Input

1
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

2
Input Hardware

• Keyboards convert letters, numbers, and
  characters into electrical signals
• How keyboards work
• You press a key
• This interrupts the current flowing through the
  circuits
• It compares the input with the (x,y) character
  map for the language on the keyboards ROM chip
• A character is stored in 16-byte keyboard memory
  buffer
• 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

3
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

4
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 computers 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

5
Input Hardware Pointing Devices

• Other types of Mice
• Optical Mouse
• Trackball
• Touchpad
• Pointing Stick

6
Input Hardware Pointing Devices

• Touch Screens
• A video display screen sensitized to receive
  input from a finger
• 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
  handwriting into data

7
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
• Less crude than a touch screen

8
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) higher the
  better quality

9
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

10
Input HardwareMark Recognition Readers

• Mark Recognition readers
• MICR Magnetic-ink character recognition
• Uses special magnetized inks
• Must be read by a special scanner that reads this
  ink
• Used by Banks to read checks
• 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 dont have the source files

11
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

12
Input HardwareWebcams and Video-input Cards

• Webcams
• Video cameras attached to a computer to record
  live moving images into a computer
• Require special software, usually included with
  the camera
• Full-motion video card
• Can convert analog to digital signals at rates up
  to 30 frames per second
• Typically used to capture TV signals and convert
  to digital video

13
Input HardwareSpeech-Recognition Systems

• Uses a microphone or telephone as an input
  device. Converts a persons 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

14
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

15
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

16
Output Hardware

• Softcopy
• Data that is shown on a display screen or is in
  audio or voice form exists electronically
• Non-Physical (Virtual) representation
• Hardcopy
• Printed and film output
• Physical (Real) representation

17
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

18
Output HardwareMonitors

• Cathode Ray Tube (CRT) is a vacuum tube used in a
  computer or terminal display screen
• 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
  watching video (but the technology is advancing
  quickly)

19
Output HardwarePrinters

• 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
• Expensive
• 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

20
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

21
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 workers 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

22
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

23
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