Immediate Addressing Mode in 8086 Microprocessor

Last Updated : 26 Apr, 2024

Immediate addressing mode in 8086 microprocessor contains the instruction where the first operand may be a register or memory location and the second operand is an immediate value that represents the operand. In this article, we will explore the immediate addressing mode in detail along with the examples of immediate addressing mode. Also, we will discuss the advantages and disadvantages and applications of immediate addressing mode.

Table of Content

Immediate Addressing Mode
8086 Microprocessor Instruction
Operations
Examples
Advantages and Disadvantages
Applications

What is Immediate Addressing Mode in 8086 Microprocessor?

The immediate addressing mode in the 8086 microprocessor is the addressing mode in which the value of the operand is given directly in the instruction itself. In other words, in the immediate addressing mode in the 8086 microprocessor, the operand is present in the source operand of the instruction. The immediate addressing mode is commonly used addressing mode for initializing the value to the registers then the operation is performed. Some instructions directly take the value from the source operand in the immediate addressing mode and perform operations on it. Also, the destination operand cannot have immediate data. The segment registers cannot be initialized using the immediate data it needs to register to be initialized.

8086 Microprocessor Instruction with Immediate Addressing Mode

Representation of 8086 microprocessor instruction with immediate addressing modes.

Opcode Destination Operand, Source Operand
Opcode Register, Immediate Value

Operations of Immediate Addressing Mode

We know that in immediate addressing mode the operand in present in the instruction only as an immediate value. So, to perform any operation on the operand we directly fetch the operand from the source address field of the instruction. Consider the instruction format given below.

Opcode	Destination Address	Source Address
↓	↓	↓
Operation Decode	Destination address	Operand (immediate value)

Consider an example instruction.

MOV AL, 20H

Operations performed while executing the above instruction is given below.

AL ← 20H

Examples of 8086 Instruction with Immediate Addressing Mode

Some examples of immediate addressing modes in 8086 microprocessors are given below.

Instructions of 8086 microprocessor (immediate addressing used)	Description
MOV AX, 0103H	This instruction has an immediate value 0103H as its source operand and initializes the value of register AX with the immediate data.
MOV DH, 50H	This instruction has an immediate value 50H as its source operand and initializes the value of register DH with the immediate data.
ADD BX, 1025H	This instruction has an immediate value 1025H as its source operand and adds the immediate data with the content of register BX.
MUL AH, 10H	This instruction has an immediate value 10H as its source operand and multiplies the immediate data with the content of register AH.

Advantages and Disadvantages of Immediate Addressing Mode

Some of the advantages and disadvantages of immediate addressing modes are listed below.

Advantages of Immediate Addressing Mode in 8086 Microprocessor

Some of the advantages of immediate addressing modes are listed below.

Operand is specified in the instruction itself, so no computation and calculation are required to fetch the operand.
The effective address not required for the operand as it is present within the instruction.
The additional fetches for the operand are not required hence simplifying the instruction execution cycle.

Disadvantages of Immediate Addressing Mode in 8086 Microprocessor

Some of the disadvantages of immediate addressing modes are listed below.

The size of the operand is limited according to the instruction format.
The size of immediate value is constrained with the size of address field in the instruction.
The first operand in the instruction cannot be an immediate value.

Applications of Immediate Addressing Mode

Some applications of immediate addressing modes are listed below.

Immediate addressing mode can be used to initialize the registers.
The immediate value in the immediate addressing mode can be directly used as operand.

Conclusion

From the above discussion we can conclude that the 8086 microprocessors have different addressing modes. In the immediate addressing mode of 8086 microprocessor the operand in which the operation is to be performed is present within the instruction. The operand is fetched from the address part of the instruction of 8086 microprocessor and the desired operation is performed on this operand.