The Fetch, Decode, Execute Cycle

Question 1

Explain the Fetch part

Answer 1

• PC gets the new instruction by fetching the address of the next instruction from the RAM via the address buss
• The address in the PC is copied to the MAR
• PC increments to the next instruction
• Instruction stored at the location held by the MAR is copied to the MDR via the data bus

Question 2

Explain the Decode part

Answer 2

• Control Unit will decode the instruction and send control signals to the component that needs to act

Question 3

Explain the Execute part

Answer 3

• The component that is needed performs the operation
  This may be the:
• ALU