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