Final answer:
The CPU fetches instructions according to the value of the program counter which holds the address of the next instruction.
Step-by-step explanation:
The CPU fetches the instruction from memory according to the value of the program counter. The program counter (PC) holds the address of the next instruction to be executed. Each time an instruction is fetched, the PC is updated to point to the next instruction. This is typically done by incrementing the PC, but it can also be modified directly by branch and jump instructions which alter the flow of execution. The status register, instruction register, and program status word serve different purposes. The status register indicates the current state of the processor, the instruction register holds the current instruction being executed, and the program status word holds status bits that reflect the state of the CPU.