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 so that operation is analogous to switch closures. A third dimension of control is provided by the Trazor's inherent ability to sense the presence or absence of the user's finger. All these modes of control can be utilized in designing new games, taking advantage of the flexibility and power provided by microprocessors. We will look at a few examples of video games that might be played with a universal control console with four Trazors spaced so they could be used by four players or by two players each controlling a Trazor with each hand.

The agility that the Trazor provides suggests adding a wrinkle to traditional games such as tennis by making the ball rebound velocity proportional to the velocity with which the player hits the ball. With four Trazors, we can also play doubles. Team games such as hockey can be played with pairs of figures passing the puck back and forth between them. One player can control a set of figures with each hand, or there can be two players on each side, making it a true team game.

A three-dimensional color Etch-a-sketch can be implemented with two Trazors. One provides X and Y axis locations. The X and Y information is translated along a diagonal Z axis by one axis of the second Trazor, simulating depth, while the second axis of the second Trazor controls the color of the display. Lines do not have to be connected, since lifting a finger will end a line and the next will begin where the player puts his finger down.

A duck-hunting game can be played in which the player must "lead" the bird. He touches a point on the Trazor and a little cloud of shot zips up from the bottom of the screen and (hopefully) intercepts the duck at that point.

Battle games of various sorts can be played using Trazors in the polar coordinate mode to control velocity and rotation of game features. A tank game for four people can be played with four Trazors, firing of the tank guns being accomplished by lifting a finger. A different tank game would use one Trazor to control the velocity and rotation of a tank hull and a second Trazor to rotate the tank gun turret.

Rectangular and polar coordinate modes of operation could be combined in a two-player game of battleship. Each player would use one Trazor to control the velocity and direction of his ship. With the other Trazor he would fire at his opponent's ship by touching the Trazor at a point calculated to intercept the ship. Three seconds after he touched the Trazor, there would be a shell-burst at the corresponding point on the screen.

Only a few Trazors have so far been built for demonstration and evaluation, but much of our effort in recent weeks has gone into lowering the cost for quantity production.

Our first models were built using operational amplifiers and similar integrated circuit modules. Since then we have made a discrete-component design as a first step in integrating the electronics. We are currently holding discussions with semiconductor manufacturers and believe the circuitry for a Trazor can be reduced to one chip and a handful of passive components, with modest power requirements. A reasonable estimate of the cost of the electronics in large quantities is between one and two dollars.