[rescue] DEC PDP-11/23 memory expansion

Jochen Kunz jkunz at unixag-kl.fh-kl.de
Mon Jul 12 01:22:49 CDT 2010

On Sun, 11 Jul 2010 05:23:30 -0600
Scott M <scott.m.16 at atsgate.com> wrote:

> Does it involve removing the CPU board (M8186 KDF11-A), and replacing it 
> with another, or can the original be somehow modified for 22-bit
> operation? 
>From pdp11-field-guide.txt:
M8186       KDF11-A     Q   11/23 CPU (Prior to etch rev. C, 18-bit
M8186                       addressing only.  Caution, uses BC1, BD1,
M8186                       BE1, BF1 for purposes other than BDAL18-21)
M8186           Refs: EB-18451-20, MP00734, EH-17898-20, EK-KDF11-UG
M8186           Refs: EK-KDFAA-CG, ED-2136-20, ED-18325-53, uNOTEs N#006
M8186           Refs: N#017

So if you have an early board you need a new CPU board. If your board is
newer then rev. C then wiring the extra bits on the backplane should be



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