The Atari 2600 has many input devices such as joysticks, paddles, and keyboards, as well as third-party components. The console was originally packaged with two standard Atari CX10 joysticks, later upgraded to the more common CX40 model, and a set of paddles. Joysticks, featuring a single button and four-directional stick, are used by most Atari games and are the predominate input device.By 1986 the CX40 was difficult to obtain. The Atari joystick port, however, appeared on many other systems. Atari-compatible joysticks were used for Commodore VIC20, Commodore 64, Amiga, Atari ST, MSX, Sinclair ZX81/Spectrum using an adaptor and several Japanese home computers. Sega video game consoles such as Sega Master System or Sega Genesis can also use Atari-compatible joysticks for games that only require one button.The other main controller, the Atari CX30-04 paddle, is used for games based on one-dimensional movement. These included Pong, Breakout, and Circus Atari, among others.The Atari CX20-01 "driving controller" appears similar in design to the paddle, but there is only one per DE-9 port rather than two paddles per port. The key difference in function between the paddle and driving controller is that the paddle's wheel had a finite amount it would turn before hitting a stop, while the driving controller's wheel could rotate continuously. This is essential for overhead-view driving games, for which the player would turn the wheel a total of 360 degrees in one direction on every lap. The driving controller is used for games such as Indy 500.The Atari CX50 keyboard controller functions as a computer keyboard and is required for games such as Star Raiders.
