Brian Eno on Generative Art, Part III
Part III

"In early 1995 I received from them (Sseyo) a CD of music that had been made by their software program called Koan. A couple of the pieces were clearly in 'my' style (they readily acknowledged that my 'ambient' work had been part of their inspiration for the Koan system), but what surprised me was that I would have been proud of them. I contacted Tim Cole at Sseyo, and he arranged for me to get a copy of the Koan 'authoring tool'- the program by which one writes the rules for these pieces- and, after a few days of typical interface frustration, I took to it like a duck to water.
Koan works by addressing the soundcard in the computer. A soundcard is a little synthesizer sold as an optional add-on to the computer. The computer sends instructions to that soundcard and tells it what noises to produce and in what patterns. Koan is a very sophisticated way of doing this, enabling a composer to control about 150 parameters that specify things like sound-timbre and envelope, scale, harmony, rhythm, tempo, vibrato, pitch range, etc. Most of Koan's instructions are probabilistic- so that rather than saying 'Do precisely this' (which is what a musical sequencer does) they say 'Choose what to do from within this range of possibilities.' The Koan program allows that range to be more or less specific- you could, if you so chose, write absolutely precise pieces of music with it, though this would probably be its least interesting use."

From "A Year With Swollen Appendices", p. 331