If you have a nostalgic turn of mind, there's a new posting over on Github that you'll just love: the earliest known C compiler by the legendary Dennis Ritchie has been published on the repository.
It's not new: long before his death in 2011, Ritchie wrote about the effort to find, recover and preserve the early work on C here.
Even as far back as 2001, the attempt to recover the earliest life of one of the world's most important programming languages was considered computer industry palaeontology.
For readers Down Under, there's even a faint Australian link, with Ritchie referring to work done by Warren Toomey, now of Bond University, who in 2010 published this paper describing the successful effort to resurrect and recover the first edition of Unix.
The Github repo is the same set of files as posted by Ritchie at Bell Labs – but should at least expose the files to the wider audience of programmers that don't much look beyond Github for their files.
As Github user Mortdeus notes, the files aren't compilable with a modern C compiler. If you have access to a PDP-11, however, you're welcome to have a shot at getting it to work; others have done so. The software is under the Caldera license, which allowed the release of ancient Unix back in 2002. ®