Atari CPS Super SALT - Joystick Ports

The final part of the CPS Super SALT test fixture we will look at is the joystick ports.

The four directional pins on the joystick ports can be can be configured as either inputs or outputs, so an output on one can be read as an input on another. The direction pins on port 1 are connected to port 3, and the pins on port 2 are connected to port 4, this allows for the testing of all the direction pins. If the test is being run on an XL series computer the analog switch U12 is enabled which connects the direction pins on port 1 to port 2. 

The trigger inputs are connected to the direction pins as follows:

Trigger J1  -J1(3)
Trigger J2 - J2(3)
Trigger J3 - J3(1)
Trigger J4 - J4(1)

The paddle inputs are connect through resistors to direction pins as follows:

Pot J1(A) - J1(4)    
Pot J1(B) - J1(3)
Pot J2(A) - J2(4)
Pot J2(B) - J2(3)

Pot J3(A) - J3(2)    
Pot J3(B) - J3(1)
Pot J4(A) - J4(2)
Pot J4(B) - J2(1)