tricky stuff

• aplication software


  carries out task useful for end to end
• example of aplication software

  word processors

  image editing
• two types of system software

  utility software

  operating systems
• what is utility software

  support the running of the computer system
• types of utility software

  antivirus

  compression
• what is operating systems


  manages hardware and other programs
• example of what operating systems manage

  processors

  memory

  input/output devices

  applications

  security
• how does the operating system manage processors

  • allocates instructions to cores
  • schedule instructions
  • rapidly switch between programs - enables multitasking
  • can interrupt itself if it need to do something more urgent.
• how does the operating system manage memory

  • load memory in and out of RAM / Cache
• how does the operating system manage input and output devices

  • installs drivers as they are plugged in
• assemblers


  assembly -> machine code

  • line by line
• compilers


  high-level -> machine code

  • all in one go
• interpreters


  high-level -> machine code

  • line by line
• ALU


  logic calculations
• Control unit


  Coordinates the FDE cycles

  decodes instructions
• Cache


  small, fast memory

  hold frequently used info
• clock


  synchronize components
• fetch


  next instruction loaded from main memory
• decode


  instruction is interpreted by the control unit
• execute


  instruction is carried out

  any additional data is fetched
• increase in cache size results in


  more storage for frequently used instructions
• embedded systems


  computers inside other devices

  usually simple and have one purpose only
• pan


  personal area network

  • used by one person
• lan


  local area network

  • small geographical area
• wan


  wide are network

  • infrastructure owned by multiple entities
• acronym for protocol layers

  Agile Turtles In Love
• what are the protocol layers

  application

  transport

  internet

  link
• application layer


  (for sending/receiving)
• HTTP/S


  for web pages / encryption
• FTP


  sending files
• IMAP- Internet message access protocol

  receiving emails
• SMTP


  sending emails
• Transport layer


  splitting data into packets
• TCP - Transmission control protocol

  splits data into packets and handles errors
• UDP - user datagram protocol


  splits data into packets, doesn't check if they arrive or not
• Internet layer


  assigning a location
• IP - internet protocol


  assigns an IP address, shows where the device is located
• Link Layer


  type of connection
• WiFiLink


  Wirless
• Bluetooth Link


  Warless (Pan)