【正文】 攀枝花學(xué)院本科畢業(yè)設(shè)計(jì)（論文） 外語(yǔ)文翻譯 攀枝花學(xué)院本科畢業(yè)設(shè)計(jì)（論文） 外文譯文 院 （系）： 機(jī)電工程學(xué)院 專 業(yè)： 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 姓 名： 賀 兵 學(xué) 號(hào)： ZJD02078 指導(dǎo)教師評(píng)語(yǔ)： 簽名： 年 月 日 攀枝花學(xué)院本科畢業(yè)設(shè)計(jì)（論文） 外語(yǔ)文翻譯 1 外語(yǔ)文獻(xiàn)翻譯 原文： HARDWARE Computers There are two major types of hardware used in a CAD system. Computer and input/output (I/O) devices. In the early days of CAD. Some mercial CAD systems used proprietary puters. Today, nearly all CAD software runs on a generalpurpose puter. Depending on the plexity of the CAD package, it may require a mainframe puter, a miniputer, or simply a microputer. In general, the more functionalities a CAD system provides, the more powerful the puter needed. Three dimensional solid modelers require much more puting than do twodimensional drafting systems。 thus, they need more powerful puters. Systems that integrate engineering analysis or simulation packages generally are more putationintensive. A powerful puter not only speeds up the response of a CAD system, but also can support multiple users without significant performance degradation. Several other parameters and ponents concerning the puter also have to be considered. CAD HARDWARE randomaccess memory (RAM)capacity permanent diskstorage capacity special graphics accelerator tape backups RAM is the actual physical memory (vs. virtual memory)of a puter. A small memory capacity means slow processing due to frequent swapping between the physical memory and the virtual memory on disk. Because CAD is extremely storage demanding, disk capacity is important. Small disk capacity limits the system to the storage of only a few drawings. CAD is graphicsbased and requires tremendous data processing. A graphics accelerator can drastically increase the performance of the system. Another ponent, the hard disk, is typically the major cost of a puter system. Therefore, it is not costjustifiable to store all drawings on line on disk. Magic tape is still the most economical medium to use for offline data storage. It is necessary for a CAD system to have a tape backup subsystem. Currently, all levels of puters are used in CAD systems. Personal puters are used in lowcost,2D drafting applications, and with the new power of these puters, hey are also being used for some 3D solid modeling applications. Engineering workstations have been the mainstay in CAD, and are usually a singleuser CAD workstation in a work. Miniputers are used in multiuser CAD systems. Mainframes are used for large multiuser CAD systems to support real time simulation and engineering analysis. Sometimes, in a large corporation, all levels 攀枝花學(xué)院本科畢業(yè)設(shè)計(jì)（論文） 外語(yǔ)文翻譯 2 of CAD systems are implemented. All these systems are linked together through a hierarchical puter work. Input. Output (I/O)Devices Figure shows the typical I/O devices used in a CAD system. Input devices are generally used to transfer information from a human or storage medium to a puter where ”CAD functions” are carried out. A keyboard is the standard input device used to transmit alphanumeric data to the system. Function keypads are also used to make input easier. Joysticks, track balls, and mousse are also used to manipulate a cursor. They can be used to position the gra