20 Oct
2021
20 Oct
'21
5:10 p.m.
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:
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 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.)