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1、1.2 Computer Generations 1.2.4 Fourth-Generation Computers:1971?Software development during the fourth computer generation started off with little change from the third generation.Operating systems were gradually improved,and new languages were designed.Database software became widely used during th
2、is time.The most important trend,however,resulted from the microcomputer revolution.Packaged software became widely available for microcomputers so that today most software is purchased,not developed from scratch.在计算机的第四代期间，软件的发展开始与第三代有所不同。操作系统在计算机的第四代期间，软件的发展开始与第三代有所不同。操作系统在逐渐地改进，而新的语言被发明。期间数据库软件被广
3、泛使用。然而，在逐渐地改进，而新的语言被发明。期间数据库软件被广泛使用。然而，最重要的趋势起因于微型计算机革命。用于微型计算机的软件包随处可最重要的趋势起因于微型计算机革命。用于微型计算机的软件包随处可得，因此今天大多数的软件可以购得得，因此今天大多数的软件可以购得,而不需从头开始开发。而不需从头开始开发。1.2.5 Generationless ComputersWe may have defined our last generation of computers and begun the era of generationless computers.Even though compu
4、ter manufacturers talk of“fifth”and“sixth”-generation computers,this talk is more a marketing play than a reflection of reality.我们可能已经定义了我们最新一代计算机而且开始了计算机的无代时代。即使计算机制造商谈到“第五”和“第六”代计算机,这些说法更多是市场行为，而不是真实的反映。Advocates of the concept of generationless computers say that even though technological innovat
5、ions are coming in rapid succession,no single innovation is,or will be,significant enough to characterize another generation of computers.无代计算机的观念提倡者说，即使科技革新接二连三地迅速出现,没有一种革新是,或将是足够重要，作为另一代计算机的特征。1.2 Computer Generations New Words&Expressions:glean vt.,vi.搜集搜集(情报或事实情报或事实)MD abbr.Maryland(马里兰马里兰)Tflop
6、s abbr.teraflops 每秒兆兆每秒兆兆(1012)次次 architecture n.体系机构体系机构terabit n.兆兆位兆兆位factor n.阶乘阶乘bandwidth n.带宽带宽 Terabyte n.兆兆兆兆(1012)字节；字节；Petabyte n.千兆兆千兆兆(1015)字节字节microprocessor n.计计微处理器微处理器contemplate v.凝视凝视,沉思沉思order n.阶阶,次次turbulence n.扰动；湍流扰动；湍流GB=GigaBit,千兆位千兆位;=GigaByte,吉字节吉字节flops n.每秒浮点运算次数每秒浮点运算次
7、数(floating-point operation per second)1.3 Near-future Supercomputer Directions Some idea of what might be happening in the near future in supercomputer design can be gleaned from a press release issued by the US Department of Energy(DoE).It came out of the SUPERCOMPUTING 2002 Conference held last No
8、vember in Baltimore,MD.The press release announced that the DoE had awarded IBM a$290(USD)million contract to build the two fastest supercomputers in the world with a combined peak speed of 460 TFlops.To get an idea of the speed computing throughput 460 teraflops represents,the press release states
9、that,“These two systems will have more than one-and-a-half times the combined processing power of all 500 machines on the recently announced TOP 500 List of Supercomputers.”从从美美国国能能源源部部发发行行的的通通告告中中，可可以以收收集集一一些些有有关关在在不不久久的的将将来来超超级级计计算算机机设设计计中中可可能能发发生生的的事事情情的的概概念念。它它来来自自在在马马里里兰兰州州巴巴尔尔的的摩摩市市召召开开的的20022
10、002年年超超级级计计算算会会议议。该该通通告告称称能能源源部部已已给给IBMIBM拨拨款款2.92.9亿亿美美元元建建造造世世界界上上最最快快的的两两部部超超级级计计算算机机，其其最最高高综综合合速速度度为为每每秒秒460460兆兆兆兆次次。为为了了理理解解每每秒秒460460兆兆兆兆次次速速度度的的含含义义，通通告告解解释释说说,“,“这这两两个个系系统统将将会会具具有有最最近近发发布布的的500500强强超级计算机的总处理能力的超级计算机的总处理能力的1.51.5倍还多。倍还多。”1.3 Near-future Supercomputer Directions The first sys
11、tem,“ASCI Purple,”apparently the DoE likes colorful names will be the worlds first supercomputer capable of 100 Tflops.ASCI Purple will have a massive cluster of POWER-based IBM eServer systems and IBM storage systems.This supercomputer represents a fifth-generation system under the Advanced Simulat
12、ion and Computing Initiative(ASCI)Program.It will serve as the primary supercomputer for DoE.第一个系统第一个系统“ASCI Purple”,“ASCI Purple”,显然能源部；生动的名字显然能源部；生动的名字 将会将会是世界的第一部能够运算每秒是世界的第一部能够运算每秒100100兆兆次的超级计算机。兆兆次的超级计算机。ASCI ASCI PurplePurple将具有基于将具有基于POWERPOWER系列的系列的IBM eServer IBM eServer 系统和系统和 IBM IBM 存储存
13、储系统的宏大组群。这台超级计算机代表模拟和计算行动计划系统的宏大组群。这台超级计算机代表模拟和计算行动计划(ASCI)(ASCI)支持的第五代系统。它将作为能源部主要的超级计算机。支持的第五代系统。它将作为能源部主要的超级计算机。1.3 Near-future Supercomputer Directions 1.3 Near-future Supercomputer Directions According to the press release,the second system will be a research machine called Blue Gene/L.It will
14、employ advanced IBM semiconductor and system technologies based on new architectures being developed by DoE and IBM.Blue Gene/L is expected to achieve a peak performance of 360 TFlops with 130,000 processors running under the Linux operating system.It will have the capability to process data at a ra
15、te of one terabit per second,equivalent to the data transmitted by ten thousand weather satellites.Applications are expected to include the simulation of very complex physical phenomena in areas such as turbulence,biology and high explosives.根根据据通通告告，第第二二个个系系统统将将会会是是一一部部被被称称为为Blue Gene/L的的研研究究机机器器，它
16、它将将使使用用基基于于新新结结构构的的先先进进的的IBM半半导导体体和和系系统统技技术术,该该新新结结构构是是能能源源部部和和IBM共共同同开开发发的的。Blue Gene/L具具有有13万万台台处处理理器器，在在Linux操操作作系系统统下下运运行行，可可望望达达到到每每秒秒360兆兆兆兆次次的的性性能能。它它将将具具有有以以每每秒秒1兆兆兆兆位位的的速速度度处处理理数数据据的的能能力力,等等同同于于一一万万个个气气象象卫卫星星传传输输的的数数据据。其其应应用用预预期期包包括括对对非非常常复复杂杂现象的模拟，如湍流、生物学和高空爆炸。现象的模拟，如湍流、生物学和高空爆炸。1.3 Near-f
17、uture Supercomputer Directions The ASCI Purple system will use IBMs next generation microprocessor,the POWER5,employing a total of 12,544 of them.These 12,544 processors will be spread among 196 individual computers.The total memory bandwidth will be 156,000 GBs,the equivalent of simultaneously play
18、ing 31,200 DVD movies.A super-fast data highway with a total interconnect bandwidth of 12,500 GB will interconnect the 196 computers.The IBM AIXL operating system will be used to run this configuration.The operating system will contain 50 terabytes of memory,an amount that is 400,000 times the capac
19、ity of the average desktop PC.There will also be two petabytes of disk storage or holding the content of approximately one billion books.ASCI ASCI PurplePurple系系统统将将使使用用IBMIBM的的下下一一代代微微处处理理器器POWER5,POWER5,总总数数为为12,54412,544个个。这这12,54412,544个个处处理理器器将将分分布布在在196196部部单单独独的的计计算算机机之之中中。总总内内存存带带宽宽将将是是15.6G
20、B,15.6GB,等等同同于于同同时时地地播播放放 31,20031,200部部DVDDVD电电影影。一一条条具具有有12,500 12,500 GBGB带带宽宽的的超超快快速速数数据据通通道道将将会会把把196196台台计计算算机机互互相相连连接接。IBM IBM AIXL AIXL 操操作作系系统统将将用用于于运运行行一一个个配配置置。该该操操作作系系统统将将包包5050兆兆兆兆字字节节内内存存，容容量量是是平平均均桌桌面面个个人人计计算算机机的的4040万万倍倍。还还将将有有2 2千千兆兆兆兆字字节节的的磁磁盘盘存存储储，或或可可容容纳纳大大约约十十亿亿本本书书的内容。的内容。1.3 N
21、ear-future Supercomputer Directions Finally,since the UNIVAC-1s introduction,raw computer speed has increased by about 11 to 12 orders of magnitude in about 50 years,or a factor of 10 every five years.This is a truly remarkable achievement.Its also interesting to contemplate that,if this growth cont
22、inues over the next 50 years,then by the 100th anniversary of the UNIVAC-1,computers will be operating at speeds on the order of 1023 Flops!最最后后,自自从从UNIVAC-1的的发发明明以以来来,计计算算机机的的原原始始速速度度在在50年年内内增增加加了了11至至12个个数数量量级级，或或每每五五年年增增加加10倍倍。这这是是一一个个真真正正显显著著的的成成就就。设设想想一一下下也也很很有有趣趣,如如果果在在未未来来50年年间间仍仍以以这这样样的的速速度度
23、持持续续增增长长,到到UNIVAC-1诞诞生生的的100周周年年，计计算算机将会以大约每秒机将会以大约每秒1023次的浮点运算速度运行次的浮点运算速度运行!一、复杂长句多一、复杂长句多科科技技文文章章要要求求叙叙述述准准确确，推推理理谨谨严严，因因此此一一句句话话里里包包含含三三四四个个甚甚至至五五六六个个分分句句的的，并并非非少少见见。译译成成汉汉语语时时，必必须须按按照照汉汉语语习习惯惯破破成成适适当当数数目目的的分分句句，才才能能条条理理清清楚楚，避避免免洋洋腔腔洋洋调调。这这种种复复杂杂长长句句居居科科技技英英语语难难点点之之首首，要要学学会运用语法分析方法来加以解剖，以便以短代长，化
24、难为易会运用语法分析方法来加以解剖，以便以短代长，化难为易。例如。例如：Factories will not buy machines unless they believe that the machine will produce goods that they are able to sell to consumers at a price that will cover all cost.这这是是由由一一个个主主句句和和四四个个从从句句组组成成的的复复杂杂长长句句，只只有有进进行行必必要要的的语语法法分分析析，才能正确理解和翻译。现试译如下：才能正确理解和翻译。现试译如下：除除非非相相
25、信信那那些些机机器器造造出出的的产产品品卖卖给给消消费费者者的的价价格格足足够够支支付付所所有有成成本本，否否则则厂家是不会买那些机器的。厂家是不会买那些机器的。节译：节译：要不相信那些机器造出的产品售价够本，厂家是不会买的。要不相信那些机器造出的产品售价够本，厂家是不会买的。后后一一句句只只用用了了24个个字字，比比前前句句40个个字字节节约约用用字字40%，而而对对原原句句的的基基本本内内容容无无损损。可可见见，只只要要吃吃透透原原文文的的结结构构和和内内涵涵，翻翻译译时时再再在在汉汉语语上上反反复复推推敲敲提提炼，复杂的英语长句，也是容易驾驭的。炼，复杂的英语长句，也是容易驾驭的。科技英
26、语的特点科技英语的特点 科技英语的特点科技英语的特点 二、被动语态多二、被动语态多英英语语使使用用被被动动语语态态大大大大多多于于汉汉语语，如如莎莎士士比比亚亚传传世世名名剧剧罗罗密密欧欧与与朱朱丽丽叶叶中的一句就两次用了被动语态：中的一句就两次用了被动语态：Juliet was torn between desire to keep Romeo near her and fear for his life,should his presence be detected.朱朱丽丽叶叶精精神神上上受受到到折折磨磨，既既渴渴望望和和罗罗密密欧欧形形影影不不离离，又又担担心心罗罗密密欧欧万万一一让让
27、人发现，难免有性命之忧。人发现，难免有性命之忧。科技英语更是如此，有三分之一以上用被动语态。例如：科技英语更是如此，有三分之一以上用被动语态。例如：(a)No work can be done without energy.译文：没有能量决不能做功。译文：没有能量决不能做功。(b)All business decisions must now be made in the light of the market.译文：所有企业现在必须根据市场来作出决策。译文：所有企业现在必须根据市场来作出决策。科技英语的特点科技英语的特点 三、非谓语动词多三、非谓语动词多英英语语每每个个简简单单句句中中，只只
28、能能用用一一个个谓谓语语动动词词，如如果果读读到到几几个个动动作作，就就必必须须选选出出主主要要动动作作当当谓谓语语，而而将将其其余余动动作作用用非非谓谓语语动动词词形形式式，才才能能符符合英语语法要求。合英语语法要求。非非谓谓语语动动词词有有三三种种：动动名名词词、分分词词（包包括括现现在在分分词词和和过过去去分分词词）和和不定式不定式。例如：。例如：要成为一个名符其实的内行，需要学到老。要成为一个名符其实的内行，需要学到老。这这句句中中，有有“成成为为”、“需需要要”和和“学学”三三个个表表示示动动作作的的词词，译译成成英语后为：英语后为：To be a true professional
29、 requires lifelong learning.可以看出，选好可以看出，选好“需要需要”（require）作为谓语，其余两个动作：）作为谓语，其余两个动作：“成为成为”用不定式形式用不定式形式 to be，而，而“学学”用动名词形式用动名词形式learning，这样才，这样才能符合英语语法要求。能符合英语语法要求。科技英语的特点科技英语的特点 四、词性转换多四、词性转换多英英语语单单词词有有不不少少是是多多性性词词，即即既既是是名名词词，又又可可用用作作动动词词、形形容容词词、介介词词或或副副词词，字字形形无无殊殊，功功能能各各异异，含含义义也也各各不不相相同同，如如不不仔仔细细观观察
30、察，必必致致谬误。例如谬误。例如,light名词：名词：(启发启发)in(the)light of由于，根据；由于，根据；(光光)high light(s)强光，精华；强光，精华；(灯灯)safety light 安全指示灯安全指示灯形容词形容词：(轻轻)light industry 轻工业；轻工业；(明亮明亮)light room 明亮的房间；明亮的房间；(淡淡)light blue 淡蓝色；淡蓝色；(薄薄)light coating 薄涂层薄涂层动词动词：（点燃）（点燃）light up the lamp 点灯点灯副词副词：（轻快）（轻快）travel light 轻装旅行轻装旅行 （容易
31、）（容易）light come,light go 来得容易去得快来得容易去得快诸诸如如此此类类的的词词性性转转换换，在在科科技技英英语语中中屡屡见见不不鲜鲜，几几乎乎每每个个技技术术名名词词都都可可转转换换为为同同义义的的形形容容词词。词词性性转转换换增增加加了了英英语语的的灵灵活活性性和和表表现现力力，读读者者必必须须从从上上下下文文判判明明用用词词在在句句中中是是何何种种词词性性，而而且且含含义义如如何何，才才能能对对全全句句得得到到正确无误的理解。正确无误的理解。Computer English Chapter 2 Organization of ComputersKey points:
32、useful terms and organization of computersDifficult points:describing the organization of computersRequirements:1.Terms of computer hardware 2.Organization of computers and their functions3.掌握专业词汇的构成规律，特别是常用词缀及复合词掌握专业词汇的构成规律，特别是常用词缀及复合词的构成的构成 New Words&Expressions:instruction cycle 指令周期指令周期decode vt
33、.解码解码,译解译解bus n.总线总线pins n.插脚插脚,管脚管脚uppermost adj.最高的；最高的；adv.在最上在最上address bus 地址总线地址总线data bus 数据总线数据总线via prep.经经,通过通过,经由经由multibit 多位多位bidirectional 双向的双向的unidirectional 单向的单向的hierarchy n.层次，层级层次，层级microprocessor n.微处理器微处理器register n.寄存器寄存器timing n.定时；时序；时间选择定时；时序；时间选择synchronize vt.使使.同步同步asser
34、t vt.主张，发出主张，发出deassert vt.撤销撤销trigger vt.引发引发,引起引起,触发触发map v.映射映射port n.端口端口2.1 Basic Organization of Computers Abbreviations:CPU(Central Processing Unit)中央处理器中央处理器 I/O(Input/Output)输入输出输入输出(设备设备)2.1 Basic Organization of ComputersFig.2-1 Generic computer organization2.1 Basic Organization of Compu
35、tersMost computer systems,from the embedded controllers found in automobiles and consumer appliances to personal computers and mainframes,have the same basic organization.This organization has three main components:the CPU,the memory subsystem,and the I/O subsystem.The generic organization of these
36、components is shown in Figure 2-1.大多数计算机系统，从汽车和日用电器中的嵌入式控制器到大多数计算机系统，从汽车和日用电器中的嵌入式控制器到个人计算机和大型主机，都具有相同的基本组成。其基本组个人计算机和大型主机，都具有相同的基本组成。其基本组成包括三个主要部件：成包括三个主要部件：CPU、存储器子系统和、存储器子系统和I/O子系统。这子系统。这些部件的一般组成如图些部件的一般组成如图2-1所示。所示。Physically,a bus is a set of wires.The components of the computer are connected t
37、o the buses.To send information from one component to another,the source component outputs data onto the bus.The destination component then inputs this data from the bus.As the complexity of a computer system increases,it becomes more efficient(in terms of minimizing connections)at using buses rathe
38、r than direct connections between every pair of devices.Buses use less space on a circuit board and require less power than a large number of direct connections.They also require fewer pins on the chip or chips that comprise the CPU.2.1.1 System Buses从物理上来说，总线就是一组导线。计算机的部件就是连在总线上的。为了将信息从从物理上来说，总线就是一
39、组导线。计算机的部件就是连在总线上的。为了将信息从一个部件传到另一个部件，源部件先将数据输出到总线上，然后目标部件再从总线上一个部件传到另一个部件，源部件先将数据输出到总线上，然后目标部件再从总线上接受这些数据。随着计算机系统复杂性的不断增长，使用总线比每个设备对之间直接接受这些数据。随着计算机系统复杂性的不断增长，使用总线比每个设备对之间直接连接要有效得多（就减少连接数量而言）。与大量的直接连接相比，总线使用较少的连接要有效得多（就减少连接数量而言）。与大量的直接连接相比，总线使用较少的电路板空间，耗能更少，并且在芯片或组成电路板空间，耗能更少，并且在芯片或组成CPU的芯片组上需要较少的引脚
40、。的芯片组上需要较少的引脚。The system shown in Figure 2-1 has three buses.The uppermost bus in this figure is the address bus.When the CPU reads data or instructions from or writes data to memory,it must specify the address of the memory location it wishes to access.It outputs this address to the address bus;mem
41、ory inputs this address from the address bus and use it to access the proper memory location.Each I/O devices,such as a keyboard,monitor,or disk drive,has a unique address as well.When accessing an I/O device,the CPU places the address of the device on the address bus.Each device can read the addres
42、s off of the bus and determine whether it is the device being accessed by the CPU.Unlike the other buses,the address bus always receives data from the CPU;the CPU never reads the address bus.图图2-1所示的系统包括三组总线。最上面的是地址总线。当所示的系统包括三组总线。最上面的是地址总线。当CPU从存储器读取数据或从存储器读取数据或指令，或写数据到存储器时，它必须指明将要访问的存储器单元地址。指令，或写数
43、据到存储器时，它必须指明将要访问的存储器单元地址。CPU将地址将地址输出到地址总线上，而存储器从地址总线上读取地址，并且用它来访问正确的存储单输出到地址总线上，而存储器从地址总线上读取地址，并且用它来访问正确的存储单元。每个元。每个I/O设备，比如键盘、显示器或者磁盘，同样都有一个唯一的地址。当访问设备，比如键盘、显示器或者磁盘，同样都有一个唯一的地址。当访问某个某个I/O设备时，设备时，CPU将此设备的地址放到地址总线上。每一个设备均从总线上读取将此设备的地址放到地址总线上。每一个设备均从总线上读取地址并且判断自己是否就是地址并且判断自己是否就是CPU正要访问的设备。与其他总线不同，地址总线
44、总是正要访问的设备。与其他总线不同，地址总线总是从从CPU上接收信息，而上接收信息，而CPU从不读取地址总线。从不读取地址总线。2.1.1 System BusesData is transferred via the data bus.When the CPU fetches data from memory,it first outputs the memory address on its address bus.Then memory outputs the data onto the data bus;the CPU can then read the data from the d
45、ata bus.When writing data to memory,the CPU first outputs the address onto the address bus,then outputs the data onto the data bus.Memory then reads and stores the data at the proper location.The processes for reading data from and writing data to the I/O devices are similar.数据是通过数据总线传送的。当数据是通过数据总线传
46、送的。当CPU从存储器中取数据时，它首先把存储器从存储器中取数据时，它首先把存储器地址输出到地址总线上，然后存储器将数据输出到数据总线上，这样地址输出到地址总线上，然后存储器将数据输出到数据总线上，这样CPU就就可以从数据总线上读取数据了。当可以从数据总线上读取数据了。当CPU向存储器中写数据时，它首先将地址向存储器中写数据时，它首先将地址输出到地址总线上，然后把数据输出到数据总线上，这样存储器就可以从数输出到地址总线上，然后把数据输出到数据总线上，这样存储器就可以从数据总线上读取数据并将它存储到正确的单元中。对据总线上读取数据并将它存储到正确的单元中。对I/O设备读写数据的过程设备读写数据的
47、过程与此类似。与此类似。2.1.1 System BusesThe control bus is different from the other two buses.The address bus consists of n lines,which combine to transmit one n-bit address value.Similarly,the lines of the data bus work together to transmit a single multibit value.In contrast,the control bus is a collection
48、of individual control signals.These signals indicate whether data is to be read into or written out of the CPU,whether the CPU is accessing memory or an I/O device,and whether the I/O device or memory is ready to transfer data.Although this bus is shown as bidirectional in Figure 2-1,it is really a
49、collection of(mostly)unidirectional signals.Most of these signals are output from the CPU to the memory and I/O subsystems,although a few are output by these subsystems to the CPU.We examine these signals in more detail when we look at the instruction cycle and the subsystem interface.控制总线与以上两种总线都不相
50、同。地址总线由控制总线与以上两种总线都不相同。地址总线由n根线构成，根线构成，n根线联合传送一个根线联合传送一个n位位的地址值。类似地，数据总线的各条线合起来传输一个单独的多位值。相反，控制总的地址值。类似地，数据总线的各条线合起来传输一个单独的多位值。相反，控制总线是单根控制信号的集合。这些信号用来指示数据是要读入线是单根控制信号的集合。这些信号用来指示数据是要读入CPU还是要从还是要从CPU写出，写出，CPU是要访问存储器还是要访问是要访问存储器还是要访问I/O设备，是设备，是I/O设备还是存储器已就绪要传送数据等设备还是存储器已就绪要传送数据等等。虽然图等。虽然图2-1所示的控制总线看起