Introduction

An operating system is software that manages a computer’s hardware. It also provides a basis for application programs and acts as an intermediary between the computer user and the computer hardware. An amazing aspect of operating systems is how they vary in accomplishing these tasks in a wide variety of computing environments. Operating systems are everywhere, from cars and home appliances that include “Internet of Things” devices, to smart phones, personal computers, enterprise computers, and cloud computing envi- ronments.

In order to explore the role of an operating system in a modern computing environment, it is important first to understand the organization and architec- ture of computer hardware. This includes the CPU, memory, and I/O devices, as well as storage. A fundamental responsibility of an operating system is to allocate these resources to programs.

Because an operating system is large and complex, it must be created piece by piece. Each of these pieces should be a well-delineated portion of the system, with carefully defined inputs, outputs, and functions. In this chapter, we provide a general overview of the major components of a contemporary computer system as well as the functions provided by the operating system. Additionally, we cover several topics to help set the stage for the remainder of the text: data structures used in operating systems, computing environments, and open-source and free operating systems.

CHAPTER OBJECTIVES

• Describe the general organization of a computer system and the role of interrupts.

• Describe the components in a modern multiprocessor computer system.

• Illustrate the transition from user mode to kernel mode.

• Discuss how operating systems are used in various computing environ- ments.

• Provide examples of free and open-source operating systems.