The Architecture of Computer Hardware, System Software, and Networking PDF

 The Self-Operating Napkin The professor walks in his sleep, strolls through a (I) which opens and lights automatic cigar lighter cactus field in his bare feet, and screams out an (J), setting off sky-rocket (K) which causes sickle idea for self-operat...

 The Self-Operating Napkin The professor walks in his sleep, strolls through a (I) which opens and lights automatic cigar lighter cactus field in his bare feet, and screams out an (J), setting off sky-rocket (K) which causes sickle idea for self-operating napkin. (L) to cut string (M) and allow pendulum with As you raise spoon of soup (A) to your mouth attached napkin to swing back and forth thereby it pulls string (B), thereby jerking ladle (C) which wiping off your chin. throws cracker (D) past parrot (E). Parrot jumps After the meal, substitute harmonica for the after cracker and perch (F) tilts, upsetting seeds napkin and you’ll be able to entertain the guests (G) into pail (H). Extra weight in pail pulls cord with a little music. Rube GoldbergT and a C of Rube Goldberg, Inc. Distributed by United Media.  Englander f01.tex V2 - December 9, 2013 10:19 A.M. Page i FIFTH EDITION THE ARCHITECTURE OF COMPUTER HARDWARE, SYSTEMS SOFTWARE, & NETWORKING AN INFORMATION TECHNOLOGY APPROACH Irv Englander Bentley University  Englander f01.tex V2 - December 9, 2013 10:19 A.M. Page ii Publisher: Don Fowley Editor: Beth Lang Golub Project Manager: Katie Singleton Editorial Assistant: Jayne Ziemba Photo Editor: Felicia Ruocco Cover Designer: Maureen Eide Associate Production Manager: Joyce Poh Senior Production Editor: Jolene Ling Production Management Services: Laserwords Cover Credit: Norm Christiansen This book was set by Laserwords Private Limited. Founded in 1807, John Wiley & Sons, Inc. has been a valued source of knowledge and understanding for more than 200 years, helping people around the world meet their needs and fulfill their aspirations. Our company is built on a foundation of principles that include responsibility to the communities we serve and where we live and work. 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Upon completion of the review period, please return the evaluation copy to Wiley. Return instructions and a free of charge return mailing label are available at www.wiley.com/go/returnlabel. If you have chosen to adopt this textbook for use in your course, please accept this book as your complimentary desk copy. Outside of the United States, please contact your local sales representative. Library of Congress Cataloging-in-Publication Data Englander, Irv. The architecture of computer hardware, systems software, & networking : an information technology approach/ Irv Englander, Bentley University.—Fifth edition. pages cm Includes bibliographical references and index. ISBN 978-1-118-32263-5 (paper) 1. Computers. 2. Systems software. I. Title. QA76.5.E566 2014 005.4’3--dc23 2013027578 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1  Englander f01.tex V2 - December 9, 2013 10:19 A.M. Page iii To four outstanding teachers and great human beings: With your guidance, inspiration, and patience, you showed me that everything is possible. Dr. Sidney H. Englander (1900–1980) and Mildred K. Englander (1906–2008), in memoriam my father and mother Albert L. Daugherty, in memoriam teacher of Science in Cleveland Heights, Ohio from 1927 to 1970 Edith B. Malin, in memoriam teacher of English in Cleveland Heights, Ohio from 1924 to 1958  Englander btoc.tex V2 - December 9, 2013 2:57 P.M. Page iv BRIEF CONTENTS PART ONE AN OVERVIEW OF COMPUTER SYSTEMS 2 n CHAPTER 1 Computers and Systems 4 n CHAPTER 2 An Introduction to System Concepts and Systems Architecture 38 PART TWO DATA IN THE COMPUTER 70 n CHAPTER 3 Number Systems 72 n CHAPTER 4 Data Formats 100 n CHAPTER 5 Representing Numerical Data 136 PART THREE COMPUTER ARCHITECTURE AND HARDWARE OPERATION 176 n CHAPTER 6 The Little Man Computer 178 n CHAPTER 7 The CPU and Memory 194 n CHAPTER 8 CPU and Memory: Design, Enhancement, and Implementation 234 n CHAPTER 9 Input/Output 266 iv  Englander btoc.tex V2 - December 9, 2013 2:57 P.M. Page v BRIEF CONTENTS v n CHAPTER 10 Computer Peripherals 294 n CHAPTER 11 Modern Computer Systems 332 PART FOUR NETWORKS AND DATA COMMUNICATIONS 358 n CHAPTER 12 Networks and Data Communications—an Overview 360 n CHAPTER 13 Ethernet and TCP/IP Networking 400 n CHAPTER 14 Communication Channel Technology 442 PART FIVE THE SOFTWARE COMPONENT 474 n CHAPTER 15 Operating Systems: An Overview 476 n CHAPTER 16 The User View of Operating Systems 510 n CHAPTER 17 File Management 544 n CHAPTER 18 The Internal Operating System 586 SUPPLEMENTARY CHAPTERS On the Web at www.wiley.com/college/englander n SUPPLEMENTARY CHAPTER 1 An Introduction to Digital Computer Logic n SUPPLEMENTARY CHAPTER 2 System Examples n SUPPLEMENTARY CHAPTER 3 Instruction Addressing Modes n SUPPLEMENTARY CHAPTER 4 Programming Tools  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page vi CONTENTS Preface xviii About the Author xxv PART ONE AN OVERVIEW OF COMPUTER SYSTEMS 2 n CHAPTER 1 Computers and Systems 4 1.0 Introduction 5 1.1 The Starting Point 9 1.2 Components of the Computer System 11 The Hardware Component 13 The Software Component 16 The Communication Component 18 The Computer System 18 1.3 The Concept of Virtualization 20 1.4 Protocols and Standards 20 1.5 Overview of This Book 22 1.6 A Brief Architectural History of the Computer 23 Early Work 24 Computer Hardware 25 Operating Systems 28 Communication, Networks, and the Internet 33 Summary and Review 34 For Further Reading 34 Key Concepts and Terms 35 Reading Review Questions 35 Exercises 36 n CHAPTER 2 An Introduction to System Concepts and Systems Architecture 38 2.0 Introduction 39 2.1 The General Concept of Systems 40 2.2 IT System Architectures 47 Distributed Processing Systems 49 The Role of the System Architect 59 vi  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page vii CONTENTS vii Google: A System Architecture Example 60 Another Example: Facebook’s Application Architecture 64 Summary and Review 65 For Further Reading 66 Key Concepts and Terms 66 Reading Review Questions 67 Exercises 67 PART TWO DATA IN THE COMPUTER 70 n CHAPTER 3 Number Systems 72 3.0 Introduction 73 3.1 Numbers as a Physical Representation 74 3.2 Counting in Different Bases 74 3.3 Performing Arithmetic in Different Number Bases 78 3.4 Numeric Conversion Between Number Bases 82 An Alternative Conversion Method 83 3.5 Hexadecimal Numbers and Arithmetic 85 3.6 A Special Conversion Case—Number Bases that are Related 87 3.7 Fractions 88 Fractional Conversion Methods 90 3.8 Mixed Number Conversions 93 Summary and Review 94 For Further Reading 94 Key Concepts and Terms 95 Reading Review Questions 95 Exercises 96 n CHAPTER 4 Data Formats 100 4.0 Introduction 101 4.1 General Considerations 101 4.2 Alphanumeric Character Data 104 4.3 Visual Data 111 Bitmap Images 112 Object Images 116 Representing Characters as Images 119 Video Images 120 4.4 Audio Data 120 4.5 Data Compression 124 4.6 Page Description Languages 125 4.7 Internal Computer Data Format 126 Numerical Character to Integer Conversion 128 Summary and Review 129 For Further Reading 130 Key Concepts and Terms 130 Reading Review Questions 131 Exercises 132  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page viii viii CONTENTS n CHAPTER 5 Representing Numerical Data 136 5.0 Introduction 137 5.1 Unsigned Binary and Binary-Coded Decimal Representations 138 5.2 Representations for Signed Integers 141 Sign-and-Magnitude Representation 141 Nine’s Decimal and 1’s Binary Complementary Representations 143 Ten’s Complement and 2’s Complement 149 Overflow and Carry Conditions 152 Other Bases 153 Summary of Rules for Complementary Numbers 153 5.3 Real Numbers 154 A Review of Exponential Notation 154 Floating Point Format 156 Normalization and Formatting of Floating Point Numbers 158 A Programming Example 161 Floating Point Calculations 162 Floating Point in the Computer 164 Conversion between Base 10 and Base 2 166 5.4 Programming Considerations 167 Summary and Review 168 For Further Reading 169 Key Concepts and Terms 169 Reading Review Questions 169 Exercises 170 PART THREE COMPUTER ARCHITECTURE AND HARDWARE OPERATION 176 n CHAPTER 6 The Little Man Computer 178 6.0 Introduction 179 6.1 Layout of the Little Man Computer 179 6.2 Operation of the LMC 181 6.3 A Simple Program 182 6.4 An Extended Instruction Set 184 6.5 The Instruction Cycle 187 6.6 A Note Regarding Computer Architectures 190 Summary and Review 190 Key Concepts and Terms 191 Reading Review Questions 191 Exercises 191  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page ix CONTENTS ix n CHAPTER 7 The CPU and Memory 194 7.0 Introduction 195 7.1 The Components of the CPU 196 7.2 The Concept of Registers 197 7.3 The Memory Unit 200 The Operation of Memory 200 Memory Capacity and Addressing Limitations 204 Primary Memory Characteristics and Implementation 205 7.4 The Fetch–Execute Instruction Cycle 207 7.5 Buses 210 Bus Characteristics 210 7.6 Classification of Instructions 214 Data Movement Instructions (LOAD, STORE, and Other Moves) 215 Arithmetic Instructions 217 Boolean Logic Instructions 218 Single Operand Manipulation Instructions 218 Bit Manipulation Instructions 218 Shift and Rotate Instructions 218 Program Control Instructions 219 Stack Instructions 220 Multiple Data Instructions 223 Other Instructions 224 7.7 Instruction Word Formats 224 7.8 Instruction Word Requirements and Constraints 226 Summary and Review 229 For Further Reading 229 Key Concepts and Terms 230 Reading Review Questions 230 Exercises 231 n CHAPTER 8 CPU and Memory: Design, Enhancement, and Implementation 234 8.0 Introduction 235 8.1 CPU Architectures 236 Overview 236 Traditional Modern Architectures 237 8.2 CPU Features and Enhancements 238 Introduction 238 Fetch–Execute Cycle Timing Issues 239 A Model for Improved CPU Performance 241 Scalar and Superscalar Processor Organization 245 8.3 Memory Enhancements 248  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page x x CONTENTS Wide Path Memory Access 249 Memory Interleaving 249 Cache Memory 250 8.4 The Compleat Modern Superscalar CPU 254 8.5 Multiprocessing 256 8.6 A Few Comments on Implementation 260 Summary and Review 260 For Further Reading 261 Key Concepts and Terms 262 Reading Review Questions 262 Exercises 263 n CHAPTER 9 Input/Output 266 9.0 Introduction 267 9.1 Characteristics of Typical I/O Devices 268 9.2 Programmed I/O 273 9.3 Interrupts 275 Servicing Interrupts 275 The Uses of Interrupts 277 Multiple Interrupts and Prioritization 282 9.4 Direct Memory Access 286 9.5 I/O Controllers 289 Summary and Review 291 For Further Reading 292 Key Concepts and Terms 292 Reading Review Questions 292 Exercises 293 n CHAPTER 10 Computer Peripherals 294 10.0 Introduction 295 10.1 The Hierarchy of Storage 296 10.2 Solid-State Memory 298 10.3 Magnetic Disks 299 Disk Arrays 306 10.4 Optical Disk Storage 307 10.5 Magnetic Tape 309 10.6 Displays 310 Basic Display Design 310 Graphical Processing Units (GPUs) 312 Liquid Crystal Display Technology 316 OLED Display Technology 317 10.7 Printers 317 Laser Printers 319 Inkjet Printers 320 10.8 User Input Devices 320  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page xi CONTENTS xi Keyboards 320 Pointing Devices 321 Alternative Sources of Alphanumeric Input 322 Scanners 324 Multimedia Input 324 Mobile Devices 325 10.9 Network Communication Devices 326 Summary and Review 327 For Further Reading 327 Key Concepts and Terms 328 Reading Review Questions 328 Exercises 329 n CHAPTER 11 Modern Computer Systems 332 11.0 Introduction 333 11.1 Putting All the Pieces Together 335 11.2 System Architecture 340 Basic System Interconnection Requirements 341 Bus I/O 343 Channel Architecture 347 Blurring the Line 349 11.3 Computer Interconnection: A Brief Overview 349 11.4 Clusters 350 Overview 350 Classification and Configuration 350 Beowulf Clusters 352 11.5 High-Performance Computing 353 Grid Computing 354 Summary and Review 354 For Further Reading 355 Key Concepts and Terms 355 Reading Review Questions 356 Exercises 356 PART FOUR NETWORKS AND DATA COMMUNICATIONS 358 n CHAPTER 12 Networks and Data Communications—An Overview 360 12.0 Introduction 361 12.1 The Impact of Networking on Business Processes and User Access to Knowledge and Services 362 12.2 A Simple View of Data Communications 363 12.3 Basic Data Communication Concepts 366 Messages 366  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page xii xii CONTENTS Packets 367 General Channel Characteristics 369 12.4 Networks 373 Network Topology 373 Types of Networks 376 Network Interconnection 390 12.5 Standards 393 Summary and Review 395 For Further Reading 396 Key Concepts and Terms 396 Reading Review Questions 397 Exercises 397 n CHAPTER 13 Ethernet and TCP/IP Networking 400 13.0 Introduction 401 13.1 TCP/IP, OSI, and Other Communication Protocol Models 402 13.2 Program Applications Versus Network Applications 406 13.3 The Physical and Data Link Layers 407 The Physical Layer 408 The Data Link Layer 408 Hub-Based Ethernet 410 Switched Ethernet 411 Wireless Ethernet (Wi-Fi) 411 13.4 The Network Layer 413 13.5 The Transport Layer 416 13.6 IP Addresses 421 IPv4 and DHCP 421 IPv6 425 13.7 Domain Names and DNS Services 425 13.8 Quality of Service 430 13.9 Network Security 431 Physical and Logical Access Restriction 432 Encryption 432 13.10 Alternative Protocols 433 A Comparison of TCP/IP and OSI 433 Other Protocol Suites and Components 434 SCSI Over IP 434 Cellular Technology 435 MPLS 435 SONET/SDH 436 Frame Relay 436 Summary and Review 436 For Further Reading 437 Key Concepts and Terms 437 Reading Review Questions 438 Exercises 439  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page xiii CONTENTS xiii n CHAPTER 14 Communication Channel Technology 442 14.0 Introduction 443 14.1 Communication Channel Technology 444 14.2 The Fundamentals of Signaling Technology 447 Analog Signaling 448 Digital Signaling 456 Modems 461 14.3 Transmission Media and Signaling Methods 462 14.4 Alternative Technologies 464 Cellular Technology 464 Wi-Fi 466 Bluetooth 466 Summary and Review 467 For Further Reading 468 Key Concepts and Terms 468 Reading Review Questions 469 Exercises 470 PART FIVE THE SOFTWARE COMPONENT 474 n CHAPTER 15 Operating Systems: An Overview 476 15.0 Introduction 477 15.1 The Barebones Computer System 478 15.2 The Operating Systems Concept: An Introduction 479 15.3 Services and Facilities 485 User Interface and Command Execution Services 486 File Management 487 Input/Output Services 489 Process Control Management 489 Memory Management 490 Scheduling and Dispatch 491 Secondary Storage Management 493 Network and Communications Support Services 494 Security and Protection Services 494 System Administration Support 495 15.4 Organization 499 15.5 Types of Computer Systems 502 Summary and Review 506 For Further Reading 506 Key Concepts and Terms 507 Reading Review Questions 507 Exercises 508  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page xiv xiv CONTENTS n CHAPTER 16 The User View of Operating Systems 510 16.0 Introduction 511 16.1 Purpose of the User Interface 512 16.2 User Functions and Program Services 514 Program Execution 514 File Commands 515 Disk and Other I/O Device Commands 516 Security and Data Integrity Protection 516 Interuser Communication and Data Sharing Operations 517 System Status Information and User Administration 518 Program Services 519 16.3 Types of User Interface 519 The Command Line Interface 520 Batch System Commands 522 Graphical User Interfaces 523 Touchless Gesture- and Voice-Based Interfaces 528 Trade-offs in the User Interface 529 Software Considerations 530 16.4 X Window and Other Graphics Display Methodologies 532 16.5 Command and Scripting Languages 535 The Elements of a Command Language 536 The Command Language Start-up Sequence Files 537 16.6 Services to Programs 538 Summary and Review 540 For Further Reading 540 Key Concepts and Terms 540 Reading Review Questions 541 Exercises 541 n CHAPTER 17 File Management 544 17.0 Introduction 545 17.1 The Logical and Physical View of Files 545 17.2 The Role of the File Management System 550 17.3 Logical File Access Methods 555 Sequential File Access 555 Random Access 556 Indexed Access 557 17.4 Physical File Storage 557 Contiguous Storage Allocation 558 Noncontiguous Storage Allocation 559 Indexed Allocation 561 Free Space Management 564 Tape Allocation 565  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page xv CONTENTS xv CD, DVD, and Flash Drive Allocation 566 17.5 File Systems, Volumes, Disks, Partitions, and Storage Pools 566 17.6 The Directory Structure 569 Tree-Structured Directories 570 Acyclic-Graph Directories 573 17.7 Network File Access 576 17.8 Storage Area Networks 578 17.9 File Protection 578 17.10 Journaling File Systems 581 Summary and Review 581 For Further Reading 582 Key Concepts and Terms 582 Reading Review Questions 583 Exercises 584 n CHAPTER 18 The Internal Operating System 586 18.0 Introduction 587 18.1 Fundamental OS Requirements 588 Example: A Simple Multitasking Operating System 590 18.2 Starting the Computer System: The Bootstrap 592 18.3 Processes and Threads 595 Process Creation 597 Process States 598 Threads 600 18.4 Basic Loading and Execution Operations 600 18.5 CPU Scheduling and Dispatching 601 High-Level Scheduler 601 Dispatching 603 Nonpreemptive Dispatch Algorithms 605 Preemptive Dispatch Algorithms 606 18.6 Memory Management 608 Memory Partitioning 608 18.7 Virtual Storage 610 Overview 610 Pages and Frames 610 The Concept of Virtual Storage 616 Page Faults 617 Working Sets and the Concept of Locality 619 Page Sharing 620 Page Replacement Algorithms 620 Thrashing 624 Page Table Implementation 624 Segmentation 626 Process Separation 627  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page xvi xvi CONTENTS 18.8 Secondary Storage Scheduling 627 First-Come, First-Served Scheduling 627 Shortest Distance First Scheduling 628 Scan Scheduling 628 n-Step c-Scan Scheduling 628 18.9 Network Operating System Services 629 OS Protocol Support and Other Services 629 18.10 Other Operating System Issues 632 Deadlock 632 Other Issues 632 18.11 Virtual Machines 634 Summary and Review 636 For Further Reading 636 Key Concepts and Terms 637 Reading Review Questions 638 Exercises 639 Bibliography 645 Index 657 SUPPLEMENTARY CHAPTERS On the Web at www.wiley.com/college/englander n SUPPLEMENTARY CHAPTER 1 An Introduction to Digital Computer Logic S1.0 Introduction S1.1 Boolean Algebra S1.2 Gates and Combinatorial Logic S1.3 Sequential Logic Circuits Summary and Review For Further Reading Key Concepts and Terms Reading Review Questions Exercises n SUPPLEMENTARY CHAPTER 2 System Examples S2.0 Introduction S2.1 Hardware Examples The x86 Family The POWER Family The IBM System 360/370/390/zSeries Family S2.2 Operating System Examples The Microsoft Windows Family UNIX and Linux The IBM z/OS Operating System  Englander ftoc.tex V2 - December 10, 2013 12:46 A.M. Page xvii CONTENTS xvii S2.3 Networking Examples Google Summary and Review For Further Reading Key Concepts and Terms Reading Review Questions Exercises n SUPPLEMENTARY CHAPTER 3 Instruction Addressing Modes S3.0 Introduction S3.1 Register Addressing S3.2 Alternatives to Absolute Addressing S3.3 Alternatives to Direct Addressing Immediate Addressing Indirect Addressing Register Indirect Addressing Indexed Addressing Indirect Indexed and Indirect Indexed Addressing Summary and Review For Further Reading Key Concepts and Terms Reading Review Questions Exercises n SUPPLEMENTARY CHAPTER 4 Programming Tools S4.0 Introduction S4.1 Program Editing and Entry S4.2 The Concept of Program Translation S4.3 Assembly Language and the Assembler Operation of the Assembler Assembly Language Formats Features and Extensions Relocatability S4.4 Program Language Description and Rules A Description of Written English Programming Language Rules Computer Language Descriptions The Compilation Process Interpreters S4.5 Linking and Loading S4.6 Debuggers Summary and Review For Further Reading Key Concepts and Terms Reading Review Questions Exercises  Englander f02.tex V2 - December 9, 2013 2:51 P.M. Page xviii PREFACE T he modern world offers a lot of readily available online resources for learning. Wikipedia, Google, news sources, millions of Web sites and blogs, even YouTube, offer access to information in nearly any subject that triggers your curiosity and interest. Nonetheless, I continue to believe that for deep understanding of something, nothing beats the integrated approach and focus of an old-fashioned printed-on-paper textbook. Well—maybe the e-book equivalent, but, still, a textbook. When I open a new book, in any subject, the first thing I want to know is what the book has to offer that makes it worth my while to read it. I would like to try to help you answer that question for the book that you’re holding in your hand or on your tablet. The information systems and technology fields are wonderfully exciting places to be! It seems as though every day brings new developments that alter the ways we create and work with information. Of course, with this excitement comes a challenge. To be a successful player in IS or IT, we have to be adaptable and flexible. Much of the change occurs around computer system technology. The computer is, after all, at the foundation of information systems. A deep understanding of computer systems is, therefore, an essential element of success. We must be able to understand each new development, assess its value, and place it in the context of our knowledge of computer systems. The subject of this book is the architecture of computer systems. Computer architecture is about the structure and operation of digital computers and computer-based devices. Computer architecture is concerned with the operational methods of the hardware; with the services provided by operating system software; with the acquisition, processing, storage, and output of data; and with the interaction between computer-based devices. There is a tendency for people in information systems and technology to neglect a study of computer architecture. After all, the technology changes so rapidly—is it really worth trying to understand something that may be out of date by the time I finish this book? There is no question that computer technology has evolved rapidly. The computer in a smartphone is far more powerful than the mainframe computer of twenty-five years ago, with memory, disk and flash storage capacity, display and multimedia capability, and ease of use that would have been unthinkable just a few years ago. Even more important, connecting systems to work together is now routine and simple. Interestingly enough, however, as profound as advances in the technology have been, the concepts of computer architecture that really matter have changed only nominally over the last seventy years. The new technologies are based on a foundation of architectural concepts that were developed many years ago. The architecture of a modern computer system was developed in the 1940s. The instruction set in a modern personal computer or smartphone is nearly identical to that of computers built in the 1950s and 1960s. Modern operating system xviii  Englander f02.tex V2 - December 9, 2013 2:51 P.M. Page xix PREFACE xix techniques were developed in the 1960s. The graphical user interface is based on a 1960s’ project. The Internet is built from concepts developed more than forty years ago. So you see that an understanding of computer architecture makes it possible to “ride the wave” of technological change, secure in the feeling that you are equipped to deal with new developments as they occur, and to have fun doing so. When you are done reading this book, you will have substantial knowledge about how a computer works and a good understanding of the operating concepts, the hardware, and system software that make up a computer. You will see the interaction between computers and between data and the computer. Plus, you will have learned lots of jargon that you can show off at parties and job interviews. This textbook is designed for a wide range of readers, both undergraduate and graduate. The material is specifically directed toward IS and IT majors. There are no explicit prerequisites, although the book assumes that the student is familiar with a personal computer. It also assumes (but does not require) some basic programming skills: although there is no programming in the book, program code is occasionally used as an example to clarify an idea, and a knowledge of programming is helpful at understanding instruction set design and program execution concepts. The material in this textbook conforms to the criteria of the IT Infrastructure courses and core concepts, as described in the ACM and AIS standard IS2010 and IT2008 curricula. Although the material in this book may be useful as background for system design and implementation project courses, the course can be placed anywhere in the curriculum. Most instructors will not cover the entire textbook in a single semester. The organization of this book is designed to allow an instructor to cover the major topic areas in different levels of depth, depending on the experience and needs of the students. On the other hand, it is my intention that this book will serve a student as a useful reference long after the formal course is completed. It is designed for use as a book where a professional can look up the basic concepts that clarify new developments as they occur. This text is the outgrowth of courses that I have taught to CIS majors and minors at Bentley University at both the undergraduate and graduate levels for more than thirty years. Student responses to the material and the approach have generally been very enthusiastic. Many students have returned after graduation to tell me that their knowledge in this area has directly contributed to their career development. Along the way, student comments have also been extremely helpful to me in the book’s continuing evolution. Those familiar with previous editions will notice that the organization of recent editions has undergone substantial revision to reflect current technological practices and trends. In particular, it is no longer reasonable to discuss computers as individual units without also considering the networks that tie them together; computer networking is now covered thoroughly in its own section, and there is an increased emphasis on the integration and synergy of the various components of the computer system and on the system as a whole. Still, the basic philosophy, organization, and approach remain essentially similar to those of the first edition, reflecting the unchanging nature of the underlying principles. ORGANIZATION OF THE FIFTH EDITION, NOTING CHANGES FROM PREVIOUS EDITIONS The biggest challenge for me as the author of this book has been to preserve the guiding principles established in the first edition, while reflecting the major changes in the way computers are  Englander f02.tex V2 - December 9, 2013 2:51 P.M. Page xx xx PREFACE used, in the rapid deployment of new technology, and in the resulting evolution of IS/IT curriculum to reflect those changes. The fifth edition is a substantial, though incremental, update to previous editions. It reflects the rapid growth in the use of tablets and smartphones as important computing devices. The material on networking has been substantially reorganized. Still, users of previous editions will find that much of the material is familiar; after all, the way in which computers are used in IS/IT may have changed, but the basic guiding principles of computer architecture are essentially the same as they have been for many years. This book is organized into five parts totaling eighteen chapters, plus four additional supplementary chapters that are posted on the Web. The first part serves as an introduction and overview of the role of the computer in information systems; it introduces the concept of a system and provides a brief introduction to each of the components that make up a modern computer system. Each of the remaining four parts deals with a single architectural aspect of the computer system. Part Two discusses the role and representation of data in the computer. Here, we consider numbers, text, sound, images, video, and other data forms. Part Three presents the hardware architecture and operational concepts. It introduces the components of a computer and shows how they collaborate to execute computer instructions, discusses the nature of a computer instruction set, and explores the interaction between the CPU, memory, and I/O peripheral devices. Part Four presents a thorough introduction to the basics of computer networking. Part Five discusses the system software, the programs that function to make the resources of the computer system, and other interconnected computer systems and components, accessible to the user and to application programs. The approach within each group of chapters is layered. Each new layer builds upon the previous material to add depth and understanding to the reader’s knowledge. Each topic section consists of a short introduction that places the topic to be discussed into the context of the computer system as a whole and then lays out in detail the organization of the chapters within the section. Each topic area is introduced as gently as possible, using ideas and examples that are already familiar to students. Successive material is progressive and accumulative. In addition to the numerous examples that are used throughout the text, the supplementary chapters offer substantial case studies that show application of the text material to current examples of importance. Overall, the approach is gentle, progressive, and accumulative. As much as possible, each section is self-contained. An overview of the organization of each part follows. A few comments about the differences between the fourth and fifth editions are included for those who are familiar with the previous edition. More details can be found in the introductions to each section. Part One consists of two chapters that present a short overview of computing and placing architectural concepts into the context of information technology. Chapter 1 introduces the components of a computer system and shows the relationships among the components. In the new edition, I have assumed that today’s students are more familiar with computer technology and terminology than previous generations, so there is less introduction of “IT101”-type material. Chapter 1 also presents a simple model of computing and discusses the importance of standards and protocols in the development of computer systems. This chapter concludes with a short history of computers from the architectural point of view. Chapter 2 focuses on the concepts of systems, models, and system architectures, using various types of computer systems as examples. There are several relatively small but important additions and updates in this chapter. In Section 2.2, there is an increased emphasis on n-tier architectures and distributed  Englander f02.tex V2 - December 9, 2013 2:51 P.M. Page xxi PREFACE xxi computing. Section 2.2 also contains a new section on cloud computing, which is presented as a variation of the client–server concept. A new Facebook application architecture example has also been added. Chapters 3 through 5 comprise Part Two. Chapter 3 introduces number systems and basic number system operations; it then explores the relationships between numbers in different number bases and the conversion techniques between the different representations. Chapter 4 investigates different types of data formats, including alphanumeric, image, video, and audio formats. It considers the relationship between numerical and character-based representations. Previously, Chapter 4 also introduced various devices and data formats used for data input and output. Much of that material has been moved to Chapter 10 since it is more directly related to the devices themselves. Chapter 5 studies the various formats that are used to represent and to perform calculations on integer and floating point numbers. Part Three discusses the hardware architecture and operational aspects of the computer. Chapter 6 begins the study with the introduction of the Little Man Computer, a simple model that provides a surprisingly accurate representation of the CPU and memory. The model is used to develop the concept of an instruction set and to explain the basic principles of the von Neumann architecture. Chapter 7 extends the discussion to a real computer. It introduces the components of the CPU and shows their relationship to the Little Man Computer model. It introduces the bus concept, explains the operation of memory, presents the instruction fetch–execute cycle, and discusses the instruction set. It identifies important classes of instructions and discusses the ways in which instructions can be categorized. The ARM instruction set is offered as an illustration of a typical current CPU model. Chapter 8 expands the material in Chapter 7 to consider more advanced features of the CPU and memory. It offers an overview of various CPU architectures. It continues with a discussion of techniques for improving memory access, particularly cache memory, and an introduction to current CPU organization, design, and implementation techniques, including pipelining and superscalar processing. This chapter also introduces multiprocessing (or multicore, in current terminology) concepts. Chapter 8 received basic updating from the previous edition, including elimination of the VLIW and EPIC architectures that never caught on. Chapter 9 presents the principles of I/O operation, and Chapter 10 illustrates how I/O is performed in various I/O devices. With the advent of powerful tablets and smartphones, Chapter 10 received a substantial overhaul. Solid-state storage is of increased importance, and Section 10.2 has been expanded to increase the coverage. Section 10.3, the display section, has a new discussion of graphical processing units. CRTs have been eliminated altogether. The discussions of text-mode display processing and different types of raster scans have been minimized. The discussion of printers in Section 10.4 now considers only laser and inkjet technologies. Section 10.8, user input devices, now includes the alternative sources of alphanumeric input, moved from Chapter 4, plus more on touch screens and voice input. There is an additional section discussing the sensors available on mobile devices, including GPS, accelerometers, gyroscopes, magnetic field sensors, and near-field communication sensors. Chapter 11 discusses the computer system as a whole. It discusses the interconnection techniques and integration of the various hardware components. Chapter 11 has been updated to reflect modern systems, including mobile systems and radically changed bus architecture technology. The new, just-introduced Intel Haswell architecture and System on a Chip concepts are included. Firewire was removed; the Thunderbird port is introduced in its place. Chapter 11  Englander f02.tex V2 - December 9, 2013 2:51 P.M. Page xxii xxii PREFACE also addresses the interconnection of computers to increase the performance and reliability of a computer with a specific focus on clustering and grid computing. Three supplementary chapters on the Web provide additional resources to support the chapters in Part Three. Supplementary Chapter 1 (SC1) offers an introduction to Boolean algebra, combinatorial logic, and sequential logic for those readers that would like a deeper understanding of the computer in its simplest and most elegant form. Supplementary Chapter 2 (SC2) offers three detailed case studies of important architectures: the Intel x86 family, the Power computer, and the IBM zSystem. As of this writing, this supplement is currently being updated. Supplementary Chapter 3 (SC3) discusses alternative approaches to instruction addressing. Part Four, Chapters 12–14, presents a thorough introduction to networking. For the fifth edition, Chapters 12 and 13 received a major reorganization; to a much lesser extent, Chapter 14 is also affected by the change. The goal was a more unified and systematic presentation of networking material. Chapter 12 introduces the concept of a communication channel and explores its charac- teristics and configurations. This includes the communication channel model, the concept of links, packets, basic channel characteristics, network topology, types of networks (LAN, MAN, etc.), and basic network interconnection and routing. All of the material related to protocols and movement of data through the network has been moved to Chapter 13. The chapter is retitled as Networks and Data Communications—An Overview. Chapter 13 now focuses on the passage of data packets through a network. The chapter is now titled Ethernet and TCP/IP Networking. Section 13.1 introduces TCP/IP and OSI and the concept of layered communication. Section 13.2 describes the differences between program applications and network applications. Following these two sections, the next three sections carefully describe the process of moving packets, one layer at a time, from the bottom-up. It should be noted that wireless networking has been moved from Chapter 14 and is now included as part of the Ethernet discussion. Sections 13.6 and 13.7 explain IPv4 and IPv6 addressing and DHCP, and DNS, respectively. Quality of Service and network security are briefly introduced in Sections 13.8 and 13.9. The chapter concludes with a discussion of alternative protocols, including a comparison of OSI and TCP/IP, as well as brief discussions of MPLS, cellular technology, and other protocol suites. Chapter 14 focuses primarily on communication channel technology, including analog and digital signaling, modulation and data conversion techniques between analog and digital, and the characteristics of transmission media. Sections 14.1–14.3 are relatively unchanged. Section 14.4, however, is mostly new. Titled Alternative Technologies, it offers advanced introductions to the radio technologies of LTE cellular technology, Wi-Fi, and Bluetooth. Part Five is dedicated to a discussion of system software. Chapter 15 provides an overview of the operating system. It explains the different roles played by the operating system and introduces the facilities and services provided. Chapter 16 presents the role of the operating system from the viewpoint of the user of a system. The fifth edition offers new screenshots of Windows 8 and recent versions of Linux. Chapter 17 discusses the all-important topic of file systems, including an introduction to Microsoft’s new Resilient File System, intended to replace NTFS. Chapter 18 discusses the operating system as a resource manager, with an in-depth discussion of memory management, scheduling, process control, network services, and other basic operating system services. Chapter 18 includes a detailed introduction to virtual memory technique, rewritten for the fifth edition, with a new, detailed, worked-out example, carefully illustrating the different page replacement algorithms. The chapter also includes an introduction  Englander f02.tex V2 - December 9, 2013 2:51 P.M. Page xxiii PREFACE xxiii to virtual machines. In addition to its hardware discussions, Supplementary Chapter 2, when completed, will also provide current Windows, UNIX/Linux, and z/OS case studies. A fourth supplementary chapter provides an introduction to the system development software that is used for the preparation and execution of programs. This book has been a continuing labor of love. My primary goal has been to create and maintain a textbook that explains computer architecture in a way that conveys to you, the reader, the sense of excitement and fun that I believe makes a career in information systems and technology so satisfying. I hope that I have succeeded to some extent. ADDITIONAL RESOURCES Additional resources for students and instructors may be found at the textbook’s Web site, www.wiley.com/college/englander. I can also be reached directly by e-mail at [email protected]. Although I am happy to communicate with students, I am unable to supply tutorial help or answers to review questions and exercises in this book. ACKNOWLEDGMENTS I’ve discovered that a major, ongoing textbook project is a formidable task. Many individuals have helped to make the task manageable—and kept me going when, from time to time, I became convinced that textbooks really do appear by magic and are not written by humans. It is impossible to thank people adequately for all their help and support. First and foremost, a special thank you to four friends who have helped me survive through all five editions, Wilson Wong, Ray Brackett, Luis Fernandez, and Rich Braun. Their continuing backup has been amazing! I couldn’t have asked for a better support team. Dinner is ready and the champagne is on ice. Yet again! My continuing thanks, too, to Stuart Madnick. Stuart, your technical inspiration and personal encouragement was invaluable to me when I struggled to get the first edition of this book going. You helped me to believe that this project was actually possible and worthwhile. That support has continued to inspire me through every subsequent edition. Next, I thank the many colleagues at Bentley University who shared their ideas, experiences, and encouragement. In particular, colleagues Wilson Wong, David Yates, Doug Robertson, and Mary Ann Robbert have all offered contributions that have substantially improved the book over five editions. A special thank you, David, for your helpful technical discussions and reviews of the data communications material in the fourth and fifth editions, and to you, Wilson, for serving as a technical reviewer for the last three (!) editions, providing many comments, rewrites, examples, and suggestions for clarification, and for creating many of the ancillary materials for the book. Thanks to the editors, production people, and marketing personnel at John Wiley & Sons and the editors and production people at SPi Global. Sometimes the process is difficult, but we always managed to get through it in a way that made the book better. I consider myself fortunate to have worked with such committed people. Particular thanks to Beth Lang Golub, Katie Singleton, and Felicia Ruocco for your ongoing efforts to make this book perfect, even though we all know it’s impossible!  Englander f02.tex V2 - December 9, 2013 2:51 P.M. Page xxiv xxiv PREFACE I would like to acknowledge the reviewers who have given of their time and effort over many editions to assure that this book was as good as it could be: Dr. Stu Westin, The University of Rhode Island; Alan Pinck, Algonquin College; Mark Jacobi, Programme Director for Undergrad Computing at Sheffield Hallam University; Dr. Dave Protheroe, South Bank University, London; Julius Ilinskas, Kaunas University of Technology; Anthony Richardson, United States Army Informations Systems Engineering Command; Renee A. Weather, Old Dominion University; Jack Claff, Southern Cross University; Jan L. Harrington, Marist College; YoungJoon Byun, California State University, Monterey Bay; William Myers, Belmont Abbey College; Barbara T. Grabowski, Benedictine College; G.E. Strouse, York College of Pennsylvania; Martin J. Doyle, Temple University; Richard Socash, Metropolitan State College of Denver; and Fred Cathers, Franklin University. Your comments, suggestions, and constructive criticism have made a real difference in the quality of this book. Thank you. Thank you, too, to the reviewers of the current edition: Bob Brown, Southern Polytechnic State University; Ming-Hsing Chiu, Dillard University; Angela Clark, University of South Alabama; Chin-Tser Huang, University of South Carolina; Theresa Kraft, Capella University; Ng Shu Min, HELP University College; Carl Nehlig, Tulane University; Leasa Perkins, University of Maryland University College; and Mahbubur Syed, Minnesota State University, as well as to testbank author Ronald Munsee, University of Maryland University College, and to users from around the world who responded to the 2011 user survey. Many colleagues offered corrections to previous editions that have had important impact on the quality of the current edition. To each and everyone, your assistance in eliminating errors has been much appreciated. Among these, I especially wish to acknowledge David Feinstein and his crew at the University of South Alabama, Gordon Grimsey of AIT in Auckland, New Zealand, and Stu Westin of University of Rhode Island for efforts well above and beyond the call of duty. Stu has also generously made his excellent Little Man Simulator publicly available, for which I am truly grateful. Thanks for everything, Stu. Numerous students, too many to name you all, also offered corrections, made suggestions, and provided ideas. Please accept my deepest appreciation and thanks. I hope that I have not forgotten anyone. If I have, I apologize. I have strived to make this book as technically accurate as is humanly possible. Nonetheless, I know that errors have a way of creeping in when one least expects them. I would greatly appreciate hearing from readers who find errors that need correction. Your comments and suggestions about the book are also welcome. Irv Englander Boston, Massachusetts  Englander f03.tex V2 - December 9, 2013 2:50 P.M. Page xxv ABOUT THE AUTHOR D r. Irv Englander has been involved in many different aspects of the computing field for more than fifty years. He has designed logic circuits, developed integrated circuits, developed computer architectures, designed computer-controlled systems, designed operating systems, developed application software, created the initial system design for a large water-monitoring system, performed software auditing and verification of critical control software, and developed and specified hardware components and application software as a consultant for business systems large and small. As an educator, he has contributed papers and given workshops on end-user computing, e-commerce, and on various aspects of IS and IT pedagogy. He was an invited contributor and reviewer for the IS-97 and IS-2002 information systems curricula, and continues to publish and take an interest in the technical infrastructure components of the IS/IT curriculum. He is actively involved in the application of new technology to information systems. Most recently he served as a faculty advisor to a low-cost supercomputing student research project, which was presented at the ACM/IEEE Computer Society Supercomputing Conference SC13. Dr. Englander has a Ph.D. from MIT in Computer Science. His doctoral thesis was based on the design of a large image-processing software laboratory. At MIT, he won the Supervised Investors Award for outstanding teaching. He holds the rank of Professor Emeritus of Computer Information Systems at Bentley University, where he taught full-time for thirty-three years. xxv  Englander p01.tex V2 - November 30, 2013 9:04 A.M. Page 2 PART ONE A computer-based information system is made up of a number of different elements: n The data element. Data is the fundamental representation of facts and observations. Data is processed by a computer system to provide the information that is the very reason for the computer’s existence. As you know, data can take on a number of different forms: numbers, text, images, and sounds. But it’s all numbers in the computer. n The hardware element. Computer hardware processes the data by executing instructions, storing data, and moving data and information between the various input and output devices that make the system and the information accessible to the users. n The software element. Software consists of the system and application programs that define the instructions that are executed by the hardware. The software determines the work to be performed and controls operation of the system. n The communication element. Modern computer information systems depend on the ability to share processing operations and data among different computers and users, located both locally and remotely. Data communication provides this capability. The combination of hardware, software, communication, and data make up the architecture of a computer system. The architecture of computer systems is remarkably similar whether the system is a playstation, a personal computer that sits on your lap while you work, an embedded computer that controls the functions in your cell phone or in your car, or a large mainframe system that is never actually seen by the hundreds of users who access it every day. Amazingly, the changes in computer technology that you’ve seen in just the last few years are essentially superficial; the basic architecture of computer systems has changed surprisingly little over the last sixty years. The latest IBM mainframe computer executes essentially the same instruction set as the mainframe computer of 1965. The basic communication techniques used in today’s systems were developed in the 1970s. As new as it might seem, the Internet celebrated its fortieth anniversary in 2010. All of this is surprising considering the growth of computing,  Englander p01.tex V2 - November 30, 2013 9:04 A.M. Page 3 AN OVERVIEW OF COMPUTER SYSTEMS the rapid change of technology, and the increased performance, functionality, and ease of use of today’s systems. This makes the study of computer architecture extremely valuable as a foundation upon which to understand new developments in computing as they occur. Computer system architecture is the subject of this textbook. Each element of the system is addressed in its own section of the text, always with an eye to the system as a whole. Part I is made up of two chapters that present an overview of systems, and of the computer system in particular. Chapter 1 addresses a number of issues, including: n The ways in which a knowledge of computer architecture enhances our abilities as computer users and professionals n A simplified view of typical computer system architectures n The basic components that make up a computer system n The fundamental operations that are performed by computer systems. Chapter 1 concludes with a brief architectural history of the computer. An encompassing theme throughout this text is that of systems and system architecture. The words “system” and “architecture” appear throughout this book: we talk about information systems, computer systems, operating systems, file systems, software architecture, I/O architec- ture, network architecture and more. You will probably take a course in System Analysis and Design sometime in your college career. Although most people have an instinctive understanding of what a system is, it is more important for us as system professionals to understand the concepts of systems and system architecture at a deeper level than the average person. Chapter 2 offers careful definitions and examples of the concept of systems and system architecture, both generally and in the specific context of the computer systems that are the focus of this book. 3  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 4 CHAPTER 1 COMPUTERS AND SYSTEMS CATHY C 1986 Cathy Guisewite. Reprinted with permission of UNIVERSAL PRESS SYNDICATE. All rights reserved  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 5 1.0 INTRODUCTION Welcome to the wonderful modern world of computers. Where the technology changes daily. Or does it? It’s true that the computer of today looks nothing like the computer of even five or ten years ago. It is nearly impossible today to escape the immediate and ubiquitous reach of computers and computer-based systems and devices. There is probably a smartphone in your pocket or on your desk. For many of you, your laptop or tablet is sitting nearby as you read this paragraph. (Or, maybe you’re even reading this paragraph on your tablet or E-book.) Furthermore, your smartphone probably has more computing power than most of the computers on the market ten years ago. It fits easily in your pocket or purse. It weighs less than 1/100 of that old desktop computer and has at least ten times as much memory! And that’s not all. Your car has several embedded computers controlling various automotive functions, and perhaps a touch screen for hands-free telephone, navigation, the radio, Internet access, and more. Which is almost unnecessary, because you can probably tell it what you want verbally anyway. Even your microwave oven and the machine that launders your clothes depend on computers to function. As you are likely aware, most of these machines can talk to each other, using the Internet or some other networking technology. Just for fun, Figure 1.1 shows pictures typical of a 2005 laptop, a 2013 smartphone, and a current embedded computer that controls many functions in your car. Although the focus of this book is on IT systems, our discussion of computer hardware, software, and networking applies equally well to workplace computers, tablets, smartphones, and, even, computers embedded in other equipment. In this figure, we have three seemingly very different looking pieces of equipment working on different types of applications. And yet, it’s hopefully obvious to you that these three systems share a lot in common. They are all computer based. All contain at least one central processing unit (CPU, some contain more) and memory. All provide a facility for interacting with long-term storage and other devices and with users. What may be less obvious to you is that the programs that they run are also essentially similar, differing mostly in the details required by the different components of the particular system and by the nature of the applications. For example, systems may have different amounts of memory, different types of displays, different I/O devices, and different operating systems, as well as running different types of applications and serving different purposes. In fact, a modern IT system may contain elements of many different types of systems, with networking that ties everything together. When creating an IT system, our concerns are whether the various components provide the features and performance that the users require. To be an effective designer and user, you have to understand the specifications, their importance and their meaning; the terminology; and the jargon. Which features are important to the users? Is this the right combination of features that you need in your computer to have the computer perform the work that you wish to get done? Are there features missing that we need? Perhaps we are paying too much for the performance that we need. Or maybe we need more. What other information about this system would allow you to make a more informed decision? 5  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 6 6 PART ONE AN OVERVIEW OF COMPUTER SYSTEMS FIGURE 1.1 Computer Devices, Old and New © 2007 Hewlett-Packard Company Photo by David Shepperd Delphi Automotive There is obviously no need to understand the inner workings of most modern computer-based systems to operate them adequately. Indeed, in many cases, the presence of the computer is hidden from us, or embedded, and its operation is invisible to us as users. We don’t need to know how a computer works to read an E-book. Even as experienced users, we can run standard software packages on a personal computer or apps on a smartphone without understanding exactly how they work; we can program a computer in a high-level or a scripting language without understanding the details of how the machine executes the individual instructions; we can design and implement Web pages without understanding how the Web browser gets its pages from a Web server or how the Web server creates those pages; we can purchase a tablet or a laptop computer from a salesperson without understanding the specifications of the system. And yet, there is something missing. Perhaps the software doesn’t do exactly what we want, and we don’t understand the machine well enough to risk fooling around with the software’s options. Perhaps if we understood the system better we might have written and configured the program to be faster and more efficient. Perhaps we could create Web pages that load faster and work better. Perhaps the salesperson did not sell us the optimum system for our job. Or perhaps it’s nothing more than a sense of excitement that’s missing. But that’s important, too!  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 7 CHAPTER 1 COMPUTERS AND SYSTEMS 7 You are reading this book because you are a student studying to become a computer professional, or maybe you are simply a user wanting a deeper understanding of what the computer is all about. In either case, you know you’ll be interacting with computer systems in some form or other for the rest of your life. It’s nice (as well as useful) to know something about the tools of the trade. More important, understanding the computer system’s operations has an immediate benefit: it will allow you to use the machine more effectively. As a user, you will be more aware of the capabilities, strengths, and limitations of a computer system. You will have a better understanding of the commands that you use. You will understand what is taking place during the operation of the program applications that you use. You will be able to make better informed decisions about your computer equipment and application programs. You will understand more clearly what an operating system is, and how to use it effectively and to your advantage. You will know when it is preferable to do a job manually, and when the computer should be used. You will understand the most efficient way to “go online”, and what benefits might be gained from your home network. You will improve your ability to communicate with system analysts, programmers, and other computer specialists. As a programmer, it will allow you to write better programs. You will be able to use the characteristics of the machine to make your programs operate more effectively. For example, choosing the appropriate data type for a variable can result in significantly faster performance. Soon you will know why this is so, and how to make the appropriate choices. You will discover that some computers will process nested loops much more quickly if the index variables are reversed. A rather surprising idea, perhaps, and you’ll understand why this is true. You will understand why programs written in a compiled language like C++ usually run much faster than those written in interpreted program languages like BASIC or scripting languages like JavaScript. Similarly, you’ll see why the basic layout of a program can have a major impact on the program’s run-time efficiency. As a systems architect or system analyst, you will be responsible for the design and implementation of systems that meet an organization’s information technology (IT) needs, recognizing that the differences in the cost and capabilities of the components that you select may have significant impact on the organization. With the knowledge gained here you will be in a better position to determine and justify the set of computer system components and the system architecture that are appropriate for a particular job and to determine the trade-offs with other possible system architectures. You’ll be able to assist management in making intelligent decisions about system strategy: should the company adopt a large mainframe/virtual machine system approach for its Web servers, or would a system consisting of a network of off-the-shelf blade servers provide better performance at lower cost? You’ll be better prepared to analyze the best way to provide appropriate facilities to meet the needs of your users. In an era of fast-changing technology, you’ll be more able to differentiate between simple technological obsolescence that does not affect the organization’s requirements significantly and major advances that suggest a real need to replace older equipment. You will understand the trade-offs inherent in the use of cloud and other remote services. When selecting computers, you would like to purchase the computers that best meet the needs of the organization’s applications and the users. You must be able to read and understand the technical specifications in order to compare different alternatives and to match the system  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 8 8 PART ONE AN OVERVIEW OF COMPUTER SYSTEMS to the users’ needs. This book will teach you what you need to know to specify and purchase a system intelligently. You’ll know the differences between various CPU technologies and the advantages and disadvantages of each. You will learn what peripheral hardware is appropriate for your organization’s files and the trade-offs between different file system formats, what is required to build an intranet, and what the speed, size, and performance limitations of a particular system are. You’ll be able to compare the features of OS/X, Windows, and Linux knowledgeably and decide which ones are important to you. You’ll be able to apply your basic understanding of computers to new technologies and concepts such as mobile IT, new network protocols, virtual machines and cloud services as they appear. You’ll learn to understand the jargon used by computer salespeople and judge the validity of their sales claims. As a networking professional, you are responsible for the design, maintenance, support, and management of the networks that connect your computer systems together and provide the required interfaces to the outside world. You must be able to specify network layouts that optimize your equipment and network resources. Your understanding of basic network configurations and protocols will allow you to control and provide sufficient and appropriate access to your users in an efficient manner. This text offers the basic tools as a starting point to prepare for a career in networking. As a Web services designer, you must be able to make intelligent decisions to optimize your Web system configurations, page designs, data formatting and scripting language choices, and operating systems to optimize customer accessibility to your Web services. As a system administrator or manager, your job is to maximize the availability and efficiency of your systems. You will need to understand the reports generated by your systems and be able to use the information in those reports to make changes to the systems that will optimize system performance. You will need to know when additional resources are required, and be able to specify appropriate choices. You will need to specify and configure operating system parameters, set up file systems, select cloud services, manage system and user PC upgrades in a fast-changing environment, reconfigure networks, provide and ensure the robustness of system security, and perform many other system management tasks. The configuration of large systems can be very challenging. This text will give you an understanding of operating system tools that is essential to the effective management of systems. In brief, when you complete this book, you will understand what computer hardware and software are and how programs and data interact with the computer system. You will understand the computer hardware, software, and communication components that are required to make up a computer system and what the role of each component in the system is. You will have a better understanding of what is happening inside the computer when you interact with the computer as a user. You will be able to write programs that are more efficient. You will be able to understand the function of the different components of the computer system and to specify the computer equipment and resources you need in a meaningful way. You will understand the options that you have as a system administrator or Web services or network designer. In an era in which technology changes extremely rapidly, the architecture of the computer system rests on a solid foundation that has changed only slightly and gradually over the last sixty years. Understanding the foundations of computer system architecture makes it possible to flow comfortably with technological change and to understand changes in the context of the improvements that they make and the needs that they meet. In fact, interviews with former students and with IT executives and other IT professionals clearly indicate that a deep  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 9 CHAPTER 1 COMPUTERS AND SYSTEMS 9 understanding of the basic concepts presented here is fundamental to long-term survival and growth in the field of information technology and IT management. This type of understanding is at the very foundation of being a competent and successful system analyst, system architect, system administrator, or programmer. It may not be necessary to understand the workings of an automobile engine in order to drive a car, but you can bet that a top-notch race car driver knows his or her engine thoroughly and can use it to win races. Like the professional race car driver, it is our intention to help you to use your computer engine effectively to succeed in using your computer in a winning way. The typical end user might not care about how their computer system works, but you do. These are the goals of this book. So let’s get started! 1.1 THE STARTING POINT Before we begin our detailed study of the architecture of computer systems, let us briefly review some of the fundamental principles, characteristics, and requirements that guide computer system design and operation. The fundamentals described here apply to computers in general, regardless of size or purpose, from the smallest embedded device to the largest mainframe computer. In a simple scenario, you use your tablet, laptop, or desktop personal computer to word process a document. You probably use a pointing device such as a mouse or stylus or finger to move around the document and to control the features of the word processor software application, and you use a keyboard or touch screen to enter and modify the document text data. The word processor application program, together with your document, appears on a screen. Ultimately, you might print the document on a printer. You store the document on a disk or flash drive or some other storage device. The fundamentals of a typical computer system are readily exposed in this simple example. Your pointing device movements and clicks and your text data entry represent input to the system. The computer processes the input and provides output to the screen, and, perhaps, to a printer. The computer system also provides a storage medium of some sort, usually flash memory or a hard disk, to store the text for future access. In simplest terms, your computer receives input from you, processes it, and outputs results to the screen. Your input takes the form of commands and data. The commands and programs tell the computer how to process the data. Now consider a second, slightly more complex example. Your task in this example is to access a Web page on the Internet. Again, your input to the computer is via keyboard and pointer control device. When you type the Web page URL, however, your computer sends a message to another computer that contains Web server software. That computer, in turn, sends a Web page file that is interpreted by the browser on your computer and presented on your screen. You are probably already aware that HyperText Transfer Protocol (HTTP) is used as a standard for Web message exchanges. The elements of this example differ only slightly from the first example. Your command inputs tell a Web browser software application on your computer what processing is to take place; in this case, your desire to access a Web page. The output from your computer is a message to a Web server on the remote computer requesting the data that represents the Web page. Your computer receives the data as input from the network; the Web browser processes the data and presents the Web page output on the screen. Figure 1.2 illustrates the layout for this example.  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 10 10 PART ONE AN OVERVIEW OF COMPUTER SYSTEMS FIGURE 1.2 Typical Web Browser Application Use Web Browser Web Server User Page Request Page Request Message Message (http) Communication Channel (http) URL HTML HTML file file The major differences between this and the first example are the source of the input data and the fact that network connectivity is required between the two computers. Instead of the keyboard, the input data to be processed by your Web browser comes from a communication channel. (Note that the exact nature of the channel is not important for this discussion.) In both cases, your computer receives data input to process, and control input, usually HTML or XML, that determines how the data is to be processed, performs the processing, and provides output. These two examples contain all of the key elements found in any IT system, large or small. n An IT system consists of one or more computer systems; multiple computer systems are connected together using some type of network interconnectivity. As a matter of necessity, network interfaces must conform to standard agreements, known as protocols, for messages to be understood by both computers during a message exchange between a pair of computers. The network itself can take on a variety of forms, provided that the interface requirements are met, and are determined by such characteristics as performance, convenience, and cost. n The work performed by an individual computer system within the IT system can be characterized by input, processing, and output. This characterization is often represented by the Input-Process-Output (IPO) model shown in Figure 1.3. Storage is also represented within this model. Alternatively, storage can be interpreted as output to be saved for use as future input. Storage is also used to hold the software programs that determine the processing operations to be performed. The ability to store programs and data on a temporary, short-term, or long-term basis is fundamental to the system. In Chapter 2, Section 2.2, we will show that all IT systems can ultimately be characterized by the same basic IPO model at all levels, from a single computer to a complex aggregation of computers, although the complexity of large systems may obscure the model and make it more difficult to determine the actual inputs, outputs, and processing operations. The IPO model provides an important basic tool for system analysis and design practices.  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 11 CHAPTER 1 COMPUTERS AND SYSTEMS 11 FIGURE 1.3 A Computer Process Storage Input Process Output n The components of an individual computer system consist of processing hardware, input devices, output devices, storage devices, application software, and operating system software. The task of the operating system software is to provide overall control of the individual system, including management of input, output, and file storage functions. The medium of exchange, both with users and between computers within a larger system, is data. (Note that the messages between computers in the second example are a form of data.) Figure 1.4 is a simple illustration of computer systems embedded in a larger IT system. Figure 1.5 summarizes the basic operations that are performed during computer processing. These operations, in turn, can be reduced to the primitive operations that are also familiar to you from your understanding of programming languages. The primitive processing operations common to high-level programming languages are shown in Figure 1.6. 1.2 COMPONENTS OF THE COMPUTER SYSTEM As noted in the previous section, there are three components required for the implementation of a computerized input-process-output model: 1. The computer hardware, which provides the physical mechanisms to input and output data, to manipulate and process data, and to electronically control the various input, output, and storage components. 2. The software, both application and system, which provides instructions that tell the hardware exactly what tasks are to be performed and in what order. 3. The data that is being manipulated and processed. This data may be numeric, it may be alphanumeric, it may be graphic, or it may take some other form, but in all cases it must be representable in a form that the computer can manipulate. In modern systems, input entry, output display, and storage of the data and software used for processing often take place at a location different from the computer where the actual processing occurs. In many installations, actual processing is distributed among computer  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 12 FIGURE 1.4 A Simplified IT Computer System Layout Intranet Database Apps. Internet web server server server web server Firewall To Internet Order Fulfillment Sales Purchasing Order entry Service Inventory Warehousing Support Web design Printer Shipping Marketing Finance Research & Printer Financial planning planning Printer Accounts Accounts receivable Sales payable Advertising Printer Credit Accounting 12  Englander c01.tex V2 - November 28, 2013 9:38 P.M. Page 13 CHAPTER 1 COMPUTERS AND SYSTEMS 13 FIGURE 1.5 Basic Computer Operations ◼ Input/output ◼ Basic arithmetic and logical calculations ◼ Data transformation or translation (e.g., program compilation, foreign language translation, file updating) ◼ Data sorting ◼ Searching for data matches ◼ Data storage and retrieval ◼ Data movement (e.g., movement of text or file data to make room for insertion of additional data) FIGURE 1.6 Basic High-Level Language Constructs ◼ Input/output (including file storage and retrieval) ◼ Arithmetic and logical assignment statements ◼ Tru