PDP-10 software archive
Computers, Hardware, Historical, DEC - PDP-10 Software Archive. PDP-10 commercial software covered by the hobbyist license.
http://pdp-10.trailing-edge.com/
pdp11.org
Computers, Hardware, Historical, DEC - Pdp11.org. Dedicated to preserving the history and legacy of the PDP-11 series of 16-bit minicomputers.
http://www.pdp11.org/
Managed Services
Computers, Hardware, Historical, DEC - Mentec. PDP-11 operating systems plus layered products and services.
https://www.mentec.com/
Classic Computing Mailing List
Computers, Hardware, Historical, DEC - Classic Computing Mailing List. Mailing list of nearly 1000 members dedicated to preserve and archive classic computer documentation and software.
https://classiccmp.org/