本书第1章介绍计算机专业英语词汇特点以及阅读与翻译计算机专业资料的方法、技巧;第2章介绍计算机硬件基础、处理器、存储器、输入/输出系统、计算机并行系统、数据结构、操作系统、程序设计语言等;第3章介绍计算机网络基础知识、ISO参考模型、互联网技术、网络**及电子商务;第4章介绍文字处理技术、多媒体技术、软件工程及软件测试与维护知识、数据库应用及计算机病毒等;第5章介绍云计算、大数据、物联网、移动商务等。

第3章

第3章Computer Network Knowledge

3.1Computer Network〖*4/5〗3.1.1TextComputer network can be used for numerous services,both for companies and for individuals. For companies,networks of personal computers using shared servers often provide flexibility and a good price/ performance ratio. For individuals,networks offer access to a variety of information and entertainment resources.
Roughly speaking,networks can be divided up into LANs,MANs,WANs,and Internet works,each with their own characteristics,technologies,speeds,and niches. LANs cover a building,MANs cover a city,and WANs cover a country or continent. LANs and MANs are unswitched (i.e.,do not have routers); WANs are switched.
Network software consists of protocols,or rules by which processes can communicate[1]. Protocols can be either connectionless or connectionoriented. Most networks support protocol hierarchies,with each layer providing services to the lower layers. Protocol stacks are typically based either on the OSI model or the TCP/IP model. Both of these have network,transport,and application layers,but they differ on the other layers.
Network establishes communication among computers. This system is especially helpful when people work on different place. It improves the speed and accuracy of communication,prevents messages from being misplaced and automatically ensures total distribution of key information.
1. Local Area Networks (LANs)
A local area networks,or LAN,is a communication network that is privately owned and that covers a limited geographic area such as an office,a building,or a group of building. The LAN consists of a communication channel that connects either a series of computer terminals together with a minicomputer or,more commonly,a group of personal computers to one another. Very sophisticated LANs can connect a variety of office devices such as word processing equipment,computer terminals,video equipment and personal computers.
Two common applications of local area networks are hardware resource sharing and information resource sharing. Hardware resource sharing allows each personal computer in the network to access and use devices that would be too expensive to provide for each user. Information resource sharing allows anyone using a personal computer on the local area network to access data stored on any other computer in the network[2]. In actual practice,hardware resource sharing and information resource sharing are often combined.
计算机专业英语(第3版)第3章Computer Network Knowledge2. Wide Area Networks (WANs)
A wide area network,or WAN,is geographic in scope (as opposed to local) and uses telephone lines,microwaves,satellites,or a combination of communication channels. Public wide area network companies include socalled common carriers such as the telephone companies. Telephone company deregulation has encouraged a number of computers of companies to build their own wide area networks.
3. Network Configuration
The configuration,or physical layout,of the equipment in a communication network is called topology. Communication networks are usually configured in one or a combination of three patterns. These configurations are star,bus,and ring networks. Although these configurations can be used with wide area networks,we illustrate them with local area networks. Devices connected to a network,such as terminal,printers,or other computers,are referred to as nodes.
(1) Star Network
A star network (Fig.31) contains a central computer and one or more terminals or personal computers connected to it,forming a star[3]. A pure star network consists of only pointtopoint lines between the terminals and the computer,but most star networks,such as the one shown in Fig.31,include both pointtopoint lines and multidrop lines. A star network configuration is often used when the central computer contains all the data required to process the input from the terminals,Such as an airline reservation system. For example,if inquiries were being processed in the star network,all the data to answer the inquiry would be contained in the database stored on the central computer.
Fig.31A star network
A star network can be relatively efficient,and close control can be kept over the data processed on the network. Its major disadvantage is that the entire network is dependent on the central computer and the associated hardware and software. If any of these elements fail,the entire network is disabled. Therefore,in most large star networks,backup computer systems are available in case the primary system fails.
(2) Bus Network
When a bus network is used,all the devices in the network are connected to a single cable. Information is transmitted in either direction from any one personal computer to another. Any message can be directed to specific device. An advantage of the bus network is that devices can be attached or detached from the network at any point without disturbing the rest of the network. In addition,if one computer on the network fails,this does not affect the other users of the network. Fig.32 illustrates a simple bus network.
Fig.32A bus network
(3) Ring Network
Fig.33A ring networkA ring network does not use a centralized host computer. Rather,a circle of computers communicate with one another (Fig.33). A ring network can be useful when the processing is not done at a central site,but at local sites. For example,computers could be located in three departments: accounting,personnel,and shipping and receiving. The computers in each of these departments could perform the processing required for each of the departments. On occasion,however,the computer in the shipping and receiving department could communicate with the computer in the accounting department to update certain data stored on the accounting department computer. Data travels around a ring network in one direction only and passes through each node. Thus,one disadvantage of a ring network is that if one node fails,the entire network fails because the data does not get past the failed node[4]. An advantage of a ring network is that less cable is usually needed and therefore network cabling costs are lower.
(4) Connecting Networks
Sometimes you might want to connect separate network. You do this by using gateways and bridges. A gateway is a combination of hardware and software that allows users on one network to access the resources on a different type of network. For example,a gateway could be used to connect a local area network of personal computers to a mainframe computer network. A bridge is a combination of hardware and software that is used to connect similar networks. For example,if a company had similar but separate local area networks of personal computers in their accounting and marketing departments,the networks could be connected with a bridge[5]. In this example,using a bridge makes more sense than joining all the personal computer together in one large network because the individual department only occasionally needs to access information on the other network.
Key Words
accuracy**,正确
channel 通道,频道
classify分类,归类
common carriers 承运商
connectionoriented面向连接的
detach使分离,分遣
disadvantage 缺点
establish建立,确立
gateway网关
geographic地理的
hierarchy等级体系
inquiry质询,探索
misplace放错地方
multidrop多分支的,多点(网络)
node网络节点,连接到网络上的设备
privately私人地,秘密地
reservation保留,保留品
scope范围,广度
topology拓扑学,地志学
Notes
[1] Network software consists of protocols,or rules by which processes can communicate.
本句中的or rules作同位语,by which processes can communicate作宾语补足语。
译文: 网络软件由协议或过程通信的规则组成。
[2] Information resource sharing allows anyone using a personal computer on the local area network to access data stored on any other computer in the network.
本句中的anyone作宾语,using a personal computer on the local area network作anyone的定语,to access data作宾语补足语。
译文: 信息资源共享允许局域网上每一个计算机用户访问存储于网上其他计算机中的数据。
[3] A star network contains a central computer and one or more terminals or personal computers connected to it,forming a star.
本句中的a central computer and one or more terminals or personal computers作宾语。
译文: 星状网络由一台**计算机和一台或多台连接到该**计算机上并形成星形结构的终端或计算机组成。
[4] Thus,one disadvantage of a ring network is that if one node fails,the entire network fails because the data does not get past the failed node.
本句中的that引导表语从句,if one node fails作条件状语,而because the data does not get past the failed node作原因状语。
译文: 因此,环状网络的缺点是如果一个节点出现故障,由于数据不能通过出现故障的节点,就会使整个网络无法工作。
[5] For example,if a company had similar but separate local area networks of personal computers in their accounting and marketing departments,the networks could be connected with a bridge.
本句由if引导条件状语从句。
译文: 例如,某公司在其财务部和市场部各有一套由个人计算机组成的类似的但相互独立的局域网,这两个网络就可通过网桥连接起来。
3.1.2Exercises〖*2〗1. Translate the following phrases into English(1) 局域网

第1章计算机专业英语基础知识1 1.1计算机专业英语的特点分析1 1.1.1专业英语的专业性与客观性2 1.1.2计算机专业英语中长句的运用4 1.1.3被动语态在计算机专业英语中的应用6 1.1.4英语的句子成分简介8 1.2计算机专业英语的词汇特点9 1.2.1专业英语词汇的构成特点9 1.2.2词汇缩略14 1.2.3计算机专用术语与命令15 1.2.4专业英语中常用的符号和数学表达式19 1.3计算机专业文献的阅读与翻译21 1.3.1计算机专业文献的阅读方法21 1.3.2计算机专业文献翻译的基本方法23 第2章Hardware and Software Knowledge37 2.1Computer Hardware Basics37 2.1.1Text37 2.1.2Exercises41 2.1.3Reading Material42 2.2CPU44 2.2.1Text44 2.2.2Exercises47 2.2.3Reading Material48 2.3Memory50 2.3.1Text50 2.3.2Exercises54 2.3.3Reading Material55计算机专业英语(第3版)目录2.4Input/Output Devices56 2.4.1Text56 2.4.2Exercises61 2.4.3Reading Material62 2.5Data Structures64 2.5.1Text64 2.5.2Exercises68 2.5.3Reading Material69 2.6Operating System70 2.6.1Text70 2.6.2Exercises74 2.6.3Reading Material75 2.7Programming Languages77 2.7.1Text77 2.7.2Exercises81 2.7.3Reading Material82 第3章Computer Network Knowledge84 3.1Computer Network84 3.1.1Text84 3.1.2Exercises88 3.1.3Reading Material89 3.2Internet Security91 3.2.1Text91 3.2.2Exercises95 3.2.3Reading Material96 3.3ECommerce98 3.3.1Text98 3.3.2Exercises103 3.3.3Reading Material104 3.4Electronic Payment System106 3.4.1Text106 3.4.2Exercises110 3.4.3Reading Material111 3.5Logistics and Supplychain Management113 3.5.1Text113 3.5.2Exercises117 3.5.3Reading Material119 第4章Computer Applications121 4.1Database Applications121 4.1.1Text121 4.1.2Exercises125 4.1.3Reading Material126 4.2Software Engineering127 4.2.1Text127 4.2.2Exercises131 4.2.3Reading Material132 4.3Multimedia134 4.3.1Text134 4.3.2Exercises139 4.3.3Reading Material140 4.4Animation141 4.4.1Text141 4.4.2Exercises146 4.4.3Reading Material147 4.5Computer Virus148 4.5.1Text148 4.5.2Exercises153 4.5.3Reading Material154 第5章Computer New Technologies156 5.1Cloud Computing156 5.1.1Text156 5.1.2Exercises160 5.1.3Reading Material161 5.2Big Data163 5.2.1Text163 5.2.2Exercises167 5.2.3Reading Material168 5.3The Internet of Things170 5.3.1Text170 5.3.2Exercises174 5.3.3Reading Material176 5.4Mobile Commerce177 5.4.1Text177 5.4.2Exercises182 5.4.3Reading Material183 练习答案185 参考译文192第2章硬件和软件知识192 第3章计算机网络知识215 第4章计算机应用231 第5章计算机领域新技术248 附录A计算机专业英语常用术语表261 附录B计算机专业英语缩写词表267参考文献276