4.3  Wheelies

Wheelies (1992) designed by Chris Brown, used the computer network band as a giant, multi-limbed, rhythm machine. The purpose was to create variations on complex rhythmic synchronizations among the players' machines, while allowing players to control each other's rhythmic performance. Each player programmed the implementation of their system, and could change the voicing of their instrument's rhythms, but all were locked into a tempo set globally for the group, while their ICTUS, METER, and DENSITY parameters were set and changed during the performance by other players, but never by themselves.

audio track of Wheelies

56K modem version



A screen shot from Chris Brown's Wheelies software, showing the HMSL shape editor (a software language written at Mills College by Phil Burk, Larry Polansky and David Rosenboom) for editing the tempo curves in the piece.

MIDI clock signals were generated by Chris and broadcast to the whole group, which set down a common, but changing tempo that all players locked to. This tempo was divided by each player independently by a number from 1 to 10 set by the ICTUS parameter. METER set the rhythmic cycle, implemented as the repetition of notes or timbres around a cycle of numbers of beats, where one beat equals ICTUS number of timing clocks. Complex polyrhythmic textures not normally performable by humans could develop when up to six METERS with different ICTI cycled at the same time. The DENSITY parameter specified a percentage of beats to be sounded by playing a note, so a low DENSITY meant only a low percentage of beats would be played.

Every player could send at any time STOP, CONTINUE, or START messages, which all players had to obey. The STOP message functioned as a group mute: everyone had to program their machines to stop playing, but not to stop counting cycles and beats. A CONTINUE message meant "un-mute", and every machine resumed playing at the same point in their cycles where they had stopped. START meant first to send three messages out to other members of the group (one each of ICTUS, METER, and DENSITY, each sent to any member of the group), then to read new values of those parameters into the rhythm generating instrument, reset the timing clock counters, and start playing anew.

Characterized not just by its spunky rhythmic character, the multi-dimensionality of the networking protocol in Wheelies was unique. While Chris controlled the global tempo, dominating that aspect of the conductor's role, any player could start or stop the whole group and thus conduct the phrasing of its rhythms. And an unusual kind of ensemble behavior resulted from the rule that players could only change each other's rhythmic behavior and not their own. One listened to recognize which part of the whole group sound each player was creating, and then tried to shape it by specifying parameter changes for them. Everyone could affect everyone else's sound, but no one could control everything about even their own sound. Because data exchanges happened only at START signals, these were like moments when the cards were shuffled for a hand which would proceed unchanged in character until the next STOP. The tempo and rhythm of this rhythmic change was under the control of any player, all the time, which meant that the whole group became attuned to shared control of this most important structural element in the piece.


Hub Mills trio



Brown, Gresham-Lancaster, and Trayle, 1989.

photo: Jim Block Photography

next Variations II