Computer Abstractions and Technology
// 计算机抽象原理和技术
Civilization advances by extending the number of important operations which we can performs which without about them.
Alfred North Whitehead
// 重要操作数不加思索地被执行的数量的扩展， 体现文明的进步。
(civilization /ˌsɪv.əl.aɪˈzeɪ.ʃən/ n. human society with its well developed social organizations, or the culture and way of life a society or country at a particular period in time. 文明社会，（特定时期或特定社会或国家的）文明，文化； )
1.1 Introduce // 简介
1.2 Eight Great Ideas in computer Architecture // 计算机体系架构的八大思想
1.3 Below Your program // 程序的背后
1.4 Under the cover // 机盖的下面
1.5 Technologies for Building Processors and Memory // 构造处理器和内存的技术
1.6 Performance //性能
1.7 The Power Wall // 功耗墙
1.8 The sea changes : The switch from Uniprocessors to Multiprocessors // 巨大变化：从单处理器到多处理器
1.9 Real stuff : Benchmarking the Intel Core i7 // 实例： Intel Core i 7 基准测试
1.10 Fallacies and Pitfalls // 误区和陷阱 （fallacy /ˈfæl.ə.si/ n. an idea that a lot of people think is ture but is in fact false. 谬见，谬论。[+that] It is a common fallacy that women are worse drivers than men. 女性司机开车不如男性好这是人们常有的谬见。
pitfall /ˈpɪt.fɑːl/ n. a likely mistake or problem in a situation 隐患， 陷阱；）
1.11 Concluding Remarks // 结束语
1.12 Historical Perspective and Further Reading // 历史视觉和前沿阅读
1.13 Exercises // 练习
1.1 Introduce // 简介
Welcome to this book! We're delighted to have this opportunity to convey the excitement of the world of computer systems. This is not a dry and dreary field, where progress is glacial and where new ideas atrophy from neglect. No! Computers are the product of incredibly vibrant information technology industry, all aspects of which are responsible for almost 10% of the gross national product of the United States, and whose economy has become dependent in part on the rapid improvements in information technology promised by Moore's Law. This unusual industry embraces innovation at a breath-taking rate. In the last 30 years, there have been a number of new computers whose instruction appeared to revolutionize the computing industry; these revolutions were cut short only because someone else built an even better computer.
// 欢迎来到这本书。我们很高兴有这次机会去传达计算机系统世界的令人兴奋的事情。这不是一个干燥而沉闷的领域，进步举步维艰；新思想因疏忽而萎缩。不！计算机是信息技术行业活跃程序最大的产品，在各个方面，计算机几乎占有了美国GNP的10%,其经济在一定的程度上依赖于摩尔定律所承诺的信息技术的快速提高。 这个不寻常的行业，以惊人的速度催生着的新的概念。在过去的30年里，有许多新的计算机，他们的指令似乎给计算机行业带来了革命性的变化， 这些革命之所以被缩短，仅仅是因为其他的人设计打造了一台更好的计算机。
（ delight /di'lait/ vt. to give someone great pleasure or satisfacition 使高兴， 使满足；
convey /kən'vei/ vt. to express a though, feeling, or idea so that it is understood by the other people 表达，传达（思想、感情、想法）；
dreary /'driəri/ adj. boring and making you feel unhappy.沉闷的；单调泛味的，令人沮丧的； a dreary little town沉闷的小城；She had spent another dreary day in the office. 她在办公室渡过了枯燥的一天。
atrophy / ˈæt.rə.fi/ vi. (of a part of the body) to be reduced in size and therefore strength, or more generally, to become weaker.(身体部位)萎缩 ；衰退
neglect /'niglekt/ vt. to not give enough care or attention to people or things that are your responsibility. 疏于照管；忽视；疏忽；
glacial /ˈɡleɪ.ʃəl/ adj. extremely unfriendly 冷若冰霜；冷冰冰的；
incredibly /ɪnˈkred.ə.bli/ adv. used for saying that something is very difficult to believe. 难以置信的；
vibrant /ˈvaɪ.brən / adj. energetic, exciting, and full of enthusiasm 活跃的；精力充沛的；热情扬溢的；
responsible /rɪˈspɒn.sə.bəl/ adj. be responsible for sth./ doing sth. = to be the person who caused something to happen, especially something bad = 对（尤指坏事）负责任；应对...承担责任；
the gross national product = GNP = the total value of the goods and services produced in a country, which includes the effect of inflation and also the income from the goods and services sold in other country.
embrace /im'breis/ vt. to accept somthing enthusiastically. 欣然接受，乐意采纳；
innovation /ˌɪn.əˈveɪ.ʃən/ n. (the use of ) a new idea or methold 新观念，新方法；
breath-taking/ ˈbreθˌteɪ.kɪŋ / adj. extremely exciting, beautiful, or surprising 极其刺激的、 美的惊人的、 惊人的；
revolutionize /ˌrev.əˈluː.ʃən.aɪz/ vt. to completely change something so that it is much better. ）
This race to innovate has led to unprecedented progress since the inception of electionic computing in the late 1940s. Had the transportation industry kept pace with the computer industry, for example, today we could travel from New York to London in a second for a penny. Take just a moment to contemplate how such an improvement would change society --living in Tahiti while working in San Francisco, going to Moscow for an evening at the Bolshoi Ballet-- and you can appreciate the implications of such a change.
自从20世纪40年代后期，电子计算机的问世，这种改革的速度已达到了史无前例的进步。运输行业与计算机行业齐头并进， 例如，
(unprecedented /ʌnˈpres.ɪ.den.tɪd/ adj. never having happened or existed in the past; 史无前例的；空前的；绝无仅有的；
innovate /ˈɪn.ə.veɪt/ vi. to introduce changes and the new ideas. 改革，创新；
inception /ɪnˈsep.ʃən/ n. the beginning of an organization or official activity.成立，创立；
keep pace with = walk or run as fast as 跟上；
pace /peis/ n. the speed at which someone or something moves, or with which something happens or changes发生的速度，节奏；（移动的）步速； )
Computers have led to a third revolution for civilization, with the information revolution taking its place alongside the agricultural and the industrial revolutions. The resulting multiplication of humankind's intellectual strength and reach naturally has affected our everyday lives profoundly and changed the ways in which the search for new knowledge is carried out. There is now a new vein of scientific investigation, with computational scientists joining theoretical and experimental scientists in the explorational of new frontiers in astronomy, biology, chemistry, and physics, among others.
//计算机已经导致了第三次文明革命，随着信息革命，工农业革命也同时进行。 结果，人类智慧力量的成倍增长，自然也影响了我们的日常生活，并改变了我们寻找新知识的方法。 现在有一个新的科学调查脉胳，计算机科学家联合理论和实践科学家， 在天文学，生物学，化学和物理，在它们之间探索新的尖端科学。
( alongside /əˌlɒŋˈsaɪd/ = next to , or together with;
profoundly /prəˈfaʊnd.li/ adv. deeply & extremely 深刻的，极度的；
multiplication / mʌl.tɪ.plɪˈkeɪ.ʃən ˌsaɪn/ n. the symbol × or the symbol . used between two numbers to show that they should be multiplied together. 乘号；
intellectual /ˌɪn.təlˈek.tʃu.əl/ n. relating to your ability to think and understand things, especially complicated ideas. 智力的，脑力的；
strength /streŋθ/ n. the ability to do things that need a lot of physical or mental effort. 体力，力气，力量，实力；
affected /əˈfek.tɪd / adj. artificial and not sincere 矫柔造作， 做作的， 装模作样的， 不自然的；
vein /veɪn/ n. a particular quality or characteristic 特征；
investigation /ɪnˌves.tɪˈɡeɪ.ʃən/ n. the act or process of examining a crime, problem, statement, etc. carefully, especially to discover the truth. （对犯罪、问题、陈述等的）调查(尤指为了发现真象)
frontier /ˈfrʌn.tɪər / n. the border between two countries. 国境，边境；
astronomy / əˈstrɒn.ə.mi/ n. 天文学；
)
The computer revolution continues. Each time the cost of computing improves by another factor of 10, the opportunities for computers multiply. Applications that were economiacally infeasible suddenly become practical. In the recent past, the following applications were "computer science fiction."
- Computers in automobiles : Unitl microprocessors improved dramatically in price and performance in the early 1980s, computer control of cars was ludicrous. Today, computers reduce pollution, improve fuel efficiency via engine controls and increase safety through blind spot warnings, lane departure warnings, moving object detection, and air bag inflation to protect occupants in a crash.
- Cell phones: Who would have dreamed that advances in computer systems would lead to more than half of the planet having mobile phones, allowing person-to-person communication to almost anyone anywhere in the world?
- Human genome project: The cost of computer equipment to map and analyze human DNA sequences was hundreds of millions of dollars. It's unlikely that anyone would have considered this project had the computer costs been 10 to 100 times higher, as they would have been 15 to 25 years earlier. Moreover, costs continue to drop; you will soon be able to acquire your own genome, allowing medical care to be tailored to you.
- World wide web: Not in existence at the time of the first edition of this book, the web has transformed our society. For many, the web has replaced libraries and newspapers.
- Search engines : As the content the web grew in size and in value, finding relevant information became increasingly important. Today, many people rely on search engines for such a large of their lives that it would be a hardship to go without them.
Clearly, advances in this technoology now affect almost every aspect of our society. Hardware advances have allowed programmers to create wonderfully useful software, which explains why computers are omnipresent. Today's science fiction suggests tomorrow's killer applications: already on their way are glasses that augment reality, the cashless society, and cars that can drive themselves.
// 计算机革命仍在继续。每次计算机的成本都以10的另一个因数增加，计算机的机遇也增加。过去在经济方面溃乏行不通的应用程序突然变得可以实现。 在最近过去的几年里，以下的应用存在于“计算机科学小说”中。
- 汽车行业中的计算机： 直到20世纪80年代微处理器在性能和价格方面明显的提高以前，计算机控制汽车简直是荒谬的。 今 天，计算机减少排污，通过引擎控制提高燃油使用率，增加安通过盲点测试警告，道路偏离警告，移动物体侦测，气囊充气来提高安全性， 以保护事故中的用户。
- 移动电话。 谁也没有梦想到，计算机体系的升级导致了这颗行星上一半以上的人有了移动电话，不论你在何时何地都可以进行人与人之间的交流。
- 人类基因工程： 用于绘制和分析人类DNA序列的计算机设备的成本是数亿美元。这项工程的成本是所使用计算机成本的10到100倍，至少在15年前到25年前这是不可能的。 然而， 成本持续下降，不久你也可以得到你的基因序列， 请求医疗保护为你量身打造。
- World wide web : 这本书的第一版并不存在万维网， web 已经改变了我们的社会，在很多方面，web 已经取谛了图书馆和报纸。
- Search engines: (搜索引擎) 随着网站的尺寸和价值的增长，查找相关信息的重要性也增加了。 今 天， 许多人都依赖搜索引擎去查找他们生活中的大部分， 没有搜索引擎，这将会很困难。
清晰地， 这种技术的进步，现在影响到了我们社会的各个方面。 硬件的进步已经允许程序员去生产更奇妙有效的软件，同时，也诠释了计算机为什么无处不在。今天的科幻小说提出了明天的杀手级的应用程序：已经在路上的增强现实感的眼镜，无现金的社会，和无人驾驶的汽车。
（ infeasible /ɪnˈfiː.zə.bəl/ = unfeasible /ʌnˈfiː.zə.bəl / = not feasible = able to be done or achieved 不可行的， 行不通的；
economiacally /ˌiː.kəˈnɒm.ɪ.kəl.i/ adv. using little money, time etc. 经济地、 节约的；节俭的；
fiction /ˈfɪk.ʃən/ n. the type of book or story that is written about imaginary characters and events and not based on real people and facts. 小说；
automobile /ˈɔː.tə.mə.biːl/ n. = a car 汽车；
dramatically / drəˈmæt.ɪ.kəl.i/ adv. suddenly or obviously. 剧烈的；明显的；
ludicrious /ˈluː.dɪ.krəs/ adj. stupid or unreasonable and deserving to be laught at. 愚蠢可笑的；荒谬的；
microprocessor /ˌmaɪ.krəʊˈprəʊ.ses.ər/ n. a part of a computer that controls its main operations. 微处理器；
lane /lein/ n. a special strip of a road, sport track, or swimming pool that is used to keep vehicles or competitors sparate 车道，（田径比赛的）跑道；泳道；
departure / dɪˈpɑː.tʃər/ n. a change from what is expected, or from what has happened before 偏离，背离，脱离。
inflation/ɪnˈfleɪ.ʃən/ n. a general, continuous increase in prices. 通货澎涨
occupant /ˈɒk.jə.pənt/ n. a person who is in car, room, seat, place, or position.占有人，占用者。
planet / ˈplæn.ɪt/ n. a extremely large, round mass of rock and metal, such as Earth, or of gas, such as Jupiter, that moves in a circal path around the sun or another star. 行星，
relevant / ˈrel.ə.vənt/ adj. connected with what is happening or being discussed. 有关的，相关联的；切题的；
omnipresent /ˌɒm.nɪˈprez.ənt / adj. present or having an effect everywhere at the same time. 无所不在的，遍及各处的； ）
Classes of computing Applications and their characteristics
// 计算机应用产品以及它们的特征
Although a common set of hardware technologies (see section 1.4 and 1.5) is used in computers ranging from smart home appliances to cell phones to the largest supercomputers, these different applications have different design requirements and employ the core hardware technologies in different ways. Broadly speaking, computers are used in three different classes of application.
//
Personal computers (PCs) are possibly the best known form of computing, which readers of this book have likely used extensively. Personal computers emphasize deliverly of good performance to single users at low cost and usually execute third-party software. The class of computing drove the evolution of many cbomputing technologies, which is only about 35 years old.
Servers are the modern form of what were once much larger computers, and are usually accessed only via a network. Servers are oriented to carrying large workloads, which may consist of either single complex applications -- usually a scientific or engineering application -- or handling many small jobs, such as would occur in building a large web server. These applications are usually based on software from another source (such as a database or simulation system), but are often modified or costomized for a particular function. Servers are built from the same basic technology as desktop computers, but provide for greater computing,storage, and input /output capacity. In general, severs also place s greater emphasis on dependability, since a crash is usually more costly than it would be on a single-user PC.
Server span the widest range in cost and capability. At the low end, a server may be little more than a desktop computer without a screen or keyboard and cost a thousand dollars. These low-end servers are typically used for file storage, small business applications, or simple web serving (see section 6.10). At the other extreme are supercomputers, which at the present consist of tens of thousands of processors and many terabytes of memory, and cost tens to hundreds of millions of dollars. Supercomputers are usually used for high-end scientific and engineering calculations, such as weather forecasting, oil exploration, protein structure determination, and other large-scale problems. Although such supercomputers represent the peak of computing capability, they represent a relatively small fraction of the servers and a relatively small fraction of the overall computer market in terms of total revenue.
Embedded computers are the largest class of computers and span the widest range of applications and performance. Embedded computers include the microprocessors found in your car, the computers in a television set, and the networks of processors that control a modern airplane or cargo ship. Embedded computer systems are designed to run one application or one set of related applications that are normally integrated with the hardware and delivered as a single system; thus, despite the large number of embedded computer, most users never really see that they are using a computer.
Personal computer (PC) A computer designed for use by an individual, ususally incorporating a graphics display, a keyboard, and a mouse.
Server A computer used for running larger programs for multiple users, often simultaneously, and typically accessed only via a network.
Super-computer A class of computers with the highest performance and cost; they are configured as servers and typically cost tens to thunsands of millions of dollars.
terabytes(TB) Originally 1,099,511,627,776 (240) bytes, although communications and secondary storage systems developers started using the term to mean 1,000,000,000,000 (1012) bytes. Figure 1.1 shows the full range of decimaland binary values and names.
embedded computer A computer inside another device used for running one perdetermined application or collection of software.
| Decimal term | Abbreviation | value | Binary term | Abbreviation | value | % Larger |
| kilobyte | KB | 103 | kibibyte | KiB | 210 | 2% |
| Megabyte | MB | 106 | Mebibyte | MiB | 220 | 5% |
| Gigabyte | GB | 109 | Gibibyte | GiB | 230 | 7% |
| Terabyte | TB | 1012 | Tebibyte | TiB | 240 | 10% |
| Petabyte | PB | 1015 | Pebibyte | PiB | 250 | 13% |
| Exabyte | EB | 1018 | Exbibyte | EiB | 260 | 15% |
| Zettabyte | ZB | 1021 | Zebibyte | ZiB | 270 | 18% |
| Yottabyte | YB | 1024 | Yobibyte | YiB | 280 | 21% |
Figure 1.1 The 2x vs 10y bytes ambiguity was resolved by adding a binary notation for all the common size terms. In the last column we note how much larger the binary term is than its corresponding decimal term, which is compounded as we head down the chart. These prefixes work for bits as well as bytes, so gigabit (Gb) is 109 bits while gibibits is 230 bits.
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Embedded applications often have unique application requirements that combine a minimum performance with stringent limitation on cost or power. For example, consider a music player: the processor nedd onlybe as fast as necessary to handle its limited function, and beyond that, minimizing coat and power are the most important objectives. Despite their low cost, embedded computers often have lower tolerance for failure,since the results can vary from upsetting (when your new television crashes) to devastating (such as might occur when the computer in a plane or cargo ship crashes). In consumer-oriented embedded appplications, such as a digital home appliance,dependability is achieved primarily through simplicity -- the emphasis is on doing one function as perferctly as possible. In large embedded system, techniques of redundancy from the server world are often employed. Although this book focuses on general-purpose computers, most concepts apply directly, or with slight modifications, to embedded computers.
Elaboration : Elaborations are short sections used throughout the text to provide more detail on a particular subject that may be of interest. Disinterested readers may skip over an elaboration, since the subsequent material will never depend on the contents of elaboration.
Many embedded processors are designed using processor cores, a version of a processor written in a hardware description language, such as Verilog or VHDL (see Chapter 4). The core allows a designer to integrate other application-specific hardware with the processor core for fabrication on a single chip.
Welcome to the PostPC Era
The continuing march of technology brings about generational changes in computer hardware that shake up the entire information technology industry.Since the last edition of the book we have undergone such a change, as significant in the past as the switch starting 30 years ago to personal computers. Replacing the PC is the personal mobile device (PMD). PMDs are battery operated with wireless connectivity to the Internet and typically cost hundres of dollars, and like PCs, users can download softeware ("apps") to run on them. Unlike PCs, they no longer have a keyboard and mouse, and are more likely to rely on a touch-sensitive screen or even speech input. Today's PMD is a smart phone or a table computer, but tomorrow it may include electronic glasses. Figure 1.2 shows the rapid growth time of tablets and smart phones versus that of PCs and traditional cell phones.
Taking over from the traditional server is Cloud computing, which relies upon giant datacenters that are now known as Warehouse Scale Computers (WSCs). Companies like Amazon and Google build these WSCs containing 100,000 servers