of Microprocessors

124 MUSICAL ApPLICATIONS OF MICROPROCESSORS
shapes, and actual waveforms would also be present. Finally, text representing
perhaps statements in one or more music languages or just lists of
instructions would be there too.
The purpose of a program in the loosely structured system is to either
convert data from the data base into sound; take data out, process it, and put
it back in a different form; or convert external information into a suitable
form and enter it into the data base. A sound output program is an example
of the first type because it would take sample data from the data base and
convert it to sound through the DAC. A reverberation simulator would take
sample data and perhaps a list of instructions from the data base and return
reverberated samples to the data base. A synthesizer program would take
language statements and curves out and produce samples. A macroprocessor
could take statements in a very powerful, structure-oriented rather than
note-oriented music language and convert them into statements (probably
much more numerous) in a lower music language. This would circumvent
the immediate necessity of an interpreter for the new language. An input
processor program might look at a keyboard interfaced to the system and
convert the key action it sees into music language statements or other suitable
form. A sound analysis program could take sample data and produce
curves representing the changing parameters of the sound analyzed. Nearly
an infinite variety of possibilities exist for programs in such a system.
Using a loosely structured system is not unlike tape-editing methods for
producing electronic music. Initial sound material or language statements
are taken through a sequence of steps using various programs until the final
result is obtained. At intermediate points, the piece may exist as a number of
fragments at various stages of processing. Contrast this to a highly structured
system in which the entire specification for the piece is self-contained in a
string of language statements.
Because of its very nature, the loosely structured system is easily and
almost infinitely expandable. The only limitation is the structure of the data
base itself. Even that can be expanded by adding more data types, but a
proliferation of conversion programs could develop if many were added.