Addressing Modes Of 8086 j1z67

MICROPROCESSOR ARCHITECTURE UOP S.E.COMP (SEM-I)

8086 MICROPROCESSOR ARCHITECTURE

Prof.P.C.Patil Department of Computer Engg Matoshri College of Engg.Nasik [email protected].

8086 Programmers Model

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8086 Programmers Model

8086 Addressing Modes

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8086 Addressing Modes

1. 2. 3. 4. 5. 6.

Addressing Mode Immediate Addressing Mode Memory Addressing Mode String Addressing Mode I/O Addressing Mode Implied Addressing Mode

8086 Addressing Modes

1. Addressing Mode

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Addressing Mode 



Data is in and Instruction Specifies the perticular E.g MOV AX,BX

2.Immediate Addressing Mode

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2.IMMEDIATE ADDRESSING MODE 





Immediate operand is Constant data contained in an Instruction i.e. The source operand is a part of instruction instade of memory E.g MOV CL,02H

3.Memory Addressing Mode

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Memory Addressing Mode

3.1 Direct 3.2 Indirect 3.3 Based Indexed 3.4 Relative 3.5 Relative Based Indexed

Memory Addressing Mode

EFFECTIVE ADDRESS 



 

The offset of a memory operand is called the operand’s effective address (EA). Is an unsiged 16 bit no. That expresses the operands distance in byte from the begining of the segment 8086 has Base and Index So EU calculates EA by summing a Displacement, Content of Base and Content of Index .

Memory Addressing Mode

 

 



Displacement is an 8 or 16 bit no It is generally derived from the position of operand name. It’s value is constant. Pogrammer may specify either BX or BP is to be used as Base Similarly either SI od DI may be specified as Index

Memory Addressing Mode

3.1 DIRECT MEMORY ADDRESSING MODE

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Memory Addressing Mode  

EA is taken from the displacement field of instruction. PA=This addr. Is added with Seg.Regi*10 H MOV[1023],AL

Memory Addressing Mode

3.2 INDIRECT ADDRESSING MODE

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Memory Addressing Mode  

EA of may be taken directly from one of the base or index . PA=This addr. Is added with Seg.Regi*10 H MOV[SI],AL

Memory Addressing Mode

3.3 BASED INDEXED ADDRESSING MODE

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Memory Addressing Mode   

EA is sum of Base and Index . Both of which are specified by the instruction PA=This addr. Is added with Seg.Regi*10 H MOV[BX+SI],AL

Memory Addressing Mode

3.4 RELATIVE ADDRESSING MODE

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Memory Addressing Mode  

EA is Sum of 8 or 16 bit displacement and contents of base or an index PA=This addr. Is added with Seg.Regi*10 H MOV[BX+1100],AL

Memory Addressing Mode

3.5 RELATIVE BASED INDEXED MODE

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Memory Addressing Mode  

EA is Sum of a Base ,an Index and Displacement . PA=This addr. Is added with Seg.Regi*10 H MOV CX,[BX+SI+0400]