As part of his 1,680-page book Mac OS X Internals: A Systems Approach, author Amit Singh produced an in-depth history of Appleis operating systems. Since he had to discard much of the material while whittling down the first chapter to a manageable length, Mr. Singh has decided to make "A Technical History of Appleis Operating Systems" freely available as a PDF.
The 139-page document starts with the original Apple I and Apple II computers and moves through Appleis own version of DOS and other pre-Mac OS operating systems. In addition to an in-depth look at the Mac OS, Mr. Singh also examines NeXTSTEP, since it was the predecessor to Mac OS X, as well as the Pippin, Newton, and iPod operating systems.
Mr. Singhis book is currently available for US$64.99.
Thanks to Macworld UK for the link.