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A computer is a device or machine for making calculations or controlling operations that are expressible in numerical or logical terms. Computers are made from components that perform simple well-defined functions. The complex interactions of these components endow computers with the ability to process information. If correctly configured (usually by programming) a computer can be made to represent some aspect of a problem or part of a system. If a computer configured in this way is given appropriate input data, then it can automatically solve the problem or predict the behavior of the system. The discipline which studies the theory, design, and application of computers is called computer science. Computer can be catagorized by their speed and size, purpose,or other methods. When thery're classified by speed and size, they consist of super computers, mainframes, minicomputers and microcomputers. Supercomputer are use for manipulating large amount of data in a relatively very short time. Mainframe are used in large companies and organizations and serve hundreds of terminals simutanously. Minicomputers serve hundreds of terminals and meet the needs of a small organization. Microcomputers consist of workstations and personal computers. Workstations are faster in performance than personal computers and are intended for one user at a time. Personal computers are made for individual uses and consist desktop computers, laptop/notebook computers, tablet computers, and personal digital assistant (PDA). Desktop computers are made especially for ues on a desk in an office or at home.They are the most common computers and usually come to our minds when we think about computers in general. Laptop/Notebook computers are mobile computers that have similar uses as desktop computers but are usually less powerful. Tablets are portable computers usually with touchpad screens. PDAs are handhled computers that are originally designed as personal organizers. They include clock, address book, task list, memo pad, and simple claculator. There are also other divisions that are less used. Notebooks lessthan the size of A4 paper and weigh around 1kg are called sub-notebooks. Other laptops that weigh around 5kg are called desknote computers. Computer larger than PDAs but smaller than notebooks are sometimes called Palmtops. They can be built for general use or may be developed for a specific purpose. There are two main parts to a computer system. The Hardware and Software. The hardware consists of all the physical features of the machine. The Sofware are all programs and instructions that the computer performs. This two parts are dependant on each other. The absence of one of them means that the computer can't function. Computers' hardware can be arranged to 4 parts. They are input, output, processing, and storage. Input devices are such as a keyboard, mouse, scanner, webcams and microphone. Output components include monitors, speakers, printers. The Central Processing unit(CPU) is the main processing device. Floppy disks, CDs , hard drives, magnetic taps are examples of storage devices. Software are divided to system/platform softwares, application softwares and user-written softwares. System/platform softwares are softwares that are responsible for controlling, integrating, and managing individual hardware components. Loading programs, operating systems, device drivers, programming tools, compilers, assemblers, linkers, and utilities are system/platform softwares. Application softwares are used to accomplish tasks the user requests. Examples include computer games, word processors, spreadsheets, databases, media players and web browser.There is a doubt that user-written softwares should be considered as part of softwares. Anyway, they inclue files you type in a text editor, graphics that you produce, spreadsheet templates, etc... Several computers can be hooked up to form a network. Computers in a network will be able to share resources and files. Other peripherals such as printers and scanners can also be connected to a network. There are two types of newtowrks. Wide Area Networks(WAN) and Local Area Network(LAN). LANs are used for an office or a building. LANs can be connected to create WANs which, as its name suggests, covers and wide geographical area. WANs can be connected to create very large networks such as the Internet. |