PDP-11 Memory

Most Probable cause is interrupt grant is broken. For most microspheres backplanes the first three slots are different than remaining. Phoned this in! On Jan 11, 2019, at 12:28 PM, Bill Gunshannon via cctalk <cctalk at classiccmp.org> wrote: Well, it has been so long since I had to put together an entire system I forgot what fun it can be. With almost documentation I was able to configure 4 1meg memory modules and I tested them all in my 11/23+ box. KDJ11-B with 4 different (but similar) memory cards. "MAP" option of the KDJ11 shows 4 meg (minus the I/O Page) and all the right CSR's for the first four blocks. Really wanted to make this a deskside so I moved the cards to a MicroPDP box (Yes, I have a coule of the deskside pedestals). Power on, Memory CSR error. Move then back to the 11/23+ works fine. If I only put the first three in the MicroPDP box it works. But as soon as I try to put in a fourth module I get the memory CSR error. Tried different cards (although working in the 11/23+ box would make me think it is not a problem with the card) no help. Anybody care to take a stab at what might be causing this problem? bill