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
一般要求是1w字以上的，本科的话最好2W字，我看我同学都是写6-2w左右的，每个学校，每个老师要求都不一样，你最好是问一下你的指导老师
紧接着相信不少人会在拿到毕设的题目之后，开始思考着该如何下手去写，用哪些编程语言会比较好，在这里我详细介绍一下Java （一）Java的编程原理：Java语言编写的源程序在计算机上需要经过编译和解释执行两个严格区分的阶段。Java的编译源程序先将Java源程序翻译成与机器无关的节码（bytecode），不是通常的编译程序将源程序翻译成特定计算机的机器代码。运行时系统装载和链接需要执行的类，并做必须的优化后，解释执行字节码程序。 （二）Java的四大核心技术：一、Java虚拟机；二、类装载器的体系结构；三、Java class文件；四、Java API。 （三）Java的优势：Java是一种纯面向对象的语言。《Java编程思想》中提到Java语言是一种“Everything is object”的语言，它能够直观反映我们现实生活中的对象，例如房子、动物等，因此通过它编写程序更容易。2、平台无关性。Java语言可以做到“一次编译，到处执行”。无论是在Windows平台还是在Linux、MacoS等其他平台上对Java程序进行编译，编译后的程序在其他平台上都可以正常运行。由于Java是解释性语言，编译器会将Java代码变成“中间代码”，然后在Java虚拟机（Java Virtual Machine，即JVM）上解释执行。由于中间代码与平台无关，因此Java语言可以很好的跨平台执行，具有很好的可移植性。3、Java提供了很多内置的类库，通过这些类库，简化了开发人员的程序设计工作，同时缩短了项目的开发时间，例如，Java语言提供了对多线程的支持，提供了对网络通信的支持，最主要的是提供了垃圾回收器，这使得开发人员从内存的管理中解脱出来。4、提供了对Web应用开发的支持。例如，Applet、Servlet和JSP可以用来开发Web应用程序；Socket、RMI可以用来开发分布式应用程序。5、具有良好的安全性和健壮性。Java语言经常被用在网络环境中，为了增强程序的安全性，Java语言提供了一个防止恶意代码攻击的安全机制（数组边界检测和Bytecode校验等）。Java的强类型机制、垃圾回收器、异常处理和安全检查机制使得用Java语言编写的程序具有很好的健壮性。6、去除了C++语言中一些难以理解、容易使人混淆的特性，如头文件、指针、结构、单元、运算符重载、虚拟基础类、多重继承等，让程序变得更加严谨简洁。 (四）Java缺点：解释型语言，运行速度效率极低，不支持底层操作，没有C和C++快Java一般都不用于建立大型项目。 取消了指针操作，不够C语言那样灵活。 使用JAVA能够运用在如图所示
计算机病毒论文 计算机病毒是一个程序,一段可执行码。就像生物病毒一样,计算机病毒有独特的复制能力。计算机病毒可以很快地蔓延,又常常难以根除。它们能把自身附着在各种类型的文件上。当文件被复制或从一个用户传送到另一个用户时,它们就随同文件一起蔓延开来。 除复制能力外,某些计算机病毒还有其它一些共同特性:一个被污染的程序能够传送病毒载体。当你看到病毒载体似乎仅仅表现在文字和图象上时,它们可能也已毁坏了文件、再格式化了你的硬盘驱动或引发了其它类型的灾害。若是病毒并不寄生于一个污染程序,它仍然能通过占据存贮空间给你带来麻烦,并降低你的计算机的全部性能。 可以从不同角度给出计算机病毒的定义。一种定义是通过磁盘、磁带和网络等作为媒介传播扩散, 能“传染”其他程序的程序。另一种是能够实现自身复制且借助一定的载体存在的具有潜伏性、传染性和破坏性的程序。还有的定义是一种人为制造的程序, 它通过不同的途径潜伏或寄生在存储媒体(如磁盘、内存)或程序里。当某种条件或时机成熟时, 它会自生复制并传播, 使计算机的资源受到不同程序的破坏等等。这些说法在某种意义上借用了生物学病毒的概念, 计算机病毒同生物病毒所相似之处是能够侵入计算机系统和网络, 危害正常工作的“病原体”。它能够对计算机系统进行各种破坏, 同时能够自我复制, 具有传染性。所以, 计算机病毒就是能够通过某种途径潜伏在计算机存储介质(或程序)里, 当达到某种条件时即被激活的具有对计算机资源进行破坏作用的一组程序或指令集合。 与生物病毒不同的是几乎所有的计算机病毒都是人为地故意制造出来的, 有时一旦扩散出来后连编者自己也无法控制。它已经不是一个简单的纯计算机学术问题, 而是一个严重的社会问题了。 几年前,大多数类型的病毒主要地通过软盘传播,但是,因特网引入了新的病毒传送机制。随着现在电子邮件被用作一个重要的企业通信工具,病毒就比以往任何时候都要扩展得快。附着在电子邮件信息中的病毒,仅仅在几分钟内就可以侵染整个企业,让公司每年在生产损失和清除病毒开销上花费数百万美元。 今后任何时候病毒都不会很快地消失。按美国国家计算机安全协会发布的统计资料,已有超过10,000种病毒被辨认出来,而且每个月都在又产生200种新型病毒。为了安全,我们说大部分机构必须常规性地对付病毒的突然爆发。没有一个使用多台计算机的机构,可以是对病毒免疫的。 计算机病毒是在什么情况下出现的? 计算机病毒的产生是计算机技术和以计算机为核心的社会信息化进程发展到一定阶段的必然产物。它产生的背景是: (1)计算机病毒是计算机犯罪的一种新的衍化形式 计算机病毒是高技术犯罪, 具有瞬时性、动态性和随机性。不易取证, 风险小破坏大, 从而刺激了犯罪意识和犯罪活动。是某些人恶作剧和报复心态在计算机应用领域的表现。 (2)计算机软硬件产品的危弱性是根本的技术原因 计算机是电子产品。数据从输入、存储、处理、输出等环节, 易误入、篡改、丢失、作假和破坏;程序易被删除、改写;计算机软件设计的手工方式, 效率低下且生产周期长;人们至今没有办法事先了解一个程序有没有错误, 只能在运行中发现、修改错误, 并不知道还有多少错误和缺陷隐藏在其中。这些脆弱性就为病毒的侵入提供了方便。 (3)微机的普及应用是计算机病毒产生的必要环境 1983年11月3日美国计算机专家首次提出了计算机病毒的概念并进行了验证。几年前计算机病毒就迅速蔓延, 到我国才是近年来的事。而这几年正是我国微型计算机普及应用热潮。微机的广泛普及, 操作系统简单明了, 软、硬件透明度高, 基本上没有什么安全措施, 能够透彻了解它内部结构的用户日益增多, 对其存在的缺点和易攻击处也了解的越来越清楚, 不同的目的可以做出截然不同的选择。目前, 在IBM PC系统及其兼容机上广泛流行着各种病毒就很说明这个问题。 计算机病毒的来源有哪些? (1)搞计算机的人员和业余爱好者的恶作剧、寻开心制造出的病毒, 例如象圆点一类的良性病毒。 (2)软件公司及用户为保护自己的软件被非法复制而采取的报复性惩罚措施。因为他们发现对软件上锁, 不如在其中藏有病毒对非法拷贝的打击大, 这更加助长了各种病毒的传播。 (3)旨在攻击和摧毁计算机信息系统和计算机系统而制造的病毒----就是蓄意进行破坏。例如1987年底出现在以色列耶路撒冷西伯莱大学的犹太人病毒, 就是雇员在工作中受挫或被辞退时故意制造的。它针对性强, 破坏性大, 产生于内部, 防不胜防。 (4)用于研究或有益目的而设计的程序, 由于某种原因失去控制或产生了意想不到的效果。 参考资料: 还有很多: 自己看吧
要看是哪种类型的毕业论文 本科毕业论文,字数:文科的,5000-12000字,工科的里面有些图表,字数不一定这么多,但是页数一般是25页左右 。
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
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
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计算机，方面的英语论的
内容提要：本文就机房管理中如何最大限度给学生提供个性化学习空间，如何更高效地管理机房计算机介绍了七种实用技术方法。关键词：硬盘拷贝、 硬盘还原、 网络拷贝、 多重引导、 虚拟光驱、终端服务、桌面共享摘 要： 机械制图与计算机辅助设计CAD整合式教学具有学用结合、提高教学效果及绘图效率、培养的人才适应社会需要等优点。本文就机械制图与计算机辅助设计CAD两门课程整合的教学改革进行探讨和研究。……关键词： 机械制图、计算机辅助设计CAD、教学改革、二维绘图、三维绘图