MEM11 Status Update

-----Oorspronkelijk bericht----- From: Guy Sotomayor Sent: Tuesday, January 20, 2015 6:27 AM To: cctalk at classiccmp.org Subject: MEM11 Status Update As some of you know I've been working (on and off again) a multi-function Unibus board that contains all of the more difficult items to allow a PDP-11/20 to run Unix V1 entirely within the CPU chassis. Other than the CPU and the RK11-D controller, everything else will be on the MEM11 board. Here's the background on what the MEM11 is and the current progress. TTFN - Guy Awesome Guy, excellent job! Looking forward to see some documentation. Having read the responses, these are my thoughts. Your current implemented device list is "good enough" for me, although I can understand that people would like simulated RK05 drives. But I do have an RK11 ... but RP11 will never be possible, isn't that MASSBUSS!? A real RX01 is not too difficult to obtain and would go nice with the /20. BTW, the RX01 emulator would also fit, giving you an emulated RX floppy drive on a PC connected via the LPT: port ... I'm rambling ... ;-) Ahhh, the "old story" of correct PDP-11 bus receivers/transceivers ... If you install the MEM11 "option", how much additional bus loading will you ever do? I can see an RK11 or RX11, but what else? So, wouldn't it be possible to use the TTL "replacements"? IIRC 7439 or something with those numbers. If I can afford the MEM11, I am in for one ... probably have to get my 11/20 CPU back in working order first though ! A stupid idea just came to me, forgive me. If there is room left on the PCB, would it be possible to add two 8-bit DACs? One connects to address lines 0~7, and the other to 8~15. If you add an old-style TEK scope (the one with the rectangular CRT in the middle and at both sides one plug-in unit) and connect the DAC outputs to X and Y, you can see "where in the memory" the CPU is fetching/storing data. I saw that "screen output device" once on a picture :-) Thanks for this great effort, looking forward to read/see more! - Henk, PA8PDP