Many folks probably think the PDA began with the release of the first Palm Pilot. Other folks may think it began with the Apple Newton. Evan Koblentz, editor of Computer Collector Newsletter posted a very complete history of the milestones in the development of the Personal Digital Assistant. Koblentz’ article also gives a short definition of what constitutes a PDA: It has to be digital, palm-sized, function independently, and have a non-appliance, non-mathematical application set.
The article shows a rich series of devices dating all the way back to the early 1970s. His definition helps to show why the feature set of PDAs is constantly growing and improving.