计算机组成与体系结构（英文版）

.exercises 34
chapter data representation in computer systems 37
2
2.1 introduction 37
2.2 positional numbering systems 38
2.3 decimal to binary conversions 38
2.3.1 converting unsigned whole numbers 39
2.3.2 converting fractions 41
2.3.3 converting between power-of-two radices 44
2.4 signed integer representation 44
2.4.1 signed magnitude 44
2.4.2 complement systems 49
2.5 floating-point representation 55
2.5.1 a simple model 56
2.5.2 floating-point arithmetic 58
2.5.3 floating-point errors 59
2.5.4 the ieee-754 floating-point standard 61
2.6 character codes 62
2.6.1 binary-coded decimal 62
2.6.2 ebcdic 63
2.6.3 ascii 63
2.6.4 unicode 65
2.7 codes for data recording and transmission 67
2.7.1 non-return-to-zero code 68
2.7.2 non-return-to-zero-invert encoding 69
2.7.3 phase modulation (manchester coding) 70
2.7.4 frequency modulation 70
2.7.5 run-length-limited code 71
2.8 error detection and correction 73
2.8.1 cyclic redundancy check 73
2.8.2 hamming codes 77
2.8.3 reed-soloman 82
chapter summary 83
further reading 84
references 85
review of essential terms and concepts 85
exercises 86
chapter boolean algebra and digital logic 93
3
3.1 introduction 93
3.2 boolean algebra 94
3.2.1 boolean expressions 94
3.2.2 boolean identities 96
3.2.3 simplification of boolean expressions 98
3.2.4 complements 99
3.2.5 representing boolean functions 100
3.3 logic gates 102
3.3.1 symbols for logic gates 102
3.3.2 universal gates 103
3.3.3 multiple input gates 104
3.4 digital components 10s
3.4.1 digital circuits and their relationship to boolean algebra 105
3.4.2 integrated circuits 106
3.5 combinational circuits 106
3.5.1 basic concepts 107
3.5.2 examples of typical combinational circuits 107
3.6 sequential circuits 113
3.6.1 basic concepts 114
3.6.2 clocks 114
3.6.3 flip-flops 115
3.6.4 examples of sequential circuits 117
3.7 desiguing circuits 120
chapter summary 121
further reading 122
references 123
review of essential terms and concepts 123
exercises 124
focus on karnaugh maps 130
3a.1 introduction 130
3a.2 description of kmaps and terminology 131
3a.3 kmap simplification for two variables 133
3a.4 kmap simplification for three variables 134
3a.5 kmap simplification for four variables 137
3a.6 don't care conditions 140
3a.7 summary 141
exercises 141
chapter marie: an introduction toa simple computer 14!
4
4.1 introduction 145
4.1.1 cpu basics and organization 145
4.1.2 the bus 147
4.1.3 clocks 151
4.1.4 the input/output subsystem 153
4.1.5 memory organization and addressing 153
4.1.6 interrupts 156
4.2 marie 157
4.2.1 the architecture 157
4.2.2 registers and buses 159
4.2.3 the instruction set architecture 160
4.2.4 register transfer notation 163
4.3 instruction processing 166
4.3.1 the fetch-decode-execute cycle 166
4.3.2 interrupts and fo 166
4.4 a simple program 169
4.5 a discussion on assemblers 170
4.5.1 what do assemblers do? 170
4.5.2 why use assembly language? 173
4.6 extending our instruction set 174
4.7 a discussion on decoding: hardwired vs. microprogrammed
control 179
4.8 real-world examples of computer architectures 182
4.8.1 intel architectures 183
4.8.2 mips architectures 187
chapter summary 189
further reading 190
references 191
review of essential terms and concepts 192
exercises 193
chapter a closer look at instruction set architectures 199
5
5.1 introduction 199
5.2 instruction formats 199
5.2.1 design decisions for instruction sets 200
5.2.2 little versus big endian 201
5.2.3 internal storage in the cpu: stacks versus registers 203
5.2.4 number of operands and instruction length 204
5.2.5 expanding opcodes 208
5.3 instruction types 210
5.4 addressing 211
5.4.1 data types 211
5.4.2 address modes 212
5.5 instruction-level pipelining 214
5.6 real-world examples of isas 219
5.6.1 intel 220
5.6.2 mips 220
5.6.3 java virtual machine 221
chapter summary 225
further reading 226
references 227
review of essential terms and concepts 228
exercises 229
chapter memory 233
6
6.1 memory 233
6.2 types of memory 233
6.3 the memory hierarchy 235
6.3.1 locality of reference 237
6.4 cache memory 237
6.4.1 cache mapping schemes 239
6.4.2 replacement policies 247
6.4.3 effective access time and hit ratio 248
6.4.4 when does caching break down? 249
6.4.5 cache write policies 249
6.5 virtual memory 250
6.5.1 paging 251
6.5.2 effective access time using paging 258
6.5.3 putting it all together: using cache, tlbs, and paging 259
6.5.4 advantages and disadvantages of paging and virtual memory 259
6.5.5 segmentation 262
6.5.6 paging combined with segmentation 263
6.6 a real-world example of memory management 263
chapter summary 264
further reading 265
references 266
review of essential terms and concepts 266
exercises 267
chapter input/output and storage systems 273
7
7.1 introduction 273
7.2 amdahl's law 274
7.3 i/o architectures 275
7.3.1 i/o control methods 276
7.3.2 i/o bus operation 280
7.3.3 another look at interrupt-driven i/o 283
7.4 magnetic disk tedmology 286
7.4.1 rigid disk drives 288
7.4.2 flexible (floppy) disks 292
7.5 optical disks 293
7.5.1 cd-rom 294
7.5.2 dvd 297
7.5.3 optical disk recording methods 298
7.6 magnetic tape 299
7.7 raid 301
7.7.1 raid level 0 302
7.7.2 raid level 1 303
7.7.3 raid level 2 303
7.7.4 raid level 3 304
7.7.5 raid level 4 305
7.7.6 raid level 5 306
7.7.7 raid level 6 307
7.7.8 hybrid raid systems 308
7.8 data compression 309
7.8.1 statistical coding 311
7.8.2 ziv-lempel (lz) dictionary systems 318
7.8.3 gif and png compression 322
7.8.4 jpeg compression 323
chapter summary 328
further reading 328
references 329
review of essential terms and concepts 330
exercises 332
focus on selected disk storage implementations 335
7a. 1 introduction 335
7a.2 data transmission modes 335
7a.3 scsi 338
7a.4 storage area networks 350
7a.5 other i/o connections 352
7a.6 summary 354
exercises 354
chapter system software 357
8
8.1 introduction 357
8.2 operating systems 358
8.2.1 operating systems history 359
8.2.2 operating system design 364
8.2.3 operating system services 366
8.3 protected environments 370
8.3.1 virtual machines 371
8.3.2 subsystems and partitions 374
8.3.3 protected environments and the evolution of systems architectures 376
8.4 programming tools 378
8.4.1 assemblers and assembly 378
8.4.2 link editors 381
8.4.3 dynamic link libraries 382
8.4.4 compilers 384
8.4.5 interpreters 388
8.5 java: all of the above 389
8.6 database software 395
8.7 transaction managers 401
chapter summary 403
further reading 404
references 405
review of essential terms and concepts 406
exercises 407
chapter alternative architectures 411
9
9.1 introduction 411
9.2 risc machines 412
9.3 flynn's taxonomy 417
9.4 parallel and multiprocessor architectures 421
9.4.1 superscalar and vliw 422
9.4.2 vector processors 424
9.4.3 interconnection networks 425
9.4.4 shared memory multprocessors 430
9.4.5 distributed computing 434
9.5 alternative parallel processing approaches 435
9.5.1 dataflow computing 435
9.5.2 neural networks 438
9.5.3 systolic arrays 441
chapter summary 442
further reading 443
references 443
review of essential terms and concepts 445
exercises 446
caapter performance measurement and analysis 451
10
10.1 introduction 451
10.2 the basic computer performance equation 452
10.3 mathematical preliminaries 453
10.3.1 what the means mean 454
10.3.2 the statistics and semantics 459
10.4 benchmarking 461
10.4.1 clock rate, mips, and flops 462
10.4.2 synthetic benchmarks: whetstone, linpack, and dhrystone 464
10.4.3 standard performance evaluation cooperation benchmarks 465
10.4.4 transaction performance council benchmarks 469
10.4.5 system simulation 476
10.5 cpu performance optimization 477
10.5.1 branch optimization 477
10.5.2 use of good algorithms and simple code 480
10.6 disk performance 484
10.6.1 understanding the problem 484
10.6.2 physical considerations 485
10.6.3 logical considerations 486
chapter summary 492
further reading 493
references 494
review of essential terms and concepts 495
exercises 495
chapter network organization and architecture 501
11
11.1 introduction 501
11.2 early business computer networks 501
11.3 early academic and scientific networks: the roots and architecture of
the internet 502
11.4 network protocols i: iso/osi protocol unification 506
11.4.1 a parable 507
11.4.2 the osi reference model 508
11.5 network protocols ii: tcp/ip network architecture 512
11.5.1 the ip layer for version 4 512
11.5.2 the trouble with ip version 4 516
11.5.3 transmission control protocol 520
11.5.4 the tcp protocol at work 521
11.5.5 ip version 6 525
11.6 network organization 530
11.6.1 physical transmission media 530
11.6.2 interface cards 535
11.6.3 repeaters 536
11.6.4 hubs 537
11.6.5 switches 537
11.6.6 bridges and gateways 538
11.6.7 routers and routing 539
11.7 high-capacity digital links 548
11.7.1 the digital hierarchy 549
11.7.2 isdn 553
11.7.3 asynchronous transfer mode 556
1 1.8 a look at the internet 557
11.8.1 ramping on to the intemet 558
11.8.2 ramping up the intemet 565
chapter summary 566
further reading 566
references 568
review of essential terms and concepts 568
exercises 570
appendix data structures and the computer 575
a
a.1 introduction 575
a.2 fundamental strnctures 575
a.2.1 arrays 575
a.2.2 queues and linked lists 577
a.2.3 stacks 578
a.3 trees 581
a.4 network graphs 587
summary 590
further reading 590
references 590
exercises 591
glossary 595
answers and hints for selected exercises 633
index 647

.　　AR4. Memory system organization and architecture (core): Chapter 6
　　AR5. Interfacing and communication (core): Chapter 7
　　AR6. Functional organization (core): Chapters 4 and 5
　　AR7. Multiprocessing and alternative architectures (core): Chapter 9
　　AR8. Performance enhancements (elective): Chapters 9 and 10
　　AR9. Architecture for networks and distributed systems (elective):
　　Chapter 11
　　Why another text?
　　No one can deny there is a plethora of textbooks for teaching computer organization and architecture already on the market. In our 25-plus years of teaching these courses, we have used many very good textbooks. However, each time we have taught the course, the content has evolved, and, eventually, we discovered we were writing significantly more course notes to bridge the gap between the material in the textbook and the material we deemed necessary to present in our classes. We found that our course material was migrating from a computer engineering approach to organization and architecture toward a computer science approach to these topics. When the decision was made to fold the organization class and the architecture class into one course, we simply could not find a textbook that covered the material we felt was necessary for our majors, written from a computer science point of view, written without machine-specific terminology, and designed to motivate the topics before covering them.
　　 In this textbook, we hope to convey the spirit of design used in the development of modem computing systems and what impact this has on computer science students. Students, however, must have a strong understanding of the basic concepts before they can understand and appreciate the non-tangible aspects of design. Most organization and architecture textbooks present a similar subset of technical information regarding these basics. We, however, pay particular attention to the level at which the information should be covered, and to presenting that information in the context that has relevance for computer science students. For example, throughout this book, when concrete examples are necessary, we offer examples for personal computers, enterprise systems, and mainframes, as these are the types of systems most likely to be encountered. We avoid the "PC bias" prevalent in similar books in the hope that students will gain an appreciation for the differences, similarities, and the roles various platforms play within today's automated infrastructures. Too often, textbooks forget that motivation is, perhaps, the single most important key in learning. To that end, we include many real-world examples, while attempting to maintain a balance between theory and application.
　　Features
　　We have included many features in this textbook to emphasize the various concepts in computer organization and architecture, and to make the material more accessible to students. Some of the features are listed below:
　　· Sidebars. These sidebars include interesting tidbits of information that go a step beyond the main focus of the chapter, thus allowing readers to delve further into the material.
　　· Real-World Examples. We have integrated the textbook with examples from real life to give students a better understanding of how technology and techniques are combined for practical purposes.
　　· Chapter Summaries. These sections provide brief yet concise summaries of the main points in each chapter.
　　· Further Reading. These sections list additional sources for those readers who wish to investigate any of the topics in more detail, and contain references to definitive papers and books related to the chapter topics.
　　· Review Questions. Each chapter contains a set of review questions designed to ensure that the reader has a firm grasp on the material.
　　· Chapter Exercises. Each chapter has a broad selection of exercises to reinforce the ideas presented. More challenging exercises are marked with an asterisk.
　　· Answers to Selected Exercises. To ensure students are on the right track, we provide answers to representative questions from each chapter. Questions with answers in the back of the text are marked with a blue diamond.
　　· Special "Focus On" Sections. These sections provide additional information for instructors who may wish to cover certain concepts, such as Kmaps and input/output, in more detail. Additional exercises are provided for these sections as well.
　　· Appendix. The appendix provides a brief introduction or review of data structures, including topics such as stacks, linked lists, and trees.
　　· Glossary. An extensive glossary includes brief definitions of all key terms from the chapters.
　　· Index. An exhaustive index is provided with this book, with multiple crossreferences, to make finding terms and concepts easier for the reader.
　　About the Authors
　　We bring to this textbook not only 25-plus years of combined teaching experience, but also 20 years of industry experience. Our combined efforts therefore stress the underlying principles of computer organization and architecture, and how these topics relate in practice. We include real-life examples to help students appreciate how these fundamental concepts are applied in the world of computing.
　　 Linda Null received a Ph.D. in Computer Science from Iowa State University in 1991, an M.S. in Computer Science from Iowa State University in 1989, an M.S. in Computer Science Education from Northwest Missouri State University in 1983, an M.S. in Mathematics Education from Northwest Missouri State University in 1980, and a B.S. in Mathematics and English from Northwest Missouri State University in 1977. She has been teaching mathematics and computer science for over 25 years and is currently the Computer Science graduate program coordinator at The Pennsylvania State University Harrisburg campus, where she has been a member of the faculty since 1995. Her areas of interest include computer organization and architecture, operating systems, and computer security.
　　 Julia Lobur has been a practitioner in the computer industry for over 20 years. She has held positions as a systems consultant, a staff programmer/analyst, a systems and network designer, and a software development manager, in addition to pm-time teaching duties.
　　Prerequisites
　　The typical background necessary for a student using this textbook includes a year of programming experience using a high-level procedural language. Students are also expected to have taken a year of college-level mathematics (calculus or discrete mathematics), as this textbook assumes and incorporates these mathematical concepts. This book assumes no prior knowledge of computer hardware.
　　 A computer organization and architecture class is customarily a prerequisite for an undergraduate operating systems class (students must know about the memory hierarchy, concurrency, exceptions, and interrupts), compilers (students must know about instruction sets, memory addressing, and linking), networking (students must understand the hardware of a system before attempting to understand the network that ties these components together), and of course, any advanced architecture class. This text covers the topics necessary for these courses.
　　General Organization and Coverage
　　Our presentation of concepts in this textbook is an attempt at a concise, yet thorough, coverage of the topics we feel are essential for the computer science major. We do not feel the best way to do this is by "compartmentalizing" the various topics; therefore, we have chosen a structured, yet integrated approach where each topic is covered in the context of the entire computer system.
　　 As with many popular texts, we have taken a bottom-up approach, starting with the digital logic level and building to the application level that students should be familiar with before starting the class. The text is carefully structured so that the reader understands one level before moving on to the next. By the time the reader reaches the application level, all of the necessary concepts in computer organization and architecture have been presented. Our goal is to allow the students to tie the hardware knowledge covered in this book to the concepts learned in their introductory programming classes, resulting in a complete and thorough picture of how hardware and software fit together. Ultimately, the extent of hardware understanding has a significant influence on software design and performance. If students can build a firm foundation in hardware fundamentals, this will go a long way toward helping them to become better computer scientists.
　　 The concepts in computer organization and architecture are integral to many of the everyday tasks that computer professionals perform. To address the numerous areas in which a computer professional should be educated, we have taken a high-level look at computer architecture, providing low-level coverage only when deemed necessary for an understanding of a specific concept. For example, when discussing ISAs, many hardware-dependent issues are introduced in the context of different case studies to both differentiate and reinforce the issues associated with ISA design.
　　 The text is divided into eleven chapters and an appendix as follows:
　　· Chapter 1 provides a historical overview of computing in general, pointing out the many milestones in the development of computing systems, and allowing the reader to visualize how we arrived at the current state of computing. This chapter introduces the necessary terminology, the basic components in a computer system, the various logical levels of a computer system, and the yon Neumann computer model. It provides a high-level view of the computer system, as well as the motivation and necessary concepts for further study.
　　· Chapter 2 provides thorough coverage of the various means computers use to represent both numerical and character information. Addition, subtraction, multiplication and division are covered once the reader has been exposed to number bases and the typical numeric representation techniques, including one's complement, two's complement, and BCD. In addition, EBCDIC, ASCII, and Unicode character representations are addressed. Fixedand floating-point representation are also introduced. Codes for data recording and error detection and correction are covered briefly.
　　· Chapter 3 is a classic presentation of digital logic and how it relates to Boolean algebra. This chapter covers both combinational and sequential logic in sufficient detail to allow the reader to understand the logical makeup of more complicated MSI (medium scale integration) circuits (such as decoders). More complex circuits, such as buses and memory, are also included. We have included optimization and Kmaps in a special "Focus On" section.
　　· Chapter 4 illustrates basic computer organization and introduces many fundamental concepts, including the fetch-decode-execute cycle, the data path, clocks and buses, register transfer notation, and of course, the CPU. A very simple architecture, MARIE, and its ISA are presented to allow the reader to gain a full understanding of the basic architectural organization involved in program execution. MARIE exhibits the classical von Neumann design, and includes a program counter, an accumulator, an instruction register, 4096 bytes of memory, and two addressing modes. Assembly language programming is introduced to reinforce the concepts of instruction format, instruction mode, data format, and control that are presented earlier. This is not an assembly language textbook and was not designed to provide a practical course in assembly language programming. The primary objective in introducing assembly is to further the understanding of computer architecture in general. However, a simulator for MARIE is provided so assembly language programs can be written, assembled, and run on the MARIE architecture. The two methods of control, hardwiring and microprogramming, are introduced and compared in this chap: ter. Finally, Intel and MIPS architectures are compared to reinforce the concepts in the chapter.
　　· Chapter 5 provides a closer look at instruction set architectures, including instruction formats, instruction types, and addressing modes. Instruction-level pipelining is introduced as well. Real-world ISAs (including Intel, MIPS, and Java) are presented to reinforce the concepts presented in the chapter.
　　· Chapter 6 covers basic memory concepts, such as RAM and the various memory devices, and also addresses the more advanced concepts of the memory hierarchy, including cache memory and virtual memory. This chapter gives a thorough presentation of direct mapping, associative mapping, and set-associative mapping techniques for cache. It also provides a detailed look at overlays, paging and segmentation, TLBs, and the various algorithms and devices associated with each. A tutorial and simulator for this chapter is available on the book's website.
　　· Chapter 7 provides a detailed overview of FO fundamentals, bus communication and protocols, and typical external storage devices, such as magnetic and optical disks, as well as the various formats available for each. DMA, programmed FO, and interrupts are covered as well. In addition, various techniques for exchanging information between devices are introduced. RAID architectures are covered in detail, and various data compression formats are introduced.
　　· Chapter 8 discusses the various programming tools available (such as compilers and assemblers) and their relationship to the architecture of the machine on which they are mn. The goal of this chapter is to tie the programmer's view of a computer system with the actual hardware and architecture of the underlying machine. In addition, operating systems are introduced, but only covered in as much detail as applies to the architecture and organization of a system (such as resource use and protection, traps and interrupts, and various other services).
　　· Chapter 9 provides an overview of alternative architectures that have emerged in recent years. RISC, Flynn's Taxonomy, parallel processors, instruction-level parallelism, multiprocessors, interconnection networks, shared memory sys. tems, cache coherence, memory models, superscalar machines, neural networks, systolic architectures, dataflow computers, and distributed architectures are covered. Our main objective in this chapter is to help the reader realize we are not limited to the von Neumann architecture, and to force the reader to consider performance issues, setting the stage for the next chapter.
　　· Chapter 10 addresses various performance analysis and management issues. The necessary mathematical preliminaries are introduced, followed by a discussion of MIPS, FLOPS, benchmarking, and various optimization issues with which a computer scientist should be familiar, including branch prediction, speculative execution, and loop optimization.
　　· Chapter 11 focuses on network organization and architecture, including network components and protocols. The OSI model and TCP/IP suite are introduced in the context of the Intemet. This chapter is by no means intended to be comprehensive. The main objective is to put computer architecture in the correct context relative to network architecture.
　　An appendix on data structures is provided for those situations where students may need a brief introduction or review of such topics as stacks, queues, and linked lists.
　　 The sequencing of the chapters is such that they can be taught in the given numerical order. However, an instructor can modify the order to better fit a given curriculum if necessary. Figure P. 1 shows the prerequisite relationships that exist between various chapters.
　　Intended Audience
　　This book was originally written for an undergraduate class in computer organization and architecture for computer science majors. Although specifically directed toward computer science majors, the book does not preclude its use by IS and IT majors.
　　 This book contains more than sufficient material for a typical one-semester (14 week, 42 lecture hours) course; however, all of the material in the book cannot be mastered by the average student in a one-semester class. If the instructor plans to cover all topics in detail, a two-semester sequence would be optimal. The organization is such that an instructor can cover the major topic areas at different levels of depth, depending on the experience and needs of the students. Table P. 1 gives the instructor an idea of the length of time required to cover the topics, and also lists the corresponding levels of accomplishment for each chapter.
　　 It is our intention that this book will serve as a useful reference long after the formal course is complete.
　　Support Materials
　　A textbook is a fundamental tool in learning, but its effectiveness is greatly enhanced by supplemental materials and exercises, which emphasize the major concepts, provide immediate feedback to the reader, and motivate understanding through repetition. We have, therefore, created the following ancillary materials for The Essentials of Computer Organization and Architecture:
　　· Instructor's Manual. This manual contains answers to exercises and sample exam questions. In addition, it provides hints on teaching various concepts and trouble areas often encountered by students.
　　· Lecture Slides. These slides contain lecture material appropriate for a onesemester course in computer organization and architecture.
　　· Figures and Tables. For those who wish to prepare their own lecture materials, we provide the figures and tables in downloadable form.
　　· Memory Tutorial and Simulator. This package allows students to apply the concepts on cache and virtual memory.
　　· MARIE Simulator. This package allows students to assemble and run MARIE programs.
　　· Tutorial Software. Other tutorial software is provided for various concepts in the book.
　　· The Companion website. All software, slides, and related materials can be downloaded from the book's website:
　　 http: //computerscience. jbpub, com/ECOA The exercises, sample exam problems, and solutions have been tested in numerous classes. The Instructor's Manual, which includes suggestions for teaching the various chapters in addition to answers for the book's exercises, suggested programming assignments, and sample example questions, is available to instructors who adopt the book. (Please contact your Jones and Bartlett Publishers Representative at 1-800-832-0034 for access to this area of the web site.)
　　The Instructional Model: MARIE
　　In a computer organization and architecture book, the choice of architectural model affects the instructor as well as the students. If the model is too complicated, both the instructor and the students tend to get bogged down in details that really have no bearing on the concepts being presented in class. Real architectures, although interesting, often have far too many peculiarities to make them usable in an introductory class. To make things even more complicated, real architectures change from day to day. In addition, it is difficult to find a book incorporating a model that matches the local computing platform in a given department, noting that the platform, too, may change from year to year.
　　 To alleviate these problems, we have designed our own simple architecture, MARIE, specifically for pedagogical use. MARIE (Machine Architecture that is Really Intuitive and Easy) allows students to learn the essential concepts of computer organization and architecture, including assembly language, without getting caught up in the unnecessary and confusing details that exist in real architectures. Despite its simplicity, it simulates a functional system. The MARIE machine simulator, MarieSim, has a user-friendly GUI that allows students to: (1) create and edit source code; (2) assemble source code into machine object code; (3) run machine code; and, (4) debug programs.
　　 Specifically, MarieSim has the following features:
　　· Support for the MARIE assembly language introduced in Chapter 4
　　· An integrated text editor for program creation and modification
　　· Hexadecimal machine language object code
　　· An integrated debugger with single step mode, bre
　　· A graphical memory monitor displaying the 4096 addresses in MARIE's memory
　　· A graphical display of MARIE's registers
　　· Highlighted instructions during program execution
　　· User-controlled execution speed
　　· Status messages
　　· User-viewable symbol tables
　　· An interactive assembler that lets the user correct any errors and reassemble automatically, without changing environments
　　· Online help
　　· Optional core dumps, allowing the user to specify the memory range
　　· Frames with sizes that can be modified by the user
　　· A small learning curve, allowing students to learn the system quickly
　　MarieSim was written in the JavaTM language so that the system would be portable to any platform for which a JavaTM Virtual Machine (JVM) is available. Students of Java may wish to look at the simulator's source code, and perhaps even offer improvements or enhancements to its simple functions.
　　 Figure P.2, the MarieSim Graphical Environment, shows the graphical environment of the MARIE machine simulator. The screen consists of four parts: the menu bar, the central monitor area, the memory monitor, and the message area.
　　 Menu options allow the user to control the actions and behavior of the MARIE Machine Simulator system. These options include loading, starting, stopping, setting breakpoints, and pausing programs that have been written in MARIE assembly language.
　　 The MARIE Simulator illustrates the process of assembly, loading, and execution, all in one simple environment. Users can see assembly language statements directly from their programs, along with the corresponding machine code (hexadecimal) equivalents. The addresses of these instructions are indicated as well, and users can view any portion of memory at any time. Highlighting is used to indicate the initial loading address of a program in addition to the currently executing instruction while a program runs. The graphical display of the registers and memory allows the student to see how the instructions cause the values within the registers and memory to change.
　　If You Find an Error
　　We have attempted to make this book as technically accurate as possible, but even though the manuscript has been through numerous proof readings, errors have a way of escaping detection. We would greatly appreciate hearing from readers who find any errors that need correcting. Your comments and suggestions are always welcome by sending email to ECOA@jbpub.com.
　　Credits and Acknowledgments
　　Few books are entirely the result of one or two people's unaided efforts, and this one is no exception. We now realize that writing a textbook is a formidable task and only possible with a combined effort, and we find it impossible to adequately thank those who have made this book possible. If, in the following acknowledgements, we inadvertently omit anyone, we humbly apologize.
　　 All of the students who have taken our computer organization and architecture classes over the years have provided invaluable feedback regarding what works and what doesn't when covering the various topics in the classes. We particularly thank those classes that used preliminary versions of the textbook for their tolerance and diligence in finding errors.
　　 A number of people have read the manuscript in detail and provided useful suggestions. In particular, we would like to thank Mary Creel and Hans Royer. We would also like to acknowledge the reviewers who gave their time and effort, in addition to many good suggestions, to ensure a quality text, including: Victor Clincy (Kennesaw State University); Robert Franks (Central College); Karam Mossaad (The University of Texas at Austin); Michael Schulte (University of Missouri, St. Louis); Peter Smith (CSU Northridge); Xiaobo Zhou (Wayne State University).
　　 We extend a special thanks to Karishma Rao for her time and effort in producing a quality memory software module.
　　 The publishing team at Jones and Bartlett has been wonderful to work with, and each member deserves a special thanks, including Amy Rose, Theresa DiDonato, Nathan Schultz, and J. Michael Stranz.
　　 I, Linda Null, would personally like to thank my husband, Tim Wahls, for his patience while living life as a "book widower," for listening and commenting with frankness about the book's contents, for doing such an extraordinary job with all of the cooking, and for putting up with the almost daily compromises necessitated by my writing this book. I consider myself amazingly lucky to be married to such a wonderful man. I extend my heart-felt thanks to my mentor, Merry McDonald, who taught me the value and joys of learning and teaching, and doing both with integrity. Lastly, I would like to express my deepest gratitude to Julia Lobur, as without her, this book and its accompanying software would not be a reality.
　　 I, Julia Lobur, am deeply indebted to my partner, Maria Cattermole, for making possible my work on this book through her forbearance and fidelity. She has nurtured my body through her culinary delights and my spirit through her wisdom. She has taken up my slack in many ways while working hard at her own career and her own advanced degree. I would also like to convey my profound gratitude to Linda Null: Foremost for her unsurpassed devotion to the field of computer science education and dedication to her students, and consequently, for giving me the opportunity to share with her the ineffable experience of textbook authorship.