Unit 2: Computer Systems

1. What is a Computer

A computer is an electronic machine that stores, retrieves, and manipulates or processes data. It cannot think or reason; it can only carry out instructions given to it. A set of instructions that directs its actions is called a program. Different programs are used to solve different problems. Ability to accept, store, and execute various sets of instructions (or programs) makes the computer the invaluable, all-purpose business tool.

The first step of solving a problem by a computer is to develop a suitable computer program and then store in its memory. The computer then carries out the instructions in the program. The instructions of a program generally direct the computer to perform three basic functions over and over again; these functions are input, processing, and output. Collectively, these functions constitute the data processing cycle.

· Input: input devices are connected to feed the computer facts or data to be processed.

· Processing: the control and storing of data, numerical comparisons, and arithmetic operations are performed on the input data to produce the desired results.

· Output: the computer feeds the processed data or information, to the output devices.