楼主要加分啊！Computer network virus and precautionsWith the new network technology and application of the continuous rapid development of the computer network should Use of becoming increasingly widespread, the role played by the increasingly important computer networks and human More inseparable from the lives of the community's reliance on them will keep With With the continuous development of computer technology, the virus has become increasingly complex and senior, the new generation of Computer viruses make full use of certain commonly used operating systems and application software for protection of the weak low Spots have rampant in recent years as the popularity of the Internet in the world, will be attached document containing the virus The situation in the mail has been increasing spread of the virus through the Internet, making the spread of the virus speed Sharp also increased, by an ever-increasing scope of the Therefore, the protection of the security of computer networks will be Will become increasingly A computer virus The definition of computer virus computer virus (Computer Virus) in the "people's republic of China The computer information system security protection regulations "which has been clearly defined, the virus" refers to the preparation or Computer program inserted in the damage or destruction of computer data functions, affecting computer use Self-replication and can a group of computer instructions, or " Second, network virus With the development of network and the Internet, a wider spread, the greater New harm The virus emerged This is the Internet The virus is an emerging concept in the traditional The virus was not classified network virus this concept, because the development of networks, the traditional virus The network also has a number of Today's Internet virus is a broad notion of a As as long as it is carried out using the Internet to spread destruction can be known as network viruses, such as: "Love the back door", "Panda burning " Third, network virus and the distinction between computer virus The original common computer virus is nothing more than the devastating formatted hard drive, delete system With the users documents, databases, The mode of transmission is through nothing but also by virus infection Mutual copy of the software, carrying the virus, such as the use of pirated optical discs, such as infection disk systems The pilot virus and infected executable file virus, in addition to a network virus These are the common characteristics of the virus, but also steal users with remote data, remote control of the other side Computers and other damaged properties, such as Trojan and consumption of funding the operation of the network computer Source collapse of the network server Fourth, the network against virus Network destructive virus, will directly affect the work of the network, ranging from lowering speed video Ring for the efficiency of the network, while in the collapse, undermining the server information to a multi-year work destroyed D Because viruses and other network annually fraud led to economic losses of over 16 billion yuan, But this figure is constantly rising year by The next few years, the size of the market will reach Security 60 billion One antivirus software experts pointed out: "Network avian flu virus even " Such as: "Xiong Cat burning incense "In addition to virus infection through the web site users, the latest virus also through QQ Loopholes in propagating itself through file-sharing networks, the default sharing, weak password systems, U disk and windows Forms bottom of the top mobile hard drives, and other means of While LAN once a computer machine For infection, it can spread through the entire network instant, or even within a very short period of time can be infected Thousands of computers, can lead to serious Symptoms of poisoning in the performance of computers There are Exe files have become a strange pattern, the pattern shown as "Panda Burning incense, "and then System blue screen, restart the frequent, hard drive data destruction, serious entire company All computer LAN will all "Panda burning incense," only more than half a month, a few varieties have high Of more than 50, and the number of its users infected constantly Makes infected, "Panda burn incense" disease The personal drug users has been as high as several million people infected with a few more corporate users is rising Network More on the computer network the greater the harm caused by the V network transmission of the virus Features Infection fast: single machine environment, the virus can only be passed from one computer diskette To another, and in the network can be adopted by the rapid spread of network communication According to measurement Set against a typical PC network use in normal circumstances, once a computer workstation sick Drugs, and will be online within 10 minutes in the several hundreds of all infected Proliferation of a wide range: in the network due to the spread of the virus very quickly and spread to encompass a large area, not only the rapid transmission of all LAN computer, but also through remote workstations virus in一瞬Inter spread to thousands of miles Dissemination in the form of complex and varied: computer viruses in general through the network " Station server workstation "channels of communication, but in the form of complex and diverse Difficult to completely wipe: the standalone computer virus carriers sometimes can be deleted documents Or low-level formatted drives, and other measures to eliminate the virus completely, and the network once a computer work Clean stations failed to disinfect the entire network can be re-infected by the virus, or even just completed removal The work of a workstation is likely to be on-line by another workstation virus Therefore, Only workstations in addition to killing viruses, and can not solve the virus harm to the network 6, the type of network virus As the network increasingly developed, the type of network virus has been increasing, generally summed up as The following categories: Worm It is the use of the transmission mechanism of replication and dissemination network, the mode of transmission is through the network And e-mail, the prefix is W For example, in recent years the great harm "Nimda" virus is Demodex A worm The virus used Microsoft's Windows operating system, computer flu With this virus, will continue to automatically dial-up Internet access and use information in the document or the address Sharing network spreads, and ultimately undermine the most important user Macro Virus Hong virus is a Storage in the document or template in the Acer computer The prefix Macro, once open such documents, which Acer will be implemented, then the virus would Acer Been enabled transferred to the computer, and in the presence of the Normal From then on, all since The document will be kept moving "infection" that the Hong virus, and if other users opened the flu Documents with the virus, the Hong virus will be transferred to his Destructive procedures virus The prefix destructive virus program is: H The characteristics of this virus is a good in itself Look at the user clicks on icons to temptation, when the user clicks on the virus, the virus will direct users Computer generated If C formatted disk (HformatCf), the killer orders (H CKiller) System virus The prefix system for the virus: Win32, PE, Win95, W32, W95, and so These viruses The characteristics of the general public can be infected with the windows operating system * exe and * dll file, And through these documents for If the CIH Backdoor virus Backdoor virus prefix is B The total of such virus through network - Sowing, opened the back door to the system to the user and potential safety Bundling machine virus Bundled-virus prefix is: B The characteristics of this virus is the virus writers will use Specific procedures will be bundled with a number of applications such as QQ, IE bundled up on the surface It is normal to see the paper, when users run these bundled virus, will run these applications on the surface Procedures, and then tied to the operation of hidden virus, which caused harm to the Such as: baled Tied QQ (BQQPQQBin), the system killer (Bkillsys) Script virus The virus is usually JavaScript scripting code prepared by the malicious code, prefix is usually Spript, with the general nature of advertising, will modify your IE Home, modify registry, and other information, Computer user inconvenience Planting procedures virus virus This virus is of the public will run from the in vivo release of one or several new Under the virus to the system directory, by the release of a new virus If the glaciers are sowing (DBingH2C), MSN striker (DWSmibag) Joke virus The prefix is the virus joke: J Also called prank The characteristics of this virus is itself a nice user clicks on icons to temptation, When the user clicks of this virus, the virus will be made to disrupt the operation scare users, in fact The virus did not destroy any computer Such as: ghost (JGirlghost) Trojan hacking virus Trojan its prefix is: Trojan, hackers virus prefix General for H Public special Sex is through the network or system loopholes into the user's system and hidden, and then leaked to the outside world User information, hackers virus there is a visual interface to the user's computer remotely C Trojans, hackers often paired virus emerging, Trojan horse virus responsible for the invasive power users Brain, and hackers virus will be passed to the Trojan horse virus General Trojan such as QQ News tail Trojan TQQ3344, there are big TLMPSW Virus Form A PSW or anything like PWD general said that the virus has stolen password function, If some hacker programs, such as network枭雄HNC 7, the mode of transmission and network anti-virus Through the above, we can see that e-mail viruses spread Click homepage, users download, Others implant, implant, and other loopholes through five computer transmission, so long as holding these five A thoroughfare, we will be able to live better anti-virus 计算机网络病毒与防范随着各种新的网络技术的不断应用和迅速发展, 计算机网络的应用范围变得越来越广泛, 所起的作用越来越重要, 计算机网络与人类的生活更加密不可分, 社会对其的依赖程度也会随之不断增长。而随着计算机技术的不断发展, 病毒也变得越来越复杂和高级, 新一代的计算机病毒充分利用某些常用操作系统与应用软件的低防护性的弱点不断肆虐, 最近几年随着因特网在全球的普及, 将含病毒文件附加在邮件中的情况不断增多, 通过网络传播病毒, 使得病毒的扩散速度也急骤提高, 受感染的范围越来越广。因此, 计算机网络的安全保护将会变得越来越重要。一、计算机病毒计算机病毒的定义计算机病毒(Computer Virus)在《中华人民共和国计算机信息系统安全保护条例》中被明确定义, 病毒“指编制或者在计算机程序中插入的破坏计算机功能或者破坏数据, 影响计算机使用并且能够自我复制的一组计算机指令或者程序代码”。二、网络病毒随着网络和Internet 的发展,一个传播范围更广,危害更大的新型病毒应运而生这就是网络病毒。网络病毒是一个新兴的概念, 在传统的病毒分类里没有网络病毒这个概念, 由于网络的发展, 传统的病毒也就具有了一些网络的特性。如今的网络病毒是一个广义的概念, 一般只要是利用网络来进行传播、破坏的都可以被称为网络病毒, 如:“爱情后门”、“熊猫烧香”等。三、网络病毒与计算机病毒的区别原先常见的计算机病毒的破坏性无非就是格式化硬盘, 删除系统与用户文件、破坏数据库等等。而传播途径也无非是通过遭病毒感染的软件的互相拷贝, 携带病毒的盗版光盘的使用等, 如感染磁盘系统区的引导型病毒和感染可执行文件的文件型病毒, 而网络病毒除了具有普通病毒的这些特性外, 还具有远端窃取用户数据、远端控制对方计算机等破坏特性, 比如特洛伊木马病毒和消耗网络计算机的运行资源, 拖垮网络服务器的蠕虫病毒。四、网络病毒的危害网络上病毒破坏性大, 将直接影响网络的工作, 轻则降低速度, 影响工作效率, 重则使网络崩溃, 破坏服务器信息, 使多年工作毁于一旦。每年由于病毒等网络欺诈行为导致的经济损失高达160 亿多元,而且这个数字逐年还在不断地攀升。未来几年, 安防市场规模将达到600 亿元。一位杀毒软件专家指出: “网络病毒更甚于禽流感”。如: “熊猫烧香”除了通过网站带毒感染用户之外, 此病毒还会通过QQ 最新漏洞传播自身, 通过网络文件共享、默认共享、系统弱口令、U 盘及窗体顶端窗体底端移动硬盘等多种途径传播。而局域网中只要有一台机器感染, 就可以瞬间传遍整个网络, 甚至在极短时间之内就可以感染几千台计算机, 严重时可以导致网络瘫痪。中毒症状表现为电脑中所有可执行的xe 文件都变成了一种怪异的图案, 该图案显示为“熊猫烧香”, 继而系统蓝屏、频繁重启、硬盘数据被破坏等, 严重的整个公司局域网内所有电脑会全部中毒。“熊猫烧香”仅半个多月, 变种数已高达50 多个, 并且其感染用户的数量不断扩大。使得感染“熊猫烧香”病毒的个人用户已经高达几百万, 企业用户感染数更是成倍上升。网络上的计算机越多, 网络病毒造成的危害越大。五、网络病毒传播特点感染速度快: 在单机环境下, 病毒只能通过软盘从一台计算机带到另一台, 而在网络中则可以通过网络通讯机制迅速扩散。根据测定, 针对一台典型的PC 网络在正常使用情况, 只要有一台工作站有病毒, 就可在几十分钟内将网上的数百台计算机全部感染。扩散面广: 由于病毒在网络中扩散非常快, 扩散范围很大, 不但能迅速传染局域网内所有计算机, 还能通过远程工作站将病毒在一瞬间传播到千里之外。传播的形式复杂多样: 计算机病毒在网络上一般是通过“工作站服务器工作站”的途径进行传播的, 但传播的形式复杂多样。难于彻底清除: 单机上的计算机病毒有时可通过删除带毒文件或低级格式化硬盘等措施将病毒彻底清除, 而网络中只要有一台工作站未能消毒干净就可使整个网络重新被病毒感染, 甚至刚刚完成清除工作的一台工作站就有可能被网上另一台带毒工作站所感染。因此,仅对工作站进行病毒杀除, 并不能解决病毒对网络的危害。六、网络病毒的类型由于网络越来越发达, 网络病毒的种类也越来越多, 大体归纳为以下几类:蠕虫病毒它的传染机理是利用网络进行复制和传播, 传染途径是通过网络和电子邮件,前缀是Worm。比如近年危害很大的“尼姆达”病毒就是蠕虫病毒的一种。这一病毒利用了微软视窗操作系统的漏洞, 计算机感染这一病毒后, 会不断自动拨号上网, 并利用文件中的地址信息或者网络共享进行传播, 最终破坏用户的大部分重要数据。宏病毒宏病毒是一种寄存在文档或模板的宏中的计算机病毒。前缀是Macro, 一旦打开这样的文档, 其中的宏就会被执行, 于是宏病毒就会被激活, 转移到计算机上, 并驻留在Normal 模板上。从此以后, 所有自动保存的文档都会“感染”上这种宏病毒, 而且如果其他用户打开了感染病毒的文档, 宏病毒又会转移到他的计算机上。破坏性程序病毒破坏性程序病毒的前缀是: Harm。这类病毒的特性是本身具有好看的图标来诱惑用户点击, 当用户点击病毒时, 病毒便会直接对用户计算机产生破坏。如格式化C 盘(HformatCf) 、杀手命令(HCKiller) 等。系统病毒系统病毒的前缀为:Win32、PE、Win95、W32、W95 等。这些病毒的一般公有的特性是可以感染windows 操作系统的*xe 和*dll 文件,并通过这些文件进行传播。如CIH 病毒。后门病毒后门病毒的前缀是Backdoor。该类病毒的共有特性是通过网络传播, 给系统开后门, 给用户带来安全隐患。捆绑机病毒捆绑机病毒的前缀是: Binder。这类病毒的特性是病毒作者会使用特定的捆绑程序将病毒与一些应用程序如QQ、IE 捆绑起来, 表面上看是正常文件, 当用户运行这些捆绑病毒时, 会表面上运行这些应用程序, 然后隐藏运行捆绑在一起的病毒, 从而给用户造成危害。如: 捆绑QQ(BQQPQQBin) 、系统杀手(Bkillsys) 等。脚本病毒脚本病毒通常是JavaScript 代码编写的恶意代码, 前缀是通常为Spript, 一般带有广告性质, 会修改您的IE 首页、修改注册表等信息,造成用户使用计算机不方便。病毒种植程序病毒这类病毒的公有特性是运行时会从体内释放出一个或几个新的病毒到系统目录下, 由释放出来的新病毒产生破坏。如冰河播种者(DBingH2C) 、MSN 射手(DWSmibag)等。玩笑病毒玩笑病毒的前缀是: Joke。也称恶作剧病毒。这类病毒的特性是本身具有好看的图标来诱惑用户点击,当用户点击这类病毒时, 病毒会做出各种破坏操作来吓唬用户, 其实病毒并没有对用户电脑进行任何破坏。如: 女鬼( JGirlghost) 病毒。木马黑客病毒木马病毒其前缀是: Trojan, 黑客病毒前缀名一般为Hack。公有特性是通过网络或者系统漏洞进入用户的系统并隐藏, 然后向外界泄露用户信息, 黑客病毒则有一个可视的界面, 能对用户的电脑进行远程控制。木马、黑客病毒往往是成对出现的, 木马病毒负责侵入用户的电脑, 而黑客病毒则会通过该木马病毒来进行控制。。一般的木马如QQ消息尾巴木马TQQ3344, 还有大TLMPSW60。病毒名中有PSW或者什么PWD 之类的一般表示这个病毒有盗取密码的功能,一些黑客程序如网络枭雄HNClient 等。
加入这项意见，并形成标签所有JavaServer界面的网页是由一树的组成部分，所谓的看法。观点标签代表的根本的看法。所有JavaServer界面组件标签必须insie一期标签，它的定义是在核心标签库。 该表单标签代表着一种投入的形式组成，这使用户能够输入一些数据，并提交给服务器，通常是通过点击all的UI组件标签的代表可编辑组件（如文本字段和菜单） ，必须在嵌套方形式in至于jsp页，其中一些标签载于表格outputtext ， inputext ， commandbutton ，和讯息。你可以指定一个ID为形式his身份证地图向美联社形式的UI组件放在服务器上。 这一观点，并形成标签补充说，我们可以看到这样的（减去HTML和头部标签） ： … … 加入一个标签组件该outputtext标签代表了he jsp页有两个outputtext 的标签显示he其他标签显示号码10 ： … … 价值属性的标签获得价值，从最低和最高性能的usernumberbean利用价值的表述中，哪些是用来参考的数据储存在其他物体，如see "后盾豆" ，对309页的更多信息，价值表情。 与增补的outputtext标签（加上一些静态文本） ，贺页看起来象如下： … … 加入图像显示图像时，你可以使用graphicimage he urlattribute的标签指明的道路，以形象let奇摩放入杜克至该页面使用graphicimage标签： … … 添加文本该imputtext标签代表一个文本场in该guessnumber举例说，此文本字段需要一个整型输入值的实例此标签列入jsp有三个特质：身份证， laber和价值… … 身份证属性对应的ID的组件对象为代表的这in这种情况下，一个身分属性，是因为所需的信息标签（这是用来显示验证错误信息）的需要，它是指用户没有其它的组件。 标签属性指定的名字被人利用的错误讯息转介给元件。在这个例子中，标签，是一套以用户as为例，如果用户要进入23条的规定，错误信息将被显示的是： 用户号码：确认错误：价值大于所允许的最多10个。 价值属性的结症userno组成价值向bean属性usernumber ，掌握数据进入文本字段 而在加入imputtext标签，迎接页看起来象如下：
海外英语杂志欢迎投稿，详情见我的空间
-_-! 想的很是美美，英语论文就算了，随便找找，还得翻译中文哇天下没那等没事哟~ 祝福LZ呢~
随着互联网的迅速的发展，基于互联网的各种应用日益受到人们的重视，基于Web的考试系统在这种形势下应运而生，它可以利用网络，随时随地对学生进行考试，是传统考场的延伸。本文在基于一般考试系统的设计与实现技术上，结合公务员考试的特点，通过对系统的结构设计、后台设计、前端开发，构建了一个基于B/S三层结构的、以JSP为开发平台和Oracle9i为数据库的公务员考试系统。本系统基本实现了招考信息发布、学生注册报名、单位进行资格审查、管理员对用户及角色进行管理等功能。本公务员考试系统采用的技术较为新奇，在今后的应用将会很广泛。该系统既可以用于政府机关招聘公务员，也可用于各事业单位招聘。Along with the rapid development of the Internet, Web based applications increasingly attention, the test system based on Web in this situation arises at the historic moment, it can use the network to students, anytime, anywhere, is a traditional examination Based on the general test system based on the design and implementation of the technology, combining the characteristics of the civil service examination system, the structure design, development, design, front back to construct a three layers based on B/S structure, with the JSP development platform of Oracle9i and the civil service examination system for This system realizes the recruitment information release, student registration, unit of user credentials, administrator management role and The civil service exam system adopts the technology of the future, in relatively novel application will be very This system not only can be used for civil servants, and can also be used for each business
Information literacy Knowing how to find data from several sources, select relevant material, analyse and organise it into a form that can be used to make Computers have become the tools people use to access and manage Information technologists are people who analyse and design the What is a computer? Tradition definitions of computers include • A machine that accepts data and processes it into use • A computer is a binary, digital, electronic, stored program • While a computer is commonly a digital machine, analogue machine do An electronic device, operating under the control of instructions stored in its own memory unit, that can accept data (input), process data arithmetically and logically, produce results (output) from the processing and stores results for future Many computers receive and send data (communicate) across networks LAN and W A computer system consists of hardware and What is hardware? Hardware Hardware is physical devices or components that can be physically handled – you can thou Input Devices Input devices convert data that humans collect into coded electrical signals that a computer can The central processing unit The electronic processing takes place in the CPU The CPU consists of • A control unit that controls all of the computer’s functions and an • Arithmetic and logical unit (ALU) that performs any calculation Memory Memory holds all programs and What is RAM currently open? Data (notes) Word processor OS Output devices Output devices convert the computer’s electronic signals back into information Secondary storage devices These devices store programs and data The programs and data are not necessarily (or likely to be) in current E DVD CD Communication devices These devices enable a computer to connect to another List the six different type of hardware? Secondary storage(external), input, processor, output , memory, C Name eight pieces of hardware USB, keyboard, monitor, screen, RAM, ROM, VDU, M The system unit and peripheral devices The system unit is the computer Peripheral devices are any devices around the outside, or in other words, plugged into the (back of) the Peripheral devices include the key board, mouse, printer, joy stick and Peripheral devices are any devices around the outside, or in other words, plugged into the (back of) the Peripheral devices include the keyboard, mouse, printer, joy stick and What else does a computer have? Software Software is a computer program ,which is a detailed set of instructions that directs a computer to perform the tasks necessary to process data into These instructions are written in languages that computer can Software includes computer games, a word processing packing, an accounting package, amongst Definition of a computer system • A computer system is the configuration of hardware and software, functioning together, to process data into useful information, in order to achieve a purpose for a human What is data? • Data is raw facts, be they numbers, words, images and sounds, that can be input into a Mary a name is a piece of data What is information? • Information is processed data, that has meaning and is John is a list of names who scored an A grade on an exam John A Chai A Pam A Commodore $23 500 Magna $21 500 Falcon $19 800 The system unit contains the • Motherboard • CPU • Memory • Other electronics It is where the computer program instructions are executed and the data is manipulatedThe Processor CPU The CPU interprets and carries out basic instructions that operate the computer, the CPU contain the • Control unit and the • Arithmetic logic unit Control unit The control unit directs and coordinates the computer’s For every single instruction, the control unit repeats four basic operations, • Fetching • Decoding • Executing • Storing CPU speed The CPU’s speed may be measured in MIPS The number of millions of instructions per second Arithmetic/logic unit The ALU performs all calculations, which involve • Arithmetic operations 2+3 • Comparison operations age>=17 • Logical operations pass Processing instructions A CPU may begin executing a second machine cycle before completing the first-referred to as Current CPU’s can pipeline up to 4 Storage within the CPU Registers temporarily hold data and The computer’s clock A System clock is necessary to control the timing of all computer Each tick of the clock is referred to as a clock Clock speed is the speed at which a processor executes A hertz is one cycle per second and a megahertz is 1024 by1024 and a gigahertz is 1024 by 1024 Memory Memory is the temporary storage place for data and (program) Memory is measured in • Kilobytes 1024 bytes 2^10 • Megabytes 1024* 1024 bytes 2^20 • Gigabytes 1024*1024*1024 bytes 2^30 Representation of data Digital computers are built from many small electronic Each circuit, at any point of time can be turned OFF or ON Hence these devices are called two state Binary Digit 0and 1 Each off or on digital value is called a bit, short for binary A 1 bit computer would be able to distinguish between two values-characters, symbols or Hardly sufficient for the characters on the keyboard Bits Characters 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256
尼玛，最膈应的就是计算机系写英语作文，这不就等于让我们发挥特长，上网上抄吗！
随着互联网的迅速的发展，基于互联网的各种应用日益受到人们的重视，基于Web的考试系统在这种形势下应运而生，它可以利用网络，随时随地对学生进行考试，是传统考场的延伸。本文在基于一般考试系统的设计与实现技术上，结合公务员考试的特点，通过对系统的结构设计、后台设计、前端开发，构建了一个基于B/S三层结构的、以JSP为开发平台和Oracle9i为数据库的公务员考试系统。本系统基本实现了招考信息发布、学生注册报名、单位进行资格审查、管理员对用户及角色进行管理等功能。本公务员考试系统采用的技术较为新奇，在今后的应用将会很广泛。该系统既可以用于政府机关招聘公务员，也可用于各事业单位招聘。Along with the rapid development of the Internet, Web based applications increasingly attention, the test system based on Web in this situation arises at the historic moment, it can use the network to students, anytime, anywhere, is a traditional examination Based on the general test system based on the design and implementation of the technology, combining the characteristics of the civil service examination system, the structure design, development, design, front back to construct a three layers based on B/S structure, with the JSP development platform of Oracle9i and the civil service examination system for This system realizes the recruitment information release, student registration, unit of user credentials, administrator management role and The civil service exam system adopts the technology of the future, in relatively novel application will be very This system not only can be used for civil servants, and can also be used for each business
In 1972, IBM introduced flexible diskettes as a medium for loading programs into mainframe Because the disks were so flexible, they were nicknamed floppy They are inexpensive, small, and easy to handle, store, and send through the Most computers have at least one floppy disk Floppy disks, also called diskettes, are available in two sizes: 5 and 25 For MS-DOS based computers, the 5-inch disks are available in 720-kilobyte (double - density), 44-megabyte (high - density), and 88-megabyte (extended - density) The 25-inch disks have a density of 48 tracks per inch, whereas high-density disks have a density of 96 tracks per Almost all 5-inch floppy disks have a density of 135tracks per The earliest models of floppy disks were single- The addition of another read/write head in the disk drive led to the use of double-sided floppy disk, and doubled the capacity of the Today, all floppy disks are double- If you examine a 5-inch floppy disk, you will see that a metal sleeve covers the read/write When you insert the disk into a disk into a disk drive, the metal sleeve slides back, exposing the read/write The read/write head of the floppy disk drive can position itself over specific Because of the metal sleeve and the rigid plastic casing, the 5-inch floppy disk is less vulnerable to damage than the 25-inch floppy To use the files or programs that are on a floppy disk, you must first insert the disk into a floppy disk Floppy disk drives are commonly referred to as the A drive and the B Check your computer manual to see which drive is A and which is B
Information literacy Knowing how to find data from several sources, select relevant material, analyse and organise it into a form that can be used to make Computers have become the tools people use to access and manage Information technologists are people who analyse and design the What is a computer? Tradition definitions of computers include • A machine that accepts data and processes it into use • A computer is a binary, digital, electronic, stored program • While a computer is commonly a digital machine, analogue machine do An electronic device, operating under the control of instructions stored in its own memory unit, that can accept data (input), process data arithmetically and logically, produce results (output) from the processing and stores results for future Many computers receive and send data (communicate) across networks LAN and W A computer system consists of hardware and What is hardware? Hardware Hardware is physical devices or components that can be physically handled – you can thou Input Devices Input devices convert data that humans collect into coded electrical signals that a computer can The central processing unit The electronic processing takes place in the CPU The CPU consists of • A control unit that controls all of the computer’s functions and an • Arithmetic and logical unit (ALU) that performs any calculation Memory Memory holds all programs and What is RAM currently open? Data (notes) Word processor OS Output devices Output devices convert the computer’s electronic signals back into information Secondary storage devices These devices store programs and data The programs and data are not necessarily (or likely to be) in current E DVD CD Communication devices These devices enable a computer to connect to another List the six different type of hardware? Secondary storage(external), input, processor, output , memory, C Name eight pieces of hardware USB, keyboard, monitor, screen, RAM, ROM, VDU, M The system unit and peripheral devices The system unit is the computer Peripheral devices are any devices around the outside, or in other words, plugged into the (back of) the Peripheral devices include the key board, mouse, printer, joy stick and Peripheral devices are any devices around the outside, or in other words, plugged into the (back of) the Peripheral devices include the keyboard, mouse, printer, joy stick and What else does a computer have? Software Software is a computer program ,which is a detailed set of instructions that directs a computer to perform the tasks necessary to process data into These instructions are written in languages that computer can Software includes computer games, a word processing packing, an accounting package, amongst Definition of a computer system • A computer system is the configuration of hardware and software, functioning together, to process data into useful information, in order to achieve a purpose for a human What is data? • Data is raw facts, be they numbers, words, images and sounds, that can be input into a Mary a name is a piece of data What is information? • Information is processed data, that has meaning and is John is a list of names who scored an A grade on an exam John A Chai A Pam A Commodore $23 500 Magna $21 500 Falcon $19 800 The system unit contains the • Motherboard • CPU • Memory • Other electronics It is where the computer program instructions are executed and the data is manipulatedThe Processor CPU The CPU interprets and carries out basic instructions that operate the computer, the CPU contain the • Control unit and the • Arithmetic logic unit Control unit The control unit directs and coordinates the computer’s For every single instruction, the control unit repeats four basic operations, • Fetching • Decoding • Executing • Storing CPU speed The CPU’s speed may be measured in MIPS The number of millions of instructions per second Arithmetic/logic unit The ALU performs all calculations, which involve • Arithmetic operations 2+3 • Comparison operations age>=17 • Logical operations pass Processing instructions A CPU may begin executing a second machine cycle before completing the first-referred to as Current CPU’s can pipeline up to 4 Storage within the CPU Registers temporarily hold data and The computer’s clock A System clock is necessary to control the timing of all computer Each tick of the clock is referred to as a clock Clock speed is the speed at which a processor executes A hertz is one cycle per second and a megahertz is 1024 by1024 and a gigahertz is 1024 by 1024 Memory Memory is the temporary storage place for data and (program) Memory is measured in • Kilobytes 1024 bytes 2^10 • Megabytes 1024* 1024 bytes 2^20 • Gigabytes 1024*1024*1024 bytes 2^30 Representation of data Digital computers are built from many small electronic Each circuit, at any point of time can be turned OFF or ON Hence these devices are called two state Binary Digit 0and 1 Each off or on digital value is called a bit, short for binary A 1 bit computer would be able to distinguish between two values-characters, symbols or Hardly sufficient for the characters on the keyboard Bits Characters 1 2 2 4 3 8 4 16 5 32 6 64 7 128 8 256
计算机，方面的英语论的
【英文篇名】 Switch Router Operating System Based on a General Operating System 【下载频次】 ☆ 【作者】 潘登; 徐佩霞; 【英文作者】 PAN Deng; XU Pei xia （Department of Electronic Engineering and Information Science; University of Science and Technology of China; Hefei; 230027; China）; 【作者单位】 中国科学技术大学电子工程与信息科学系; 230027; 【文献出处】 数据采集与处理 , Journal of Data Acquisition & Processing, 编辑部邮箱 2003年 04期 期刊荣誉：中文核心期刊要目总览 ASPT来源刊 CJFD收录刊 【中文关键词】 交换式路由器; 通用操作系统; 路由器操作系统; 【英文关键词】 switch router; general operating system; router operating system; 【摘要】 提出了一种将通用操作系统及其上层路由软件移植到交换式路由器平台上的方案。此方案可以向上屏蔽交换式路由器与传统的路由器体系结构上的区别 ,从而把通用操作系统及其上层路由软件移植到交换式路由器的平台上 ;同时兼顾数据通信和管理维护方面的需求 ,为上层路由软件提供了与传统路由器相同的接口 ,从而使基于通用操作系统的路由软件可以在不损失可升级性的条件下快速移植到交换式路由器上。实际应用证实了该方案具有良好的灵活性和兼容性 【英文摘要】 A new solution to port general operating systems and their routing software to switch router is The solution shields the architecture difference between traditional router and switch router to application level software, thus it may support general operating system and their routing software on switch router The solution is also considered as requirements of both data communication and control And same ways of the access and control of the router are provied as traditional 【基金】 国家 8 63计划 ( 863 -3 1 7-0 1 -99)资助项目 【DOI】 CNKI:SUN:SJCJ2003-04-017 【分类号】 TN05 【正文快照】 引 言路由器最重要的工作是根据 IP包头和路由、过滤规则转发 IP包。其他功能还包括路由表的维护与路由器系统的维护。实际上路由器可以看成是一种针对 IP网络路由需求而设计的专用计算机。随着因特网所承载的业务的演进 ,因特网对于路由器性能的要求也日渐提高。在交换式路 看看这一篇 文章编号: 100429037 (2003) 0420450205一种基于通用操作系统的交换式路由器操作系统实现潘 登, 徐佩霞(中国科学技术大学电子工程与信息科学系, 合肥, 230027)摘要: 提出了一种将通用操作系统及其上层路由软件移植到交换式路由器平台上的方案。此方案可以向上屏蔽交换式路由器与传统的路由器体系结构上的区别, 从而把通用操作系统及其上层路由软件移植到交换式路由器的平台上; 同时兼顾数据通信和管理维护方面的需求, 为上层路由软件提供了与传统路由器相同的接口, 从而使基于通用操作系统的路由软件可以在不损失可升级性的条件下快速移植到交换式路由器上。实际应用证实了该方案具有良好的灵活性和兼容性。关键词: 交换式路由器; 通用操作系统; 路由器操作系统中图分类号: TN 915105; TP393 文献标识码:A 基金项目: 国家863 计划(8632317201299) 资助项目 收稿日期: 2003203229; 修订日期: 2003206215Switch Router Operating System Based ona General Operating SystemPA N D eng , X U P ei2x ia(Department of Elect ronic Engineering and Info rmat ion Science,U niversity of Science and Techno logy of Ch ina, Hefei, 230027,Ch ina)Abstract: A new so lu t ion to po rt general operat ing system s and their rou t ing sof tw are tosw itch rou ter is p resen The so lu t ion sh ields the arch itectu re difference betw een t radit ionalrou ter and sw itch rou ter to app licat ion level sof tw are, thu s it may suppo rt general operat ingsystem and their rou t ing sof tw are on sw itch rou ter p latfo The so lu t ion is also con sidered asrequ iremen t s of bo th data commun icat ion and con t ro l funct ion A nd same w ays of the accessand con t ro l of the rou ter are p rovied as t radit ional rou ter, so rou t ing sof tw are of the generaloperat ing system may be po rted to sw itch rou ter p latfo rm rap idly w ith the upgradeab lef lex ib P ract ical design app roves that the so lu t ion has a good compat ib ility and f lex ib Key words: sw itch rou ter; general operat ing system; rou ter operat ing system引 言路由器最重要的工作是根据IP 包头和路由、过滤规则转发IP 包。其他功能还包括路由表的维护与路由器系统的维护。实际上路由器可以看成是一种针对IP 网络路由需求而设计的专用计算机。随着因特网所承载的业务的演进, 因特网对于路由器性能的要求也日渐提高。在交换式路由器中, 包转发等绝大多数处理已经转移到以端口为中心的硬件中完成, 只有路由规则的生成与维护、网络管理和系统维护等比较复杂的工作仍由软件部分完成。实用中路由器所采用的操作系统可分为三大类: (1) 以Cisco 的IO S 为代表的专用操作系统, 常见于网络骨干节点; (2) 以V xWo rk s 为代表的嵌入式系统, 常见于小型办公ö家用接入设备上; (3)采用通用操作系统的则在骨干节点和用户接入设备上都有这类设备。例如Jun iper 的路由产品就采用L inux 作为操作系统。通用操作系统上的各种路由、网管软件的开发已经有相当长时间, 其功能、性能、稳定性和升级灵活性都很优秀, 但这些软件仍第18卷第4期2003 年12 月数据采集与处理Journal of Data A cquisit ion & P rocessingVo 18 N 4D 2003然是针对传统路由器体系结构开发的, 无法直接应用于新的路由器体系结构。本文提出在通用操作系统的驱动栈中插入一个中间层, 这样对系统内核及和运行在其上的路由、网管等上层软件屏蔽了下层硬件的特殊性, 从而把上层软件和高速硬件平台结合起来。该方案已经应用于高速边缘路由器中, 并表现出了良好的实用性和可扩展性。1 交换式路由器与传统路由器在体系结构上的差别路由器工作在网络的第三层, 其处理工作主要涵盖七层模型中的下三层, 包括: 物理接口处理、数据链路层处理、网络层的路由查找、转发以及队列管理等[1 ]。在传统的路由器体系结构中, 硬件部分只实现物理层的处理, 其余工作需要消耗系统计算资源完成: 包括CPU 周期、内存容量和总线带宽等, 因此性能也受限于这些资源。而在交换式路由器中, 路由处理机仅处理系统维护、路由表维护等少量工作, 数据流的处理都由相对独立的硬件完成, 不再受限于系统计算资源, 因此其性能远优于传统路由器[2 ]。如图1 所示。(a) 传统路由器体系结构(b) 交换式路由器体系结构图1 路由器的逻辑结构 传统路由器和交换式路由器在体系结构方面有明显的区别: 在传统路由器中, 所有的物理接口直接挂接在总线上, 内核可以通过总线直接访问这些接口; 而在交换式路由器中, 只有控制卡是直接挂接在总线上的, 内核必须通过控制卡间接访问各个接口。这导致操作系统内核中代表网络接口的驱动对象的区别: 在传统路由器中, 内核存在若干网络设备驱动对象实例, 每个实例通过总线直接维护一个端口, 为内核及其上面的上层软件提供基本操作支持。而在交换式路由器中, 普通的网络设备驱动对象无法直接维护端口, 也无法支持系统内核和上层软件操作。因此, 交换式路由器体系结构的特殊性使得通用操作系统和上层软件无法直接应用。针对这个问题有两种解决办法: (1) 大量修改内核和各种相关软件的源代码以适应新的体系结构。这种做法存在开发工作量大、周期长、局限性强的缺点, 丧失了使用通用操作系统的灵活性; (2) 在驱动栈中增加一个中间层, 支持普通网络驱动对象所能支持的一切操作, 这样系统内核和上层软件基本上不必修改就可以运行在交换式路由器上。这就是本文所提出的中间层方案。这种方案克服了第一种方法的复杂性, 在保持灵活性的基础上, 可以快速地把通用操作系统及上层软件移植到交换式路由器的硬件平台上。2 中间层设计中间层功能包括数据通信和控制两个方面。从数据通信方面考虑, 每个端口的功能都等效于传统路由器中的一个网络接口, 所以每个物理端口在内核中都应有对应的网络驱动实例。这样才能支持各种上层软件运行, 满足数据通信功能的需要。从控制功能方面考虑, 对上要把每一种可能的逻辑操作映射成硬件操作; 对下要能够和多个设备通信。上层应用包括系统维护、路由软件、网管软件; 下层设备包括处理引擎和端口。控制功能的具体实现和硬件平台有关。考虑到多种应用可能同时操作一个硬件设备, 一种应用也可能同时操作多个设备, 在实现时必须考虑到对于多并发操作的支持。基于上述考虑, 中间层由控制卡驱动模块和若干网络驱动实例组成。在图2 (a, b) 中分别给出了传统路由器的结构与驱动方式以及本文所提出的中间层所处的位置与驱动方式。第4 期潘 登, 等: 一种基于通用操作系统的交换式路由器操作系统实现451图2 中间层的位置与驱动方式 控制卡驱动模块作为中间层的核心, 维护控制卡上所有的端口、内存映射、中断和循环缓冲队列资源。它实现了数据通道和控制通道。对下直接驱动控制卡、与各个端口、处理引擎通信; 对上, 一方面通过内核调用陷阱方式提供控制通道接口; 另一方面向虚拟网络驱动实例提供数据通道接口。虚拟网络驱动实例在操作系统内核为各个物理端口实现网络驱动实例。它们工作在控制卡驱动模块的基础上, 并不直接控制硬件, 故称为虚拟网络驱动实例。虚拟网络驱动实例封装控制卡驱动模块提供的数据传输功能, 并为内核和上层软件提供与普通网络驱动实例相同的调用接口。下面分别给出数据通道和控制通道的实现方案。211 数据通道的功能与实现虚拟网络驱动实例和物理端口是一一对应的。内核数据收发的功能包括3 个方面:(1) 发往某虚拟网络驱动实例的数据包应该由其对应端口输出;(2) 这个端口所收到的包也通过该虚拟网络驱动实例向系统内核提交;(3) 中间层也可以对虚拟网络驱动实例进行流控操作, 以避免因拥塞导致数据丢失。注意到图2 (b) 中的交换结构以定长信元交换数据, 其格式如图3 所示, 其中信元头占4 字节, 包括处理引擎号和端口号域。对于收ö发信元, 处理引擎号和端口号分别为该信元的源端口的和目的端口的对应值。根据图2 (b) 所示的系统结构可知: 由处理引擎号和端口号可以确定端口的物理位置。控制卡驱动模块在其内部的驱动信息数组中维护虚拟网络驱动实例和端口之间的对应关系。图3 数据信元结构发送数据时, 虚拟网络驱动实例从内核网络部分获取待发送的数据, 偕同指向该实例自己的指针一起提交给控制卡驱动模块。一方面, 控制卡驱动模块通过这个指针可以对虚拟网络驱动实例进行流控设置; 另一方面, 控制卡驱动模块根据虚拟网络驱动实例指针查驱动信息表得到目标端口物理位置信息, 包括处理引擎号和端口号。端口物理位置信息将被填充到所有用来承载待发送数据包的信元头中。控制卡驱动模块通过控制卡把信元送到交换结构, 而交换结构和处理引擎分别根据处理引擎号和端口号将信元转发到到目标端口。最后端口从接收到的信元中恢复出原始数据发出。接收数据时, 端口也会将数据拆分到若干信元中逐级上传。考虑到交换结构的循环优先机制, 一个数据包上传的过程可能被来自其他端口的数据抢断。所以控制卡驱动模块对于接收到的信元按源端口位置信息(包括处理引擎号和端口号) 保存到不同的缓冲区中。当接收到该数据包相关的全部信元, 控制驱动模块即可重组该数据, 并根据源端口位置信息查驱动信息表以得到指向该端口对应虚拟网络驱动实例的指针, 进而激活该虚拟网络驱动实例接收数据。虚拟网络驱动实例从控制卡驱动模块中获取数据后, 按照网络驱动的常规方式调用net if- rx 接口向内核提交数据。数据收发实现结构如图4 所示。值得注意的是, 在交换式路由器中, 处理引擎通过交换结构交换的是IP 包; 而通用操作系统中452 数据采集与处理第18 卷图4 数据收发实现结构网络驱动通常处理链路层的帧。即控制卡驱动模块数据通道对上对下的数据格式是不同的。因此, 在发送数据时控制卡驱动模块需要从得到的链路帧中提取IP 包再转发到端口; 而接收数据时则对来自端口的IP 包进行链路帧封装再向上提交。以以太网为例, 需要恢复的包括源和目标站的物理地址、载荷类型和帧校验[3 ]。对于承载IP 包的以太帧, 显然其目标站物理地址和载荷类型[4 ]都是已知的。实现时采用的操作系统是L inux, 通过在虚拟网络驱动源代码中进行设置可以使内核不进行帧校验[5 ]。所以只有源站物理地址未知。如果要求硬件给出真实的源站物理地址, 则增加了硬件的复杂度; 而若在控制卡驱动模块中伪造源物理地址, 则可能导致内核的ARP 管理混乱。为简化硬件设计, 实现时采用了在控制卡驱动模块中伪造源物理地址的办法, 同时修改虚拟网络驱动源代码, 重载帧头处理函数[6 ]。这样内核ARP 表就不受伪造地址的影响, 其获取和刷新通过查询端口ARP 记录实现。212 控制通道的功能与实现控制功能的通信也是基于信元的, 其操作包括维护管理和表同步两类。维护管理主要是进行各种查询, 通常通过若干次双向通信完成。每次通信有效载荷都只有几个字节, 由一个信元即可承载。而表同步则是将上层软件维护的表复制到相关硬件中, 包括ARP 表、路由和分类表等。表同步操作涉及大量数据传输, 需要由多个信元承载。控制功能都是针对设备进行的, 所以在控制ö反馈信元中也必须包括目标设备的物理位置信息。在实际运行期间, 所有的上层应用和设备之间的控制通信复用控制通道, 其特点为:(1) 不同的应用可能同时访问同一设备;(2) 一个应用也可能同时访问多个设备;(3) 同一应用对于同一个设备的操作一般都是顺序的。为支持这种复用操作, 所有承载控制信息和反馈信息的头部除包括目标硬件的物理位置和操作指令外, 还包括命令类型、应用类型信息。控制ö反馈用信元结构如图5 所示。图5 控制ö反馈信元结构图5 中: 处理引擎号和端口号, 确定设备的物理位置; 收ö发信元分别为该信元的源端口的和目的端口的对应值; 命令码在设备和应用之间定义。每种可能的操作分配一个代码; 应用码在控制卡驱动模块和上层应用之间预定义。每种可能的应用分配一个代码。这些应用包含网管、路由维护、硬件维护和ARP 信息获取等。上层应用通过内核调用陷井( IOCTL ) 发起控制通道操作, 同时给出目标设备物理位置、命令类型代码和应用类型代码。控制卡驱动模块把这些信息填充到控制信元中再将其发往设备。设备把这些代码直接复制到反馈信元中, 再在后面追加上反馈信息。控制卡驱动模块为每一种应用分配一个循环缓冲区, 把收到的反馈根据应用类型排入相应队列中。上层应用从其所对应的循环缓冲区中读取反馈信元, 然后根据信元中的物理位置信息、命令码就可以确定该反馈对应的原始命令, 从而对反馈数据进行适当处理。这样就实现了各种控制功能对控制通道的复用。如图6 所示。第4 期潘 登, 等: 一种基于通用操作系统的交换式路由器操作系统实现453图6 控制通信实现结构3 结 论鉴于传统路由器体系结构和交换式路由器体系结构的区别, 通用操作系统及在其上开发的路由软件无法直接应用于交换式路由器。本文提出的中间层方案可以有效地解决这个问题。该方案全面考虑了数据通信和管理维护方面的需求, 为上层提供了与原有模型基本相同的接口, 并使得路由软件在不损失其灵活性和可升级性的条件下直接应用于交换式路由器中。虽然该方案只是在特定的平台和特定的操作系统上得到了实现, 但是不难看出, 这种思路对操作系统并没有特殊的依赖性, 完全可以移植到其他通用操作系统上。本文提出的方案已经在国家863 项目实用化综合接入系统的高速边缘路由器的研制中取得了良好的实际效果。本文为国产高性能路由器的软件开发提出了一种高效快捷的解决方案, 该方案具有良好的应用前景。参考文献:[1 ] Kuro se J F, Ro ss KW Computer netwo rk ing: a top2dow n app roach featuring the internet [M ] A ddisonW esley Longman′s P ress, 332～ [ 2 ] 梁阿磊, 等 路由器体系结构及其发展[J ] 小型微型计算机系统, 2001, 8: 943～ [3 ] M edia access cont ro l frame st ructure [S ] IEEE Std80213, 36～ [ 4 ] Charles Ho RFC 894: a standard fo r the t rans2m ission of IP datagram s over Ethernet netwo rk s[S ]198411～ [5 ] Bovet D P U nderstanding L inux kernel[M ] O reil2ley P ress, 683～ 685[ 6 ] Rubini A L inux device 2nd edit ion [M ]O r2eilley P ress, 455～ 458作者简介: 潘 登(19772) , 男, 博士研究生, 研究方向: 网络体系结构、网络安全, E2mail: cn;徐佩霞(19412) , 女, 教授, 博士生导师, 研究方向: 音频视频编码、非线性处理、下一代网络。454 数据采集与处理第18 卷
-_-! 想的很是美美，英语论文就算了，随便找找，还得翻译中文哇天下没那等没事哟~ 祝福LZ呢~
计算机，方面的英语论的
计算机专业英语一抄一大把~
Weliveinthe"computerage"CCForexample,writersusecomputerstowrite,teachersusethemtoteath,PCCT`PS:这篇行吗？是我们学这儿时老师让我们抄的范文，网上搜不到的，打了半天了。。你看看符合要求吗，不行了再说，我那儿还有几篇。。