MUSIC-N

MUSIC-N refers to a family of computer music programs and programming languages descended from or influenced by MUSIC, a program written by Max Mathews in 1957 at Bell Labs. MUSIC was the first computer program for generating digital audio waveforms through direct synthesis. It was one of the first programs for making music (in actuality, sound) on a digital computer, and was certainly the first program to gain wide acceptance in the music research community as viable for that task. The world's first computer-controlled music was generated in Australia by programmer Geoff Hill on the CSIRAC computer which was designed and built by Trevor Pearcey and Maston Beard. However, CSIRAC produced sound by sending raw pulses to the speaker, it did not produce standard digital audio with PCM samples, like the MUSIC-series of programs.

All MUSIC-N derivative programs have a (more-or-less) common design, made up of a library of functions built around simple signal-processing and synthesis routines (written as opcodes or unit generators). These simple opcodes are then constructed by the user into an instrument (usually through a text-based instruction file, but increasingly through a graphical interface) that defines a sound which is then "played" by a second file (called the score) which specifies notes, durations, pitches, amplitudes, and other parameters relevant to the musical informatics of the piece. Some variants of the language merge the instrument and score, though most still distinguish between control-level functions (which operate on the music) and functions that run at the sampling rate of the audio being generated (which operate on the sound). A notable exception is ChucK, which unifies audio-rate and control-rate timing into a single framework, allowing arbitrarily fine time granularity and also one mechanism to manage both. This has the advantage of more flexible and readable code as well as drawbacks of reduced system performance.

...
Wikipedia