‘When asked what musical instrument they play, few computer musicians respond spontaneously with “I play the computer.” Why not?’(Wessel and Wright 2002). Actually, most computer music performers still seem shyly reluctant to consider the computer as a regular musical instrument, but nonetheless, the computer is finally reaching the point of feeling as much at home on stage as a saxophone or an electric guitar. This assimilation was boosted over the last ten years with the arrival of affordable machines powerful enough for realtime audio processing and of versatile audio software such as Max/MSP, Pure Data or SuperCollider, but live computer music is far from being a novelty; computer-based realtime music systems started in the late 1960s and early 1970s and non-digital live electronic music goes back as far as the nineteenth century.

An ambitious goal for any new instrument is the potential to create a new kind of music. In that sense, baroque music cannot be imagined without the advances of sixteenth- and seventeenth-century luthiers, rock could not exist without the electric guitar, and jazz or hip-hop, without the redefinitions of the saxophone and the turntable. This chapter explores the potential of computers as musical instruments and analyses what it is that makes them so especially different from previous instruments, unveiling the novel possibilities as well as the drawbacks they entail.