Commodore VIC-20 User Manual page 82

You've just sounded note #128 using speaker #36874, the first
(lowest) voice. From now on, let's call this speaker S1 (short for
speaker 1); the second, S2; the third, S3; and the fourth, S4. S2
sings higher notes than S1 does, and S3 sings higher than S2.
S4 sings with a buzz in its voice...this "voice" creates "white
noise" used for sound effects.
By the way, to turn off a voice, POKE 0 into it, like this:
POKE 36874, 0 and press
This might seem a little complicated if you're not a "computer
musician" yet, so we've made it easier for you. You can save a
lot of typing if you use (he following short program to translate
the speaker numbers into shorter numbers.
Type this on your VIC exactly as shown:
NEW
51 = 36874
52 ■ 36875
53 = 36876
54 = 36877
V = 36878
This allows us to refer to the speaker numbers by the
abbreviations SI, S2, S3, S4, and V (volume). Before proceeding,
check to make sure that each line has been entered correctly
Now you are ready to make sounds the easy way!
POKE V, 10
This sets the volume
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