Computer systems are usually divided into four main types according to their size. They are supercomputers, mainframe. computers, minicomputers and microcomputers. Microcomputers, also called personal computers, are small computers fit on a desk top and are usually only used by one person. They are the least expensive types, and are widely used in businesses for all kinds of tasks, such as word-processing, small data-base management, and spreadsheets. They are also used as home computers, for family budgeting and similar jobs, as well as for games. Compared with a mainframe. computer, minicom puters are smaller systems, and fewer operators can use them. They are usually found in medium-size business or in divisions within a large organization, for example in Government departments. Mainframe. computers are large and powerful computers. Many people can use at the same time. They are also expensive systems. They are used for very large processing tasks, and perform. many important business and Government applications. Supercomputers are special, high-capacity computers used by very large organizations principally for research work. Among their uses are space research, oil exploration and worldwide weather forecasting. Microcomputers are also known as ______.