The following are primary sources of information or source code for the main software distributions available elsewhere on this site:

Martin Richards has a current BCPL compiler, language manuals, programs, and archive material.

Dennis Ritchie has a variety of historical and other materials relating to UNIX and C.

The Unix Heritage Society (TUHS) is devoted to the preservation and promotion of Early UNIX.

Vrije Universiteit has an ACK page with links to the original ACK distribution and to documentation.