tists to create realistic images and animated displays much more easily than they could with more traditional tools. "Morphing" programs allowphotographers and filmmakers to transform photographic images into any size and shape they can imagine. High-speed supercomputers can insert lifelike animated images into frames of a film so seamlessly that movie-goers cannot distinguish real actors from computer-generatedimages. Musicians can use computers to create multiple-voice compositions and to play back music with hundreds of variations. Types of ComputersThere are two fundamentally different types of computers--analog and digital. (Hybrid computers combine elements of both types.) Analog computers solve problems by using continuously changing data (such as pressure or voltage) rather than by manipulating discrete binary digits (1s and 0s) as a digital computer does. In current usage, the term computer usually refers to digital computers. Digital computers are generally more effective than analog computers for four principal reasons: they are faster; they are not as susceptible to signal interference; they can convey data with more precision; and their coded binary data are easier to store and transfer than are analog signals. Analog computers. Analog computers work by translating constantly changing physical conditions (such as temperature, pressure, or voltage) into corresponding mechanical or electrical quantities. Theyoffer continuous solutions to the problems on which they are operating. For example, an automobile speedometer is a mechanical analog computer that measures the rotations per minute of the drive shaft and translates that measurement into a display of miles per hour. Electronic analog computers in chemical plants monitor temperatures, pressures, and flow rates and send corresponding voltages to various control devices, which, in turn, adjust the chemical processing conditions to their proper levels. Digital compu...
