systems architecture

• CPU


  Central Processing Unit - Fetches, decodes and executes instructions
• CU


  Control Unit - Manages the components of the CPU.
• ALU


  Arithmetic and Logic Unit - Carries out basic mathematics and comparisons.
• Cache


  Super fast memory located next to the CPU. Stores commonly used data & instructions.
• Registers


  Small memory containers inside CPU.
• MAR


  Memory Access Register - Stores the address of the next instruction.
• MDR


  Memory Data Register - Stores the data fetched from the main memory(RAM).
• Program Counter


  A register that records the current instruction being executed.
• Accumulator


  A register used by the (ALU) to store the results of calculations.
• Clock Speed


  The speed of a computer's CPU, measured in hertz. This indicates the number of fetch-decode-execute cycles that can run per second.
• Cores


  A processing unit within a CPU. CPU's can have multiple cores.
• Embedded system


  A special purpose computer built into another device e.g. a microwave.
• Where does the CPU fetch instruction from?

  Main memory
• What model is this?

  Fetch - Execute cycle

  
• What are the key elements of Von Neumann architecture?

  • data and instructions are stored as binary digits
  • data and instructions are stored in primary storage
  • instructions are fetched one at a time, in order
  • processor decodes and executes instruction then fetches next one
  • cycle repeats until there are none left
• Von Neumann processors have 5 special registers:

  • Program counter
  • Memory address register
  • Current instruction register
  • Memory data register
  • Accumulator
• What is this?

  Von Neumann Architecture