Trimis la data: 2005-06-17
Nota: 9.74 / 10
Autor: Boris Onceanu
Tipul fisierelor: doc
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Computer, machine that performs tasks, such as mathematical 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 electronics, and the program results are stored or routed to output devices, such as video display monitors or printers. Computers are used to perform a wide variety of activities with reliability, accuracy, and speed.
People use computers in a wide variety of ways. In homes, tiny computers embedded in the electronic circuitry of most appliances control the indoor temperature, operate home security systems, tell the time, and turn videocassette recorders on and off.
Computers in automobiles regulate the flow of fuel, thereby increasing gas mileage. Computers also entertain, creating digitized sound on stereo systems or computer-animated features from a digitally encoded laser disc.
Computer programs, or applications, exist to aid every level of education, from programs that teach simple addition or sentence construction to programs that teach advanced calculus. Computers are used extensively in scientific research to solve mathematical problems, display complicated data, or model systems that are too costly or impractical to build, such as testing the air flow around the next generation of space shuttles. The military employs computers in sophisticated communications to encode and unscramble messages, and to keep track of personnel and supplies.
HOW COMPUTERS WORK
The physical computer and its components are known as hardware. Computer hardware includes the memory that stores data and instructions. The programs that run the computer are called software. Software generally is designed to perform a particular type of task.
The Operating System
When a computer is turned on it searches for instructions in its memory. Usually, the first set of these instructions is a special program called the operating system, which is the software that makes the computer work. Popular operating systems, such as Microsoft Windows and the Macintosh system have a graphical user interface —that is, a display that uses tiny pictures, or icons, to represent various commands. To execute these commands, the user clicks the mouse on the icon or presses a combination of keys on the keyboard.
Range of Computer Ability
Computers exist in a wide range of sizes and power. The smallest are embedded within the circuitry of appliances, such as televisions and wrist watches. These computers are typically preprogrammed for a specific task, such as tuning to a particular television frequency or keeping accurate time. The smallest of the computers can be held in one hand and are called personal digital assistants. They are used as notepads, scheduling systems, and address books;
Laptop computers and PCs are typically used in businesses and at home to communicate on computer networks, for word processing, to track finances, and to play games. They have large amounts of internal memory to store hundreds of programs and documents. They are equipped with a keyboard; a mouse, trackball, or other pointing device; and a video display monitor or liquid crystal display (LCD) to display information. Laptop computers usually have similar hardware and software as PCs, but they are more compact and have flat, lightweight LCD-s instead of video display monitors.
Workstations are similar to personal computers but have greater memory and more extensive mathematical abilities, and they are connected to other workstations or personal computers to exchange data. They are typically found in scientific, industrial, and business environments that require high levels of computational abilities. In the future computers will become more advanced and they will also become easier to use.
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