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　　Personal computers are designed for individual use. In other words, the entire machine is dedicated to the exclusive use of a single person,　whereas a supercomputer, mainframe, or minicomputer is shared by　many users. Personal computers, such as the PS/2 family of IBM, clones　of IBM's PC family produced by a variety of manufacturers, and the　Macintosh family of Apple Computer, Inc., are less expensive and　smaller than mainframes or minicomputers but have lower performance.

　　They are suitable for the average individual's needs, such as document　preparation with graphics and simple business calculations.

　　Personal computers are classified on the basis of size and portability.　Personal computers that can be placed on top of a desk but are not very　portable are called desktop computers. Portable computers are those　personal computers that are light enough to be easily transported.

　　Portable personal computers that are small enough to be set on the lap　of a user are called laptop computers; notebook computers are　approximately the size of a book. Portable personal computers that can　be put in a pocket are called pocket or palm-sized computers.

　　A personal computer typically has a keyboard as its input unit. When　extensive typing is not necessary, as in the case of multiple-choice　inquiry (e.g., inventory at supermarkets), pointing to different spots on a　monitor with a stylus is convenient. A pen-input computer is such a　computer.

　　A workstation is a powerful personal computer capable of　performance close to that of a minicomputer. Examples include the　SPARC stations of Sun Microsystems, Inc. and the RS/6000 family of　IBM. Workstations are extensively used for scientific and engineering　problems and for business applications. -a Brit's good essay.

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