The Earliest Unix Code: An Anniversary Source Code Release

Article about some early Unix source code found in Dennis Richie’s documents.

To mark Unix’s 50th anniversary, the CHM Software History Center is delighted to make publicly accessible for the first time some of the earliest source code produced in the Unix story.

Recently, CHM was entrusted to preserve the papers of Dennis Ritchie by the Ritchie family. Within these papers, I identified a black binder with the hand-label “Unix Book II” containing nearly 190 pages of printed source code listings, written in PDP-7 assembly code.

With invaluable early review of these listings from Warren Toomey of The Unix Heritage Society and from John Mashey, an early Unix contributor and CHM trustee, we can date these listings to 1970, perhaps early 1971, before the Unix effort migrated to a new PDP-11. A PDF of the listings contained in this Unix Book II binder is available for download via this catalog record.

These programs were written by the first participants in the Unix effort at the Bell Telephone Laboratories, starting in 1969. Ken Thompson and Dennis Ritchie were the two central, and initial, participants. Other early participants include Rudd Canaday, Doug McIlroy, Brian Kernighan, Bob Morris, and Joe Ossanna. It is likely that much of the work represented in this binder is due to the work of Thompson and Ritchie.