Unit generator

Unit generators (or ugens) are the basic formal units in many MUSIC-N-style computer music programming languages. They are sometimes called opcodes (particularly in Csound), though this expression is not accurate in that these are not machine-level instructions.

Unit generators form the building blocks for designing synthesis and signal processing algorithms in software. For example, a simple unit generator called OSC could generate a sinusoidal waveform of a specific frequency (given as an input or argument to the function or class that represents the unit generator). ENV could be a unit generator that delineates a breakpoint function. Thus ENV could be used to drive the amplitude envelope of the oscillator OSC through the equation OSC*ENV. Unit generators often use predefined arrays of values for their functions (which are filled with waveforms or other shapes by calling a specific generator function).

The unit generator theory of sound synthesis was first developed and implemented by Max Mathews and his colleagues at Bell Labs in the 1950s.