UPIC (Unité Polyagogique Informatique CEMAMu) is a computerised musical composition tool, devised by the composer Iannis Xenakis. It was developed at the Centre d'Etudes de Mathématique et Automatique Musicales (CEMAMu) in Paris, and was completed in 1977. The name is an acronym of Unité Polyagogique Informatique du CEMAMu. Xenakis used it on his subsequent piece Mycènes Alpha (1978), and it has been used by composers such as Jean-Claude Risset (on Saxatile (1992)), Takehito Shimazu (Illusions in Desolate Fields (1994)), Aphex Twin, Mari King, and Curtis Roads.
Physically, the UPIC is a digitising tablet linked to a computer, which has a vector display. Its functionality is similar to that of the later Fairlight CMI, in that the user draws waveforms and volume envelopes on the tablet, which are rendered by the computer. Once the waveforms have been stored, the user can compose with them by drawing "compositions" on the tablet, with the X-axis representing time, and the Y-axis representing pitch. The compositions can be stretched in duration from a few seconds to an hour. They can also be transposed, reversed, inverted, and subject to a number of algorithmic transformations. The system allows for real time performance by moving the stylus across the tablet.
The UPIC system has subsequently been expanded to allow for digitally sampled waveforms as source material, rather than purely synthesised tones. In 2005, Mode Records of New York released a 2-CD compilation of works composed with the UPIC, entitled Xenakis, UPIC, Continuum, which provides an overview of the machine's sonic possibilities.
There were a couple of attempts to reproduce the UPIC system using commodity hardware, for instance Iannix and HighC. IanniX, which has been sponsored by the French Ministry of Culture, is a graphical open-source sequencer which syncs via Open Sound Control events and curves to a real-time environment (like Pure Data, Super Collider, Csound, MaxMSP, openFrameworks, vvvv…). For its part, HighC is currently used as a pedagogical tool in classes ranging from early teens to Master classes in composition, while some contemporary composers, such as George Hatzimichelakis have made it part of their toolset.
Further reading 
- Jean-Baptiste Thiebaut, Patrick G. T. Healey, Nick Bryan Kinns, DRAWING ELECTROACOUSTIC MUSIC, Interaction, Media and Communication, Queen Mary, University of London
- Xenakis' original block diagram of the system.
- Nine pieces recorded with the UPIC in 2003.
- HighC, a modern version of UPIC
- IanniX home page