DEC PDP 11/23 - OK to use 22-bit memory boards in an 18-bit qbus?
pete at dunnington.plus.com
Tue Jul 20 14:10:11 CDT 2010
On 20/07/2010 19:20, Scott M wrote:
> My concern is that the 18-bit PDP 11/23 does not have enough memory.
> It currently has 128KB installed, with a maximum of 256K possible after a
> memory board upgrade (M8067, MSV11-PK = 256KB). How far do you estimate I
> can get with just 128KB memory? Can I get through Lions' book?
> I am looking at adding wires to the backplane to make it a 22-bit machine,
> and using a quad height qbus memory board, M7551 (available in 1MB, 2MB and
> 4MB sizes).
I forgot to mention one other web page:
lists most of the memory options in a table.
Specifically, I can tell you that an M8067 MSV11-PK, and an M7551
MSV11-Q are both OK in Q22-Q22 serpentine backplanes. For the MSV11-P
you need to ensure W1 and W2 are both in place to provide bus grant
Pete Peter Turnbull
University of York
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