Chapter 5 – Part 2 Input and Output Computers: Tools for An Information Age
Output: Information for the User Computer screens Printers Voice output Music output Microform
Computer Screen Technology Screen is part of computer’s monitor Screen output known as soft copy temporary Common forms Cathode ray tube (CRT) Flat-panel screens
CRT Screens Display text and graphics Most are in color Graphics card converts signals from the control unit into the image the user sees
Factors Affecting Performance Scan rate The frequency with which the image is refreshed Resolution (clarity) of screen Measured in pixels (picture elements) The more pixels, the higher the resolution Dot pitch The amount of space between dots The smaller the dot pitch, the sharper the image Video memory A high-speed form of RAM installed on graphics card
Graphic Standards Agree on resolutions, colors, other issues related to displaying graphics Super Video Graphics Adapter (SVGA) is most common standard Provides 800 (horizontal) x 600 (vertical) pixels on the display Support 16 million colors The number of colors that can be displayed depends on amount of video memory
Flat-Panel Screens Liquid crystal display (LCD) Very thin (only a few inches) Produce sharper text images than CRTs Easier on eyes than CRTs Flat-panel technologies
LCD Technologies Active-matrix Passive-matrix Gas plasma Uses many thin-film transistors (TFT) Produces brighter image and can be viewed from wider angles Passive-matrix Uses fewer transistors Cheaper and uses less power Gas plasma Supports very large displays Has brilliant color display Viewable at very wide angles
Printers Produce information on paper output Orientation settings Printed output known as hard copy Orientation settings Portrait - vertical alignment Landscape - horizontal alignment Two ways of printing Impact printer Nonimpact printer
Impact Printers Physical contact with paper required to produce image Dot-matrix printer Has print head consisting of one or more columns of pins Pins form characters and images as pattern of dots
Nonimpact Printers Places an image on a page without physically touching it Laser printer Uses light beam to help transfer images to paper Produces high-quality output at very fast speeds Ink-jet printer Sprays dots of ink Less expensive than laser printers
Voice Output Converts data to vocalized sounds Used in automated telephone-based customer service applications
Music Output Multimedia clips, games, videos include sight and sound Speakers placed on side of monitor
Computer Output Microform (COM) Output of photographically reduced images on microfilm Common use Libraries store back issues of magazines, newspapers, etc.
Terminals Combine input and output capabilities Dumb terminal Keyboard for input and monitor for output No processing capability Intelligent terminal Has limited memory and a processor
Computer Graphics Business graphics Video graphics Computer-aided design (CAD)
Business Graphics A powerful way to display information Colorful graphics, maps, and charts help managers compare data, and make quicker decisions As underlying data changes, charts and graphs are instantly updated
Terminals Combine input and output capabilities Dumb terminal Keyboard for input and monitor for output No processing capability Intelligent terminal Has limited memory and a processor
Video Graphics A series of video images Used extensively in television Displayed rapidly to give the impression of motion Used extensively in television Also used in computer and arcade video games
Computer-Aided Design (CAD) Creates two- and three-dimensional (2D and 3D designs) Serves as bridge between design and manufacturing