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Saturday, 11 May 2013

ADDRESSING MODES OF 8085 MICROPROCESSOR

ADDRESSING MODES:

The method by which address of source of the data or destination of the data is given in the instruction is called addressing modes. the way in which address of the data is specified in 
instruction is known as addressing modes

8085 uses five types of addressing modes.
  1. Direct addressing mode
  2. Register addressing mode 
  3. Register indirect addressing mode
  4. Immediate addressing mode
  5. Implicit addressing mode
Direct addressing mode:-  In this mode addressing, address of the operand is given in
 instruction itself.

       example: LDA 2500 H,
It load the content of memory location 2500 H in to accumulator.
  •  LDA  is the operation
  • 2500 H is source of data
  • accumulator is destination
 
Register addressing mode :- In this mode of addressing, operand is in general purpose

    register.
     
     example: MOV A , B
It transfer the data of register B in to accumulator. 
  • MOV is operation.
  • register B is source of data
  • accumulator is destination

Register indirect addressing mode:- In this mode of addressing , address of  operand is specified
 register pair.

    example: MOV A, M
 It transfer the data from memory specified by H-L pair of register to accumulator.
  • MOV is operation
  • memory is source.
  • accumulator is destination.

Immediate addressing mode
:- In this mode of addressing operand is specified within the

 instruction itself.

example: MVI A , 05 H
It  move data 05 H into accumulator.
  • MVI is operation
  • 05 H is source.
  • accumulator is destination.

Implicit addressing mode
:- In this mode of addressing address of source of data as well as

 address of destination of is fixed. 'means no need of operand in instruction' called implicit mode.

example: CMA
Complement accumulator.
  • CMA is operation
  • accumulator is source
  • accumulator is destination.

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