Urge is actually a virtual instrument created in the MAX/MSP programming environment. This recording is a live improvisation on that instrument performed by the composer, and recorded directly to HD. Various parameters within the instrument were adjusted in real time via MIDI. The Urge software makes use of numerous chaos algorithms which modify the timbre and frequency of the generated sounds. The Urge software is available for download at www.music.mcgill.ca/~robin.