Computer is a machine that can be programmed to accept data (input) process it into useful information (output) and stored it away (in a secondary storage device) for safekeeping or later reuse. The processing input to output is directly by the software but performed by the hardware.
To function, a computer system requires four main aspect of data handling:
Figure 1.1 the hardware responsible for these four areas
Input devices accept data or commands in a form that computer can use; they send the data or commands to the processing unit.
The processor; more formally known as Central Processing Unit (CPU); has electronic circuitry that manipulates input data into the information people want. The Central Processing Unit actually executes computer instructions.
Output devices show people the processed data-information-in understandable and usable form.
Storage usually means secondary storage, which consists of secondary storage devices such as disk-hard disk or diskettes or some other kind of disk-that can store data and programs outside of the computer itself. These devices supplement memory or primary storage, which can hold data and program only temporarily.
Input: Getting data from the user to the computer
Some input data can directly to the computer for processing. Input in this category includes barcodes, speech that enters the computer through a microphone, and data entered by means of a device tat convert motions to one screen action. Some input data, however, go through a good deal of intermediate handling, such as when it is copied from a source documents (jargon of originally written data) and translated to a medium that a machine can read, such as a magnetic disk. In either case the task is to gather data to be processed by the computer- sometimes called conventional input devices include the keyboard, mouse, trackball, touchpad and joystick.
A keyboard, which usually is similar to a typewriter keyboard, may be part of a personal computer or part of the terminal that is connected to a computer somewhere else. Not all keyboards are traditional, however. A fast-food franchise such as McDonald's for example, uses keyboard whose keys represent items such large fries or a Big Mac.
Input device over the television or a special computer screen that is used to simplify user input and response. The user touches the screen rather than a keyboard, keypad, or mouse to control the output. Touch screens work best with menus or multiple-choice decision points, and also allow some simulation of hands-on training, i.e....