Game Controllers

History of Controllers

When Atari game consoles became popular in the 1970s, the standard game controller had a single button in the corner of the four-inch square base, which held a three-inch joystick. Players could maneuver the screen cursor by moving the joystick with one hand, and pressing the button with the thumb of the other hand. The only feedback was an occasional "blip" or "doink" noise from primitive speakers, and relatively slow, jerky movements on the screen.

Joystick design evolved to include a taller, ergonomically shaped handle with a trigger mechanism and a miniature stick at the end, called a top hat. With this device, players could squeeze such triggers with their forefingers and maneuver the top hat using one of their thumbs. These controllers often featured additional buttons on both the stick and the base that performed specific actions dictated by the game's software. Games were made more realistic with livelier sound effects from more powerful speakers.

While the one-handed joystick was sufficient for early games, it proved awkward for other sophisticated software. Soon two-handled yokes, simulating a pilot's cockpit, were introduced. Car racing games were made more realistic with the introduction of steering wheel controllers, some of which included brake and gas pedals. Gun fighting games spawned the introduction of light guns and rifles. Even fishing games were enhanced with the introduction of rod-like sticks with buttons to help the player simulate casting and fishing.

Controllers for proprietary games, such as Nintendo's "Game Boy," Sega's "Dreamcast," and Sony's "PlayStation," became special two-handed devices, each with two one-inch joysticks and many multifunction action buttons.

How They Work

Although modern game controllers sport many different features, they operate in essentially the same way as joysticks do. As the stick or indicator is moved from side to side, the position of the handle is converted into a number, known as the "x" coordinate. Likewise, as the stick is moved forward and back, the handle's position is measured with a "y" coordinate. Using these xy coordinates, the computer can precisely track the stick's direction as it moves. If the stick has a rotational capability, the r-axis is tracked as well.

To calculate the distance the stick is moved, the controller's positioning sensor uses a capacitor and potentiometer. As electrical current flows through the potentiometer, the current is temporarily collected by the capacitor, which discharges it only when a certain charge is reached, say five volts. When the stick is in the resting position, not pushed from the center, the capacitor collects and discharges the current rapidly. As the joystick is pushed farther from the center, the capacitor collects and discharges current more slowly. By measuring the number of milliseconds required for the capacitor to charge and discharge, the game adapter card tracks the stick's exact distance from center.

In newer joysticks, the capacitor and potentiometer have been replaced with an optical gray-scale position sensor, which measures the amount of light emitted by an LED (light emitting diode) to track the stick's position. When a button is pushed (to simulate jumping a barrel or hitting a ball), a contact switch sends an electrical signal to the computer's game adapter card and the game software uses the signal to start the intended action. When the button is released, another signal ends the action.

Some controllers, such as those for Sony's "PlayStation 2" and Microsoft's "Xbox," measure the amount of pressure used to push a button. When a button is pushed lightly, the button's curved contact barely touches the conductive strip mounted on the controller's circuit board. But when a button is pressed forcefully, more of the button's contact touches the conductive strip. Therefore, the level of conductivity is greater, signaling to the computer that this is a more intense action than that indicated with a lighter touch.

Force Feedback Controllers

Introduced by several manufacturers in 1997, force feedback controllers allow players to experience tactile stimulation to enhance their gaming experience. In the handgrip of each controller is a built-in electric motor with an unbalanced weight attached to its shaft. When power is supplied to the motor, it spins the unbalanced weight. Ordinarily, such an imbalance would cause the motor to wobble, but since the motor is securely attached to the controller, the wobble is translated into a vibration that shakes the entire handgrip and is felt by the game player.

The force and duration of the wobble in dictated by a waveform, which is a graph or formula that tells the software when and how to turn on and off the motor. For example, if the game player drives a car that runs into a wall, the wobble will be sudden and will continue for perhaps a second or two. On the other hand, if the game player is a firing machine gun, the resulting wobble will rapidly accelerate and decelerate many times a second for as long as the button, the "machine gun trigger," on the controller is pressed. Likewise, if the game player is driving a tank over rough terrain, the controller will experience a series of wobbles that correspond to the ground's bumps and dips.

As microprocessors have become smaller and cheaper, they have been integrated into game controllers, greatly expanding their capabilities. For example, each Microsoft Sidewinder Force Feedback Pro Joystick has a 25-megahertz microprocessor in the base to interpret software commands that dictate the feedback motion. When the command is received, the microprocessor accesses a read-only memory (ROM) chip, which permanently stores 32 movement effects and unleashes the correct movement on demand. Each movement corresponds to a certain waveform. If the software should dictate a waveform that is not already loaded on the ROM chip, the data can be downloaded to a two-kilobyte random access memory (RAM) chip for the microprocessor to use.

SEE ALSO GAMES; INPUT DEVICES.

Ann McIver McHoes

Bibliography

White, Ron. How Computers Work, 6th ed. Indianapolis, IN: Que, 2002.

Internet Resources

Xbox Website. Microsoft Corporation. <http://www.xbox.com>