PAiA started selling Modular Synthesizer kits in 1972 with its 2700 series. The first ones, model 2700, used buttons for keys. They were followed by the 2720 which came with a keyboard. The series 4700 modulars came next with an improved, quieter design. The 8700 computer-based modular system was next, connecting a modular synthesizer to a 6502 processor, allowing for polyphony. According to John Simonton, PAiA Electronics, Inc., they "also had some compositional algorithms that would generate tunes on the 8700. There were a number of tricks."
[excerpted with permission from the book Vintage Synthesizers by Mark Vail, copyright Miller Freeman, Inc]