Amit Singh has released an amazingly in-depth 140-page PDF book, for free, covering the history of Apple’s operating systems:
This was the first chapter I wrote for the book. It was particularly difficult to write in terms of the time and other resources required in researching the material. I often had to find and scavenge ancient documentation, software, and hardware (all actual screenshots shown in this document were captured first hand.) However, I couldn’t include the chapter in its original form in the book. The book grew in size beyond everybody’s expectations — 1680 pages! Therefore, it was hard to justify the inclusion of this much history, even if it is interesting history.