在1972年， IBM推出了灵活的软磁盘作为一个中型载货节目到电脑主机由于磁盘这么灵活的，他们被戏称为软盘。他们是物美价廉，规模小，易于处理，存储，并通过发送邮件。大多数的计算机都至少有一个软盘驱动器。软盘，又称为软盘，有两种规格： 5 25英寸。为MS - DOS的基于计算机， 5英寸磁盘，可在720千字节（双-密度） ， 1 44兆字节（高-密度），以及 88兆字节（扩展-密度）的能力。该25英寸磁盘有一个密度的48铁轨每英寸，而高密度磁盘有一个密度的96铁轨每英寸。几乎所有的5英寸软盘的密度135tracks每英寸。最早型号的软盘被单一片面的。加上另一个读/写头在磁盘驱动导致使用双面软盘，并增加一倍的容量磁盘。今天，所有软盘是双面的如果你研究了5英寸的软盘上，你会看到一个金属套涵盖读/写插槽。当你插入磁盘到磁盘到磁盘驱动器，金属套幻灯片回来，揭露读/写插槽。读/写头的软盘驱动器，可以清楚自己的定位超过特定的轨道。由于金属套筒和僵化的塑料外壳， 5英寸软盘是那么容易受到损害比25英寸软盘。 利用档案或程式，是在软碟上，你必须先插入磁盘到软盘驱动器软盘驱动器通常被称为甲驱动器和乙驱动器。看看哪个驱动器是甲或者乙有译不正之处见谅!
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
What Is Grid Storage? Based on current and proposed products, it appears that a grid storage system should include the following: Modular storage arrays: These systems are connected across a storage network using serial ATA The systems can be block-oriented storage arrays or network-attached storage gateways and Common virtualization layer: Storage must be organized as a single logical pool of resources available to Data redundancy and availability: Multiple copies of data should exist across nodes in the grid, creating redundant data access and availability in case of a component Common management: A single level of management across all nodes should cover the areas of data security, mobility and migration, capacity on demand, and Simplified platform/management architecture: Because common management is so important, the tasks involved in administration should be organized in modular fashion, allowing the autodiscovery of new nodes in the grid and automating volume and file Three Basic Benefits Applying grid topology to a storage network provides several benefits, including the following: R A well-designed grid network is extremely Rather than providing just two paths between any two nodes, the grid offers multiple paths between each storage This makes it easy to service and replace components in case of failure, with minimal impact on system availability or P The same factors that lead to reliability also can improve Not requiring a centralized switch with many ports eliminates a potential performance bottleneck, and applying load-balancing techniques to the multiple paths available offers consistent performance for the entire S It’s easy to expand a grid network using inexpensive switches with low port counts to accommodate additional servers for increased performance, bandwidth and In essence, grid storage is a way to scale out rather than up, using relatively inexpensive storage building
计算机，方面的英语论的
搜索一篇外文数码网站的文章就ok啦
The computer is a product of advanced civilization and its invention, according to some people, signals the advent of a Second Industrial R Formerly a bulky machine that demanded much space, the computer is now becoming smaller and smaller and scientists have made it more sophisticated and accordingly more As is generally known, the computer can do a wide range of work, including complex computation and People now also use it as a teaching aid in An infinite variety of software can be put into the computer, which explains why it is so There is, however, one thing which we should bear in mind: that the computer cannot think but man So there need not be any fear that someday the computer will control us and all we should expect is try our best to bring it to A computer age is not a pipe dream and there will come a day when most of our needs can be met by this wonderful
计算机，方面的英语论的
论文题目（宋体：3号字）基金项目作者姓名、单位、地址、邮编关键词：xxx（宋体，5号字）摘 要：xxx（宋体，5号字，300字以内）正 文：……（宋体，5号字，正文字数不少于2200）参考文献: 按文章中出现的先后顺序列出,给出编号,并在文章中引用的地方上标此编号,注明引文出处、作者、出版社、页码（宋体，5号）
文中引述正确引用作品原文或专家、学者的论述是写好英语论文的重要环节；既要注意引述与论文的有机统一，即其逻辑性,又要注意引述格式（即英语论文参考文献）的规范性。引述别人的观点，可以直接引用，也可以间接引用。无论采用何种方式，论文作者必须注明所引文字的作者和出处。美国学术界通行的做法是在引文后以圆括弧形式注明引文作者及出处。现针对文中引述的不同情况，将部分规范格式分述如下。若引文不足三行，则可将引文有机地融合在论文中。如:The divorce of Arnold's personal desire from his inheritance results in “the familiar picture of Victorian man alone in an alien universe”。被引述的文字如果超过三行，则应将引文与论文文字分开，如下例所示：Whitman has proved himself an eminent democratic representative and precursor, and his “Democratic Vistas”is an admirable and characteristicAnd if one is sorry that in it Whitman is unable to conceive the extreme crises of society, one is certain that no society would be tolerable whoses citizens could not find refreshment in its buoyant democratic idealism。这里的格式有两点要加以注意。一是引文各行距英语论文的左边第一个字母十个空格，即应从第十一格打起；二是引文不需加引号，末尾的句号应标在最后一个词后。若引文出自一部多卷书，除注明作者姓和页码外，还需注明卷号。如：Professor Chen Jia's A History of English Literature aimed to give Chinese readers“a historical survey of English literature from its earliest beginnings down to the 20thcentury”。圆括弧里的1为卷号，小写罗马数字i为页码，说明引文出自第1卷序言(引言、序言、导言等多使用小写的罗马数字标明页码)。如果英语论文中引用了同一作者的两篇或两篇以上的作品，除注明引文作者及页码外，还要注明作品名。如：Bacon condemned Platoas“an obstacle to science”。Farrington points out that Aristotle's father Nicomachus, a physician, probably trained his son in medicine。扩展资料基本要求Clear：思路清晰、概念清楚、层次清楚、表达清楚Complete：内容完整、结构完整匀称，切忌虎头蛇尾，有始无终Correct：科学内容正确（不出错）、资料数据正确（数据可靠、可信）、语言正确（无语法错）Concise：论述深刻、充分揭示其科学内涵、使用定量方法只有克服心理障碍，建立自信心， 熟悉SCI文章的思维方式及语言风格，勇于尝试，才能取得成功！注意事项撰写英语教学论文要有务实的精神。作者要沉得住气、耐得住寂寞，做到严谨、细致、认真，切忌浮躁、冲动、急功近利。要实事求是，深入实际，将教学研究植根于日常教学中。在教学中研究，在研究中提高，不搞闭门造车、坐而论道。我们有些英语教师工作十分勤恳，但平时缺乏积累、疏于动笔，对论文写作望而生畏，不能用大纲、用先进的教育、教学理论武装自己的作品，不注意吸纳他人的成果，使作品成为单纯的经验、感受；或者只谈理论，不能用宝贵的实践经验来证明自己的论点，使作品缺乏说服力。理论与实践相结合是英语教学论文写作应遵循的一项基本原则。第六、英文毕业论文摘要各部分的写作根据《EI》对英文摘要的写作要求，英文摘要的写作并没有一成不变的格式，但一般来说，英文摘要是对原始文献不加诠释或评论的准确而简短的概括并要求它能反映原始文献的主要信息。第七、英语毕业论文——目的（What I want to do?）目的。主要说明作者写作此文的目的，或本文主要解决的问题。一般来说，一篇好的英文摘要，一开头就应该把作者本文的目的或要解决的主要问题非常明确地交待清楚。必要时，可利用论文中所列的最新文献，简要介绍前人的工作，但这种介绍一定要极其简练。在这方面，《EI》提出了两点具体要求：1） Eliminate or minimize background information(不谈或尽量少谈背景信息)。2） Avoid repeating the title or part of the titlein the first sentence of the abstract(避免在摘要的第一句话重复使用题目或题目的一部分）。第八、英语毕业论文——过程与方法(How I did it？)过程及方法。主要说明作者主要工作过程及所用的方法。在英文摘要中，过程与方法的阐述起着承前启后的作用。开头交待了要解决的问题(What I want to do)之后，接着要回答的自然就是如何解决问题(How I did it)，而且，最后的结果和结论也往往与研究过程及方法是密切相关的。大多数作者在阐述过程与方法时，最常见的问题是泛泛而谈、空洞无物，只有定性的描述，使读者很难清楚地了解论文中解决问题的过程和方法。因此，在说明过程与方法时，应结合(指向)论文中的实例、实验框图等来进行阐述，这样可以既给读者一个清晰的思路。第九、英语毕业论文——结果和结论(What results did I get and what conclusionscan I draw?)结果和结论部分代表着论文的主要成就和贡献，英语毕业论文有没有价值，值不值得读者阅读，主要取决于你所获得的结果和所得出的结论。因此，在写作结果和结论部分时，一般都要尽量结合实验结果或仿真结果的图、表、曲线等来加以说明，使结论部分言之有物，有根有据；同时，对那些看不懂中文的英文读者来说，通过这些图表，结合英文摘要的说明就可以比较清楚地了解论文的结果和结论。也只有这样，论文的结论才有说服力。如有可能，在结尾部分还可以将论文的结果和他人最新的研究结果进行比较，以突出论文的主要贡献和创新、独到之处(回答 What is new and original in this paper)。参考资料来源：百度百科-英文论文参考资料来源：百度百科-SCI论文
计算机，方面的英语论的
选择章节标题后，右键-段落-大纲级别设置成一级标题或二级标题。 比如，把第一页做成了第一章节，第二页以后的做做为第二章节。 你在第一页设置一个标题并设置成一级标题，第二页设置一个标题设置成一级标题就可以了。 或者,打开格式中的样式,然后选一个标题1、2、3随意选就行了。可以点击更改，再点击格式-段落、字体更改。扩展资料：古典文学常见论文一词，谓交谈辞章或交流思想。当代，论文常用来指进行各个学术领域的研究和描述学术研究成果的文章，简称之为论文。它既是探讨问题进行学术研究的一种手段，又是描述学术研究成果进行学术交流的一种工具。它包括学年论文、毕业论文、学位论文、科技论文、成果论文等。撰写英文题名的注意事项： 英文题名以短语为主要形式，尤以名词短语最常见，即题名基本上由一个或几个名词加上其前置和(或)后置定语构成;短语型题名要确定好中心词，再进行前后修饰。各个词的顺序很重要，词序不当，会导致表达不准。 一般不要用陈述句，因为题名主要起标示作用，而陈述句容易使题名具有判断式的语义，且不够精炼和醒目。少数情况(评述性、综述性和驳斥性)下可以用疑问句做题名，因为疑问句有探讨性语气，易引起读者兴趣。 同一篇论文的英文题名与中文题名内容上应一致，但不等于说词语要一一对应。在许多情况下，个别非实质性的词可以省略或变动。 国外科技期刊一般对题名字数有所限制，有的规定题名不超过2行，每行不超过42个印刷符号和空格;有的要求题名不超过14个词。这些规定可供我们参考 。 在论文的英文题名中。凡可用可不用的冠词均不用。英语（English）属于印欧语系中日耳曼语族下的西日耳曼语支，由古代从欧洲大陆移民大不列颠岛的盎格鲁、撒克逊和朱特部落的日耳曼人所说的语言演变而来，并通过英国的殖民活动传播到世界各地。根据以英语作为母语的人数计算，英语是最多国家使用的官方语言，英语也是世界上最广泛的第二语言，也是欧盟，最多国际组织和英联邦国家的官方语言之一。但仅拥有世界第三位的母语使用者，少于官话汉语和西班牙语。上两个世纪英国和美国在文化、经济、军事、政治和科学上的领先地位使得英语成为一种国际语言。如今，许多国际场合都使用英语做为沟通媒介。英语也是与电脑联系最密切的语言，大多数编程语言都与英语有联系，而且随着网络的使用，使英文的使用更普及。英语是联合国的工作语言之一。英语（English）作为世界通用语言，是联合国的工作语言之一，也是事实上的国际交流语言。英语属于印欧语系中日耳曼语族下的西日耳曼语支，由古代从欧洲英语大陆移民大不列颠岛的盎格鲁、撒克逊和朱特部落的日耳曼人所说的语言演变而来，并通过英国的殖民活动传播到世界各地。由于在历史上曾和多种民族语言接触，它的词汇从一元变为多元。语法从“多曲折”变为“少曲折”，语音也发生了规律性的变化。根据以英语作为母语的人数计算，英语是世界上最广泛的语言。但它可能是世界上第二大或第四大语言（1999年统计为380,000,000人使用英语），世界上60%以上的信件是用英语书写的，50%以上的报纸杂志是英语的。英语也是与计算机联系最密切的语言，大多数编程语言都与英语有联系，而且随着互联网的使用，使英文的使用更普及。与英语最接近的无疑是弗里西语，这种语言现在仍然在荷兰北部弗里斯兰省中使用，大约有50万个使用者。一些人认为低地苏格兰语是与英语接近的一个独立语言，而一些人则认为它是英语的一个方言。苏格兰语、荷兰东部和德国北部的低地撒克逊语与英语也很接近。其他相关的语言包括荷兰语、南非荷兰语和德语。诺曼人于11世纪征服英国，带来大量法语词汇，很大程度地丰富了英语词汇。
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
What is a Computer?A computer is a programmable The two principal characteristics of a computer are: it responds to a specific set of instructions in a well-defined manner and it can execute a prerecorded list of instructions (a program)Modern Computers DefinedModern computers are electronic and The actual machinery -- wires, transistors, and circuits -- is called hardware; the instructions and data are called All general-purpose computers require the following hardware components:memory: enables a computer to store, at least temporarily, data and ass storage device: allows a computer to permanently retain large amounts of Common mass storage devices include disk drives and tape input device: usually a keyboard and mouse, the input device is the conduit through which data and instructions enter a utput device: a display screen, printer, or other device that lets you see what the computer has al processing unit (CPU): the heart of the computer, this is the component that actually executes In addition to these components, many others make it possible for the basic components to work together For example, every computer requires a bus that transmits data from one part of the computer to Computer Classification, By Size and PowerComputers can be generally classified by size and power as follows, though there is considerable overlap:personal computer: a small, single-user computer based on a In addition to the microprocessor, a personal computer has a keyboard for entering data, a monitor for displaying information, and a storage device for saving workstation: a powerful, single-user A workstation is like a personal computer, but it has a more powerful microprocessor and a higher-quality inicomputer: a multi-user computer capable of supporting from 10 to hundreds of users ainframe: a powerful multi-user computer capable of supporting many hundreds or thousands of users supercomputer: an extremely fast computer that can perform hundreds of millions of instructions per Computer Related Q What is computer history? What is computer hardware? What is computer software? What is computer science? What is computer interface? What is computer history?The history of computer development is often referred to in reference to the different generations of computing Each of the five generations of computers is characterized by a major technological development that fundamentally changed the way computers The history of computer development is often referred to in reference to the different generations of computing Each of the five generations of computers is characterized by a major technological development that fundamentally changed the way computers operate, resulting in increasingly smaller, cheaper, more powerful and more efficient and reliable computing In this Webopedia reference article you'll learn about each of the five generations of computers and the technology developments that have led to the current devices that we use Our journey starts in 1940 with vacuum tube circuitry and goes to the present day -- and beyond -- with artificial Related Webopedia Definitions: computer, magnetic drums, binary, integrated circuit, semiconductor, nanotechnologyFirst Generation (1940-1956) Vacuum TubesThe first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of First generation computers relied on machine language, the lowest-level programming language understood by computers, to perform operations, and they could only solve one problem at a Input was based on punched cards and paper tape, and output was displayed on The UNIVAC and ENIAC computers are examples of first-generation computing The UNIVAC was the first commercial computer delivered to a business client, the US Census Bureau in A UNIVAC computer at the Census BureauA UNIVAC computer at the Census BImage Source: United States Census BureauSecond Generation (1956-1963) TransistorsTransistors replaced vacuum tubes and ushered in the second generation of The transistor was invented in 1947 but did not see widespread use in computers until the late The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum Second-generation computers still relied on punched cards for input and printouts for Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core The first computers of this generation were developed for the atomic energy Third Generation (1964-1971) Integrated CircuitsThe development of the integrated circuit was the hallmark of the third generation of Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their Fourth Generation (1971-Present) MicroprocessorsThe microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon What in the first generation filled an entire room could now fit in the palm of the The Intel 4004 chip, developed in 1971, located all the components of the computer—from the central processing unit and memory to input/output controls—on a single In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the M Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the I Fourth generation computers also saw the development of GUIs, the mouse and handheld Fifth Generation (Present and Beyond) Artificial IntelligenceFifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used The use of parallel processing and superconductors is helping to make artificial intelligence a Quantum computation and molecular and nanotechnology will radically change the face of computers in years to The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self- What is computer hardware?Hardware refers to objects that you can actually touch, like disks, disk drives, display screens, keyboards, printers, boards, and In contrast, software is Software exists as ideas, concepts, and symbols, but it has no Books provide a useful The pages and the ink are the hardware, while the words, sentences, paragraphs, and the overall meaning are the A computer without software is like a book full of blank pages -- you need software to make the computer useful just as you need words to make a book What is computer software?Software means computer instructions or Anything that can be stored electronically is software, in contrast to storage devices and display devices which are called The terms software and hardware are used as both nouns and For example, you can say: "The problem lies in the software," meaning that there is a problem with the program or data, not with the computer You can also say: "It's a software "The distinction between software and hardware is sometimes confusing because they are so integrally Clearly, when you purchase a program, you are buying But to buy the software, you need to buy the disk (hardware) on which the software is Categories of SoftwareSoftware is often divided into two Systems software includes the operating system and all the utilities that enable the computer to Applications software includes programs that do real work for For example, word processors, spreadsheets, and database management systems fall under the category of applications What is computer science?Computer science is the study of computers, including both hardware and software Computer science is composed of many broad disciplines, including artificial intelligence and software Most universities now offer bachelor, master, and doctorate degrees in computer What is computer interface?Interface is a boundary across which two independent systems meet and act on or communicate with each In computer technology, there are several types of user interface - the keyboard, mouse, menus of a computer The user interface allows the user to communicate with the operating Also see GUIsoftware interface - the languages and codes that the applications use to communicate with each other and with the hardware interface - the wires, plugs and sockets that hardware devices use to communicate with each
What Is Grid Storage? Based on current and proposed products, it appears that a grid storage system should include the following: Modular storage arrays: These systems are connected across a storage network using serial ATA The systems can be block-oriented storage arrays or network-attached storage gateways and Common virtualization layer: Storage must be organized as a single logical pool of resources available to Data redundancy and availability: Multiple copies of data should exist across nodes in the grid, creating redundant data access and availability in case of a component Common management: A single level of management across all nodes should cover the areas of data security, mobility and migration, capacity on demand, and Simplified platform/management architecture: Because common management is so important, the tasks involved in administration should be organized in modular fashion, allowing the autodiscovery of new nodes in the grid and automating volume and file Three Basic Benefits Applying grid topology to a storage network provides several benefits, including the following: R A well-designed grid network is extremely Rather than providing just two paths between any two nodes, the grid offers multiple paths between each storage This makes it easy to service and replace components in case of failure, with minimal impact on system availability or P The same factors that lead to reliability also can improve Not requiring a centralized switch with many ports eliminates a potential performance bottleneck, and applying load-balancing techniques to the multiple paths available offers consistent performance for the entire S It’s easy to expand a grid network using inexpensive switches with low port counts to accommodate additional servers for increased performance, bandwidth and In essence, grid storage is a way to scale out rather than up, using relatively inexpensive storage building
下英语论文除了专业数据库一般还有三个地方：
计算机专业英语论文及翻译，有的
ink that what is making them achieve that success and then work on those areas and try to gain that