Which of these is not part of a central processing unit (CPU)?

• A. Disk Drive
• B. Arithmetic Logic Unit
• C. Control Unit
• D. Registers

Answer: (A)

The CPU is built from components that actually process data and control instruction flow: the Arithmetic Logic Unit handles calculations and logical decisions, the Control Unit coordinates the fetch-decode-execute cycle and directs data movement, and Registers provide fast, temporary storage used during instruction execution. A disk drive is a persistent storage device outside the CPU, used to hold data and programs long-term and connected via the system bus and controllers. It does not participate in executing instructions or holding intermediate results, so it isn’t part of the CPU.