of Microprocessors

MUSIC SYNTHESIS SOFTWARE 687
information separate and with the sounds facilitates implementation of stereo
or quad at a later time.
The last task is to determine if the specified duration of sound generation
has elapsed. The time argument that was passed to this routine is simply
decremented and tested for zero. If the time has not elapsed, the routine is
simply executed again for another 30 samples. When the time is elapsed, the
Level 3 NOTRAN interpreter regains control so that more events can be
started.
NOTRAN Language
Level 3 routines in the NOTRAN system are what actually look at
NOTRAN statements. Like the lower-level routines, most of the work is
simply the manipulation of tables of information. Before discussing what
these routines do, a brief description of the NOTRAN language itself is in
ordet. Note that up to this point the sound generation routines are completely
independent (within the constraints imposed by the sound generation
models) of the actual music language used. Thus, language freaks could
completely restructure the language and still use the sound generation
routines that have been discussed.
As briefly mentioned earlier, NOTRAN uses a textual representation of
the musical score. In designing such a representation, one is immediately
faced with a problem: how should the score, which is basically a twodimensional
structure, be represented as a one-dimensional character string?
The two dimensions in this case are time in the horizontal direction and
"voices" or "parts" in the vertical dimension. Thus, the music language
designer must choose between a vertical representation where the score is
coded chord-by-chord in strict time sequence and a horizontal representation
in which all of the notes, from beginning to end, for the first voice are coded
followed by notes for the next voice, etc.
The former is probably easier to read (it can be likened to a conductor's
score, which shows all of the instrument parts at once), while the latter may
be easier to transcribe from a printed score into language statements. Of
course, when the music is actually played, it must be presented to the
synthesis routines or synthesizer in vertical form so the individual parts of a
horizontal score must be "merged" into an internal vertical form for
performance. Such a merging routine can become quite complex and unless
"checkpoints," such as measure boundaries, are included in the language, a
single duration error in a voice may misalign that voice for the remainder of
the piece. Thus, for simplicity, NOTRAN uses a vertical score
representation.
Of course, printed music scores are primarily graphic in nature. This
coupled with the improved graphic capabilities of modern microcomputers
suggests an interactive graphic score editor rather than a text language and
standard text editor program. This in fact is done frequently in commercial