 It needed to be modular and the modules had to be easily interconnected (so that the synthesiser would have more modules than slots and it would have an easy-to-use patch).It also needed to include all the major functions of a modular synthesiser including oscillators, noise-generators, filters, ring-modulators, but an intermodulation facility was viewed as the primary requirement; to enable complex synthesis processes such as frequency modulation, amplitude modulation, and modulation via an external source.No keyboard was attached to the synthesiser and instead a specific and somewhat complex envelope generator was used to shape sound.