The earliest example of computer-composed music is the Illiac Suite for String Quartet. It was created using the Illiac I computer at the University of Illinois by Lejarean Hiller and Leonard Isaacson. The two professors were working on their String Quartet No.4. The piece was a great innovation both because of the idea behind it as well as the way it operated.
The piece consisted of four musical “experiments” for string quartet, each comprised of two parts. In each experiment the computer was programmed to generate random integers representing various musical elements such as pitches, rhythm and dynamics which were subsequently screened.
The first experiment was based on simple counterpoint. The second began with random notes, with rules gradually being applied throughout the movement that imposed order, resulting in correct counterpoint by the movement’s end. The third movement explored incorporating varying rhythms and string playing techniques, with pitches first being the same for each instrument while rhythms and techniques were highlighted, then were chosen at random, then from simple compositional rules, then according to twelve-tone serial rules. The fourth movement was based on probability experiments such as Markov chains.
In 1958, Hiller established the Electronic Music Studio, making Illinois second to Columbia in starting electronic music experiments in a university, and the first to conduct musical research with a computer. The Illiac Suite remains in history as the first musical composition for traditional instruments that was made through computer-assisted composition.