To process any command, the Central Processing Unit (CPU) follows a repetitive…
To process any command, the Central Processing Unit (CPU) follows a repetitive sequence known as the Instruction Cycle. Define this cycle and describe its four distinct phases: Fetch, Decode, Execute, and Store ?
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The Instruction Cycle is the repeated sequence of steps followed by the CPU to execute every instruction in a program.
• Fetch Phase: In this phase, the CPU fetches the instruction from main memory using the address stored in the Program Counter and loads it into the instruction register.
• Decode Phase: The fetched instruction is decoded by the Control Unit to determine the operation to be performed and the required operands.
• Execute Phase: The CPU performs the specified operation, such as arithmetic, logical operation, or data transfer, using the ALU or other units.
• Store Phase: The result of execution is stored back in a register or memory location for future use.
Example: An ADD instruction is fetched, decoded, executed by the ALU, and the result is stored in memory or a register.