What is instruction cycle ?

          What is instruction cycle ?

Ans-The instruction cycle (or fetch-decode-execute cycle) is the fundamental process by which a computer's central processing unit (CPU) executes instructions. It involves several steps that are repeated for each instruction in a program. The main steps are:

1. Fetch

• The CPU retrieves the instruction from memory.
• The Program Counter (PC) holds the memory address of the next instruction to be executed.
• The instruction is loaded into the Instruction Register (IR).

2. Decode

• The CPU interprets the fetched instruction.
• The Control Unit determines what operation needs to be performed and identifies the required operands or data.

3. Execute

• The CPU performs the specified operation (e.g., arithmetic, logical operations, data transfer, or control instructions).
• This may involve accessing data from memory, registers, or input/output devices.

4. Store (Optional)

• If the instruction generates a result, it may be stored back in memory or a register for future use.
• 4. Write Back (optional)
• The results of the execution are written back to a register or memory, depending on the instruction.
• This step ensures that any computed values or updates are stored for future use.
• Additional Components:
• Interrupt Handling: During any phase, the CPU might check for and handle interrupts, which are signals that require immediate attention.
• Pipeline (if applicable): Modern CPUs may perform multiple phases simultaneously using an instruction pipeline, which significantly increases processing efficiency.
• Summary
• The cycle repeats for each instruction in the program, following the fetch-decode-execute-write-back sequence. This continuous process is the core mechanism that allows a CPU to execute programs.