Introduction

I

Introduction

Computer, machine that performs tasks, such as calculations or electronic communication, under the control of a set of instructions called a program. Programs usually reside within the computer and are retrieved and processed by the computer’s electro

nics. The program results are stored or routed to output devices, such as video display monitors or printers. Computers perform a wide variety of activit

ies reliably, accurately, and quickly.

II

Uses of Computers

People use computers in many ways. In business, computers track inventories with bar codes and scanners, check the credit status of customers, and transfer funds electronically. In homes, tiny computers embedded in the electronic circuitry of most appliances control the indoor tem

perature, operate home security systems, tell the time, and turn digital versatile disc (DVD) players on and off. Computers in automobiles regulate the flow of fuel, thereby increasing gas mileage; monitor the vehicle’s stability to prevent loss of control; and are used in anti-theft systems. Computers also entertain, creating digitized sound on stereo systems or computer-animated features from a compact disc (CD) or DVD. Computer programs, or applications, exist to aid every level of e

ducation, from programs that teach simple addition or sentence construction to programs that teach advanced calculus. Educators use computers to track grades

and communicate with students; with computer-controlled projection units, they can add graphics, sound, and animation to their communications . Computers are used extensively in scientific research to solve mathematical problems, investigate complicated data, or model systems that are too costly or impractical to build, such as testing the air flow around the next generation of aircraft. The military employs computers in sophisticated communications to encode and unscramble messages, and to

k

eep track of personnel and supplies.

III

How Computers Work

The physical computer and its components are known

as hardware. Computer hardware includes the memory that stores data and program instructions; the (CPU) that carries out program instructions; the input devices, such as a keyboard or mouse, that allow the user to communicate with the computer; the output devices, such as printers and video display monitors, that enable the computer to present information to the user; and buses (hardware lines or wires)

that connect t

hese and other computer components. The programs that run the computer are called software. Software generally is designed to perform a particular type of task—for example, to control the arm of a robot to weld a car’s body, to write a letter, to display and modify a photograph, or to direct the general operation of the computer.

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