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Data on Plessey 256KB Qbus memory card 705035

peterbbu

Experienced Member
Joined
Jun 13, 2016
Messages
81
Location
Midlands - UK
I have a Plessey 256KB QBUS memory card 705035 but am lacking any technical information on it.

It is a dual card with 36 x 4864 DRAMs (64 K x 1) so 256 KB plus parity.

There are 2 switches: S1 4pole all on
S2 10 pole 1,6,7,8 off, 2-5 & 9-10 on

Is this a Q18 or Q22 card?

Thanks

Peter
 
The Rhode Island Computer Museum has a Plessey 11/23 system with a Plessey 512KB 705155-100A SV512 Memory. It also has a Plessey 705185-100C KTV25 Mapper board. We were told that this combination uses a proprietary memory bus. We have no documentation on any of the Plessey boards.
 
I have a Plessey 256KB QBUS memory card 705035 but am lacking any technical information on it.

It is a dual card with 36 x 4864 DRAMs (64 K x 1) so 256 KB plus parity.

There are 2 switches: S1 4pole all on
S2 10 pole 1,6,7,8 off, 2-5 & 9-10 on

Is this a Q18 or Q22 card?

Thanks

Peter
Peter,
Seeing as 256K is the limit of Q18 addressing, I would have thought have switches would imply Q22 but of course the switches could be to configure card size and placement when it was populated with smaller and/or fewer chips. What type do you need. I might have some cards I rescued at the last DEC Legacy but I think they are small Q18 (or perhaps even Q16) cards.
Dave
 
I've probably got the manuals somewhere but the switches are to set base memory address and the parity CSR. Should be pretty simple to decode, if you're really sunk I'll look around and see if I have a manual.

Edit: Looks like the other guy up there had a link to the manual.
 
Et voila...

This is what one eventually finds while searching for some MTI docs for another thread :)
Atm i do not have a running scanner, so just fast pics taken with my cell phone...
There are also about half a dozen other Plessey user guides / manuals...

Have fun
 

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