Atari 800 Basic Reference Manual

SOUND (SO.)
10
SOUNDS AND GAME
CONTROLLERS
This section describes the statement used to generate musical notes and sounds
through the audio system ofthe television monitor. Up to four different sounds
can be "played" simultaneously creating harmony. This SOUND statement can
also be used to simulate explosions, whistles, and other interesting sound ef-
fects.
The other commands described in this section deal with the functions
used to manipulate the keyboard, joystick, and paddle controllers. These func-
tions allow these controllers to be plugged in and used in BASIC programs for
games, etc.
The command and functions covered in this section are:
SOUND
Format:
Example:
PADDLE
PTRIG
SOUND aexp1, aexp2, aexp3, aexp4
100 SOUND 2, 204, 10, 12
STICK
STRIG
The SOUND statement causes the specified note to begin playing as soon as the
statement is executed. The note will continue playing until the program en-
counters another SOUND statement with the same aexp1 or an END statement.
This command can be used in either Direct or Deferred modes.
The SOUND parameters are described as follows:
aexp1 =
aexp2
aexp3
aexp4
Voice. Can be 0-3, but each voice requires a separate SOUND state-
ment.
Pitch. Can be any number between 0-255. The larger the number,
the lower the pitch. Table 10-1 defines the pitch numbers for the
various musical notes ranging from two oc taves above middle C to
one octavf' below middle C.
Distortion. Can be even numbers between 0-14. Used in creating
sound effects. A 10 is used to created a "pure" tone whereas a 12
gives an interesting buzzer sound. A buzzing sound (like engines at
a race track) can be produced using two separate SOUND commands
with the distortion value (aexp3) alternating between 0 and 1. A
value of 1 is used to force output to the speaker using the specified
volume (see aexp4). The rest of the numbers are used for other
special effects, noise generation, and experimental use.
Volume control. Can be between 1 and 15. Using a 1 creates a sound
barely audible whereas a 15 is loud. A value of B is considered nor-
mal. If more than 1 sound statement is being used, the total volume
should not exceed 32. This will create an unpleasant "clipped" tone.
Sounds and Game Controllers 57

Atari 800 Specifications

General

Processor	MOS Technology 6502
Processor Speed	1.79 MHz
ROM	10 KB
Graphics	ANTIC and GTIA chips
Release Year	1979
Display Resolution	up to 320 x 192
Colors	128 colors
Sound	4 channels
Storage	Cartridge, cassette, floppy disk
Ports	Cartridge, serial, monitor
Operating System	Atari OS