I just finished reading Dealers of Lightning: Xerox PARC and the Dawn of the Computer Age by Michael A. Hiltzik, which tells the tale of Xerox PARC (Palo Alto Research Centre) during its golden age of discovery in the 1970’s and into the 1980's.
I have written a brief review of the book which you can find here: Book Reviews
During this period, one of the breakthrough innovations was the Alto computer. Two of the key designers on that project, Chuck Thacker and Butler Lampson, discuss their memories of the Xerox Alto computer in this excellent video interview presented on the Computer History Museum channel on YouTube:
Updated 2022 : note that the above post was originally published in 2010, but is left here for archival purposes.