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Hardware: Input and Output

This lecture provides an introduction to input and output hardware in computer systems, including keyboards, pointing devices, touch screens, and more.

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Hardware: Input and Output

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  1. Arizona State UniversityDepartment of Technology Management GIT 335 Computer Systems Technology Lecture 5 Hardware – Input and Output Dr. Thomas Schildgen, Professor GIT 335 Lecture 5

  2. Lecture 5 Introduction to Information Technology Content taken from the McGraw Hill Textbook Chapter 5 GIT 335 Lecture 5

  3. Hardware: Input & Output GIT 335 Lecture 5

  4. Input & Output • Input Hardware • Devices that translate data into a form the computer can process • Translates words, numbers, sounds, and pictures into binary • Output Hardware • Devices that translate information processed by the computer into a form humans can understand • Translates binary into words, numbers, sounds, and pictures GIT 335 Lecture 5

  5. Input Hardware • Keyboards: convert letters, numbers, and characters into electrical signals • English keyboards differ from foreign language keyboards • Follow this link to see what a Russian Cyrillic keyboard layout looks like • http://www.geocities.com/fontboard/cyrillic.html • Even languages that are close to ours like German have different keyboard layouts, such as can be seen on Microsoft’s web site • http://www.microsoft.com/globaldev/keyboards/kbdgr.htm • Even touch typists must watch their fingers when they travel to Internet Cafes in foreign countries! GIT 335 Lecture 5

  6. Input Hardware • How keyboards work: • You press a key • This interrupts the current flowing through the circuits • Processor determines where the break occurs • It compares the location of the break with the (x,y) character map for the language on the keyboard’s ROM chip • A character is stored in 16-byte keyboard memory buffer • Then sent to PC as a data stream via wire or wireless connection • OS interprets its own operating-system-specific commands and sends the others to the application for interpretation GIT 335 Lecture 5

  7. Input Hardware • Keyboard types • 104 – 108 keys desktop standard • 80 – 85 keys for laptops • Wired • Connect to CPU via a serial or USB port • Wireless use either • IR (infrared) technology • Radio Frequency (RF) technology • Require line of sight to connect • Virtual keyboard used with PDAs and smartphones GIT 335 Lecture 5

  8. Input Hardware Terminal Types • Dumb Terminals • a.k.a. Video Display Terminal (VDT) • Has display screen and keyboard • Can do input and output only – no data processing • Intelligent Terminals • Has screen, keyboard, and memory • Can perform some local functions • Internet Terminals • Powers directly up into a browser • Web terminal displays web pages on a TV set • Network computer is a stripped-down PC to connect people to networks • Online game player connects to internet for online gaming • PC/TV merges a full-blown PC with a TV • PDA is a handheld computer with a tiny keyboard GIT 335 Lecture 5

  9. Input Hardware • PDA Keyboards • Problem: Make them too small and they are unusable • Problem: Make them too big and the PDA is too big • Solutions: • Some PDAs use a stylus • Some PDAs use a foldable keyboard • Some PDAs use a one-hand mini-keyboard GIT 335 Lecture 5

  10. Input Hardware Pointing Devices • Control the position of the cursor or pointer on the screen and allow the user to select options displayed on the screen • Mouse is the principal pointing tool • Rolls around on a mouse pad or desktop and directs a pointer on the computer’s display screen • Ball inside the mouse touches the desktop and rolls around • Two internal rollers touch the ball • One roller picks up motion in x (up), the other in y (down) • The rollers turn a shaft that spins a disk that breaks an LED signal into light pulses that are seen by an infrared sensor • Processor chip in mouse reads the pulses and turns it into binary GIT 335 Lecture 5

  11. Input Hardware Pointing Devices • Trackball • A movable ball mounted on top of a stationary device • Good for locations where a mouse couldn’t move enough • Requires more frequent cleaning to remove finger oils • Pointing Stick • Looks like a pencil eraser in the lower center of a laptop keyboard • Touchpad • To use: slide your finger over this small flat surface • Click by tapping you finger on the surface • May require more practice to use than a mouse GIT 335 Lecture 5

  12. Input Hardware Pointing Devices • Touch Screens • A video display screen sensitized to receive input from a finger • Cruder than a mouse, because fingers are big • Problems: touch screens that show a display that is not precisely aligned with the input • Pen input • Use a pen-like stylus for input rather than typing on a keyboard • Use handwriting recognition to translate cursive writing into data GIT 335 Lecture 5

  13. Input Hardware • Light Pen • A light-sensitive pen-like device that uses a wired connection to a computer terminal • Bring the pen to the desired point on the display screen and press a button to identify the screen location • Used in situations that require gloves • Less crude than a touch screen • Digitizer • Uses an electronic pen or puck to convert drawings and photos to digital data • Digitizing tablets are used in architecture GIT 335 Lecture 5

  14. Input Hardware • Digital Pen • Writing instrument • Writers can write on paper • A tiny camera in the pen tip captures the writing • A microchip in the pen converts the pen to digital ink • The writing is sent as an image file to the computer • Original versions: Logitech’s IO pen and Leapfrog’s FLY Fusion pen required special paper • Later versions, like Mobile Digital Scribe do not require special paper GIT 335 Lecture 5

  15. Input HardwareScanning & Reading Devices • Source Data Entry devices create machine-readable data and feed it directly into the computer • Scanners • Use light-sensing equipment to translate images of text, drawings, and photos into digital form • Image scanners are used in electronic imaging • Resolution refers to the image sharpness, measured in dots per inch (dpi) • Flatbed scanners work like photocopiers – the image is placed on the glass surface, then scanned • Other types are sheet-fed, hand-held and drum GIT 335 Lecture 5

  16. Input HardwareBar-Code Readers • Photoelectric (optical) scanners that translate bar code symbols into digital code • The digital code is then sent to a computer • The computer looks up the item and displays its name and pricing info • Bar code types • 1D holds up to 16 ASCII characters • 2D can hold 1,000 to 2,000 ASCII characters • 3D is “bumpy” code that differentiates by symbol height • Can be used on metal, hard rubber, other tough surfaces GIT 335 Lecture 5 16

  17. Input HardwareMark Recognition Readers • Bar code readers • MICR – Magnetic-ink character recognition • Uses special magnetized inks • Must be read by a special scanner that reads this ink • OMR – Optical mark recognition • Uses a special scanner that reads bubble marks • Used in standardized tests like the SAT and GRE • OCR – Optical character recognition • Converts scanned text from images (pictures of the text) to an editable text format • You use this to read in non-computer documents where you don’t have the source files GIT 335 Lecture 5 17

  18. Input HardwareFax Machines • Facsimile Transmission Machines – scan an image and send it as electronic signals over telephone lines to a receiving fax, which prints out the image on paper • Dedicated fax machine • Is a stand-alone unit that only sends and receives faxed documents • Fax modem • Is a circuit board installed in the PC • Is a modem that can send and receive faxes • Can send documents directly from your word processor to a fax machine • Saves you printing out the document, then faxing it GIT 335 Lecture 5 18

  19. Input HardwareAudio Input Devices • Records analog sound and translates it into digital files for storage and processing • Two ways to digitize audio • Sound Board • An add-on board in a PC that converts analog sound to digital sound, stores it, and plays it back to speakers or amp • MIDI Board • Stands for Musical Instrument Digital Exchange • Uses a standard for the interchange between musical instruments, synthesizers, and PCs GIT 335 Lecture 5 19

  20. Input HardwareWebcams and Video-input Cards • Webcams • Video cameras attached to a computer to record live moving images then post them to a website in real time • Require special software, usually included with the camera • Frame-grabber video card • Can capture and digitize 1 frame at a time • Full-motion video card • Can convert analog to digital signals at rates up to 30 frames per second • Looks like a motion picture GIT 335 Lecture 5 20

  21. Input HardwareDigital Cameras • Use a light-sensitive processor chip to capture photographic images in digital form and store them on a small diskette in the camera or on flash memory cards • Most can be connected to a PC by USB or FireWire • Can allow you to take more pictures and decide which ones to print and save • But pictures are subject to loss by diskette or flash memory failure or computer virus if you store them on the PC GIT 335 Lecture 5 21

  22. Input HardwareCamera Phones • Digital cameras are now on cellphones • Convenience of being able to take photos, then instantly email or message them to someone else • Can provide instant record of traffic accidents, etc GIT 335 Lecture 5 22

  23. Input HardwareSpeech-Recognition Systems • Uses a microphone or telephone as an input device. Converts a person’s speech into digital signals by comparing against 200,000 or so stored patterns. • Used in places where people need their hands free – warehouses, car radios, stock exchange trades • Helpful for people with visual or physical disabilities that prevent them from using other input devices • Still not easy enough to use to substitute for the mouse/keyboard for fast document processing • ScanSoft and Nuance • Fonix Speech • Aculab • Verbio GIT 335 Lecture 5 23

  24. Input HardwareRFID Tags • Radio-frequency ID tags are based on an identifying tag with a microchip containing specific code numbers • Scanners use radio waves to read them and match the codes to a database • Enables items to be tracked without physical contact • Drivers put RFID tags in cars to automatically pay tolls • FDA is tagging certain drugs with RFID to avoid counterfeits • Carmakers are using it for car electronic keyless entry • RFID tags are implanted under skin of pets to aid in recovery and identification when they get lost GIT 335 Lecture 5 24

  25. Input HardwareBiometrics • The science of measuring individual body characteristics, then using them to identify a person through a fingerprint, hand, eye, or facial characteristic • Becoming a big business as more companies become concerned about security • Makes identity theft much more difficult when records are identified by biometrics as well as passwords • For more information see • http://www.xtec.com/ • http://www.identix.com/ • http://www.precisebiometrics.com/ GIT 335 Lecture 5 25

  26. Output Hardware • Softcopy • Data that is shown on a display screen or is in audio or voice form; exists electronically • Output that is ephemeral in nature • Hardcopy • Printed and film output • Output that is more permanent in nature GIT 335 Lecture 5 26

  27. Output HardwareDisplay Screens • Making a good choice when choosing a display • Dot pitch (dp) is the amount of space between adjacent pixels (picture elements) on screen • The closer the pixels, the crisper the image • Get .25 dp or better • Resolution refers to the image sharpness • The more pixels the better the resolution • Expressed in dots per inch (dpi) • Color depth or bit depth is the number of bits stored in a dot • The higher the number the more true the colors • 24-bit color depth is better than 8-bit color depth • Refresh rate is the number of times per second the pixels are recharged – a higher rate gives less flicker GIT 335 Lecture 5 27

  28. Output HardwareMonitors • Cathode Ray Tube (CRT) is a vacuum tube used in a computer or terminal display screen • Watch the PC ads to make sure your monitor is included • Flat panel displays are made of 2 plates of glass separated by a layer of liquid crystals that line up to transmit or block light • Preferable to CRTs because they take up less room on the desktop • Latency problems make them less desirable for online games players GIT 335 Lecture 5 28

  29. Output HardwareMonitors • Video Standard • XGA • SXGA • UXGA • QXGA • WXGA • WUXGA • Principal resolution (pixels) • 1024 x 768 • 1280 x 1024 • 1600 x 1200 • 2048 x 1536 • 1,386 x 768 • 1,920 x 1,200 GIT 335 Lecture 5 29

  30. Output HardwarePrinters • Form characters or images by striking a print hammer or wheel against an ink ribbon • Dot matrix printers • Use drums and toner like in photocopiers • Page Description Language (PDL) • PostScript and PCL are PDL types • Produce crisp, professional pages • Spray ink from 4 nozzles at high speed • Quiet, inexpensive color printers • Often less precise than laser printers • Low to medium resolution printers that use thermal paper that darkens in time • Impact Printers • Laser Printers • Inkjet Printers • Thermal Printers GIT 335 Lecture 5 30

  31. Output HardwarePlotters • A specialized output device designed to produce large high-quality graphics in a variety of colors • The earliest output device that could produce graphics • Pen plotters use one or more colored pens • Electrostatic plotters lie partially flat on a table and use toner like photocopiers • Large-format plotters are large-scale inkjet printers used by graphic artists GIT 335 Lecture 5 31

  32. Output HardwareMixed Output • Sound output • You need a sound card and sound software • Good equipment can produce very high-quality 3-D sound • Voice Output • TTS systems (text to speech) are becoming popular • Requires a sound card and speakers with TTS software • Video Output • Requires a powerful processor and a video card • Video files are large, so a lot of storage is needed too. GIT 335 Lecture 5 32

  33. I/O Quality of Life: Health & Ergonomics • PCs impact health • Overuse injuries and repetitive stress injuries • Result when muscle groups are forced through fast, repetitive motions • May effect data-entry operators who average 15,000 keystrokes an hour • May effect PC users whose monitor, keyboard, and workstation are not arranged for comfort • Carpal tunnel syndrome is caused by pressure on the median nerve in the wrist, caused by short repetitive movement • Computer vision syndrome is eyestrain, headaches, and double vision caused by improper use of computer display screens GIT 335 Lecture 5 33

  34. I/O Quality of Life: Health & Ergonomics • Ergonomics is the methodology of designing a workplace to make working conditions and equipment safer and more efficient • Keyboards must be placed at the correct height depending on each worker’s size • Monitor refresh rates must be fast enough to avoid eyestrain • Monitor heights must be correct for comfortable viewing • Sound-muffling should be used for loud printers to reduce workplace noise • Wrist rests may help avoid carpal tunnel syndrome GIT 335 Lecture 5 34

  35. Future of Input and Output • This is a fruitful area for research, including • Intelligent sensors • More data input from remote locations • More source data automation • Input help for the disabled • More sophisticated touch devices • Better speech recognition • Improved digital cameras • Gesture recognition GIT 335 Lecture 5 35

  36. Future of Input and Output • This is a fruitful area for research, including • Pattern-recognition and biometric devices • Brainwave devices • Better and cheaper display screens • Improved video on PCs • 3-Dimensional output • Miniaturization for improved data transfer speeds to I/O devices GIT 335 Lecture 5

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