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Commodore



Joystick Pinouts

Commodore 64

There are two joystick ports on the Commodore 64 known as 'Control Port 1' and 'Control Port 2'. Apart from a standard joystick, the C64 can also support analogue paddles, a light pen and a mouse (1350/1351).


Paddles

Each joystick port has two analog inputs (pins 5 and 9), so in most of the cases I've seen, paddles come in pairs, each with their own lead, but both leads going into a single DB9 connector that matches the joystick port connector. 

The SID sound chip in the C-64 has two analog inputs also, which are connected to the joystick ports through analog multiplexing (allowing a total of four paddles to connect cia the two inputs at the SID). The analog parts (excluding fire buttons etc) of a (dual) paddle is shown in the diagram below.


The potentiometers P0 and P1 are coupled as variable resistors, which supplies a charge current to the capacitors C0 and C1. The SID times this charging process, and discharges the capacitors for the next measurement, and uses the results to report the "position" of the paddle knob.