Using Information Technology Chapter 5 Hardware—Input Output

Using Information Technology Chapter 5 Hardware--Input & Output

Hardware--Input & Output Taking Charge of Computing & Communications 5. 1 Input & Output 5. 2 Input Hardware 5. 3 Output Hardware

5. 1 Input & Output • Input hardware devices that translate data into a form the computer can process • Output hardware devices that translate information processed by the computer into a form that humans can understand

5. 2 Input Hardware • Keyboard - a device that converts letters, numbers, and other characters into electrical signals that can be read by the computer’s processor Braille keyboard • Traditional keyboards… One-handed keyboard

Keyboards • Specialty keyboards and terminals: • Dumb terminal, VDT, display & keyboard, but no processing • Intelligent terminal • Internet terminal Dumb terminal

Keyboards • Specialty keyboards and terminals: • Dumb terminal • Intelligent terminal Has own memory & processor • Internet terminal • Examples of intelligent terminals: • Automatic teller machine (ATM) • Point-of-sale (POS) terminal

Keyboards • Specialty keyboards and terminals: • Dumb terminal • Intelligent terminal • Internet terminal: – – – Web terminal Network computer Online game player PC/TV PDA (Internet terminal)

Pointing Devices • Pointing devices control the position of the cursor or pointer on the screen • • Mouse Trackball Pointing stick Touchpad Mouse for right-handed user

Pointing Devices • The mouse and its variants: – – Touch pad Mouse Trackball Pointing stick Touchpad Ergonomic trackball Pointing stick

Pointing Devices • Touch screen - a video display screen that has been sensitized to receive input from the touch of a finger Touch screen

Pointing Devices Pen input: • Pen-based computer system allows users to enter handwriting and marks onto a computer screen by means of a penlike stylus rather than by typing on a keyboard • Light pen - a light-sensitive penlike device connected by a wire to the computer terminal

Pointing Devices Pen input: • Digitizer - converts drawings and photos to digital data using a mouselike device called a puck • Digitizing tablet electronic plastic board on which each specific location corresponds to a location on the screen Digitizing tablet

Source Data-Entry Devices Scanning devices - imaging systems: • Scanners - devices that use light-sensing equipment to translate images of text, drawings, photos, and the like into digital form

Source Data-Entry Devices Scanning devices – bar-code readers: • Bar codes - vertical zebrastriped marks you see on most manufactured retail products • Bar-code readers - optical scanners that translate the symbols in the bar code into digital code

Source Data-Entry Devices Scanning devices - mark- & character-recognition: • MICR - Magnetic-ink character recognition. Reads the strange-looking numbers printed at the bottom of checks • OMR • OCR

Source Data-Entry Devices Scanning devices - mark- & character-recognition: • • • MICR OMR - Optical mark recognition. Uses a device that reads pencil marks and converts them into computerusable form OCR

Source Data-Entry Devices Scanning devices: mark- & character-recognition: • MICR • OMR • OCR - Optical character recognition. Uses a device that reads preprinted characters in a particular font and converts them to digital code

Source Data-Entry Devices • Scanning devices fax machines… • Types of fax machines: • Dedicated fax machine • Fax modem Dedicated fax machine Fax modem

Other Source Data-Entry Devices • Audio-input devices • Webcams and videoinput cards • Digital cameras • Voice-recognition systems

Other Source Data-Entry Devices • Audio-input devices • Webcams and video-input cards • Digital cameras • Voice-recognition systems • Human-biology input devices (biometrics)

5. 3 Output Hardware • Softcopy - data that is shown on a display screen or is in audio or voice form • Hardcopy - printed output

Softcopy Output: Display Screens • Display screens - output devices that show programming instructions and data as they are being input and information after it is processed

Softcopy Output: Display Screens • Screen clarity… • Pixel (picture element) - the smallest unit on the screen that can be turned on and off or made different shades

Softcopy Output: Display Screens • Screen clarity… • Dot pitch (dp) - the amount of space between the centers of adjacent pixels; the closer the dots, the crisper the image

Softcopy Output: Display Screens • Screen clarity… • Standard resolutions • (horizontal x vertical) • Resolution - the image sharpness of a display screen; the more pixels there are per square inch, the finer the level of detail • dpi = dots per inch • • • 640 x 480 800 x 600 1024 x 768 1280 x 1024 1600 x 1200 1920 x 1440

Softcopy Output: Display Screens • Screen clarity… • Refresh rate - the number of times per second that the pixels are recharged so that their glow remains bright • The higher the refresh rate, the more solid the image looks (less flicker).

Softcopy Output: Display Screens Two types of monitors: • CRT - a vacuum tube used as a display screen in a computer or video display terminal • Flat-panel display made up of two plates of glass separated by a layer of a substance in which light is manipulated

Softcopy Output: Display Screens Active-matrix versus passive-matrix flat-panel displays: – Active-matrix - each pixel on the screen is controlled by its own transistor (brighter & sharper, but more expensive) – Passive-matrix - a transistor controls a whole row or column of pixels (provides sharper image for single color screens but more subdued for color)

Softcopy Output: Display Screens Color & resolution standards: • SVGA – Super video graphics array (most common w/ 15” monitors) • XGA – Extended graphics array (17 -19” monitors) • SXGA – Super extended graphics array (19”-21” monitors) • UXGA - Ultra extended graphics array (popular w/ design & graphic artists

Hardcopy Output: Printers • Printer - an output device that prints characters, symbols, and perhaps graphics on paper or another hardcopy medium • Dpi (dots per inch) - resolution measure for printers. Specifies the number of dots that are printed in a linear inch

Hardcopy Output: Printers • Impact printer - forms characters or images by striking a mechanism such as a print hammer or wheel against an inked ribbon, leaving an image on paper (dot matrix printer) • Non-impact printer - forms characters and images without direct physical contact between the printing mechanism and paper –Laser printer - creates images on a drum which are treated with a magnetically charged toner, & then transferred from drum to paper –Ink-jet printers - spray small, electrically charged droplets of ink from four nozzles through holes in a matrix at high speed onto paper –Thermal printers - use colored waxes and heat to produce high quality images by burning dots onto special paper

Hardcopy Output: Printers • Multifunction printer - output device that combines several capabilities, such as printing, scanning, copying, and faxing

Other Output • Sound output - devices which produce digitized sounds, ranging from beeps and chirps to music • Voice output - devices which convert digital data into speech-like sounds • Video output - photographic images which are played at 15 -29 frames per second to give the appearance of full motion

Concept Check • Which type of scanning technology reads the special characters printed at the bottom of checks? • Magnetic-ink character recognition (MICR)

Concept Check • What is the smallest unit on the screen that can be turned on and off or made different shades? • Pixel (short for picture element)

Concept Check • What is the measure specifying the number of times per second that screen pixels are recharged? • Refresh rate

Concept Check • How is screen resolution specified--vertical x horizontal, or horizontal x vertical? • Horizontal x vertical

Concept Check • What is the measure of resolution for printers? • Dots per inch (dpi)

Concept Check • What is the amount of space between the centers of adjacent pixels? • Dot pitch (dp)

Concept Check • What type of scanning technology is used to read pencil marks, such as those made by students on examination forms? • OMR (Optical mark recognition)

Concept Check • What is an example of an impact printer? • Dot-matrix printer

Concept Check • Which type of printer produces the very highest-quality color output? • Thermal printer

Concept Check • What type of input device consists of a small, flat surface over which you slide your finger, using the same movements as you would with a mouse? • Touchpad

Concept Check • What is the term for printed output? • Hardcopy

Concept Check • Does a very crisp image require a small dot pitch or a large dot pitch? • A small dot pitch (the closer the dots, the crisper the image)