Read the textEveryday uses of computers Most machines are designed to do one job. Computers are different: they are general purpose machines. Unlike most machines, computers do not have a fixed purpose. They are multipurpose tools. They can be used in a very wide variety of situations and are found in a wide range of systems including security systems, cars and phones. Advanced systems, known as expert systems, enable computers to “think” like experts. Medical expert systems, for example, can help doctors diagnose an illness and decide on the best treatment. As computer systems are developed, they are becoming more common and are gradually being used for more and more purposes. How they are developed, and for what purposes they are actually used in the future, can be influenced by computer users. A computer is a device that processes data according to a set of instructions known as a program. By changing the program instructions, computers can be used to process information in very different ways. The equipment is known as the hardware and the programs and data are the software. A special set of programs, called an operating system, provides an interface for the user and allows applications programs to communicate with the hardware. Computers are therefore used in almost every type of work and are found almost everywhere. For example: a word processor program allows the computer to process text, a spreadsheet program enables the computer to perform calculations, a database program is used for searching and sorting records, and a browser program is used for looking at pages on the Internet (the Internet is the connection of computers from different parts of the world). Anti-virus programs are used to detect and remove viruses (harmful programs that can reproduce themselves and attach themselves to other programs). Some operating systems have graphical user interfaces that allow the computer user to select items from menus (list of choices) and to start programs using an input device called a mouse. This is done by pressing a button on the mouse i.e. clicking the mouse. The main device for inputting the data is a typewriter-style keyboard and the output is commonly displayed on a monitor screen that looks like a small television screen. A variety of devices can be attached to the computer. Input devices are used to enter data into the computer for processing. An input device called a magnetic ink character reader (MICR) is used to read characters printed using magnetic ink. Magnetic ink characters are commonly found on bank cheques. An optical input device called a barcode reader uses the reflection of a light beam to read a sequence of printed parallel bars called a barcode. The bars are of different thickness, and each thickness of bars represents a different number according to a standard code. Barcode labels are used to code items. Each item can be identified by a computer, using a barcode reader to scan the labels. Barcodes are used in industry, shops and supermarkets for stock control and to allow a computer to look up the price of item being purchased. A variety of devices known as peripherals can be added externally to a computer. One of the most common peripherals is a printer used for printing the computer output (the processed data or signals that come out of a computer system) on paper.
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