single large knob identical to the one on the paddles. In comparison to the driving controllers, paddle controllers rotate just under one full rotation before hitting a hard stop. They also come in pairs that plug into a single port, whereas the driving controllers were one to a port. Finally, they have a picture of a tennis racquet and the word "paddle" on it, as opposed to a racing car and the word "driving". Because two controllers connect to each port and the 2600 has two controller ports, four players simultaneously can play in games that support it. The Atari paddles are also compatible with the Atari 800 home computer, with its four-game controller ports. This would allow eight paddles in simultaneous play. Super Breakout is one example that supported up to 8 players. Atari also offered driving controllers for use with games like Indy 500, which requires wheels that can spin around continuously in one direction. Driving controllers have a picture of a car and the word "driving" on it and a single controller attaches to each controller port. The driving controller is not compatible with paddle games. Like a mechanical computer mouse, the driving controller is a quadrature encoder-based device and thus only sensed relative position, not absolute position. This controller is functionally identical to the spin-dial controller used in Atari's Tempest arcade game. Since only one controller attaches to each port, only two people can play driving games simultaneously. Several similar relative spinner controllers have emerged as part of the home-built arcade cabinet scene to facilitate play of such games as Tempest, including spinners from Oscar Controls and the SlikStik Tornado spinner. These devices are typically made to plug directly into a computer as a single-axis mouse. See also Joystick Racing wheel Scroll wheel References Computing input devices Game controllers