Atari 400 Hardware Manual

AUDF1, AUDF2, AUDF3, AUDF4 (Audio Frequency) (D200, D202, D204, D206)
These addresses write data into each of the four Audio Frequency Control
Registers. Each register controls a divide by "N" counter.
I
I
I I
I
D7
I D6 I
D5
I
D4
I D3 I
0 0 0 0 0
0 0 0 0 0
ETC.
1 1 1 1 1
I
D2
J
D1
0 0
0 0
1 1
I
l
DO
0
1
1
"N"
1
2
256
Note: "N" is one greater
than the binary number
in Audio Frequency
Register AUDF(X).
AUDC1, AUDC2, AUDC3, AUDC4 (Audio Channel Control)(D201, D203,
D205, D207):
These addresses write data into each of the four Audio Control
Registers. Each Register controls the noise content and volume of the
corresponding Audio Channel.
Noise Content or Distortion Volume
I I I I I I
Divisor "N" set
HEX D7
I D6 I D5 I D4
D3 I
D2
I D1 I
DO by audio frequency
register.
0 0 0 0 0
- 17 BIT
poly- 5 BIT
poly - N
2
0 0 1
0
- 5 BIT
poly
- N - 2
4
0 1 0
0
- 4
BIT
poly -
5
BIT
poly - N
6 0 1 1
0
- 5 BIT
poly - N -
2
8 1 0 0 0 - 17 BIT poly
- N
A
1 X
1 0
-
Pure Tone -
N -
2
c
1 1
0
0
- 4 BIT
poly - N
1
X
X X 1 -
Force Output
(Volume only)
0 0
0 0 0 -
Lowest Volume
(Off)
8 1
0
0 0
- Half Volume
F
1
1 1 1 -
Highest Volume
III .13

Atari 400 Specifications

General

Manufacturer	Atari
Model	400
Type	Home Computer
Release Year	1979
CPU	MOS Technology 6502
CPU Speed	1.79 MHz
ROM	10 KB
Operating System	Atari OS
Keyboard	Membrane keyboard
RAM	8 KB (expandable to 48 KB)
Graphics	ANTIC and GTIA chips
Sound	4 channels
Display	RF output for connection to TV
Storage	Optional cassette tape drive or floppy disk drive
Ports	Cartridge
Display Resolution	320x192 (16 colors)