I just finished scanning the DEC documentation for the KH11-A "NPR
Expansion" option for the PDP11/20 and the PDP11/05 machines. (I just
bought this drawing set on eBay...)
As far as I can tell, this is the only documentation for this CPU
modification that's online - aside of course for my own reverse-engineering
drawings from earlier this year.
You can find the drawings here.
<https://deramp.com/downloads/mfe_archive/011-Digital%20Equipment%20Corporation/08%20PDP-11/05%20Unibus%20Options/KH11-A%20NPR%20Expansion%20Option/>
I believe this is a complete documentation set. The page order is a bit
funky, but it is in the original page order - I had to remove the (very
rusty) original staples to be able to scan it all.
Note that in addition to the complete print set, I've also included
additional drawings for the M724-YA, for later revisions of that board.
Martin