>.. single PDP11 simulator can simulate different PDP11 models .
Yes, and the UNIBUS and QBUS peripherals don't always map exactly in functionality. Actually I'm surprised this situation hasn't come up before with other devices. >Feel free not to use the extra ports that are provided free of charge. J You're right - for the most part it doesn't matter. But, . if you're using the DZV/DZQ simulation with a TELNET port (which I imagine is what most people do) then I don't think you can stop simh from accepting a connection for lines 4..7 if the first four lines are already busy. And if you want to simulate a QBUS machine with 8 lines and two DVZ/DZQ cards, then what the OS actually sees is all eight connections coming in on the first card and none on the second card. I haven't tried it yet, but I don't know what the various -11 OSes will do when they get activity on lines that can't physically exist. Probably they use the same driver for both the DZ and DZV so they won't care, but I don't know that. > What should happen when an odd number of DZV11's are configured and the CPU type is changed . Well, ideally there should be an error or warning message, but I imagine that's difficult to implement. For me, I'd be happy if simh was changed to accept "SET LINES=." in multiples of 4 rather than multiples of 8. It's true that this would possibly allow you to create invalid DZ configurations, but in my mind the possibility of deliberately defining an invalid configuration is less annoying than the impossibility of defining a valid configuration. Bob
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