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Saturday, May 7, 2011

8085 Addressing Modes


Addressing Modes


The microprocessor has different ways of specifying the data for the instruction. These are called “addressing modes”.


The 8085 has Five addressing modes:


1)  Implied Addressing mode: In this type of addressing mode, No operand (register or data) is specified in the instruction. The operand is inherent to the instruction. 
    
Example:   CMA (Complement Accumulator) , SIM , RIM etc 
  
2)  Immediate Addressing Mode: In this type of addressing mode, immediate data byte is provided with the instruction. 


Example: MVI A  32H; 
         MVI B  AAH; 
etc. 


3)  Direct Addressing Mode: In this type of addressing mode, the 16bit memory address is directly provided with the instruction. 


Example:   LDA C500H ;
etc 


4)  Indirect Addressing Mode: In this type of addressing mode, the 16bit memory address is indirectly provided with the instruction using a register pair


Example:   LDAX  D;   
(Load the accumulator with the contents of the memory location whose address is stored in the register pair DE)

5)  Register Addressing mode:   This type of addressing mode specifies register or register pair that contains data. 


Example:   ADD B;  
           MOV B, A;
   

2 comments:

  1. thaaaaaaaaaaaaaaaaaaaaaaaaxxxxxxxxxxxxx

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  2. This was really helpful. I would love to get a more detailed example of each of the instructions under the various addressing modes.

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