Question

In which addressing mode does the instruction contain the actual operand value itself rather than the address of operand?

• A. Direct Addressing
• B. Indirect Addressing
• C. Immediate Addressing
• D. Register Addressing

Hint:

Immediate addressing is the fastest way to get data because no memory reference is required after the instruction is fetched. However, the range of the value is limited by the number of bits available in the address field.

Answer 1

The Correct Option is C

Concept: Addressing modes are the various ways in which the location of an operand is specified in an instruction.
• Direct Addressing: The address field contains the effective address of the operand.
• Indirect Addressing: The address field contains the address where the effective address is stored.
• Immediate Addressing: The operand is part of the instruction itself.
• Register Addressing: The operand is stored in a CPU register specified by the instruction.

Step 1: Understanding the instruction structure.
Typically, an instruction consists of an Opcode (operation) and an Address/Data field. In most addressing modes, the processor must perform a memory or register access to fetch the data.

Step 2: Identifying the 'Immediate' characteristic.
In Immediate Addressing, the "Address" field doesn't actually contain an address. Instead, it contains the constant value (operand) that the instruction needs to use. For example, in an assembly instruction like MOV R1, #5, the value 5 is provided immediately.

Step 3: Conclusion.
Since the instruction itself holds the actual value, there is no need to look up a memory address or a register to find the data. This perfectly matches the description of Immediate Addressing.