Computer System Fundamentals - Input and Output Devices B chap 1

CPU

  • Computer System Fundamentals: Input and Output Devices

Input-Process-Output Cycle

  • Data conversion to information involves three steps:
    1. Data input.
    2. Program processes data (retrieval/update).
    3. Meaningful information output.
  • This is the input-process-output (IPO) cycle.

Input Devices

  • Responsible for the first step in the IPO cycle.
  • Can be wired or wireless (RF, Bluetooth, Wi-Fi).

Keyboard

  • Full-sized: 100+ keys, each with a unique code.
  • Numeric (numpad): Used for number/arithmetic input in banks/POS terminals.

Pointing Devices

  • Allow interaction with computer interface (pointing, clicking, etc.).
  • Types: motion-tracking and position-tracking.

Audio Input Devices

  • Microphones:
    • Convert analog sound waves to electrical signals, then to digital audio files.
    • Can input text via speech recognition.
  • MIDI Keyboards:
    • MIDI (Musical Instrument Digital Interface) stores musical notes/sampled sounds data.
    • Not affected by ambient noise.

Image Input Devices

  • Used for creating digital image files.
    • Image scanners.
      • Flatbed scanners are common.
    • Digital cameras.
  • 3D scanners: Produce digital 3D models.
  • OCR (Optical Character Recognition): Converts scanned images to text files for word processing.

Video Input Devices

  • Used for creating digital video files.
    • Digital video cameras.
    • Webcams: Stream recordings online, connect directly to a computer.

Automatic Input Devices

  • Minimize human effort for data input.
    • Optical Readers: Convert visual data to digital.
      • Barcode scanners
      • QR code scanners
      • Optical mark readers. Use optical mark recognition.
    • Magnetic stripe card readers/smart card readers.
      • Magnetic stripe cards store data via magnetism.
      • Smart cards store data in a microchip.
    • Sensors (light, ultrasonic, compass, temperature, gyroscope).
    • Biometric devices (fingerprint, face, iris, voice).

Output Devices

  • Responsible for the last step in the IPO cycle; can be wired or wireless.

Monitor

  • Displays user interface and results of information processing.
  • Types:
    • LCD(Liquid Crystal Display): Uses backlight (CCFL or LED) and liquid crystals with polarizers for color.
      • Lower price, more screen size options.
    • OLED(Organic Light-Emitting Diode): OLED acts as the light and color source, no backlight needed.
      • Higher contrast, brightness consistency, wider viewing angle, lighter; can be foldable/flexible.
  • Attributes:
    • Screen size: Diagonal length in inches.
    • Resolution: Number of dots/pixels on the screen.
    • Pixel density: Dots per inch (ppi); Pixeldensity=diagonalresolution/screensizePixel density = diagonal resolution / screen size
    • Color depth: Number of possible colors per pixel.
    • Aspect ratio: Width to height ratio.
    • Refresh rate: Screen update frequency in Hz.
    • Interface: Connection types (VGA, DVI, HDMI, DisplayPort).
    • Contrast ratio: Luminance ratio of white to black.

Projector

  • Projects images onto a surface.
  • Advantages over monitors:
    • Adjustable screen size, suitable for large audiences.
    • More portable.
  • Disadvantages:
    • Lower image quality.
    • More affected by ambient light and need a flat surface.

Printer

  • Produces hard copies (paper form).
  • Types:
    • Thermal printers: Use heat on thermal paper.
    • Inkjet printers: Spray ink droplets.
    • Laser printers: High speed, low cost per page, water-resistant.
    • Plotters: Create high-quality vector drawings with continuous pen movement.
    • 3D printers: Produce physical objects from 3D models.

Speakers, Headphones, and Earphones

  • Connect to sound card, output analog signals as sound.
  • Headphones:
    • Offer privacy, portability, and are less affected by noise.

Application of Computers

Business Use

  • Video conferencing: Remote meetings over the internet.
  • Thermal printers: Fast, quiet receipt printing.
  • Electronic payment systems/self-checkout systems.
    • POS (Point-of-Sales) terminals:
      • Magnetic stripe/smart card readers.
      • Numpad.
      • Barcode/QR code scanners.
      • Receipt printer.
    • Self-service terminals: Upgrade of POS terminals.

Educational Use

  • Video conferencing for online lessons.
  • Library catalogue/self-charging terminals.
    • Smart card reader.
    • Barcode scanner.
    • Touchscreen.
    • Receipt printer.
  • Information kiosks in museums.