Unit generators (or ugens) are the basic formal units in many MUSIC-N-style computer music programming languages.[1] They are sometimes called opcodes (particularly in Csound)[2], though this expression is not considered accurate in that these are not written directly as machine-level instructions.[citation needed]
Unit generators form the building blocks for designing synthesis and signal processing algorithms in software.[3] The unit generator theory of sound synthesis was first developed and implemented by Max Mathews[4] and his colleagues at Bell Labs in the 1950s.[5]