Atari 400 Hardware Manual

the
PACTL
~Port A Control) ~D302):
This address
writes or reads data from
Port
A
Control Register.
Port A Control
D7
D6 DS D4 D3
D2
Dl
DO Register
X
0
1 1
X
X
0
X
Set up register as shown
(X = described below)
D7 - (Read only) Peripheral A Interrupt Status Bit. Serial
bus Proceed line. (Reset by reading Port A Register.
Set by Peripheral A Interrupt.)
D3- Peripheral Motor Control line on serial bus (write).
(0 = On 1 = Off)
D2 -Controls Port A addressing described above (write).
(1 =Port A Register 0 =Direction Control Register).
DO - Peripheral A Interrupt Enable Bit. (Write) 1 = Enable.
Reset by power turn-on or processor. Set by Processor.
PORTB (Port B)(D301): This address reads or writes data from Player 2
and
Player 3 controller jacks if bit 2 of PBCTL is true. This address
writes to the direction control register if bit 2 of PBCTL is zero. I/O for
both ports (A and B) goes through a 6520/6820.
Data Register-Addressed if bit 2 of PBCTL is 1
Joystick Operation
I I I I
D7 D6 DS I D4 I D3 I D2 I Dl
DO
Back Right Back
Right
Left Fwd • ./, Left Fwd.,
~'-------~~------J, ' ~~------J~
Stick3
(Jack 4)
Stick2
(Jack 3)
Paddle 0 eration
I I I I
"---PTRIG7
b
Kevl oar
d c ontro 11 0
er 1p_erat1on
I I I I I I I
D7 I D6 I DS I D4 I D3 1 D2 I
Dl I DO I
l
L_
'--Top
Row}
2nd Row Jack
3rd Row
4th Row
4
III. 20
Top
2nd
3rd
4rd
O=Switch pressed
!=Switch not pressed
O=Switch pressed
!=Switch not pressed
Row}
Row
Row
Row
Jack 3

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)