Atari XL User Manual

82 The Ater! XL Handbook
A Square Wave
In order to create distorted tones, this regular
pattern is modified by another square wave, this
one having a random pattern like this:
A Random Square Wave
When you specify a distortion parameter other
than 10 or 14, the square wave generated according
to the three other SO UND command parameters is
modified by the random square wave, such that the
only pulses of the original wave you hear are those
which coincide with a pulse of the random wave.
The diagram opposite shows how this works:
The result of the combination of the two waves
would look like the lowest wave in the diagram. As
well as distorting the quality of the sound, the pitch
of the sound you hear is lower, as some of the cycles
of
the wave are removed.The different values of the
distortion parameter select different random
waves, producing different degrees of distortion.
The following program plays a tone while stepping
through the different distortion values.
10 FOR DISTORT=O TO 14 STEP 2
20 SOUND 0,lOO,DISTORT,14
30 FOR DELAY=O TO 1000:NEXT DELAY
40 NEXT DISTORT
50 SOUND 0,0,0,0

Atari XL Specifications

General

Brand	Atari
Model	XL
Category	Desktop
Language	English