Unit generators are the building blocks of digital synthesis: generators and modifiers wired into a patch

A unit generator (UG) is the fundamental computational object in software synthesis systems such as Music V and Csound. Every UG is either a signal generator—producing audio waveforms or control envelopes—or a signal modifier that transforms an input signal (filters, amplifiers, delay lines). Composers wire UGs together into patches, creating instruments analogous to analog synthesizer signal flows. This model, invented by Max Mathews at Bell Labs in the early 1960s, underpins virtually all software synthesis to the present day, including environments like SuperCollider (UGens) and Csound (opcodes). The patch graph determines the synthesis algorithm; changing connections changes the instrument.

Examples

A simple patch: oscillator UG (signal generator) → amplitude envelope UG (modifier) → output. In Csound, asig oscil kamp, kfreq, 1 is an oscillator UG; outs asig, asig is an output UG.

Assessment

Draw a patch graph for a filtered oscillator with amplitude envelope. Label which UGs are generators and which are modifiers, and trace signal flow from source to output.