Linda Null - The Essentials of Computer Organization and Architecture, Sixth Edition

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Library of Congress Cataloging-in-Publication Data

Names: Null, Linda, author.

Title: The essentials of computer organization and architecture / Linda Null.

Description: Sixth edition. | Burlington, Massachusetts : Jones & Bartlett Learning, [2024] | Includes bibliographical references and index.

Identifiers: LCCN 2022062125 | ISBN 9781284259438 (paperback)

Subjects: LCSH: Computer organization. | Computer architecture.

Classification: LCC QA76.9.C643 N85 2024 | DDC 004.2/2dc23/eng/20230123

LC record available at https://lccn.loc.gov/2022062125

6048

Printed in the United States of America

2625242310987654321

In memory of my husband, Tim Wahls, who exemplified the beauty and wonder in everything around me and taught me that love does not end with death. How amazingly lucky I was to have someone who made saying goodbye so difficult.

L. M. N.

Paggi Eleanor/Shutterstock

Contents

Paggi Eleanor/Shutterstock

Preface

TO THE STUDENT

This is a book about computer organization and architecture. It focuses on the function and design of the various components necessary to process information digitally. Computing systems are presented as a series of layers, starting with low-level hardware and progressing to higher-level software, including assemblers and operating systems. These levels constitute a hierarchy of virtual machines. The study of computer organization focuses on this hierarchy and the issues involved with how to partition the levels and how each level is implemented. The study of computer architecture focuses on the interface between hardware and software, and emphasizes the structure and behavior of the system. The majority of information contained in this textbook is devoted to computer hardware, computer organization and architecture, and their relationship to software performance.

Students invariably ask, Why, if I am a computer science major, must I learn about computer hardware? Isnt that for computer engineers? Why do I care what the inside of a computer looks like? As computer users, we probably do not have to worry about this any more than we need to know what our cars look like under the hood in order to drive them. We can certainly write high-level language programs without understanding how these programs execute; we can use various application packages without understanding how they really work. But what happens when the program we have written needs to be faster and more efficient, or the application we are using doesnt do precisely what we want? As computer scientists, we need a basic understanding of the computer system itself in order to rectify these problems.

There is a fundamental relationship between the computer hardware and the many aspects of programming and software components in computer systems. In order to write good software, it is very important to understand the computer system as a whole. Understanding hardware can help you explain the mysterious errors that sometimes creep into your programs, such as the infamous segmentation fault or bus error. The level of knowledge about computer organization and computer architecture that a high-level programmer must have depends on the task the high-level programmer is attempting to complete.

For example, to write compilers, you must understand the particular hardware to which you are compiling. Some of the ideas used in hardware (such as pipelining) can be adapted to compilation techniques, thus making the compiler faster and more efficient. To model large, complex, real-world systems, you must understand how floating-point arithmetic should work, and how it does work (which are not necessarily the same thing). To write device drivers for video, disks, or other I/O devices, you need a good understanding of I/O interfacing and computer architecture in general. If you want to work on embedded systems, which are usually very resource constrained, you must understand all of the time, space, and price trade-offs. To do research on, and make recommendations for, hardware systems, networks, or specific algorithms, you must acquire an understanding of benchmarking and then learn how to present performance results adequately. Before buying hardware, you need to understand benchmarking and all the ways that others can