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Addressing Modes of 8086

The 8086 processor uses various addressing modes to access data. [1] These addressing modes include immediate, direct, register, register indirect, indexed, register relative, based indexed, and relative based indexed addressing. [2] Each addressing mode specifies the source or destination of data differently, such as using an immediate value, register, or memory address. [3] The 8086 instruction MOV can be used to illustrate how these addressing modes work by specifying the destination and source of data transfer in different ways.

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186 views15 pages

Addressing Modes of 8086

The 8086 processor uses various addressing modes to access data. [1] These addressing modes include immediate, direct, register, register indirect, indexed, register relative, based indexed, and relative based indexed addressing. [2] Each addressing mode specifies the source or destination of data differently, such as using an immediate value, register, or memory address. [3] The 8086 instruction MOV can be used to illustrate how these addressing modes work by specifying the destination and source of data transfer in different ways.

Uploaded by

Sunil Kumar
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Addressing Modes

of
8086
Presented By:

AL Ikhlas Rahman

Daffodil International
University

Dhaka,Bangladesh
The different ways in which a processor can
access data are called
addressing modes.
How 8086 accesses data?

 8086 assembly language instructions can


be used to illustrate the addressing modes

 Format of MOV instruction

MOV destination, source


Source of data can be

Immediate data
A specified register
A memory location specified in 1 of 24 different ways

Destination of data can be

A specified register
A memory location specified in 1 of 24 different ways
Classification of Addressing Modes

 Immediate addressing mode


 Direct addressing mode

 Register addressing mode


 Register Indirect addressing
mode
 Indexed addressing mode
 Register relative addressing
mode
 Based indexed addressing
mode
 Relative based indexed
addressing mode
Immediate addressing mode

 Immediate data is a part of instruction.


The immediate data may be 8-bit or 16-bit in size.

 MOV AX, 0005H

In the above example, 0005H is the immediate data.


Direct addressing mode

Memory Address (Offset) Is Directly Specified In


The Instruction .

MOV AX, [5000H]

Here, data besides in a memory location in the data


segment.

Physical Address Of Memory Location Is Calculated


Using DS And Offset Value 5000H.
Register addressing mode

Source/Destination Can Be One Of The 8086 Registers

Example:

MOV AX, BX ; 16-bit Data Transfer


Register Indirect addressing mode

The Offset Address Of Data Is In Either BX Or SI Or DI


Registers. The Default Segment Is Either DS Or ES.

Example: MOV AX, [BX].

Here, Data Is Present In A Memory Location In DS Whose


Offset Address Is In BX.

The Effective Address Of The Data Is Given As 10H*DS+


[BX].
Indexed addressing mode

MOV AX, [SI].

Here, data is available at an offset address


stored in SI in DS.
Register relative addressing mode

MOV Ax, 50H [BX].

Here, physical address is given as 10H*DS+50H+


[BX].
Based indexed addressing mode

MOV AX, [BX] [SI].

Here, BX is the base register and SI is the index


register. The physical address is computed as is the index
register.

The physical address is computed as 10H*DS+[BX]+[SI].


Relative based indexed addressing mode

MOV AX, 50H [BX] [SI]

Here, 50H is an immediate displacement, BX is a base


register and SI is Here, 50H is an immediate
displacement, BX is a base register and SI is an index
register.
The physical address of data is computed as 10H*DS+
[BX] + [SI] + 50H.
Thank you..

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