XL/XE models have two joystick ports. 400/800 models have four joystick ports.
At least two ports are programmable for output (not sure about PORTB of PIA).
Joy 0: port A, bits 0-3, pot 0, pot 1, trig 0
Joy 1: port A, bits 4-7, pot 2, pot 3, trig 1
Joy 2: port B, bits 0-3, pot 4, pot 5, trig 2
Joy 3: port B, bits 4-7, pot 6, pot 7, trig 3
PaddlesValues are from 228 at left to 1 at right.
Keyboard controllerController consisting of 4 rows of three buttons.
Multijoy interfaceMore info is here.
Light gunLight gun input is on pin 6 (trig). Can be only used in port 4 on Atari 400. The trigger is connected (inverted) to bit 0. That means that you can 'detect' light gun by getting 1110 when inserted (1111 when pressing fire).
Atari Touch Tablet
XEP80Back (c) 1998-2004 Jindroush Last modified: Sun Mar 25 23:48:36 2001