Atari 400 Hardware Manual

PITCH VALUES FOR THE MUSICAL NOTES-AUDCTL =0, AUDC = hex AX
AUDF
Hex
Dec
HIGH
c lD
29
NOTES
B lF
31
All or Bb
21
33
A
23
35
Gil or Ab
25
37
G
28
40
Fll or Gb
2A
42
F 2D 45
E
2F
47
D/1 or Eb 32 50
D
35
53
ell or
Db
39
57
c
3C
60
B 40
64
All
or
Bb 44 68
A
48
72
Gil or Ab 4C
76
G 51
81
Fll or Gb 55
85
F 5B
91
E 60
96
Dll or
Eb
66
102
D
6C
~ 108
ell or
Db
72 114
MIDDLE C
c 79 121
B
80 128
All
or Bb 88 136
A
90
144
Gil or Ab 99
153
G
A2 162
Fll or Gb AD
173
F
B6
182
E
Cl 193
Dll or
Eb cc 204
D
D9 217
LOW
ell or
Db E6 230
NOTES
c
F3 243
STIMER ~Start Timer)~D209):
This write address resets all audio
frequency dividers to their "AUDF" value. These dividers generate timer
interrupts when they count down to zero (if enabled by IRQEN).
(also see
IRQST)
not used
RANDOM (Random Number Generator)(D20A): This address reads the high
order 8 bits of a 17 bit polynomial counter (9 bit, if bit 7 of AUDCTL=l).
D7 D6 D5 D4 D3 D2
Dl I DO I
III.l4

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)