Music 6 is a sound synthesis software for computer music that belongs to the Music N family.
Background history – It was developed at Stanford University in 1966 by Dave Poole. From the point of view of functionality, Music 6 is presented as a sort of customized version of Music IV. The latter had been taken and implemented, two years before, at Stanford. The Music 6 does not add any substantially news compared to the Music IV, rather arises as a computer PDP-6 Assembler version (hence the name Music 6), which had replaced the IBM 7090 on which worked the Music IV. Some software features were made by Poole with Fortran IV, several of these functions were developed by John Chowning. In this way we can say that Music 6 has been a preparatory work for the next Music 10 developed by Chowning and James Moorer.
For this topic I’ve read.
 John Chowning, personal communication, 2009.  Alex Di Nunzio, Genesi, sviluppo e diffusione del software Music N nella storia della composizione musicale, Tesi di laurea, Università di Bologna: D.A.M.S. Musica, 2010.