Atari 400 Technical Reference Manual page 477

Controller Port Pinout:
PIN JOYSTICK
1
Forward
2 Back
3 Left
4 Right
5
6 Trigger Button
7
8
GND
9
* Write
** PORTA or PORTB
Male
(console)
Controllers
PADDLE (POT)
A(Left)Trigger
B(Right)Trigger
POT B(Right)
+5
GND
POTA (Left)
*** STICK 0, 1, 2 or 3
111.24
Female
(connector)
HARDWARE
KEYBOARD
REGISTERS
Top Row* Bit
°
or 4**
2nd Row* Bit 1 or 5**
3rd Row* Bit 2 or 6**
Bottom Row* Bit 3 or 7**
1st Column POT 1,3,5,7
3rd Column TRIGO,I,2,3
+5
2nd Column POT 0,2,4,6
OS
VARIABLES
Bit 0***
Bit 1***
PTRIGO,2,4,6
Bit 2***
PTRIGl,3,5,7
Bit 3***
PADDLl,3,5,7
STRIGO,1,2,3
PADDLO,2,4,6