uVAX II Memory Board

Jerome Fine replies: I knew that part already - must be that way since the uVAX II can use 16 MBytes of memory whereas the Qbus can handle only 4 MBytes of memory. I was sort of hoping (dreaming) that someone has noticed these 8 Mbyte boards going to sleep and the PDP-11 still looking for additional memory. I realize it is probably impossible, but how does the 11/83 manage to use both the Qbus for disk I/O and the PMI for memory? And if the PMI memory is below the CPU rather than on top, the 11/83 reverts to an 11/73. If I ask enough dumb questions, maybe one of them might lead somewhere? Didn't you once make a (very small) disk memory out of some old DEC memory board? Or was that normal Qbus memory but at a high address with a gap from the regular memory. What would it take to build a small interface that looks like the HD hard disk from E11 as far as an actual hardware interface is concerned? Could it loop right back into this uVAX II memory board via the 50 pin header on top? Since the Qbus interface is already there in the backplane, maybe that interface could be added to the 8 Mbyte of memory? See, I said I would ask dumb questions! Since I know nothing at all about hardware design, I can ask all sorts of questions since I don't know enough to know when something is impossible. Sincerely yours, Jerome Fine