Question

In standard machine language instruction which component identifies the specific operation to be performed such as addition or data movement:

• A. Register
• B. Opcode
• C. Operand
• D. Immediate Address

Hint:

Machine Instruction Format: Opcode + Operand(s) Opcode tells the CPU:

• ADD

• SUB

• MUL

• MOV

• DIV
Operands tell the CPU where the data is located.

Answer 1

The Correct Option is B

Step 1: Break an instruction into parts.
A machine instruction is built from an opcode plus one or more operands: instruction = opcode + operand.
Step 2: Define the opcode.
Opcode is short for operation code, and it tells the CPU which operation to perform, such as ADD, SUB or MOV.
Step 3: See an example.
In ADD R1, R2 the part ADD is the opcode and R1, R2 are the operands; the opcode is what selects addition.
Step 4: Reject register and operand.
A register is a storage location and an operand names the data to work on, but neither chooses the operation.
Step 5: Reject immediate address.
An immediate value is data embedded in the instruction, again not the operation selector.
Step 6: Conclude.
The field that identifies the specific operation is the opcode.
\[ \boxed{\text{Opcode}} \]