PDP-11 Memory

[Bill Gunshannon]

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