Instruction Fetch Execute Cycle

                                        
1. Fetch Cycle 
2. Decode Cycle 
3. Execute Cycle

Working Of Instruction fetch Execute Cycle : 
1.fetch an instruc:on from memory. 
2.fetch any data required by the instruc:on from memory. 
3.execute the instruc:on (process the data). 
4.store results in memory. 
5.go back to step (1)
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1. Fetch Cycle: The fetch cycle begins with retrieving the address stored in the Program Counter (PC). The address stored in the PC is some valid address in the memory holding the instruction to be executed. (In case this address does not exist we would end up causing an interrupt or exception).

The Central processing unit completes this step by fetching the instruction stored at this address from the memory and transferring this instruction to a special register – Instruction Register (IR) to hold the instruction to be executed. The program counter is incremented to point to the next address from which the new instruction is to be fetched.


2. Decode Cycle: The decode cycle is used for interpreting the instruction that was fetched in the Fetch Cycle. The operands are retrieved from the addresses if the need be. 

3. Execute Cycle: This cycle as the name suggests , simply executes the instruction that was fetched and decoded.

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