NIMCET 2026 — Computer PYQ

The correct option is 2. Opcode.

Explanation:

A standard machine language instruction is divided into distinct functional fields that the CPU control unit decodes to execute a task. Let's analyze the role of each component mentioned in the options:

• Opcode (Operation Code): This is the mandatory portion of a machine language instruction that specifies the exact operation the hardware processor must execute (e.g., $ADD$, $SUB$, $LOAD$, $STORE$, $MOV$). For instance, an instruction sequence like $0001$ might tell the CPU's Arithmetic Logic Unit (ALU) to perform an addition operation.

• Operand: This field specifies the data or the locations of the data that the opcode will manipulate. Operands can be constants, CPU register names, or memory addresses.

• Register: This is a high-speed storage location directly inside the CPU processor used to hold temporary data operands during computation. It is not the component that determines the action type.

• Immediate Address: This is a specific addressing mode where the target operand value is contained directly inside the instruction itself rather than referencing an external memory cell address or index pointer.

Structural Representation:

$$\text{Machine Instruction}=\underset{\text{Specifies the Operation Type}}{\underbrace{\text{[ Opcode ]}}}+\underset{\text{Specifies the Data / Location}}{\underbrace{\text{[ Operand Field(s) ]}}}$$