4.7.3.2 The Fetch-Execute cycle and the role of registers within it

Question 1

Describe the steps in the Fetch part of the Fetch Decode Execute Cycle

Answer 1

The contents of the PC are transferred to the MAR
The address bus carries this address to main memory
The contents of the addressed memory location are moved into the MDR/MBR using the data bus
The PC is incremented
The contents in the MDR/MBR is transferred to the CIR

Question 2

What does the accumulator do?

Answer 2

Holds the result of the processed data by the ALU

Question 3

Describe the steps in the Decode part of the Fetch Decode Execute Cycle

Answer 3

The Control Unit decodes the instruction held by the CIR by splitting it into opcode and operand

Question 4

Describe the steps in the execute part of the Fetch Decode Execute Cycle

Answer 4

The opcode identifies the instruction to execute by the Control Unit or ALU. The result is stored in the accumulator.