EDGE uses as its composition environment two plug-in modules of the music sequencing software KCS (Keyboard Controlled Sequencer) created by Dr Emile Tobenfeld in 1985. The first module, responsible for the creation of the first section Improvisation, is called Fingers. This is essentially an improvising instrument controlled from the computer keyboard able to control four instrumental parts simultaneously. The second, known as the Programmable Variations Generator (PVG), was probably the first menu-driven algorithmic generator and editor

commercially available that did not require any specialist knowledge of computer languages. This module was responsible for the second and third sections titled Interpolation and Transformation. PVG enabled the composer to explore quite elaborate 'what-ifs' in a multi-part composition. executed simultaneously, taking in conventional musical devices such as transposition and inversion as well as more novel procedures such as the application of Gaussian distribution and probability curves to musical parameters.