computer science

• Control unit


  Main part of the CPU that controls everything
• Arithmetic logic unit


  Does maths and logic calculations
• Memory


  RAM (random access memory)
• Fetch-decode-execute cycle


  1. Fetch task

  2. Decode task

  3. Execute task
• Program counter


  Holds the address of the task
• Memory address register


  Takes the address from the program counter
• Memory data register


  Copies the instruction stored at the address
• Increment of program counter

  If 1, address of task 1, if 2, address of task 2
• Registers


  • Memory address register
  • Memory data register
  • Program counter
  • Accumulator
• Accumulator


  Stores the results of calculations from the arithmetic logic unit
• Arithmetic logic unit


  Does maths and logic operations
• Control unit


  Manages the fetch-decode-execute cycle
• Cache


  Stores frequently used data for quick access
• RAM (random access memory)


  Volatile, data lost when power is lost
• ROM (read-only memory)


  Non-volatile, data retained when power is lost
• RAM


  Stores data currently in use by the CPU, read and write
• ROM


  Contains startup instructions for the CPU, read-only
• Virtual memory


  Uses part of secondary storage as extra RAM when RAM is full
• The disadvantage of virtual memory is that it's slower
• Secondary storage types


  • Optical
  • Magnetic
  • Solid state