History of Unix and causes for its popularity. "This document is designed to give people with no previous UNIX experience some sense of what UNIX is. This document will cover the history of UNIX and an introduction to UNIX."
Several classic Unix papers dating back to 1973. Most reports are Gzipped PostScript, some are in PDF.
The full source archives of the University of California at Berkeley's Computer Systems Research Group, for sale on a 4-CD set.
Various drawings, pictures, and information on the red devil BSD mascot.
1979 conference paper by Dennis Ritchie. "Concentrates on the evolution of the file system, the process-control mechanism, and the idea of pipelined commands. Some attention is paid to social conditions during the development of the system."
Several historic technical reports, anecdotes, and stories from one of the fathers of Unix.
History paper detailing the people and places involved in developing Unix.
Archives at Bell Labs of the 1979 manual. Troff source and formatted Gzipped PostScript/PDF versions.
Built to foster the "the preservation and maintenance of historical and non-mainstream UNIX systems." Mailing list and archives. Includes early Unix source code, from 1973 through the 1990s.
Ritchie and Thompson's famous Communications of the ACM paper from 1974. An authoritative and technical overview of the operating system.