Introduction

Computer systems have two major components:

• hardware-electronic,mechanical, optical devices
• software-programs.

Without support software, a computer is of little use. With its software, however, a computer can store, manipulate, and retrieve information, and can engage in many other activities. Software can be grouped into the following categories:

• systems software (operating system & utilities)
• applications software (user programs)

Summary,

• Hardware provides basic computing resources (CPU, memory, I/O devices).
• Operating system controls and coordinates the use of the hardware among the various application programs for the various users.
• Application programs define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs).
• Users (people, machines, other computers).

Figure 1: Abstract view