Commodore 128 Programmer's Reference Manual page 346

336 COMMODORE 128
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INTRODUCTION
The Commodore 128 has one of the most sophisticated built-in sound synthesizers
available in a personal computer. The synthesizer, called the Sound Interface Device
(SID), is a chip dedicated solely to generating sound and music. The SID chip is capable
of producing three independent voices (sounds) simultaneously. Each of the voices can
be played in one of four types of sounds, called waveforms. The SID chip also has
programmable Attack, Decay, Sustain and Release (ADSR) parameters. These parame
ters define the quality of a sound. In addition, the synthesizer has a filter you can use to
choose certain sounds, eliminate others, or modify the characteristics of a sound or sounds.
All these features add up to a powerful and versatile synthesizer.
To make it easy for you to select and manipulate the many capabilities of the SID
chip, Commodore has developed new and powerful BASIC music statements.
Here are the new sound and music statements available on the Commodore 128:
SOUND
ENVELOPE
VOL
TEMPO
PLAY
FILTER
The beginning of this section explains these sound statements, in an encyclopedia
format. The second half describes how to program the SID chip in machine
language.
ENVELOPE J
Define a musical instrument envelope j i
ENVELOPE n,[,atk] [,dec] [,Sus] [rel][,wfj [,pw] LI
where:
n Envelope number (0-9) ^
atk Attack rate (0-15)
dec Decay rate (0-15) j j
sus Sustain (0-15) [J
rel Release rate (0-15)
wf Waveform: 0 = triangle r
1 = sawtooth j
2 = variable pulse (square) Uj
3 = noise
4 = ring modulation j j
pw Pulse width (0-4095) U