There are three main components of a computer system:
i) Input/Output Unit which allows the user to interact with the computer through input and output devices.
ii) Central Processing Unit (CPU) which controls and coordinates the operations of the computer by processing input data.
iii) Memory Unit which stores data, instructions, and output during processing.
The document provides details on these three components, describing the input, processing, and output functions of the computer system. It also discusses different types of computers based on size (microcomputers, minicomputers, mainframe computers, and supercomputers) and components of computer hardware.