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.
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.
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.
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.
For printing the screen data on to paper. The copy printed on paper is called hard copy.
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.
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.
Computer language often uses American spellings. Disk is the preferred spelling for disc; and program, not programme.Color instead of colour.
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.
Reproduced from FIND OUT MORE