On 1/11/19 3:38 PM, Pete Turnbull via cctalk wrote: > On 11/01/2019 19:59, Bill Gunshannon via cctalk wrote: > >> MicroPDP box has first three slots A-B-C-D to support PMI >> memory and the rest are serpentine A-B. >> >> Even giving a bus grant problem, I can't see that causing a CSR >> error. I will probably have to dig out another box this weekend >> just to be sure there isn't a problem with the backplane. > > Without knowing exactly what cards you've got in there, it's hard to > tell. There are quad-height cards that work only in straight (A.B.C.D) > backplanes/slots, and quad cards that work in either straight or > serpentine. There are cards that use or expect (or won't permit) certain > signals on some pins which work fine in 18-bit backplanes but not > 22-bit. There are things that will work in a BA11-S with H9276 > backplane (which is what you had, if it really was a PDP-11/23plus) but > not a BA23. You probably need to make a list of what you're using and > check through the relevant Micronotes about compatibility.
Listed what I'm using in the beginning of this thread. Just CPU and Memory at this point. Will add disk and network when I get this part working. > > BTW, BA23 and BA123 microPDP-11 backplanes aren't the same - it's the > first 4 slots that differ in a BA123, and slot 13 is different again. > Take a look at http://www.dunnington.info/public/PDP-11/QBus_chassis > Mine are all BA23. Wasn't the BA123 for the MicroVAX? bill
