تهيه كننده : علي برادران هاشمي گارگاه کامپیوتر Input/Output devices

2 I/O 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

3 Keyboard Keyboard - a device that converts letters, numbers, and other characters into electrical signals that can be read by the computer ’ s processor Braille keyboard One-handed keyboard

4 Pointing devices - control the position of the cursor or pointer on the screen Mouse Trackball Pointing stick Touchpad Pointing Devices

5 Pointing Devices (Cont.) Touch screen - a video display screen that has been sensitized to receive input from the touch of a finger Touch screen

6 Pointing Devices (Cont.) 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 Touch screen

7 Pointing Devices (Cont.) Light pen - a light- sensitive penlike device connected by a wire to the computer terminal The light pen has a button which the user presses when the pen is pointing to a desired location on the screen.

8 Pointing Devices (Cont.) Digitizer - converts drawings and photos to digital data using a mouselike device called a puck Digitizer Digitizing tablet - electronic plastic board on which each specific location corresponds to a location on the screen Digitizing tablet

9 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

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

11 Scanning devices - mark- and character- recognition: MICR Magnetic-ink character recognition. Reads the strange-looking numbers printed at the bottom of checks OMR Optical mark recognition. Uses a device that reads pencil marks and converts them into computer-usable form 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

12 Scanning devices - fax machines … scans an image and sends it as electronic signals over telephone lines to a receiving fax machine, which prints out the image on paper. Also called facsimile transmission machine. Types of fax machines: Dedicated fax machine Fax modem Source Data-Entry Devices

13 Audio-input devices Record analog sound and translate it for digital storage and processing Require either an audio board or a MIDI board Audio board - an add-on circuit board that converts analog sound to digital sound and stores it for further processing and/or plays it back, directly to speakers or an external amplifier. MIDI (Musical Instrument Digital Interface) board - provides a standard for the interchange of musical information between musical instruments, synthesizers, and computers. Audio-input devices

14 Webcam - a camera that attaches to a computer to record moving images that can then be posted on a website in real time. Video-capture card - a special digitizing card that converts the analog signals that come from a VCR or a camcorder into digital form. Webcams and video-input cards

15 Digital camera - uses a light-sensitive processor chip to capture photographic images in digital form on a small diskette inserted in the camera or on flash- memory chips. Digital cameras

16 Sensors Radio-frequency identification Also known as RF-ID tagging. Human-biology input devices Biometrics - the science of measuring individual body characteristics. More Source Data-Entry Devices

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

18 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

19 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

20 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

21 Softcopy Output: Display Screens Screen clarity… Resolution - the image sharpness of a display screen; the more pixels there are per square inch, the finer the level of detail Standard resolutions (horizontal x vertical) 640 x x x x x x 1440

22 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

23 Two types of monitors: CRT - a vacuum tube used as a display screen in a computer or video display terminal Cathode Ray Tube, and is used in television sets in addition to monitors. CRT

24 Flat-panel display - made up of two plates of glass separated by a layer of a substance in which light is manipulated Liquid crystal display (LCD) - one technology used in flat-panel displays. Molecules of liquid crystal line up in a way that alters their optical properties, creating images on the screen by transmitting or blocking out light. Flat-panel displays cost far more than CRT displays. Flat-panel display

25 SVGA (Super Video Graphics Array) XGA (Extended Graphics Array) SXGA (Super Extended Graphics Array) UXGA (Ultra Extended Graphics Array) Color & resolution standards:

26 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 Impact printer Non-impact printer - forms characters and images without direct physical contact between the printing mechanism and paper Hardcopy Output: Printers

27 contains a print head of small pins, which strike an inked ribbon against paper to form characters or images. Advantage of dot-matrix printer: Can be used to print multi-part forms Disadvantage of dot-matrix printer: Noisy! Dot-matrix printer

28 Laser printer - creates images on a drum which are treated with a magnetically charged toner, and then transferred from drum to paper PDL (Page Description Language). Software which tells the printer how to lay out the printed page. Two types of PDL: 1. PostScript - developed by Adobe. 2. PCL (Printer Control Language( - developed by Hewlett-Packard. Laser printer

29 Ink-jet printers - spray small, electrically charged droplets of ink from four nozzles throaugh holes in a matrix at high speed onto paper Advantages of ink-jet printers: Cheaper than laser Quieter than laser Disadvantages of ink-jet printers: Slower than laser Lower resolution than laser Ink-jet printers

30 Thermal printers - use colored waxes and heat to produce images by burning dots onto special paper Thermal printers produce the highest- quality color output of any printer, but are expensive and require expensive paper. Thermal printers

31 Plotter - a specialized output device designed to produce high-quality graphics in a variety of colors Plotter

32 Multifunction printer - output device that combines several capabilities, such as printing, scanning, copying, and faxing Multifunction printer

33 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 frames per second to give the appearance of full motion Other Output

34 High-capacity bar codes can be read vertically, as well as horizontally, allowing them to store more than 100 times as much data. 3-D scanners can make online shopping for clothing much more reliable. Touch devices linked to mobile electronic “yellow pages” may be installed in cars. Toward More Source Data Automation

35 Smart cards may evolve into all-purpose cards containing everything from medical records to frequent flier program information. Sensor examples: a “smart needle” with embedded sensors can be inserted into a tumor to provide more information about it; a “canary on a chip” can be used to detect and identify chemical and biological agents;, etc. Toward More Source Data Automation

36 Voice recognition possibility: a translation device for travelers which could take your spoken English and instantly translate it into spoken French, Japanese, etc. Smaller electronic cameras: Camera-on-a-chip? Pattern-recognition & biometric devices Brainwave devices: Users moving a cursor through sheer power of thought! Toward More Source Data Automation

37 Electronic news tablet - a textbook- sized device for downloading a newspaper and then carrying around to read Toward More Output in Remote Locations

38 Health Matters: Health Matters RSIs Eyestrain & headaches Back & neck pains Electromagnetic fields Noise Input & Output Technology & Quality of Life: Health & Ergonomics Carpal tunnel syndrome

39 RSIs (Repetitive stress injuries) - several wrist, hand, arm, and neck injuries resulting when muscle groups are forced through fast, repetitive motions. Carpel tunnel syndrome (CTS) - a form of RSI caused by pressure on the median nerve in the wrist, producing damage and pain to nerves and tendons in the hands. Health & Ergonomics

40 Computer vision syndrome (CVS) - eyestrain, headaches, double vision, and other problems caused by improper use of computer display screens. Electromagnetic fields (EMFs) are waves of electrical energy and magnetic energy. Health & Ergonomics

41 Ergonomics - a field devoted to making working conditions and equipment safer and more efficient Ergonomics Ergonomic keyboard

42 Serial port sends bits one at a time, one after another Parallel port transmits 8 bits simultaneously SCSI port allows data to be transmitted in a “ daisy chain ” to up to 7 devices USB port can theoretically connect up to 127 peripheral devices daisy-chained to one general-purpose port Dedicated port mouse port, modem port, and keyboard port Infrared port allows a computer to make a cableless connection with infrared-capable devices Ports & Cables

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