1. Addressing Modes of 8085

2. Addressing Modes of 8085
Addressing Modes : is the technique used to fetch the desired operand during the execution of an instruction.
Instructions can be categorized according to their method of addressing the hardware registers and/or memory.

3. Addressing Modes of 8085 • The 8085 MPU uses five addressing Modes:
Immediate Addressing Modes
Register Addressing Modes
Direct Addressing Modes
Register Indirect Addressing Modes
Implied Addressing Modes

4. Addressing Modes of 8085 Immediate Addressing Mode:
Data immediately follow the opcode in program memory
The operand comes from next byte in program memory
Example: MVI E,08h
ADI 7Ah
LXI B,0001h

5. Addressing Modes of 8085 Register Addressing Mode:
• Many 8085 MPU instructions use register addressing
• Specify one of the registers A through E, H or L as well as the operation code.
• The operand is retrieved from internal CPU Register
Example: MOV A,B
ANA E
SUB H

6. Addressing Modes of 8085 Direct Addressing Mode:
• Address is given directly in the instruction
The operand is accessed from the given address of memory / IO device
Example: STA 2005h
LHLD 8200h
IN 96h
OUT 01h

7. Addressing Modes of 8085 Register Indirect Addressing Mode:
• Address is given indirectly by specifying register pair
The content of register pair will be taken address of memory
The content of memory location is the original operand
Example: MOV A,M
SUB M
LDAX B

8. Addressing Modes of 8085
Implied / Implicit / Inherent Addressing Mode:
• Some Instructions specify the operand within the opcode itself
Example: STC, CMA, RAL
Some other instructions do not deal with operands
Example: HLT

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