Further 11/40 unibus questions...

Paul Anderson <useddec at gmail.com> wrote: I can't remember that there should be any functional difference between a M930 and a M9300. The later is just an improved design. As for the original posters problems. When you get a stuck machine when the terminator is in, but a somewhat more functional machine when the bus terminator is out, you have a problem on the bus. Most likely a bus grant or NPR grant. A third possibility is a problem in the CPU with the logic related to these signals. I'd go over the bus grants once more. Check that they *really* are the right way, since it's so easy to put them in the wrong way, and there is basically no visible clue to which way they should go. Look at some other card to get help. They will also have connections on the same places the BG cards have, except they will likely run them up to the priority plug. If you have some Unibus memory, they are nice, since they have the BG lines wired straight through, just like the BG cards. I would have started by removing *all* cards from the Unibus (with the exception of some memory), and make sure all bus grants and NPRs were in, the terminator was in place and that all power supplies were delivering the right voltage. Also check that all cards in the CPU box are in place, and are firmly seated. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol