I downloaded the tarball and had a look through it. Almost everything has source code included, which is pretty cool to see.

There’s an entire C compiler from 1972, bootstrapped to be written in C. There was also a SNOBOL III compiler written in C, and some Fortran stuff.

Unsurprisingly grep was written in assembly, but it’s source is there.

There’s also a games folder, but unfortunately these look like they’re just binaries: bj, chess, cubic, moo, ttt, wump I’ll have to load up a pdp11 emulator later to see what they are.