn off memory in the QBone configuration the cascade of traps goes away. Still complaining about the "...DOES NOT DISABLE LKS.." issue, but since I'm not running in the proper BA23 backplane I'm guessing something is missing - maybe a register to control LTC on the backplane? At any rate, the CPU is alive and well.

UPDATE: The message about the LKS register is another QBone emulation incompatiblity. If I turn off KW11 emulation the message does not appear. I'll report this stuff to Joerg.
 
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Oh that one's a pretty simple fix: One of the - power supplies is out, probably due to a blown transistor. On my VT52 it was the -15v supply, I started to troubleshoot it then just said screw it for now and put in a 7815. Worked perfectly since.
 
Steve Toner said:
Wouldn't it be a 7915 for a -15V supply?
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Yep. Mis-remembered it. Once I decided to go this route the toughest part was finding a spot to mount it on the big heat sink in there. I thought about replacing the transistors, but just figured it's easier to go with modern technology sometimes.

Oh and make sure to put heat sink compound on the part of the sink that attaches to the back of the unit. That's a part of the heat distribution network as well.
 
Roland Huisman said:
A huge pile of RX8E / RX28 controllers for sale? :oops:

www.ebay.nl

DEC M8357 RX8-E OMNIBUS INTERFACE 5011374 B for PDP-8 SYSTEMS | eBay

DEC M8357 RX8-E OMNIBUS INTERFACE 5011374 B for PDP-8 SYSTEMS | Computers/Tablets & Networking, Vintage Computing, Vintage Parts & Accessories | eBay!
www.ebay.nl
Click to expand...
I offered $100 for one of these boards and it arrived yesterday. It works perfectly, was well packed, very clean and the gold edge connector fingers look as if the board has only been inserted and removed once. There are some pen marks on the dip switch and some small scratch marks on the blue connector, but otherwise the board seems almost new. The seller still has more than 10 available.
 
Well I finally caved in and offered $300 for the Clearpoint 4mb PMI memory card. After someone here said they had one and it worked, it was too much to resist.

Positive side, it's small and I can swap out the MSV11-QD card.
Negative side, $300. But PMI!

I'll benchmark it against the Q bus memory and see how it does in the 11/83.
 
Private memory interconnect. It's.... well I used to think it was a separate memory bus for Q-bus systems but in reality it uses the CD bus to provide signaling allowing the processor to load two 16 bit words into cache in every memory cycle. Which is still nice, and does allow the processor to work at closer to its max speed than if it has to wham away at the Q bus to get instructions and data.

You can use a PMI memory as a normal Q bus memory (yes, even the 11/84 specific PMI memory) but it should work quicker in PMI mode.
 
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