Improvisation on a “Concerto Generator” (1977)
Laurie Spiegel Playing the Bell Labs Digital Synthesizer, better known as the Alles Machine or Alice, was an experimental additive synthesizer designed by Harold G. Alles and Douglas Bayer at Bell Labs in 1977-78.
This composition was commissioned by Bell Labs and the Motion Picture Academy for the 50th anniversary of talking pictures. Working with the Alles synthesizer, with its extensive array of input and output channels for control, was a real pleasure after years of GROOVE’s extreme restrictions. The interactive software I wrote for this composition recycles the player’s keyboard input into an ongoing accompaniment. However, writing the software from a remote DEC PDP-11 computer (see also the PDP-11 FAQ and PDP Music Survey) in the new “C” computer language still undergoing frequent change, within a still-experimental UNIX operating system, without the control inputs or sonic output, under a tight deadline, while the Alles synthesizer hardware was still under construction, turned out to be quite an adventure.
It can orchestrate and perfome musicale scores as fast as a composer at its controls can think them up; create previously unheard musical sounds; and raise or lower the pitch of an instrument or human voice in real time-instantly-so that a man speaking into a microphone can be made sound like Donald Duck or Ezio Pinza. The machine divides sound into its frequencies and amplitudes, processing it un up to 200 million operations per sesond.