Computers in Cars You're far from home on a lonely road. Shadowy forests stretch away on both sides. A thick mist (雾) makes it difficult to see far beyond your car's windshield (挡风玻璃). 'Can this be route 90A?' you wonder. If it is, you should be near a town. Yet there's no hint of one. Night is closing in. And you're low on gasoline. This is a situation where an in-car computer that can navigate would be a big help. A car computer that navigates? Yes! Such computers exist. Several experimental models are being tested by General Motors, Ford, Chrysler, and several foreign car makers. These computers vary in detail. But they all contain series of maps on videodiscs or videotapes. For example, one computer system contains 13,300 maps covering the continental US. Before starting out on a trip, a driver can type in the code for the region he or she plans to drive through. The computer then shows a map of that region. At the same time, a tiny radio receiver linked to the computer goes to work. It picks up signals from navigation satellites such as the NAVSTAR network. Using these signals, the computer shows the car's position at all times and displays this position on the map. The computer can also calculate and display the best route to follow. A navigation computer may also receive and use data about road construction, weather conditions, and traffic jams. This information would be displayed to the driver and the computer would also use the information to work out alternate (交替的) routes. Most cars nowadays also contain computers that help cars run more efficiently. Microprocessors (微处理机) control certain engine functions by regulating the mixing of fuel. Data on car speed, oil pressure, revolutions per minute, engine temperature, and fuel level can be displayed as digital data (numbers) or warning lights. Some auto designers suggest that a central computer display be used to clearly present such timely information as car speed and fuel level. Warning lights would indicate a drop in oil pressure or a sudden rise in engine temperature. To get more information on these conditions, the driver could call it up on the computer display screen. When needed, the computer could be 'asked' to provide navigation aid or information about the car's condition. By describing a typical situation of a lost driver on the road, the author intends to