计算机专业英语阅读材料（2）

　　计算机英语(21)

　　ARPAnet

　　A wide area network (WAN) .A network that connected Department of Defense research sites across America. Created in 1969 with funding from the Advanced Research Projects Agency (ARPA) .Undergoing constant research and development in the early-to mid-1970s,ARPAnet served as the test bed for the development of TCP/IP( the protocols that make the Internet possible ).A Major goal of the ARPAnet project was to increase the military's command and control capability by enabling communication across a variety of physically dissimilar media ,including satellites .An allied goal was to create a robust network capable of withstanding outages ,such as those that might result from a nuclear exchange .ARPAnet met these objectives ,but it also surprised its creators :It was found in short order that most ARPAnet users preferred to use the network for communication ,such as electronic mail and discussion groups .Initially ,the ARPAnet was available only to government research institutes and to universities holding Department of Defense (DoD) research contracts .In 1983,ARPAnet was divided into a high-security military network (Milnet )and an ARPAnet that was recast as a research and development network .Although it formed the foundation of the Internet ,it was decommissioned in 1990.

　　ARPA网;阿帕网

　　ARPAnet系一种广域网(WAN),一种连接整个美国的国防部研究机构的网络。它是由美国高级研究规划署(ARPA)提供资金,于1969年创建的。ARPA网作为开发TCP/IP(一种使互连网成为可能的协议)的试验台,在70年代的早期到中期就进行了不断的研究和开发。ARPA网项目的主要目标是通过能够在各种实际不相似的媒介(包括卫星)上进行通信来提高军事指挥与控制的能力。一个相关联的目标是建立一种能够耐受故障(诸如那些可能由核交换导致的故障)的健壮网络。ARPA网满足了这些要求,但也令其创建者惊奇的是,立即就发现大多数ARPA网用户更愿意将该网用于通信,如电子邮件和讨论组。最初,ARPA网仅用于政府研究机构和持有国防部研究合同的大学。1983年,ARPA网被分成高安全性军事网(Milnet)和作为一个研究和开发网络而重建的ARPA网。尽管ARPA网构成了因特网的基础,但它最终于1990年退役。

　　计算机英语(22)

　　Artifact

　　An unwanted graphic ,usually small ,that remains on a screen after an image is distorted by a mistake ,omission ,or limitation in graphics software or hardware .Artifacts may cause pixels to be dropped or to clump together .Other types of artifacts occur when the quality of a videotape is poor (if metal particles flake off the tape ,for example )or when decompression is faulty.

　　假象

　　由于错误、删除或图形软硬件中的局限性,而使图像失真以后留存在屏幕上的一种不想要的图形,通常很小。假象可能会造成像素丢失或组合到一起。当录像带质量低劣(例如,如果金属粒子从磁带上脱落)或当解压缩出现故障时,就会出现其他类型的假象。

　　计算机英语(23)

　　Access Site

　　Location on a network where users can find data or programs .Each site has a unique name .For example ,at Washington University State Library ,there is an archive database stored on a particular computer .It can be accessed by someone who has logged onto the Internet and entered the name "wuarchive.wustl.edu." A woman in Florida or a man in Beijing can each retrieve the files they need from the database .A site's address generally says something about what kind of organization is offering the data.

　　访问站点

　　网络上的位置,用户可从那里找到数据或程序。每个站点都有一个唯一的名称。例如,华盛顿大学州立图书馆有一个存储在特殊计算机上的档案数据库,它可由登录到因特网上访问并输入"wuarchive.wust1.edu."这个域名的某个人访问。佛罗里达州的一位女士或北京的一位先生可各自从该数据库中检索他们所需要的文件。一个站点的地址一般告诉什么机构在提供这些数据。