In what way does the fetch-execute cycle operate in a CPU?

The fetch-execute cycle operates in a CPU by repeatedly fetching, decoding, and executing instructions from memory.

The fetch-execute cycle, also known as the instruction cycle, is the fundamental operational process of a computer. It is the method by which a computer retrieves a program instruction from its memory, determines what actions the instruction requires, and carries out those actions. This cycle is repeated continuously by the central processing unit (CPU), from boot-up to when the system is shut down.

The cycle begins with the fetch phase. The CPU uses the program counter to identify the memory address of the next instruction to be executed. This instruction is then fetched from memory and stored in the instruction register. The program counter is then incremented to point to the next instruction.

Following the fetch phase is the decode phase. The instruction held in the instruction register is decoded by the control unit. The control unit determines what operation needs to be performed and signals the appropriate part of the CPU to carry out the operation.

The final phase is the execute phase. The operation is carried out on the data. This could involve reading data from memory, performing some arithmetic or logical operation, or writing data to memory. Once the instruction has been executed, the CPU moves on to the next instruction and the cycle begins again.

The fetch-execute cycle is a continuous process that allows the CPU to execute instructions in a sequential manner. It is the fundamental process that drives the operation of a computer. The speed at which this cycle can be completed directly impacts the overall performance of the computer. Modern CPUs can complete millions of fetch-execute cycles every second.

In summary, the fetch-execute cycle is the process by which a computer retrieves a program instruction from its memory, determines what actions the instruction dictates, and carries out those actions. This cycle is repeated continuously by the CPU, allowing it to execute a sequence of instructions that make up a program.