Instructions
Here I will explain in a fast and simple way the change to be made in the joystick cable to have 1 or 2 more buttons. Schematic
The joystick ports of Atari is a DB9 that means it has nine pins for communication, which are used for different control devices such as joystick, paddle, etc.
The joystick only uses 6 pins of the 9 that the connector has, here in this image you can clearly see what they are exactly:
Then we have 4 pins for movement (from 1 to 4) pin 8 which is ground and finally pin 6 which is the button. As we can see we have 3 free pins that are 5, 9 and 7 that are not used. That's why the joystick cable only has 6 cables and not 9.
Now let's review the paddle uses 6 too but they are different to the joystick, as shown in the following image:
Now we see clearly that from here come 2 paddles only using a joystick port. The left paddle would be pin 5 and 7 for the movement, pin 4 and 8 for the button. The right paddle would be 9 and 7 for the movement, pin 3 and 8 for its button.
After reviewing both controls, we clearly see that we can use pins 5, 9 and 7. To use it as a button. This can be done if we join the pins 5 with the 7 the Atari mark 1, if they are not joined mark 224 in the memory position PADDL0.
In short we are going to include in the joystick the own pins plus the pins 5, 9 and 7 that is we need a cable that contains the 9 pins. You can make the cable yourself or use a sega or a console that uses a DB9 connector. The union of all the cables should look like this scheme:
With this we have 2 more buttons, using the movement of the left and right paddles. A detail resistance 330 ohms can be 1/4 or 1/2 watt
This version 1.1 is compatible with ATARI 2600 and Genesis controller to use the second button in modified games 👍