image courtesy of PAiA
[from an interview with John Simonton, PAiA Electronics, Inc.]
"'That's been credited as the first programmable drum machine, and it may be. For about a year, it was dominant, because there weren't any other programmable drum sets.
"'The Programmable Drum Machine did not play digital samples of sounds like other programmable drum machines that followed it. The drum sounds were done using a technique that was popular at that time called ringing oscillators. You have a filter that's very close to oscillating all by itself, and when you hit it with a little pulse to exite it, it rings the way a drum does. It makes drum kinds of sounds.
"'A real drum has a lot of character. Ringing oscillators tend to be a pure-tone kind of sound, a sine wave that dies out very quickly. Real drums aren't really so much that way....
[excerpted with permission from the book Vintage Synthesizers by Mark Vail, copyright Miller Freeman, Inc]