The computer program Project 2 (PR2) followed Project 1 fairly quickly (around 1966). The aim was to give the composer greater control over the composition process. Instead of a work consisting of “sections”, “variants” of a model described by PR2 are composed. Control has been extended to cover the following parameters:
- Instrument: lists of instrument names; each melody or percussion instrument is defined in terms of its pitch, duration and dynamic range.
- Rhythm: lists for entry delays, durations, rests and tempi.
- Harmony: a choice of three harmonic principles: chord list, row, interval table.
- Dynamics: list of dynamic indications.
- Articulation: list of articulation modes.
The flow of data from the list into the score is effectuated in all the parameters, with the exception of Harmony, by way of “tables” and “ensembles”. A table contains “groups”, a group contains any number of elements from the appropriate list. An “ensemble” contains one or more groups. Table groups for an ensemble and ensemble elements for the score are selected by various methods: arbitrary selection (Alea), serial i.e. non-repetitive selection (Series), weighted selection (Ratio), selection with group repetition (Group), directionally defined selection (Tendency) and the composer’s own selection of individual elements (Sequence).
The parameters are hierarchically interdependent so as to avoid conflict between a subordinate and a superordinate parameter. Hierarchy is composer-defined or random.
Basically, Project 1 produces a homophonic sequence of chords which the composer may subsequently break up into polyphonic parts. PR2 is based on the same principle. It can additionally produce polyphonic structures when ensembles contain several, separate groups. Every layer is based on one of these groups; they commence simultaneously and are formed – independently of one another – in accordance with the method used to select them. They can remain harmonically independent or, pitchless at first, be given a common harmonic structure later.
Data input is effectuated by a list of more than 60 questions. The composition process is autonomous, i.e. the composer cannot intervene. The resulting score-tables can be printed, stored or played with the aid of a soundcard.