Find Out More : Computers

Most of us have used computers for playing games and know that they are good for zapping aliens. But computers perform a host of important functions, and now almost every office, school and factory uses them. A bank of computer-controlled instruments constantly processes flight, navigation, engine and other vital systems data on the flight deck of a modern aircraft. Today, computers are a huge and fast-moving field of technology. More compact, powerful and user-friendly equipment is developed almost daily. The machinery itself the electronic and mechanical components - is known as the hardware. The programs or Systems that enable you to use computers are known as software. Charles Babbage, a British inventor, is sometimes called the father of the computer. In 1823, he started to build a mechanical calculator that could do sums and print out the results. The machine was far ahead of its time and used gearwheels to carry out the calculations. Sadly, it was so complicated that he never finished making it. Over a century later, people were still trying to build efficient calculating machines. They were so big they filled entire rooms and weighed many tons. But these huge calculators were not really computers - they did not have memories. How does a computer work? A computer is a machine that can handle information(data). The data can be words, numbers, pictures or a mixture of all three. For a computer to work it has to store the data it is using. It needs a memory. Modern computer memories can store more data than a roomful of filing cabinets. They use tiny electric currents, and have thousands of circuits inside them, crammed into tiny 'microchips'. Before it can be read by the computer, the data has to be turned into an electronic code of minute on-off pulses (signals). These signals are made and translated by miniature switches, called transistors, within the microchips. Words and numbers are fed into the computer via a keyboard. Pictures are fed in through a scanner. To sort the data, a computer needs a set of instructions - a program. The computer works through these instructions until the job is done often in less than a second. DISK DRIVE For recording programs and data and for loading them back into the computer. A floppy disk drive accepts portable floppy disks; a hard disk drive holds data and programs within the computer. FLOPPY DISK For storing and transferring programs and data. The disk has a magnetic coating like a cassette tape, and a cover to protect it. It fits inside the floppy disk drive. PRINTER For printing the screen data on to paper. The copy printed on paper is called hard copy. Computer circuits are crammed on tiny slices of silicon. Each slice has a casing around it and is called an integrated circuit (IC) - or, more simply, a microchip (chip). Over one million transistors can be built into a single microchip so small that an ant can hold it in its jaws! Computers can handle more than just numbers and words. Here, on-screen icons provide a menu of options for a graphics (painting) program. Storing data Computers have two memory systems. One, called a Random Access Memory (RAM), is for storing data and programs while the computer is switched on and is in use. Microchip circuits provide this type of memory. The second type is a Read Only Memory (ROM) for storing information that the computer needs all the time and has to keep even when it is switched off. A hard disk drive within the computer, or a cassette recorder, provide this ROM. Floppy disks - bendy magnetic disks, usually held flat inside a plastic case can also be used to store data and programs. They are a means of transferring information from one computer to another. Floppy disks can also store duplicated (backup) information in case the computer's built-in memory fails. They come in two standard sizes - 5¼ inches (133mm) and 3½ inches (88mm). The recorded data runs in circular 'tracks' on the disk's surface. When it is necessary to store vast amounts of data, for instance to produce moving colour pictures, special optical disks are used. These are read by a laser. Did you know? FROM VALVES TO CHIPS AND PEAS The first electronic calculators were made during World War II. The Colossus, a huge British machine weighing several tonnes and containing 1500 valves, could break secret German Enigma codes. The first true electronic computer (having a memory) ran its first program in 1948 at Manchester University, England. Three years later, Ferranti produced the first commercial computer -their Mark I. It filled an entire room and used as much power as 27 electric fires! Early computer memory circuits used thousands of valves - looking and glowing rather like light bulbs - and ordinary wires, hence their great size and weight. Data was stored by switching these valves on and off in order. When transistors took over from valves, computers got smaller. Transistors were pea-sized and used much less power. Today, many thousands of transistors can be packed into a single chip - So computers can be even smaller. The first small, modestly priced home computer was made by the Sinclair Company in England in 1980. Today's home megadrives and hand-held video games can store more memory than early computers like Leo. The size of a computer's memory is measured in bytes. One byte is the amount of memory required to store eight digits (bits) of binary number code. A computer with a four megabyte RAM, for example, can handle up to four million digits at one time. A 100 megabyte ROM can store 100 million digits. Data is moved in or out of the memory by a central processing unit the processor - which is the 'brain'of the computer. Working through programs supplied, it makes decisions and calculations. Size and power Computers are made in three main sizes, according to their place of work and job requirements: Microcomputers, also known as micros or personal computers (PCs), are the small desk-top and lap-top computers you find in schools, houses and small offices. Most can do just one job at a time. Minicomputers (minis) are larger and more powerful than micros. If they are linked to more than one keyboard and screen (terminals), several people can use them to do different jobs at once. Mainframe computers are larger still. They have many terminals and can perform lots of complex tasks at once. Filling several cabinets, large companies usually install a mainframe in its own special computer room. But the terminals are located wherever needed. Supercomputers are the most powerful of all. Only a few hundred have ever been built, mainly for scientific purposes. Several processors work on different parts of the same task at once, speeding through millions of instructions every second. It's Amazing! Top of the flops The speed at which computers work is measured in units called flops - floating point operations per second. Cray Research Inc of Minneapolis, USA produces the world's most powerful mainframe computer - the CRAY-2. Its main memory has an enormous capacity of 2.12 thousand million (giga) bytes. It can work at up to 250 million (mega) flops. Faster still, using 16 central processing units, Cray's Y-MP C90 super-computer can peak at 16 gigaflops. Mainframe super-computers make complex calculations very speedily and have huge memories. Here, a technician uses an infrared diagnostic scanner to check for faults in the processor. Dictionary Computer language often uses American spellings. Disk is the preferred spelling for disc; and program, not programme.Color instead of colour. Peripherals Parts of a system separate from the main computer are called peripherals. They are usually linked by wires. Keyboards, printers, scanners and separate disk drives are all peripherals. A joystick and a mouse (also known as a wimp - Window Icon Mouse Pointer) may be connected to move selected things around on the computer's screen. Joy-sticks are very useful for computer games. An interface changes the computer's signals into a different form. For example, the signals may be changed into control instructions for an electrically powered remote-control vehicle. A modem (short for modulator-demodulator) converts a computer's signals into telecommunication signals which are suitable for passing down a telephone line. TERMINOLOGY BINARY NUMBERS A system of counting which uses only two digits (0 and 1); used to create on-off electronic codes for decimal numbers, words or pictures. BYTE Unit of computer memory -one byte is just enough memory to store a single letter in a word. DATA Information handled by the computer. DIGIT An individual figure used to represent a number or letter. FLOPPY DISK Bendy magnetic disk used for storing and transferring programs and data. HARD DISK Built-in, rigid magnetic disk for storing programs and data - it holds more information than a floppy disk. HARDWARE Computer equipment and any connected peripherals, such as printers and scanners. SOFTWARE Programs and other operating systems used to run a computer. PROGRAM List of instructions to be followed, line by line, by the computer. RANDOM ACCESS MEMORY (RAM) Memory used for storing prograrns and data; information in this memory is lost when the computer is switched off. READ ONLY MEMORY (ROM) Memory used for storing data which the computer needs all the time; information in this memory stays there even when the computer is switched off.

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