INTRODUCTION Computers have made great inroads in our everyday life and thinking . They are put to use for all sorts of applications ranging from complex calculations in the field or frontline research, engineering simulations down to teaching, printing books and recreational games. The ease with which computers can process data, store and retrieve it painlessly have made them inevitable in office and business environments. The areas of applications of computers are confined only by limitations on human creativity and imagination. In fact, any tasks that can be carried out systematically, can be performed by a computer. Therefore, it is essential for every educated person today to know about a computer, its strengths, its weakness and its internal structure. What is a Computer? Computer is an electronic device that executes the instructions given in a program and controls the operations that are expressible