As today s computers reach out to a broader base of users and extend into

new areas of application, so also does Information Processing. This new

edition, the fourth, is the result of careful efforts to retain the character-

istics that made earlier editions best sellers, yet modify the content to

meet current needs. Computers are becoming faster and more powerful-

yet, at the same time, smaller and less expensive. They are being used

not only in large government and business organizations but also in small

firms, in offices, schools, and homes.

This book does not attempt to be encyclopedic. It does not present all

there is to know about history, problem solving, programming, business

and nonbusiness applications, or social implications. It does present an

up-to-date survey of computer hardware and software systems in use to-

day. It does discuss a wide variety of applications. Information Processing

is designed to help you increase your understanding of computers and

of how they affect each of us and our society. Saying this another way,

Information Processing is designed to help you become computer literate.

Several hundred colleges and universities are using Information Pro-

cessing. Their criticisms and suggestions have been heeded carefully in

preparing this revision. As before, I have aimed to keep the book simple

and succinct. My intent is to provide a firm, accurate base from which

both instructors and students can gain maximum benefits, in line with

their educational objections as well as their personal interests or needs.

Today, more than ever before, almost everyone is a user of computers.

Therefore, a major focus of this edition has been to present material with

users in mind. As before, Chapters 1 and 2 explore the concept of a

processing system, with new developments and new applications noted.

A unique feature of this edition is a guided, step-by-step, hands-on inter-

action with the computer. Readers who have access to a computer are

encouraged to see how simple communicating with a computer really is.

Chapter 3 explains how data is coded for computer processing. The next

two chapters have been updated and reorganized to focus on input, in

Chapter 4, and output, in Chapter 5. Magnetic tape is now discussed, to-

gether with the wide variety of disk devices and media available for sys-

tems of all sizes, in Chapter 6.

Chapters 7 and 8 cover processors and basic operations that comput-

ers can perform. Today s tiniest central processing unit-the one-chip

microprocessor-is placed in perspective. Chapter 9 is new. For many

readers, it may be the high point of the book. In it, the concepts, compo-

nents, and operations discussed in preceding chapters are folded into

a small but meaningful whole-the microcomputer and its uses. In Chap-

ter 10, we extend this discussion to cover larger computers in a similar

manner.