19 Oct
2021
19 Oct
'21
9:57 a.m.
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
19 Oct
19 Oct
2:21 p.m.
Sounds familiar, got a picture of the board somewhere?
C
On 10/19/2021 12:57 PM, Nigel Johnson Ham via cctalk 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
3:51 p.m.
It's just a memory board and looks like one!
Picture here:
https://www.mediafire.com/file/ive7i7ax6zdibv3/Screenshot_20211019_185019.p…
cheers,
Nigel
On 2021-10-19 5:21 p.m., Chris Zach via cctalk wrote:
Sounds familiar, got a picture of the board
somewhere?
C
On 10/19/2021 12:57 PM, Nigel Johnson Ham via cctalk 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
>
4:55 p.m.
Hm, ok all my Plessy boards are dual height, 1mb boards. Are you sure
the 11/23+ is working, and do you have the CPU in slot 3 with the memory
board in slot 4 (staying away from the PMI slots)?
C
On 10/19/2021 6:51 PM, Nigel Johnson Ham via cctalk wrote:
It's just a memory board and looks like one!
Picture here:
https://www.mediafire.com/file/ive7i7ax6zdibv3/Screenshot_20211019_185019.p…
cheers,
Nigel
On 2021-10-19 5:21 p.m., Chris Zach via cctalk wrote:
> Sounds familiar, got a picture of the board somewhere?
>
> C
>
> On 10/19/2021 12:57 PM, Nigel Johnson Ham via cctalk 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
>>
5:50 p.m.
In all the hundreds of systems I have shipped, I have never put the CPU
in slot 3! I was VP Operations of Transduction, DEC's biggest components
group OEM in Canada.
No, I don't know if the CPU is good (it is a dual-width KDF11-A btw),
but it is in slot 1 AB with a DLV11J in slot 2AB.? The memory has been
in slot 3 as well as lower.? Since there is nothing above or below it on
the CD side there cannot be any interference in the CD connectors.
I do have an 11/73 dual width board arriving tomorrow so will see if I
get the same results with it.
Thanks for reading,
Nigel
On 2021-10-19 7:55 p.m., Chris Zach via cctalk wrote:
Hm, ok all my Plessy boards are dual height, 1mb
boards. Are you sure
the 11/23+ is working, and do you have the CPU in slot 3 with the
memory board in slot 4 (staying away from the PMI slots)?
C
On 10/19/2021 6:51 PM, Nigel Johnson Ham via cctalk wrote:
> It's just a memory board and looks like one!
>
> Picture here:
>
> https://www.mediafire.com/file/ive7i7ax6zdibv3/Screenshot_20211019_185019.p…
>
>
> cheers,
>
> Nigel
>
>
> On 2021-10-19 5:21 p.m., Chris Zach via cctalk wrote:
>> Sounds familiar, got a picture of the board somewhere?
>>
>> C
>>
>> On 10/19/2021 12:57 PM, Nigel Johnson Ham via cctalk 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
>>>
8:03 p.m.
It can be done, technically the 11/83 and 11/93 put the CPU in slot 3
with the PMI memories in slots 1 and 2. Putting the CPU in slot one with
the PMI memory in 2 and 3 would just cause all memory access to slug
across the Q Bus.
So you can leave slots 1 and 2 open if you really want to, makes it
easier to deal with possible PMI screwage (I always wondered if one
could put a CPU in slot 1, then the M8013/8014 RL01 controller in slots
2/3 but I don't remember if the 813/8014 will work in a 22 bit unit
without catching fire or something).
Anyway, just try running the CPU in slot 3, then the memory in slot 4,
and the DLV11J in the right side of slot 5. That would simplify things
as much as possible.
C
* PS: Right now I'm running my 11/83 in slot 1 with a 2mb PMI memory
board in slot 2 and the TK70 controller in slot 3. The reason is that
the PMI memory board is from an 11/84, and it has the bug that prevents
it from working properly in a true Q Bus system.
I *think* the bug is related to concurrent memory access from both the Q
Bus DMA and PMI bus as just using the memory as a Q Bus memory has no
problems. A true 11/84 works because there is nothing on the Q-Bus as
all memory access is done through the Unibus bridge thingie which only
does memory transfers on the PMI bus (it's not a true Quniverter for DMA
purposes).
I also *think* the bug is related to burst mode DMA as I have run my
ESDI controller in normal DMA mode (slower) with the PMI memory running
as PMI without problems. However if I turn on burst/hog mode DMA it will
crash RSX11 (but not RT11). Go figure.
On 10/19/2021 8:50 PM, Nigel Johnson Ham via cctalk wrote:
In all the hundreds of systems I have shipped, I have
never put the CPU
in slot 3! I was VP Operations of Transduction, DEC's biggest components
group OEM in Canada.
No, I don't know if the CPU is good (it is a dual-width KDF11-A btw),
but it is in slot 1 AB with a DLV11J in slot 2AB.? The memory has been
in slot 3 as well as lower.? Since there is nothing above or below it on
the CD side there cannot be any interference in the CD connectors.
I do have an 11/73 dual width board arriving tomorrow so will see if I
get the same results with it.
Thanks for reading,
Nigel
On 2021-10-19 7:55 p.m., Chris Zach via cctalk wrote:
> Hm, ok all my Plessy boards are dual height, 1mb boards. Are you sure
> the 11/23+ is working, and do you have the CPU in slot 3 with the
> memory board in slot 4 (staying away from the PMI slots)?
>
> C
>
> On 10/19/2021 6:51 PM, Nigel Johnson Ham via cctalk wrote:
>> It's just a memory board and looks like one!
>>
>> Picture here:
>>
>>
https://www.mediafire.com/file/ive7i7ax6zdibv3/Screenshot_20211019_185019.p…
>>
>>
>> cheers,
>>
>> Nigel
>>
>>
>> On 2021-10-19 5:21 p.m., Chris Zach via cctalk wrote:
>>> Sounds familiar, got a picture of the board somewhere?
>>>
>>> C
>>>
>>> On 10/19/2021 12:57 PM, Nigel Johnson Ham via cctalk 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
>>>>
8:19 p.m.
Ah, well there you see the end of my technical knowledge.
When the 11/83 came out, I was already a manager :-)
Thanks for the info, I will try it and report back!
cheers,
Nigel
ps, No way is it PMI mmeory, it is waaay too old!
On 2021-10-19 11:03 p.m., Chris Zach via cctalk wrote:
It can be done, technically the 11/83 and 11/93 put
the CPU in slot 3
with the PMI memories in slots 1 and 2. Putting the CPU in slot one
with the PMI memory in 2 and 3 would just cause all memory access to
slug across the Q Bus.
So you can leave slots 1 and 2 open if you really want to, makes it
easier to deal with possible PMI screwage (I always wondered if one
could put a CPU in slot 1, then the M8013/8014 RL01 controller in
slots 2/3 but I don't remember if the 813/8014 will work in a 22 bit
unit without catching fire or something).
Anyway, just try running the CPU in slot 3, then the memory in slot 4,
and the DLV11J in the right side of slot 5. That would simplify things
as much as possible.
C
* PS: Right now I'm running my 11/83 in slot 1 with a 2mb PMI memory
board in slot 2 and the TK70 controller in slot 3. The reason is that
the PMI memory board is from an 11/84, and it has the bug that
prevents it from working properly in a true Q Bus system.
I *think* the bug is related to concurrent memory access from both the
Q Bus DMA and PMI bus as just using the memory as a Q Bus memory has
no problems. A true 11/84 works because there is nothing on the Q-Bus
as all memory access is done through the Unibus bridge thingie which
only does memory transfers on the PMI bus (it's not a true Quniverter
for DMA purposes).
I also *think* the bug is related to burst mode DMA as I have run my
ESDI controller in normal DMA mode (slower) with the PMI memory
running as PMI without problems. However if I turn on burst/hog mode
DMA it will crash RSX11 (but not RT11). Go figure.
On 10/19/2021 8:50 PM, Nigel Johnson Ham via cctalk wrote:
> In all the hundreds of systems I have shipped, I have never put the CPU
> in slot 3! I was VP Operations of Transduction, DEC's biggest components
> group OEM in Canada.
>
> No, I don't know if the CPU is good (it is a dual-width KDF11-A btw),
> but it is in slot 1 AB with a DLV11J in slot 2AB.? The memory has been
> in slot 3 as well as lower.? Since there is nothing above or below it on
> the CD side there cannot be any interference in the CD connectors.
>
> I do have an 11/73 dual width board arriving tomorrow so will see if I
> get the same results with it.
>
> Thanks for reading,
>
> Nigel
>
>
> On 2021-10-19 7:55 p.m., Chris Zach via cctalk wrote:
>> Hm, ok all my Plessy boards are dual height, 1mb boards. Are you sure
>> the 11/23+ is working, and do you have the CPU in slot 3 with the
>> memory board in slot 4 (staying away from the PMI slots)?
>>
>> C
>>
>> On 10/19/2021 6:51 PM, Nigel Johnson Ham via cctalk wrote:
>>> It's just a memory board and looks like one!
>>>
>>> Picture here:
>>>
>>>
https://www.mediafire.com/file/ive7i7ax6zdibv3/Screenshot_20211019_185019.p…
>>>
>>>
>>>
>>> cheers,
>>>
>>> Nigel
>>>
>>>
>>> On 2021-10-19 5:21 p.m., Chris Zach via cctalk wrote:
>>>> Sounds familiar, got a picture of the board somewhere?
>>>>
>>>> C
>>>>
>>>> On 10/19/2021 12:57 PM, Nigel Johnson Ham via cctalk 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
>>>>>
20 Oct
20 Oct
10:27 a.m.
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.)
4:43 p.m.
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.)
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.)
21 Oct
21 Oct
1:29 a.m.
------ Original Message ------
From: "Nigel Johnson Ham via cctech" <cctech at classiccmp.org>
To: "Jerry Weiss via cctech" <cctech at classiccmp.org>
Sent: Thursday, 21 Oct, 2021 At 01:10
Subject: 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
I've not had any experience with third-party Q-BUS modules, with nearly
all my PDP-11's being built out of DEC cards, purely for the reason that
documentation is easy to find. However, one thing i do remember reading
up on is this: "NOTE WELL: For reasons which seem utterly
incomprehensible, many boards designed for Q/CD slots (such as PMI
<https://gunkies.org/wiki/Private_Memory_Interconnect> cards) do not
avoid the QBUS pins on the CD connectors which contain 'hazardous' (to
TTL circuitry) voltages. Plugging such a card into a Q/Q backplane will
generally destroy the card." https://gunkies.org/wiki/QBUS#Backplanes
<https://gunkies.org/wiki/QBUS#Backplanes> .
Some of the later quad-height DEC memory modules had either jumpers or
resistors/fuses/not-sure-what-they-are that could be snipped out to
convert between Q/Q and Q/CD slots. I've seen this on MSV11-P cards.
It's entirely possible that the card wasn't configured correctly, and at
some point got fried by the mismatch between Q/CD and Q/Q.
I would definitely recommend obtaining another memory board and swap it
in. Smaller capacity QBUS memory boards are usually quite cheap and
plentiful, so getting a 64K/128k card isn't impossible and won't break
the bank. It would at least help diagnose if it's the memory board, or
if the issues are deeper seated in your backplane or CPU module.
I would also add, make sure your backplane is clean and not damaged.
It's an easy thing to overlook, but corrosion, damaged traces, damaged
pins, and general detritus can lead to all sorts of funky malfunctions.
Cheers
Josh Rice
4:19 a.m.
Thank you Josh, my next move will be to get a different memory.
Like you say, Even an MSV11DDD will help sort it out. I only need enough
to get into ODT, and maybe run some XXDP.? I have tried two CPUs and two
J boards, so it is either the memory of backplane!
cheers,
Nigel
On 2021-10-21 4:29 a.m., Joshua Rice via cctech wrote:
------ Original Message ------
From: "Nigel Johnson Ham via cctech" <cctech at classiccmp.org>
To: "Jerry Weiss via cctech" <cctech at classiccmp.org>
Sent: Thursday, 21 Oct, 2021 At 01:10
Subject: 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
I've not had any experience with third-party Q-BUS modules, with
nearly all my PDP-11's being built out of DEC cards, purely for the
reason that documentation is easy to find. However, one thing i do
remember reading up on is this: "NOTE WELL: For reasons which seem
utterly incomprehensible, many boards designed for Q/CD slots (such as
PMI <https://gunkies.org/wiki/Private_Memory_Interconnect>? cards) do
not avoid the QBUS pins on the CD connectors which contain 'hazardous'
(to TTL circuitry) voltages. Plugging such a card into a Q/Q backplane
will generally destroy the card."
https://gunkies.org/wiki/QBUS#Backplanes
<https://gunkies.org/wiki/QBUS#Backplanes> .
Some of the later quad-height DEC memory modules had either jumpers or
resistors/fuses/not-sure-what-they-are that could be snipped out to
convert between Q/Q and Q/CD slots. I've seen this on MSV11-P cards.
It's entirely possible that the card wasn't configured correctly, and
at some point got fried by the mismatch between Q/CD and Q/Q.
I would definitely recommend obtaining another memory board and swap
it in. Smaller capacity QBUS memory boards are usually quite cheap and
plentiful, so getting a 64K/128k card isn't impossible and won't break
the bank. It would at least help diagnose if it's the memory board, or
if the issues are deeper seated in your backplane or CPU module.
I would also add, make sure your backplane is clean and not damaged.
It's an easy thing to overlook, but corrosion, damaged traces, damaged
pins, and general detritus can lead to all sorts of funky malfunctions.
Cheers
Josh Rice
7:04 a.m.
On 10/20/21 7:10 PM, Nigel Johnson Ham via cctalk wrote:
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
Can you read any of the CSR registers built into the serial board or cpu
without the memory card inserted??? I don't believe ODT is dependent on
working memory.
4:25 a.m.
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?
FoothillsGeek on VCFed had a number of Plessey memory manuals and had scanned
some, as mentioned here
https://www.vcfed.org/forum/forum/genres/dec/73251-dec-documents-on-manx
6:10 a.m.
Thanks, but like bitsavers they are all older that the one I have.
To be honest, I never saw anything Plessey bigger than 128kB in the
wild, so I have to wonder what kind of machine this board came from,
although it was in a pile of Qbus things that I got the J boards from.
I'm thinking that maybe it was not sold separately, but an OEM build for
military etc, and perhaps it is jumpered to get power from memory - but
without the manual or tracing the lands I can't really tell.
cheers,
Nigel
On 2021-10-21 7:25 a.m., Steve Malikoff via cctalk 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?
FoothillsGeek on VCFed had a number of Plessey memory
manuals and had scanned
some, as mentioned here
https://www.vcfed.org/forum/forum/genres/dec/73251-dec-documents-on-manx
7:58 a.m.
On 10/21/2021 9:10 AM, Nigel Johnson Ham via cctalk wrote:
Thanks, but like bitsavers they are all older that the
one I have.
To be honest, I never saw anything Plessey bigger than 128kB in the
wild, so I have to wonder what kind of machine this board came from,
although it was in a pile of Qbus things that I got the J boards from.
I'm thinking that maybe it was not sold separately, but an OEM build for
military etc, and perhaps it is jumpered to get power from memory - but
without the manual or tracing the lands I can't really tell.
Wait, that could be it: If the board is jumpered to power the memory
refresh/chips from battery then of course it wouldn't work without it.
Should be easy to check: Find the battery +5 and +12 pins on the Q bus
then use a tester meter to check from those pins to any of the jumper
pins. If you find continuity to a jumper that is closed you might have
identified the problem :-)
8:36 a.m.
No luck, there are no 12V traces continued to the edge connector, and
the 5VB goes to a three way jumper post where the jumper is between the
common and 5V
Besides, there are two LEDs on the board that light up, one red one green.
Thanks,
Nigel
On 2021-10-21 10:58 a.m., Chris Zach via cctalk wrote:
On 10/21/2021 9:10 AM, Nigel Johnson Ham via cctalk wrote:
Thanks, but like bitsavers they are all older
that the one I have.
To be honest, I never saw anything Plessey bigger than 128kB in the
wild, so I have to wonder what kind of machine this board came from,
although it was in a pile of Qbus things that I got the J boards from.
I'm thinking that maybe it was not sold separately, but an OEM build for
military etc, and perhaps it is jumpered to get power from memory - but
without the manual or tracing the lands I can't really tell.
Wait, that could be it: If the board is jumpered to power the memory
refresh/chips from battery then of course it wouldn't work without it.
Should be easy to check: Find the battery +5 and +12 pins on the Q bus
then use a tester meter to check from those pins to any of the jumper
pins. If you find continuity to a jumper that is closed you might have
identified the problem :-) 
10:30 a.m.
Hey, FoothillsGeek here! I saw this thread last night and checked to see if
I had a manual for it - it does not look like I do. Most of the Plessey
documents we received are for core memory boards.
However, when I indexed the docs we received, I did so by model number
(PM-xxxx) and not by part number. So, if I can find our stack of Plessey
docs, I'll flip through them again to look for the PN.
On Thu, Oct 21, 2021 at 8:49 AM steven--- via cctech <cctech at classiccmp.org>
wrote:
--
*Derek Newland* | (828) 234-4731 | derek.newland at gmail.com
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?
FoothillsGeek on VCFed had a number of Plessey memory manuals and had
scanned
some, as mentioned here
https://www.vcfed.org/forum/forum/genres/dec/73251-dec-documents-on-manx
1:57 p.m.
I really appreciate that, all the things I can find under that board
number (which is simple the pcb etch) are from vendors who want to sell
you one and have no idea of the model number.
I too, have no idea of the model number, but have tried search for all
sorts of PM-MSV11 etc with no luck.
I will wait with bated breath!
cheer,
Nigel
On 2021-10-21 1:30 p.m., Derek Newland via cctech wrote:
Hey, FoothillsGeek here! I saw this thread last night
and checked to see if
I had a manual for it - it does not look like I do. Most of the Plessey
documents we received are for core memory boards.
However, when I indexed the docs we received, I did so by model number
(PM-xxxx) and not by part number. So, if I can find our stack of Plessey
docs, I'll flip through them again to look for the PN.
On Thu, Oct 21, 2021 at 8:49 AM steven--- via cctech <cctech at classiccmp.org>
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?
> FoothillsGeek on VCFed had a number of Plessey memory manuals and had
> scanned
> some, as mentioned here
> https://www.vcfed.org/forum/forum/genres/dec/73251-dec-documents-on-manx
>
>
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