Input and Output Devices: Keyboards, Pointing Devices, Scanners, and Display Devices - Pro, Study notes of Computer Science

Download Input and Output Devices: Keyboards, Pointing Devices, Scanners, and Display Devices - Pro and more Study notes Computer Science in PDF only on Docsity! 1 Chapter 4 Input and Output Keyboards Keyboard: input device containing keys, arranged in a typewriter configuration, used to input letters, numbers, and other symbols Standard alphanumeric keys (letters and numbers) Numeric keypad Function keys Directional and special keys Standard configuration is QWERTY, to match typewriter Dvorak is another configuration 1-2 Keyboards, Cont'd Keyboards, Cont d Can be: Wireless Portable Foldable Handheld PCs and mobile devices today often have a mini keyboard or thumb pad 3-4 Electronic Pens, Cont d Also used with Digital writing systems Graphics tablets Signature capture devices Touch Screens Touch screen: display device that is touched with the finger to issue commands or make selections Touch screen kiosks used in retail stores, movie theaters, airports, etc., and point-of-sale (POS) systems 9-10 Other Pointing Devices Joysticks Trackballs Pointing sticks Touch pads Scanners, Readers, and Digital Cameras Source documents: documents containing data that already exists in physical form (order form, photograph, invoice, check, or price label) Source data automation: capturing data directly from a source document Most common devices used in source data automation: scanning or reading devices 11-12 Scanners Scanner (optical scanner): reads printed text and graphics and converts them to digital form Can scan photos, photo negatives, documents, drawings, etc. Input usually is a single printed image Output depends on type of scanner: An image file (GIF or JPG) saved to disk Text that can be used in word processor Display of a number Scanners, Cont'd 13-14 RFID Readers, Cont'd Optical Mark Readers Optical mark reader (OMR): reads data from special forms to score exams, questionnaires, ballots, etc. Use pencil to fill in small circles/shapes on the form to indicate their selections 19-20 Optical Character Recognition Readers Optical character recognition (OCR) reader: scans text and converts to ASCII characters Used for: Turnaround documents, such as monthly bills To get text from a scanned document, for importing into a word processor Magnetic Ink Character Recognition Readers Magnetic ink character recognition (MICR) reader: reads MICR characters on bank checks Used to process every bank check 21-22 Biometric Readers Biometric data is based on unique physiological characteristics (fingerprint, hand geometry, face, iris of the eye) or personal traits (voice, signature) Iris and retina scanners are very effective Reader can be stand-alone or built into another piece of hardware (keyboard, mouse) Also being built into computers and storage devices to allow access only by authorized individuals Most often used for access control and to verify transactions Biometric Readers, Cont'd 23-24 Digital Video Cameras, Cont'd Audio Input Voice input: Consist of a microphone or headset and software Can be used to record voices or music, dictate text, or issue commands Dictation and commands involve analysis of phonemes, the basic sounds of a language Music input: Compose or play music using Musical Instrument Digital Interface (MIDI) Both use computer's sound card MIDI demo 29-30 Voice Input Voice record demo Speech demo Display Devices Display device: output device that presents output visually Monitor: standalone display device for desktop PC Display screen: screen built into the unit of all-in-one PCs, notebook computers, handheld PCs, smart phones, consumer devices, and many other devices CRT monitor: projects images onto a display screen using same technology as older TVs Beam of electrons scans the screen Flat-panel display: forms images by manipulating electronically charged chemicals or gases sandwiched between panes of glass 31-32 CRT Monitor One pixel COLOR PIXELS. Each pixel on the screen is made up of some combination of red, green, and blue light. When red, green, and blue light of varying intensities are blended, a wide range of colors is possible. CRT vowron-—~ ae Flat-Panel Displays eececee LCD DISPLAYS OLED DISPLAYS PLASMA DISPLAYS ‘The most common type of computer Used primarily with smaller displays, Used primarily with large computer monitors monitor and flat-panel television. like diaital cameras and handheld PCs. and TVs. 33-34 Printer Characteristics Whether prints in color or black-and white only Whether personal or network printer Quality is called print resolution and measured in dots per inch (dpi) Not the same as monitor or digital camera resolution; not dots per page Print speed is measured in pages per minute (ppm) Laser Printers Uses toner powder and technology similar to that of a photocopier to produce images on paper The standard for business documents Has its own RAM, the more the better Print one entire page at a time Must have enough RAM for page Usually black and white, though can get color Common print resolution is 600 to 2,400 dpi Low cost per page, excellent print quality, high ppm 39-40 Laser Printers, Cont'd Ink-Jet Printers Ink-jet printer: sprays droplets of ink to produce images on paper Typically print in color Often the choice for home use since inexpensive Prints fairly slowly, one line at a time Quality not as good for documents as a laser Cost per page higher than laser Cost per printed photo very high 41-42 Ink-Jet Printers, Cont'd Special Purpose Printers Photo printers (designed to print photographs) Barcode printers (print barcodes; some can encode RFID tags) Label printers (print labels, electronic postage, etc.) Portable printers (designed to be carried with you) Plotters and wide-format ink-jet printers (print on large paper or other large materials) 43-44