PDP-11 Memory
Bill Gunshannon
bill.gunshannon at hotmail.com
Fri Jan 11 14:51:17 CST 2019
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
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