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
