Addressing modes are techniques used in computer architecture to specify the method for calculating the effective address of an operand.
• The effective address is the location in memory that holds the operand.
• Different addressing modes provide flexibility in accessing operands, optimizing code, and utilizing memory efficiently.
• The Intel 8085 microprocessor supports various addressing modes, which define how operands are specified in instructions.
Here are the addressing modes supported by the Intel 8085:
- Immediate Addressing Mode:
- Operand: Immediate data
- Example:
MVI A, 05H(Load immediate data 05H into register A)
- Register Addressing Mode:
- Operand: Register contents
- Example:
MOV B, C(Copy contents of register C to register B)
- Direct Addressing Mode:
- Operand: Memory address
- Example:
MOV A, M(Copy contents of memory location addressed by HL pair to register A)
- Register Indirect Addressing Mode:
- Operand: Register pair contents (HL, DE, BC)
- Example:
MOV A, M(Copy contents of memory location addressed by HL pair to register A)
- Immediate Addressing Mode (for 16-bit operations):
- Operand: Immediate data (16-bit)
- Example:
LXI H, 2030H(Load immediate 16-bit data into register pair HL)
- Relative Addressing Mode:
- Operand: 8-bit signed offset
- Example:
JC Label(Jump to the specified label if the carry flag is set)
- Indexed Addressing Mode:
- Operand: Index register (IX or IY) + Displacement
- Example:
MOV A, (IX+10)(Copy contents of the memory location at IX + 10 to register A)
- Direct Offset Addressing Mode:
- Operand: Memory address + 8-bit signed offset
- Example:
MOV A, 2050H + 10(Copy contents of the memory location at 2060H to register A)
