IEEE Spectrum article on The Strange Birth and Long Life of Unix.

This was an interesting read, especially for the cloak-and-dagger tactics they had to resort to not only to create the OS in the first place, but to do things like distribute bugfixes (because management was afraid that distributing bugfixes would be considered "support"). Literally on the level of "go to the mailbox on such-and-such street after 2pm."

(Rescued from my Google+ archive)