Gary Anthes over at Computer World has a great time line of Unix from start to present.
Ever wonder about how Unix got started, not to mention all the twists and turns it took along the way? Here are some milestones of the operating system’s four-decade-long history.
Here is one I think is pretty significant:
1973 – Unix matures. The “pipe,” a mechanism for sharing information between two programs, which will influence operating systems for decades, is added to Unix. Unix is rewritten from assembler into C.