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Lecture 3: Input and Output Devices. Computer Literacy Bishop Alemany High School Summer Session. Input Devices. input –The first stage of in formation processing; consists of data and programs that are fed into the computer system
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Lecture 3: Input and Output Devices Computer Literacy Bishop Alemany High School Summer Session
Input Devices • input –The first stage of information processing; consists of data and programs that are fed into the computer system • input devices –hardware components that capture, collect, and transmit data and programs in a way that the computer can understand
Input Devices keyboard • GUI (graphical user interface) • Mouse • Joysticks • Touch screens • Scanner • Voice Input • Video Capture
Output Devices • Output – processed data; usually text, graphics, or sound that can be immediately used by people or stored by the computer for later use. • Two types of output 1. Hard copy – recorded on a tangible medium (paper) 2. Soft copy – temporary version (monitor screen)
Printers • 2 types of Printers: 1. Impact printers – creates text and graphics by physically striking the paper; inkjet 2. Non–Impact printers – melts toner powder onto paper like a copy machine;laser printers
Monitors • The clarity of images displayed on the monitor is directly related to pixel density and screen resolution • Pixel Density – is measured by the number of pixels across the screen and the number of pixels down the screen • the higher the pixel density, the better looking the image since there are more pixels! • Screen Resolution - common sizes: 640 x 480, 1024 x 728, 1280 x 1024
Monitors – (continued) • CRT = Cathode Ray Tube – glass casing, vacuum tube • LCD = Liquid Crystal Display – each pixel is illuminated by three separate LCD glass panels (red, blue, green) • DLP = each pixel is illuminated by a DLP chip which contains a reflective surface made up of thousands of tiny mirrors; • PLASMA = each pixel is illuminated by tiny fluorescent lights (red, green and blue) to form an image
High vs. Standard Definition • All screens “refresh” the picture in one of two ways: 1. Interlaced – an analog signal; lines are refreshed in two fields, “odds” and “evens”, one after the other 2. Progressive – a digital signal; all lines are refreshed at the same time resulting in a clearer picture • Standard Definition = 480i (interlaced) • Hi Definition = 480p, 720p, 1080i, 1080p (progressive)