9 PIN D-SUB MALE at the Atari
9 PIN D-SUB FEMALE at the joystick cable
The Atari 7800 ProSystem, released in 1984, uses the same 9-pin DE-9 connector as the Atari 2600 and the broader de-facto “Atari joystick” standard shared with Commodore and MSX computers. The ProLine two-button controller extends the standard by driving pin 6 to +5V as a button-common rail, whilst the Right Button (pin 5) and Left Button (pin 9) connect to GND when pressed. In 2600 compatibility mode, both buttons ground pin 6 simultaneously, preserving single-button behaviour on older hardware. Direction inputs on pins 1–4 are active-low digital switches that short to GND when activated.
| Pin | Color | Dir | Description |
|---|---|---|---|
| 1 | WHT | IN | Up |
| 2 | BLU | IN | Down |
| 3 | GRN | IN | Left |
| 4 | BRN | IN | Right |
| 5 | RED | IN | Button (R)ight (-) |
| 6 | ORG | ? | Both buttons (+) |
| 7 | n/c | - | +5V |
| 8 | BLK | - | Ground(-) |
| 9 | YLW | IN | Button (L)eft (-) |
Notes
- Direction is Computer relative Joystick.
- The DE-9 male socket is on the console; the female plug is on the joystick cable.
- All direction inputs (pins 1–4) and button inputs (pins 5, 9) are active-low: the switch shorts the signal pin to GND (pin 8) when pressed.
- In 7800 two-button mode the console drives pin 6 to +5V (button-common); Right Button (pin 5) and Left Button (pin 9) pull low when pressed.
- In 2600 compatibility mode both buttons ground pin 6 directly, providing the standard single-fire behaviour expected by 2600 software.
- Pin 7 carries +5V from the console’s power rail; this is the same provision as on the Atari 2600 and is required to power paddle/potentiometer controllers and the ProLine button-detection circuit.
- The connector is mechanically and electrically backward-compatible with Atari 2600 joysticks and paddles for single-button use.
Signals
- Up — active-low input; grounds pin 1 when joystick is pushed forward
- Down — active-low input; grounds pin 2 when joystick is pulled back
- Left — active-low input; grounds pin 3 when joystick is pushed left
- Right — active-low input; grounds pin 4 when joystick is pushed right
- Button (R)ight (−) — active-low input (pin 5); right fire button grounds this pin in 7800 two-button mode
- Both buttons (+) — pin 6; driven to +5V by the 7800 console as a shared button-common rail in two-button mode; grounded by either button in 2600 compatibility mode
- +5V — pin 7; +5V supply provided by the console; powers paddle potentiometer controllers and the button-detection circuit
- Ground(−) — pin 8; signal and power ground reference
- Button (L)eft (−) — active-low input (pin 9); left fire button grounds this pin in 7800 two-button mode