The PDP-7 version of Unix was developed at Bell Labs by Ken Thompson, Dennis Ritchie and others in 1969 and 1970. It provided a process-oriented multitasking environment with a (sort of) hierachical filesystem for two users.
The code here is the source code to the PDP-7 Unix kernel and some of the commands. These come from a set of paper scans that Norman Wilson did while he worked at Bell Labs.
For more information about PDP-7 Unix, see The Evolution of the Unix Time-sharing System by Dennis Ritchie.