Commodore 128D - Page 143

up to three voices. Experiment and create a program which utilizes
all three voices.
Here's a sample program that will help you understand how to pro
gram the Commodore 128 synthesizer chip. The program, when run,
asks for each parameter, and then plays the sound. Here's the pro
gram listing. Type it into your computer and RUN it.
n
Here's a quick explanation of the program. Lines 10 and 20 PRINT
the introductory messages on the screen. Lines 30 through 50
INPUT the voice, frequency and duration parameters. Line 60 asks if
you want to enter the optional SOUND parameters, such as the
sweep settings and waveform. If you don't want to specify these
parameters, press the "N" key and the program jumps to line 120
and plays the sound. If you do want to specify the optional SOUND
settings, press the "Y" key and the program continues with line 80.
Lines 80 through 110 specify the sweep direction, minimum sweep
frequency, sweep step value and waveform. Line 120 INPUTS the
pulse width of the variable pulse waveform only if waveform 2 (varia
ble pulse) is selected. Finally, line 130 plays the SOUND according to
the parameters that you specif ied earlier in the program.
Line 140 asks if you want to hear the SOUND again. If you do, press
the "Y" key; otherwise, press the "N" key. Line 150 checks to see if
you pressed the "Y" key. If you did, program control is returned to
line 130 and the program plays the SOUND again. If you do not press
135 USING C128 MODE—Sound and Music In C128 Mode