In 1959 American composer and professor Lejaren Hiller, Jr. and mathematician Leonard Isaacson published the first book on the use of a computer to compose music: Experimental Music: Composition with an Electronic Computer, based on work done on the University of Illinois’s ILLIAC computer.
Prior to publication of the book Hiller collaborated with Leonard Issacson on Hiller's String Quartet No. 4, Illiac Suite, the first significant use of a computer to compose music. "The piece consists of four movements, corresponding to four experiments: the first is about the generation of cantus firmi, the second generates four-voice segments with various rules, the third deals with rhythm, dynamics and playing instructions, and the fourth with various models and probabilities for generative grammars or Markov chains (see stochastic music)." (Wikipedia article on Iliac Suite, accessed 9-2020).