The Atari 7800 came bundled with the Atari Pro-Line Joystick, a two-button controller with a joystick for movement.
The Pro-Line was originally developed for the 2600 and was advertised in 1983, but delayed until Atari proceeded with the 7800.
The right fire button only works as a separate fire button for certain 7800 games that utilize it; otherwise, it duplicates the left fire button, allowing either button to be used for 2600 games.
While physically compatible, the 7800's controllers were incompatible with the Sega Master System, and Sega's controllers were unable to use the 7800's two-button mode.

In response to criticism over ergonomic issues in the 7800's Pro-Line controllers, Atari later released a joypad controller with the European 7800.
It was similar in style to controllers found on Nintendo and Sega Systems.
The joypad was not available in the United States.

There were few add-on peripherals for the 7800, though its backwards compatibility feature allowed it to use most Atari 2600 peripherals.
The Atari XG-1 light gun, which came bundled with the Atari XEGS, was sold separately for other Atari systems and was compatible with the 7800.
Atari released five 7800 light gun games: Alien Brigade, Barnyard Blaster, Crossbow, Meltdown, and Sentinel.
The Atari 7800 came bundled with the Atari Pro-Line Joystick, a two-button controller with a joystick for movement. The Pro-Line was originally developed for the 2600 and was advertised in 1983, but delayed until Atari proceeded with the 7800. The right fire button only works as a separate fire button for certain 7800 games that utilize it; otherwise, it duplicates the left fire button, allowing either button to be used for 2600 games. While physically compatible, the 7800's controllers were incompatible with the Sega Master System, and Sega's controllers were unable to use the 7800's two-button mode.
In response to criticism over ergonomic issues in the 7800's Pro-Line controllers, Atari later released a joypad controller with the European 7800. It was similar in style to controllers found on Nintendo and Sega Systems. The joypad was not available in the United States.
There were few add-on peripherals for the 7800, though its backwards compatibility feature allowed it to use most Atari 2600 peripherals. The Atari XG-1 light gun, which came bundled with the Atari XEGS, was sold separately for other Atari systems and was compatible with the 7800. Atari released five 7800 light gun games: Alien Brigade, Barnyard Blaster, Crossbow, Meltdown, and Sentinel.
Atari 7800