Atari 2600 on a breadboard, part VI: fixing the video, adding a joystick and wrapping up - chester's blog
TV game joysticks
Nerdly Pleasures: The Forgotten Switch : The Atari 2600's B&W/Color Switch
143 Joystick Controller, Classic 3D Analog Joystick Game Control with an Operating Button and a Four-way Joystick, for All Atari 2600 Systems: Amazon.co.uk: PC & Video Games
Atari's difficulty switches are brilliant and should have been adopted by more game consoles | 8-Bit Central
Atari 2600 light sixer and his six buttons by lulrik on DeviantArt