1.1.3 Input, output and storage

• Input device

  Any device that allows you to pass information from the outside world into a computer system.
• Examples of Input devices:

  1. Keyboard
  2. Microphone
  3. Mouse
  4. Barcode scanner
• Output device

  Any device that can take data stored in digital form and convert it into another format that humans can process such as sound, images, etc.
• Examples of output devices:

  1. Printer
  2. Monitor
  3. Headphones
  4. Speakers
• Storage device

  Any device used for either temporary or permanent storage of data - can be internal or external.
• Examples of INTERNAL storage devices:

  1. Main memory
  2. RAM
  3. SSD
  4. Magnetic Drive
  5. Internal hard drive
• Examples of EXTERNAL storage devices:

  1. Optical disk (e.g. CD)
  2. USB/Flash drive
  3. Memory card
  4. External hard drive
• Drive

  The device that reads and writes data from secondary storage.
• The Media

  What the data is actually stored on.
• Optical storage Drive:

  MEDIA:

  • CDR - store and distribute music
  • CDRW
  • DVD-R - store motion pictures
  • DVD-RW
  • Blu-Ray

  Data stored in pits on surface of disk, data written with laser.
• Advantages of optical storage:

  1. Cheap
  2. Lightweight
  3. Portable
• Disadvantages of optical storage:

  1. Slow access times
  2. Prone to scratches
• Magnetic storage

  MEDIA:

  • HDD
  • Magnetic Tape

  Data stored by magnetically setting the arrangement of the magnetic material.
• Advantages of magnetic storage:

  1. Cheap
  2. Large capacity
• Disadvantages of magnetic storage:

  1. Slow access times
  2. Fragile
• Solid-State/Flash storage

  MEDIA:

  • SSD
  • Memory sticks
  • Flash memory cards

  Collection of memory chips that is controlled by its own software to make the collection of chips act like a disk drive.
• Advantages of Solid state/Flash storage:

  1. Durable
  2. Fast access time
• Disadvantages of Solid state/Flash storage:

  1. Cost
  2. Limited read/writes = limited life span
• Scenario: Helmet-mounted action

  NEEDS:

  • store video footage
  • data stored quickly
  • portable
  • durable

  BEST STORAGE = SSD
• Scenario: Home computer storing OS and apps

  NEEDS:

  • high capacity
  • data accessed quickly
  • reliable
  • low cost

  BEST STORAGE = Magnetic media
• Scenario: Travel agent backing up 800GB of data


  NEEDS:

  • high capacity
  • portable
  • durable
  • very reliable
  • medium cost

  BEST STORAGE = Magnetic media
• Scenario: transferring files between home and school

  NEEDS:

  • highly portable
  • durable
  • reliable
  • low cost

  BEST STORAGE = USB memory sticks or cloud-based server
• Scenario: Distributing a video game for a console.

  NEEDS:

  • portable
  • durable
  • reliable
  • low cost

  BEST TYPE: Optical media
• Read Only Memory (ROM)

  • Non-volatile.
  • Used to store fixed instructions such as the computer start up routine. (bootstrap.)
• Random Access Memory (RAM)

  • Volatile.
  • Holds data and programs which are currently in use.
  • High access speeds
  • Very expensive per gigabyte
• Power-On Self Test (POST)

  The POST sends signals to all connected components, wakes them up and makes the CPU aware of their existence.

  1. Hard drive -> Load OS into RAM
  2. Booting up OS can now begin
• Virtual Storage

  The concept of storing and retrieving data over the internet in the cloud.