Re: Looking for info on memory
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.)
Re: Looking for info on memory
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
Re: Looking for info on memory
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
