Components of Computer

Output The data that has been processed into useful information is called output. Types –Screen – soft copy –Printer – hard copy –Sound –Graphics

3 Output Devices Output devices are peripheral devices that enable users to view or hear the computer’s processed data Visual output – Text, graphics, and video Audio output – Sounds, music, and synthesized speech

4 Visual Display System A visual display system is composed of two parts: – Video adapter – Responsible for video quality – Monitor – Displays the video adapter’s output

5 Video Adapter A video adapter is also called display adapter, video card, or graphics card –It consists of circuit board which is attached to motherboard –It contains memory called video RAM (VRAM), VRAM send screen full of data to the monitor. –It is designed to work with digital or analog monitors –It determines a monitor’s maximum resolution (VGA/Super VGA) – It determines a monitor’s refresh rate 3D graphics adapter – Enables 3-dimensional images Multi-display video adapter – Permits a connection of two monitors at a time

Monitor Data that is entered appears on the screen Screen is part of the monitor

Monitor 1.Cathode Ray Tube (CRT) 2.Flat panel display 3.Liquid Crystal Display (LCD)

CRT Color vs. Monochrome Color –Typical monitor sold today –Display between 16 colors and 16 million colors Monochrome –Display output in single color –Less expensive than color –Used for text only displays

CRT Monitors

Flat-panel Screens Liquid Crystal Display (LCD) Primarily on laptops Moving to desktop Skinny (depth) regardless of size

Flat-Panel Screen Disadvantages: Images can be difficult to see in bright light. Limited viewing angle that is the angle from which the display image can be viewed clearly.

Comparing Monitors Size Resolution Refresh rate Dot pitch

Comparing Monitors Size With a larger monitor, you can make the objects on the screen appear bigger or you can fit more of them on the screen. Resolution It is determined by number of pixels on the screen expressed as a matrix.

Comparing Monitors Refresh rate 1.Number of times per second that the electron gun scan every pixel on the screen. 2.Screen appears to flicker if its not refresed often enough. 3.It is measured in Hertz,cycles per second. 72 Hz or higher should not cause eyestrain. Dot pitch 1.It is the distance between the phophors dots that make up a single pixel. 2.In color monitor each pixel includes three dots, red, green and blue. 3.If the dots are not close enough together, the images on the screen will not be crisp 4.Dot pitch should be less than 0.28mm

Printer Produces information on paper Orientation –Portrait –Landscape Methods of printing –Impact –Non-impact Portrait Landscape

Impact Printers Line printer One line at a time High volume Low quality Dot-matrix printer One character at a time Daisy Wheel Printer One character at a time. It uses wheel to print.

Dot Matrix Printers A dot matrix printer is an impact printer. It produces printed images when tiny pins on a print head strike an inked ribbon. When the ribbon presses against the paper it creates dots that form characters and graphics. The print head on dot matrix printers can contains nine to twenty-four pins.

Daisy Wheel Printer It is similar to typewriter. It uses a print wheel. This print wheel is called Daisy wheel. Each petal of daisy wheel contains characters. Daisy wheel printer is slower than dot matrix printers but better in quality.

Line Printer It is fastest impact printer. It prints an entire line at a time. Its speed is measured in lines per minute (lpm). Many line printers can print 3000 lines per minute. There are two types of line printers.. Band printers. Chain printers

Nonimpact Printer Laser Printer

Transfers images to paper using a light beam Laser in a laser printer aim at any point on the drum, creating an electrical charge. Toner composed of oppositely charged ink sticks to the drum in the places the laser has charged. With pressure and heat the toner is transferred off the drum onto the paper.

Non-impact Printer Laser Printer Prints one page at a time dpi – High quality Speed –Personal laser printers: 8-10 ppm –Network laser printers: ppm –High-volume laser printers: up to 1000 ppm Black and white / color

Nonimpact Printer Ink-jet Printer Spray ink at paper Black and white / color Excellent graphics Good quality Slower than laser

Nonimpact Printer Choose based upon: Speed Quality Black and white vs. color Price

25 Audio Output Audio output is the ability of the computer to output sound Two components are needed: – Sound card – Plays contents of digitized recordings – Speakers – Attached to sound card Digital formats include WAV, MPEG, MP3, and MIDI

Sound Card Complicated part of the system. A computers sound card is a circuit board that converts sound from analog to digital and vice versa, for recording or playback. The sound card accepts input in the form of analog sound waves. You can think of analog signals as fluctuations in the intensity of an electrical current. The sound card measures those signals and converts them into a digital form.

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