The earliest versions of the very first c compiler known to exist in the wild written by the late legend himself dmr.
These are not capable of being compiled today with modern c compilers like gcc. I am only posting these here for the enjoyment and reminiscing of the spark that ignited a soon to be trillion dollar industry. Enjoy. :)
You guys might be able to play around building this compilier with Aiju's pdp-11/unix emulator. I havent tried building this myself so I cant confirm it works, but I posted the link to his emulator for anybody wanting to hack around with it.
Source: [http://cm.bell-labs.com/cm/cs/who/dmr/primevalC.html] PDP-11 Emulator[http://pdp11.aiju.de/]