Unit 2 Computer Hardware

rolls on 滚滚向前

censor[5sensE] vt. 检查 cursor[5kE:sE] n. 光标

monochrome[5mCnEkrEum] adj. 单色的，黑白的

dumb terminal 哑终端 intelligent terminal 智能终端

hammering[5hAmEriN] n.捶打，捶打的声音

ribbon[5ribEn] n（打印机的）.色带

Mouse：Mouse is an input device that is used with personal computer. It rolls on a small ball and has two or three buttons on the top. When you roll the mouse across a flat surface, the screen censors the mouse in the direction of mouse movement. The cursor moves very fast with mouse giving you more freedom to work in any direction. It is easier and faster to move through a mouse.

Scanner：Scanner is an optical device that can input any graphical matter and display it back. The common optical scanner devices are Magnetic Ink Character Recognition (MICR), Optical Mark Reader (OMR) and Optical Character Reader (OCR).

Output Device

An output device is any piece of computer hardware equipm- ent used to communicate the results of data processing carried out by a computer to the outside world.

Visual Display Unit：The most popular output device is the Visual Display Unit (VDU). It is also called the monitor. A keyboard is used to input data and monitor is used to display the input data and to receive massages from the computer. A monitor has its own box which is separated from the main computer system and is connected to the computer by cable. In some systems it is compact with the system unit. It can be color or monochrome.

Terminals：It is a very popular interactive input/output unit. It can be divided into two types:hard copy terminals and soft copy terminals. A hard copy terminal provides a printout on paper whereas soft copy terminals provides visual copy on monitor. A terminal when connected to a CPU sends instructions directly to the computer. Terminals are also classified as dumb terminals or intelligent terminals depending upon the work situation.

Printer：It is an important output device which can be used to get a printed copy of the processed text or result on paper. There are different types of printers that are designed for different types of applications. Depending on their speed and approach of printing, printers are classified as impact and non-impact printers. Impact printers use the familiar typewriter approach of hammering a typeface against the paper and inked ribbon. Dot-matrix printers are of this type. Non-impact printers do not hit or impact a ribbon to print. They use electro-static chemicals and ink-jet technologies.

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