Since the synchronization and timing in a musical composition is
critical, you must make sure the notes in the upper staff for voice
1, for example, are in time agreement with the notes in the lower
staff for voice 2. The first note in the upper staff in Figure 7-12 is
an A eighth note. The first two notes for voice 2 are D and E
sixteenth notes, ln this case, you must enter the voice 1 eighth
note in the PLAY string first, then follow the voice 2 sixteenth
notes immediately after it. To continue the example, the second
note in Figure 7-12 for voice 1 (the upper staff) is a B eighth note.
The B eighth note is equal in time to the two sixteenth notes, F
and G, which appear in the bottom staff for voice 2. ln order to
coordinate the timing, enter the B eighth note in the string for
voice 1 and follow it with the two sixteenth notes F and G for
voice 2.
As a rule, always start with the note with the longer duration. For
example, if a bar starts with a series of two sixteenth notes on the
lower staff for voice 2 and the upper staff starts with an eighth
note for voice 1, enter the eighth note in the string first since it
must play for the duration while the two sixteenth notes are being
fetched by the Commodore 128. You must give the computer
time to play the longer note first, then PLAY the notes of shorter
duration, or else the composition will not be synchronized.
Here’s the program that plays Invention 13. Enter it into your
C128, SAVE it for future use and then RUN it.
10 REM INVENTION 13 BY J S BACH
20 TEMPO 6
30 A$="V1O4T7U8X0 V2O4T7U8X0": REM Vl=ORGAN, V2 = PIAN0
4 0 DO
50 PLAY A$
60 READ A$
70 LOOP UNTIL A$="END OF MUSIC"
80 END
90 REM **** FIRST MEASURE
100 DATA V201IA V103IE V202QA V103SA04C03BEM
110 DATA V202I#G V103SB04D04IC V202SAEM
120 DATA V104IE V202SA03C V103I#G V202SBEM
130 DATA V104IE V202SB03DM
140 REM **** SECOND MEASURE
150 DATA V203IC V103SAE V202IA V103SA04CM
160 DATA V202I#G V103SBE V202IE V103SB04DM
7-28
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