Atari 400 Hardware Manual

SEROUT (Serial Output Data)(D20D): This address writes to the 8 bit
parallel holding register that is transferred to the output serial shift
register when a full byte of serial output data has been transmitted. This
address is usually written in response to a serial data out interrupt (IRQ
and bit 4 of IRQST).
D7
D6 DS
D4
D3 D2 D1 DO
I. CONTROLLER PORTS (front of console)
PORTA (Port A)(D300): This address reads or writes data from Player 0
and
Player 1 controller jacks if bit 2 of PACTL is true. This address
writes to the direction control register if bit 2 of PACTL is zero. I/O for
both ports (A and B) goes through a 6520/6820
Data Register-Addressed if bit 2 of PACTL is 1.
Joystick Operation
I I I I
D7 D6
DS I D4 I D3 I D2 I D1 DO
Right
Left
Back Right Back
Fwd.
Left Fwd.
D7
I
I D7 :
Stick1
(Jack 2)
StickO
(Jack 1)
Paddle Operation
I I I
D6
I DS I D4
I
D3
D2
I D1 I DO
L PTRIG2
I
L PTRIGO
PTRIG3
PTRIG1
K b
ey oar
d c t 11 on ro 0
t'
er Jpera 1on
I I I I
I
I
DO I D6 I DS I D4 I D3 I D2 I
D1
I
I
L._
._____Top
Row
2nd Row
Jack
3rd Row
4th Row
)
Top
2nd
3rd
4rd
2
O=Switch pressed
1=Switch not pressed
O=Switch
1=Switch
Row)
Row
Row
Row
pressed
not pressed
Jack 1
Control Re ister-Addressed if bit 2 of PBCTL is 0
I I I I I I
Each bit corresponds to a jack pin
O=input
1=output
OS SHADOWS: STICKO (hex 278), STICK1 (279), PTRIG0-3 (27C-27F
III.19

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)