Hardware: Input & Output

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2. 5 Chapter Hardware: Input & Output 5.1 Input & Output 5.2 Input Hardware 5.3 Output Hardware 5.4 I/O Quality of Life: Health & Ergonomics 5.5 Future of Input & Output © 2007 The McGraw-Hill Companies, Inc. All rights reserved. McGraw-Hill/Irwin

3. 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 5-3

4. 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! 5-4

5. 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 5-5

6. Input Hardware • Keyboard types • 104 – 108 keys desktop standard • 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 5-6

7. 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 5-7

8. 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 20-key mini-keyboard 5-8

9. Input Hardware Pointing Devices • Control the position of the cursor or pointer in 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 Discussion Question: What is the difference between “cursor” and “curser”? 5-9

10. 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 • 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 • Pointing Stick • Looks like a pencil eraser in the lower center of a laptop keyboard 5-10

11. 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 5-11

12. 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 5-12

13. 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, drum, and pen scanners 5-13

14. 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 5-14

15. 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 ACT and SAT • 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 5-15

16. 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 5-16

17. 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 5-17

18. 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 Discussion Question: Why might it be unwise to install a webcam on your PC? 5-18

19. 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 5-19

20. 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 Discussion Question: Why do you suppose cellphones are now banned on secure U.S. military bases? Where else besides military bases might they pose a security problem? 5-20

21. 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’s Open Speech Dialog • Apple Speech Recognition • ScanSoft’s Navigon MobileNavigator 5 5-21

22. 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 5-22

23. 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/home.html • http://www.identix.com/ • http://www.precisebiometrics.com/ 5-23

24. 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 5-24

25. 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 5-25

26. 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 5-26

27. Video Standard SVGA XGA SXGA UXGA QXGA Principal resolution (pixels) 800 x 600 1024 x 768 1280 x 1024 1600 x 1200 2048 x 1536 Output HardwareMonitors 5-27

28. Impact Printers Laser Printers Inkjet Printers Thermal Printers 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 Output HardwarePrinters 5-28

29. 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 5-29

30. 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. 5-30

31. 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 5-31

32. 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 5-32

33. 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 5-33

34. 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 5-34