FDE

Question 1

fetch phase

Answer 1

Address from the PC is copied to the MAR
* Instruction held at that address is copied to MDR by the data bus
* Simultaneously, the contents of the PC are increased by 1
* The value held in the MDR is copied to the CIR

Question 2

decode phase

Answer 2

The contents of CIR are split into operand and opcode

Question 3

execute phase

Answer 3

The decoded instruction is executed