A spinner is a knob that turns forever. It has no end stops, so it cannot tell the machine where it is pointing, only how far it has turned and in which direction since the last look. That sounds like less information than a paddle gives, but it means a player can whirl the knob round and round, and a game can map one turn to as much movement as it likes. Tempest used it to send a ship around the rim of a tube in a single flick of the wrist.
Fast facts
- Mechanism: a rotary encoder, usually a slotted disc passing between light sources and sensors.
- Output: movement (how far and which way), not position.
- Rotation: unlimited in either direction.
- Arcade examples: Tempest (1981), Tron (1982), Major Havoc (1983), Arkanoid (1986).
- At home: Atari’s driving controller for the VCS works the same way.
Spinner or paddle?
This entry keeps spinner for the free-turning encoder and paddle for the potentiometer knob, but the words are used loosely. The Atari Book calls Pong’s controls spinners and names what was inside them: “cheap potentiometers, the electronic component that the spinners are actually made from. They’re usually rated for a certain number of turns.” A potentiometer has end stops, so by the definition used here Pong had paddles. Retro Gamer likewise calls the controller packed with the NES Arkanoid “a smaller version of the ‘spinner’ on the arcade cab”. Anyone reading period or later writing should expect either word for either device.
| Spinner | Paddle | |
|---|---|---|
| Rotation | Unlimited | Limited by end stops |
| Reports | Movement | Position |
| Sensor | Rotary encoder | Potentiometer |
How they work
The spinner uses the same method as the rollers of a trackball, and Atari’s service manual for the 5200 trackball describes it step by step. A shaft carries “a slotted encoding wheel at one end which interrupts the two light sources in the optocoupler”. That gives two square waves “approximately 90° out of phase”, and the order in which they change tells the circuit which way the wheel is turning, “depending upon which clock leads the other”. Counting the pulses gives the distance.
Nothing in that path rubs, so there is no resistive track to wear out, which was Pong’s weakness. The feel of the knob comes from its mechanics. Dave Theurer, who designed Tempest, described its controller: “Just the right amount of resistance and just the right amount of angular momentum when you stop applying the force.” Electronic Games found the same quality in Midway’s Tron in November 1982: its “rotary aiming dial spins freely”.
Arcade spinner games
| Game | Year | What the spinner did |
|---|---|---|
| Tempest | 1981 | Moved the ship around the rim of the tube |
| Tron | 1982 | Aimed the weapons |
| Major Havoc | 1983 | Steered the ship, then set the running speed of the hero |
| Arkanoid | 1986 | Moved the Vaus bat |
Tempest was not planned as a spinner game. Theurer’s first idea was a “first-person Space Invaders”, and according to The Atari Book the switch to “a ‘spinner’ controller rather than a traditional joystick” came when the game turned into the tube shooter. Theurer said much later that he still enjoyed playing Tempest “if it’s on a platform with a spinner controller”.
Tron’s cabinet paired a spinner with a joystick. Electronic Games explained that the dial sat “on the left side of the control console” for aiming and was used in every stage except the light cycles, where players only steered and pressed the button. Video Games described Major Havoc’s “bi-directional roller controller”, and noted that in the maze stages “the faster you spin the controller the faster he’ll run”.
Home versions
Atari’s VCS had a spinner of its own, the driving controller. The 1983 field service manual describes “a switching device that generates a full two-bit gray code for each quarter turn of the controller knob”, read by the RIOT chip, and contrasts it with the paddles: “Unlike the non-linear resistive game paddles, the driving controller gives the user precise linear positional control over the complete turning range of the knob.” The manual tests it with Indy 500.
Arcade spinner games otherwise reached home machines with other controls. The NES Arkanoid came with its own knob controller.
Sources
- The Atari Book (Retro Gamer, 2012): Pong’s controls and the “cheap potentiometers” (p. 127); Tempest’s development and the switch to a spinner (p. 150); Theurer on playing Tempest today (p. 153).
- Atari, CX5200 Field Service Manual, rev. 4 (1983), section 7, “CX53 Trakball”, theory of operation (pp. 7-4 to 7-5): slotted encoding wheels, optocouplers and direction sensing.
- Atari, 2600/2600A VCS Domestic Field Service Manual (1983): the driving controller and its test with Indy 500.
- Electronic Games, November 1982: the making of Tron and its controls (p. 42); the “Insert Coin Here” review of Tron (p. 66).
- Video Games, February 1984: trade-show report listing Major Havoc on Atari’s stand; April 1984, p. 50: review of The Adventures of Major Havoc.
- Retro Gamer issue 43 (2007), p. 67: the NES Arkanoid controller.