Fetch Execute cycle

Fetch-cycle cycle:

• The program counter increments by one to find the instruction set.
• The Memory Address Register copies the address.
• Address bus carries address to IAS.
• Data found in main memory.
• Returned using the data bus.
• Transferred to MDR.
• Then copied to the CIR.
• The control unit takes the instruction.
• Program counter goes up by one to repeat.
• MAR updated to find next piece of data.
• Again finds the address and updates the MDR.
• The data is loaded on to the Accumulator.
• The MAR is updated finds the next instruction.