Introduction to Operating Systems:Introduction and What Is an Operating System?

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Introduction

Welcome to the world of operating systems. During the past several decades, computing has evolved at an unprecedented pace. Computer power continues to increase at phenomenal rates as costs decline dramatically. Today, computer users have desktop workstations that execute billions of instructions per second (BIPS), and supercomputers that execute over a trillion instructions per second have been built,1, 2 numbers that just a few years ago were inconceivable.

Processors are becoming so inexpensive and powerful that computers can be employed in almost every aspect of our lives. On personal computers, users can edit documents, play games, listen to music, watch videos and manage their personal finances. Portable devices, including laptop computers, personal digital assistants (PDAs), cell phones, and MP3 players all have computers as key components. Wired and wireless network architectures are increasing our interconnectivity—allowing users to communicate instantly over vast distances. The Internet and World Wide Web have revolutionized business, creating demand for networks of large, powerful computers that service vast numbers of transactions per second. Networks of computers have become so powerful that they are used to conduct complex research and simulation projects, such as modeling the Earth’s climate, emulating human intelligence and constructing lifelike 3D animations. Such pervasive and powerful computing is reshaping the roles and responsibilities of operating systems.

In this book, we review operating system principles and discuss cutting-edge advances in computing that are redefining operating systems. We investigate the structure and responsibilities of operating systems. Design considerations, such as performance, fault tolerance, security, modularity and cost, are explored in detail. We also address more recent operating system design issues arising from the rapid growth in distributed computing, made possible by the Internet and the World Wide Web.

We have worked hard to create what we hope will be an informative, entertaining and challenging experience for you. As you read this book, you may want to refer to our Web site at www.deitel.com for updates and additional information on each topic. You can reach us at deitel@deitel.com.

What Is an Operating System?

In the 1960s, the definition of an operating system might have been the software that controls the hardware. But the landscape of computer systems has evolved significantly since then, requiring a richer definition.

Today’s hardware executes a great variety of software applications. To increase hardware utilization, applications are designed to execute concurrently. If these applications are not carefully programmed, they might interfere with one another. As a result, a layer of software called an operating system separates app cations from the hardware they access and provides services that allow each application to execute safely and effectively.

An operating system is software that enables applications to interact with a computer’s hardware. The software that contains the core components of the oper- ating system is called the kernel. Operating systems can be found in devices ranging from cell phones and automobiles to personal and mainframe computers. In most computer systems, a user requests that the computer perform an action (e.g., exe- cute an application or print a document) and the operating system manages the software and hardware to produce the desired result.

To most users, the operating system is a “black box” between the applications and the hardware they run on that ensures the proper result, given appropriate inputs. Operating systems are primarily resource managers—they manage hard- ware, including processors, memory, input/output devices and communication devices. They must also manage applications and other software abstractions that, unlike hardware, are not physical objects.

In the next several sections we present a brief history of operating systems from the simple, single-user batch systems of the  1950s to the complex, multiprocessor, distributed, multiuser platforms of today.

Self Review

1. (T/F) Operating systems manage only hardware.

2. What are the primary purposes of an operating system?

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