計算機專業(yè)英語閱讀材料（2）

　　計算機英語(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網(wǎng);阿帕網(wǎng)

　　ARPAnet系一種廣域網(wǎng)(WAN),一種連接整個美國的國防部研究機構(gòu)的網(wǎng)絡(luò)。它是由美國高級研究規(guī)劃署(ARPA)提供資金,于1969年創(chuàng)建的。ARPA網(wǎng)作為開發(fā)TCP/IP(一種使互連網(wǎng)成為可能的協(xié)議)的試驗臺,在70年代的早期到中期就進行了不斷的研究和開發(fā)。ARPA網(wǎng)項目的主要目標是通過能夠在各種實際不相似的媒介(包括衛(wèi)星)上進行通信來提高軍事指揮與控制的能力。一個相關(guān)聯(lián)的目標是建立一種能夠耐受故障(諸如那些可能由核交換導致的故障)的健壯網(wǎng)絡(luò)。ARPA網(wǎng)滿足了這些要求,但也令其創(chuàng)建者驚奇的是,立即就發(fā)現(xiàn)大多數(shù)ARPA網(wǎng)用戶更愿意將該網(wǎng)用于通信,如電子郵件和討論組。最初,ARPA網(wǎng)僅用于政府研究機構(gòu)和持有國防部研究合同的大學。1983年,ARPA網(wǎng)被分成高安全性軍事網(wǎng)(Milnet)和作為一個研究和開發(fā)網(wǎng)絡(luò)而重建的ARPA網(wǎng)。盡管ARPA網(wǎng)構(gòu)成了因特網(wǎng)的基礎(chǔ),但它最終于1990年退役。

　　計算機英語(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

　　由于錯誤、刪除或圖形軟硬件中的局限性,而使圖像失真以后留存在屏幕上的一種不想要的圖形,通常很小。假象可能會造成像素丟失或組合到一起。當錄像帶質(zhì)量低劣(例如,如果金屬粒子從磁帶上脫落)或當解壓縮出現(xiàn)故障時,就會出現(xiàn)其他類型的假象。

　　計算機英語(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.

　　訪問站點

　　網(wǎng)絡(luò)上的位置,用戶可從那里找到數(shù)據(jù)或程序。每個站點都有一個唯一的名稱。例如,華盛頓大學州立圖書館有一個存儲在特殊計算機上的檔案數(shù)據(jù)庫,它可由登錄到因特網(wǎng)上訪問并輸入"wuarchive.wust1.edu."這個域名的某個人訪問。佛羅里達州的一位女士或北京的一位先生可各自從該數(shù)據(jù)庫中檢索他們所需要的文件。一個站點的地址一般告訴什么機構(gòu)在提供這些數(shù)據(jù)。