Tony Duell wrote: Thanks -- just tried this, and I still get the same behavior from the CPU. ACLO and DCLO are now pulled high. Well, this is going to be a fun project :). Guess I need to start debugging the CPU, any suggestions on where to start? (Anyone have a Unibus extender card?)

On 4/13/09, Ian King <IanK at vulcan.com> wrote: I can recommend them as well. They have some good stuff. I have one of those boards, but since I got it from Guy as a bare board, I still have to assemble mine - I plan to do that before I get back into Unibus machine debugging (that and the KM11 - very handy for debugging/repairing certain vintage items). If you can't find a hex extender, you can use three dual-height extenders, albeit with some mechanical instability. -ethan

On Apr 13, 2009, at 7:13 PM, Josh Dersch wrote: For the KM11, you want to have the maintenance manual for the CPU. There are directions on how to use the KM11. Let me know if you if you want 2. :-) TTFN - Guy

Josh Dersch wrote: I would say a pair is a necessary tool for debugging the 11/40 if there is anything wrong beyond power supplies, etc. My PDP-11/40 had a chafed backplane wire that caused it to fail the KT-11D diagnostics. I messed around with it for a month trying to debug the problem. I had no extender cards, so I would tack solder a lead onto the signal I was interested in and then probe it with a scope while a good scope loop program was running. I figured out what the problem was, but not why. Sometimes the Virtual Address was being used when it should have been the Physical Address. I finally built two KM-11s based on some information provided by Tony Duell and the real KM-11 schematics. After I had the KM-11s in hand, I fixed the problem in two evenings. Single stepping through the microcode indicated immediately that a signal was stuck in the same state. I think it was BUPP6 H. Then I had to track down why. I removed all the non-essential cards. Then I replaced the last driver IC for that signal... and nothing worked. I then traced down each backplane connection for that signal and found one that was nicked as it was pulled around a pin. I slipped a bit of Teflon tubing over the pin and all has been well since. Here is a description of my home brew KM-11 and a link to Tony's notes. http://www.chdickman.com/pdp11/Notes/KM11 -chuck

Roy J. Tellason wrote: I made a KM11 based on Tony's design back before Guy had his boards available. You can find information on mine, including the expressPCB layout files here: http://ubanproductions.com/museum.html --tom

I still have board *and* kits available. :-) TTFN - Guy On Apr 14, 2009, at 6:25 PM, Roy J. Tellason wrote:

Roy J. Tellason wrote: Hand wired using pad per hole perf board. The edge connector was scrounged from some STD bus prototype cards. What I would really like to have is a run of DEC edge connectors that I could attach to perf board. -chuck

Tony> As would I (and for that matter, some 0.156" edge fingers to Tony> use in the same way). Tony> The DEC connecotors, are, of course, at 0.125" pitch. In theory Tony> you could cut down S100 prototyping boards, but I guess those Tony> are as hard to find now as DEC prototyping boards. Give how cheap low volume dual sided PCB fab is these days, it might make sense simply to lay out a board with the connector pattern on it and send it off to be fabricated, in the quantity you want. The basic fab would give you copper connectors, not gold plated, but that may well be good enough, certainly for prototyping purposes. If the board size is modest, you can create the layout with free tools. paul

And waht behaviour is that? Can you do anything from the front panel, for example? I haev most of the DEC extender cards (single, dual, quad, hex), but that's not a lot of use to you :-) I trick I commonly use if I don't have the right extender card is to pull the board I want to work on and solder lengths of wire to useful points on that PCB. Then put the board back in place, make sure the wires aren't shorting to anything and then power up. I can then connect my test gear to the free ends of the wires. It's slower than using an extender card, of course, but typically I only need 2 or thre 'goes' (pull board, solder on half a dozen wires, put it back, test) to find the fault. =tony

I'm closer, it'd probably be cheaper. :-) -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

Tony Duell wrote: It is an M9302. Running without it produces the same results, only the LEDs seem slightly dimmer (hmm...) Part of what I'm trying to achieve here is to get some experience, so I guess it's good that it's broken :). - Josh