instruction cycle

instruction cycle in computer architecture

what is instruction cycle

Instruction cycle state Transition Diagram

• Instructions are stored in the memory.Every time a processor has to execute an instruction,it has to fetch from memory,then decode the instruction and finally execute.
• This process of fetch,decode and execute is called in instruction cycle.
• The fetch ,decode and execute requires steps.once this steps are executed the instruction is completed.

Instruction state transition diagram

Steps in which the instruction is executed:

1) The PC provides the address to retrieve a memory instruction.

2) The instruction opcode is decoded after it has been fetched.

3) This indicates whether any operands need to be retrieved from memory.

4) The address of the operand is determined.

Operands are retrieved from memory in step 5.

6) After performing the data operation on the operands, a result is produced.

7) The instruction terminates here if the outcome needs to be placed in a register.

8) If the destination is memory, it is necessary to calculate the destination address first.

9) After that, the outcome is saved in the memory.

10) The present instruction has now been carried out.

11) To determine the address of the following instruction, Side by Side PC is incremented.

12) For more instructions, the aforementioned instruction cycle is repeated.