Introduction to using a computer
Definition of a computer, this is an electronic device that is made up of input devices such as the keyboard and is used to capture data and instructions, with the help of sets of instructions it will be able to produce results or output through devices such as printers or screens.
Classes of computers
Computers can be classified as follows:
Microcomputers, commonly called PCs
A supercomputer is used to process very large amounts of data very quickly. They are particularly useful for occasions where high volumes of calculations need to be performed, for example in meteorological or astronomical applications.
A mainframe computer system uses a powerful central computer, linked by cable or telecommunications to terminals. A mainframe has many times more processing power than a PC and offers extensive data storage facilities. Mainframes are used by organisations such as banks that have very large volumes of processing to perform and have special security needs. Many organisations have now replaced their old mainframes with networked ‘client server systems of mid-range computers and PCs because this approach is thought to be the cheaper and offer more flexibility
A minicomputer is a computer whose size, speed and capabilities lie somewhere between those of a mainframe and a PC. The term was originally used before PCs were developed, to describe computers which were cheaper but less wellequipped than mainframe computers. With the advent of PCs and of mainframes that are much smaller than in the past, the definition of a minicomputer has become rather vague. There is really no definition which distinguishes adequately between a PC and a minicomputer.
PCs are now the norm for small to medium-sized business computing and for home computing, and most larger businesses now use them for day-to-day needs
such as word processing. Often they are linked together in a network to enable sharing of information between users.
The original portable computers were heavy, weighing around five kilograms, and could only be run from the mains electricity supply line. Subsequent developments allow true portability.
a) A laptop or notebook is powered either from electricity supply or using a rechargeable battery and can include all the features and functionality of desktop PCs.
b) The palmtop or handheld is increasingly compatible with true PCs. Devices range from basic models which are little more than electronic organizers to relatively powerful processors running ‘cut-down’ versions of Windows and Microsoft Office, and including communications features.
Many computers have been designed to achieve faster computational speeds, using different architectures.
Maths co-processor and Graphics co-processor. Most processors may include specialized and faster processors (a maths co-processor/graphics co-processor) can be used for applications requiring high-speed mathematical or graphics computations. Such applications could be spreadsheet calculations or complex computer-aided design (CAD) work. The maths co-processor supports the main processor by performing the required calculations more rapidly than the main processor. In the same way, the graphics co-processor is designed to perform graphical functions, such as the construction and maintenance of images much faster than the main processor. The co-processors are under the control of the main processor.
Pipeline machines. In the pipeline machine architecture each stage in the fetchexecutive cycle is handled by a separate machine hardware unit. The first unit fetches an instruction from memory. At any one time there may be four or five instructions within the processor each at different stages of execution in different units.
Array processor. In the array processor there is one...
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