> Unix time is a system for describing a point in time.

> It is the number of seconds that have elapsed since 00:00:00 Thursday, 1 January 1970.

> The first edition Unix Programmer's Manual dated 3 November 1971 defines the Unix time as "the time since 00:00:00, 1 January 1971, measured in sixtieths of a second"

> In early 1970 we proposed acquisition of a PDP-11, which had just been introduced by Digital.

> Before long, however, funds were obtained through the efforts of L. E. McMahon and an order for a PDP-11 was placed in May.

> The processor arrived at the end of the summer, but the PDP-11 was so new a product that no disk was available until December. In the meantime, a rudimentary, core-only version of Unix was written using a cross-assembler on the PDP-7. Most of the time, the machine sat in a corner, enumerating all the closed Knight's tours on a 6×8 chess board—a three-month job.