Thanks for that, but unfortunately it is crashing into ODT and not accepting input from the console, which I remember was a symptom of no bank 0 memory.
Now,of course, it could be the receiver chip in the J board (I used to make a lot of money changing them ) but I have tried two separate J boards. Of course if it is 4 MB, it must be in bank zero. cheers, Nigel On 2021-10-20 7:43 p.m., Jerry Weiss via cctech wrote: > On 10/20/21 12:27 PM, Douglas Taylor via cctech wrote: >> On 10/19/2021 12:57 PM, Nigel Johnson Ham via cctech wrote: >>> I am trying to bring up an 11/23 system in a BA23 box, and the only >>> memory i have is an obscure Plessey one. The only identification is the >>> p/n 705920 with dash-100 in white ink. By counting the chips I make it >>> 4MB, but it does not respond. Since it takes the full 22-bit memory >>> space I can't see how any jumpers would change its accessibility. Does >>> anybody have a manual? >>> >>> any help appreciated, >>> >>> Nigel Johnson >>> >> Looking at the photo I began to wonder if Plessey made their own >> boards or are they re-badged from some other manufacturer. I don't >> know. If they are made by someone else, you might be able to dig up >> a manual. >> >> Also, if you look at the documentation for other 4MB qbus memories >> how many jumpers do they have? And what do they do? It may help you >> understand your board. >> >> Doug (of course I don't have a 4MB qbus memory, but that apparently >> didn't stop me from posting.) >> > Looking at the silk screening, there is a Plessey logo so this is > mostly likely there own design. Given the date on warranty I would > expect jumpers for 18/22 bus type, perhaps battery backup, parity CSR, > memory chip size, I/O page size,etc... But assuming the jumpers for > memory address start and length are in some functional configuration, > you should to poke/read ODT somewhere in the 4MByte addressing > range. You might also try to see you can read default parity CSR > for memory boards. The logic (and some circuity) for I/O page should > be different than memory decoding. > Suggest you obtain a another memory board (e.g. M8044) to verify the > other components. > > > Jerry