Thompson writes first version of UNICS for PDP-7 in one month while wife is on vacation. He allocates one week each to the operating system functions: the kernel, the shell, the editor, and the assembler. He does this on a machine with 4K of 18 bit words. UNICS is pun on MULTICS and stands for Uniplexed Information and Computing Services. Name is changed to UNIX which is not an acronym. This version is in assembly language.

Thompson develops the interpretive language B based upon BCPL. Ritchie improved on "B" and called it "C"