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Com Sci Paper 2 (Networks (Advantages (Allows users to share software…

- - - - Application (HTTP)
        
        Provides applications for file transfer, remote control and internet activities.
        
        FTP (File Transfer Protocol) used to transfer files from one host to another.
        
        IMAP - used to retrieve emails from a message server.
        
        SMTP - used in sending and receiving mail.
      - Transport (TCP/UDP)
        
        Data read as a byte stream. Complex but reliable.
      - Network (IP)
        
        Responsible for Routing
      - Link
- - - - Simplifies micro chip controller design because only one memory is accessed.
      - RAM can be used for both data storage and program instruction storage.
      - Allows for greater flexibility in developing software, particularly in the development of operating systems.
    - - Only one bus connecting memory and processor so only one instruction or data item can be fetched at a time.
  - - - Arithmetic Logic Unit - arithmetic and logical operations on data.
      - Control Unit - fetches, decodes and executes instructions.
      - Internal Clock - Clock = signal used to synchronize things inside the computer.
  - - - Sequential Access: passes through all files in order.
      - Direct/random access - can access data at random.
    - - Magnetic Hard Disk Drive
        
        Contains moving read/write heads that contain electromagnets.
        
        Electromagnets create a magnetic charge on the disk's surface which contains iron particles that can be given a magnetic charge in one of two directions.
        
        Advantages
        
        Large storage capacity
        
        Cheap per MB compared with other storage media.
        
        Easily replaced and upgraded.
        
        Disadvantages
        
        Have moving parts which can fail
        
        Easily damaged if dropped
        
        Can be noisy.
      - Optical Storage Devices
        
        Optical disk's surface covered with tiny pits and lands which cause light to be reflected off them differently.
        
        Advantages
        
        Easy to store and carry
        
        easy to use
        
        Long lasting if looked after properly.
        
        Disadvantages
        
        Data on write-once disks are permanent and cannot be changed.
        
        Require special drives to read/write.
        
        Fragile
- - - - Prone to interference
      - Can be tapped
      - Easy to install
    - - More expensive but does not corrode
      - Secure data transmission
      - Much higher bandwidth over a longer distance