The Apple II Timeline gives an overview of many of the events mentioned in the Apple II History, as well as some others that are not discussed. The dates given for the various entries found here are as accurate as I can make them, based on the sources cited in the footnotes that follow. In some cases I could come no closer to the correct date than the year in which it happened. If there is no reference number, it is because I cannot find the source of the information, but know that it is reasonably accurate.
With regard to the various versions of Apple II disk operating systems: For DOS I chose to use the date found on the HELLO program on System Masters; I chose for ProDOS 8 to use the date displayed when it starts up; and for GS/OS the dates it was first announced in Open-Apple or A2-Central. The dates they were completed and the dates they were available are sometimes several months apart.
One other thing that may make some of these dates slightly inaccurate is the difference between a product “announcement”, “introduction”, and “release”. Something may be “introduced” on one date, but not available or “released” until a later date (the IBM PCjr comes to mind). If anyone cares to correct me on any of these points, please feel free to contact me with your information source, and I will be glad to make the change.
“Ladies and gentlemen, the History of the Apple II Time-Sweep. Every number one event, in order, beginning in June, 1969. Sit back, for the Greatest (Computer) Hits of All Time!”