CPU

Central Processing Unit: “Brain” of computer.

• Registers: $0,...,$31, hi, lo
• Control Unit: Decodes instrs and dispatches
  • PC (Program Counter)
  • IR (Instruction Register)
• Memory: MDR (Memory Data Register) and MAR (Memory Address Register)
• ALU (Arithmetic Logic Unit): Does arithmetic.

CPU with Memory

• Bus: Data travels along the bus.
• Memory of many kinds. From fastest to slowest:
  • CPU/registers (fastest)
  • L1 cache
  • L2 cace
  • RAM
  • disk
  • network memory (outside your local machine)

CPU State

• Next place to fetch instruction from?
• What operation
• Instruction operands?
  • Within instruction
  • Registers (hold data within the CPU)
  • Outside the CPU: Memory