In a traditional CPU, which of the following is NOT considered a primary function of the Control Unit (CU)?

Introduction / Context:
The central processing unit (CPU) of a computer is typically described as having two main components: the Control Unit (CU) and the Arithmetic Logic Unit (ALU). Each part has different responsibilities. Understanding which functions belong to the CU and which belong to the ALU is important in computer architecture questions. This question asks you to identify which listed activity is not primarily a function of the Control Unit.

Given Data / Assumptions:

• The CPU is conceptually divided into a Control Unit and an Arithmetic Logic Unit.
• The Control Unit manages instruction flow and coordinates operations.
• The ALU performs arithmetic and logical computations.
• The options include interpreting, reading, executing instructions, and directing operations.
• We assume a textbook view of CPU components.

Concept / Approach:
The Control Unit is responsible for fetching instructions from memory, decoding (interpreting) them, and generating control signals that direct the ALU, registers, and other components to perform the required operations. It orchestrates the execution but does not perform arithmetic and logic operations itself. Those operations are handled by the ALU. Therefore, executing instructions in the sense of performing actual arithmetic and logical computations is not a primary function of the CU, even though the CU controls when execution happens.

Step-by-Step Solution:
Step 1: List typical Control Unit functions: fetch, decode, and control. Step 2: Recognise that the CU reads or fetches the next instruction from main memory and loads it into an instruction register. Step 3: Note that the CU interprets or decodes the instruction, determining which operation is requested. Step 4: Understand that the CU then directs other components by sending control signals, telling the ALU what operation to perform and which registers or memory addresses to use. Step 5: Identify that the actual arithmetic and logical calculations (add, subtract, AND, OR, comparisons) are carried out by the ALU, not by the CU. Step 6: Conclude that executing instructions by performing arithmetic and logic operations is not a direct function of the Control Unit, but rather the job of the ALU.

Verification / Alternative check:
Computer architecture textbooks describe the instruction cycle as fetch–decode–execute. They typically attribute fetching and decoding to the Control Unit, as well as issuing control signals, while execution is shown as happening inside the ALU and related data paths. The CU is often compared to a traffic controller or conductor, coordinating tasks but not doing the calculations itself. This division of responsibilities is consistent across many references, confirming that the CU does not itself perform arithmetic and logic, even though it oversees execution.

Why Other Options Are Wrong:
Interpret instructions: This is a core function of the CU, which decodes the instruction opcodes and determines the required operation. Read or fetch instructions from memory: The CU handles fetching the next instruction from memory during the instruction cycle. Direct operations of other parts of the processor: The CU sends control signals that direct the ALU, registers, and buses, making this a key CU role.

Common Pitfalls:
A common mistake is to interpret execute instructions in a broad sense and think that the CU executes instructions simply because it is involved in the instruction cycle. To avoid confusion, remember that in classical CPU design, execute refers specifically to performing arithmetic and logical operations, which is the ALU's responsibility. The CU arranges for this to happen but does not perform the calculations itself. Keeping this division clear will help you answer similar questions about CPU components accurately.

Final Answer:
The activity that is not primarily a function of the Control Unit is Execute instructions by performing arithmetic and logic operations.