1
Civilization advances by extending the number of important operations which we can perform without thinking about them.
Alfred North Whitehead,
An Introduction to Mathematics, 1911

Computer
Abstractions and
Technology
1.1

Introduction 3

1.2

Eight Great Ideas in Computer
Architecture 11

1.3

Below Your Program 13

1.4

Under the Covers 16

1.5

Technologies for Building Processors and
Memory 24

1.6

Performance 28

1.7

The Power Wall 40

1.8

The Sea Change: The Switch from Uniprocessors to
Multiprocessors 43

1.9

Real Stuff: Benchmarking the Intel Core i7 46

1.10

Fallacies and Pitfalls 49

1.11

Concluding Remarks 52

1.12

Historical Perspective and Further Reading 54

1.13

Exercises 54

1.1

Introduction

Welcome to this book! We’re delighted to have this opportunity to convey the excitement of the world of computer systems. This is not a dry and dreary field, where progress is glacial and where new ideas atrophy from neglect. No! Computers are the product of the incredibly vibrant information technology industry, all aspects of which are responsible for almost 10% of the gross national product of the United States, and whose economy has become dependent in part on the rapid improvements in information technology promised by Moore’s Law. This unusual industry embraces innovation at a breath-taking rate. In the last 30 years, there have been a number of new computers whose introduction appeared to revolutionize the computing industry; these revolutions were cut short only because someone else built an even better computer.
This race to innovate has led to unprecedented progress since the inception of electronic computing in the late 1940s. Had the transportation industry kept pace with the computer industry, for example, today we could travel from New
York to London