Addressing modes of 8085 microprocessor –
Table of Contents
Addressing modes of 8085 microprocessor –
What is Addressing modes –
“The various technique to specify data for instructions are caused as addressing mode.”
Intel 8085 uses the following addressing Mode –
1. Direct Addressing
2. Register Addressing
3. Register Indirect Addressing
4. Immediate Addressing
5. Implied Addressing
1. Direct Addressing –
In this mode of addressing the address of the operand ( data ) is given in the instruction itself.
Example –
(I) STA 2400 H –
Store the content of the accumulator in the memory location 2400 H.
In this instruction 2400 H is the memory address where data is to be stared. It is given in the instruction itself .
(II) IDA C200 –
“Load accumulator directly form memory location.”
in case the content of C200 memory location are transferred to accumulator.
2. Register Addressing –
In this register addressing mode the data to be operated is in the general purpose register.
The registration addressing instruction are generally to 1 byte .
I.e – OPCODE only .
Example –
(I) MOV A , B –
“Move the content of Register B to register A.”
(II) ADD B –
ADD the contents of register B to the content of register A.
3. Register Indirect Addressing –
In this mode of addressing the address of the operand is specified by a register pair .
Example
(I). LXIH 2400H –
load H-L pair with 2400H
(II). mov A , M –
Move the contents of memory “AM”.
4. Immediate Addressing –
In immediate addressing mode the operand is specified within the instruction itself.
Example
(I) MVIA , 05H –
Move 05 in register A.
(II) LZIH , 2400H –
Move 16 bit immediate data 2400 to H-L register pair.
5. Implicit Addressing –
There are certain instructions which operate on the content of the accumulator.
Example –
(I) CMA , RAL , RAR etc.
RAL – “Rotate accumulator last , it operators on the data accumulator only.
Multiplying of two 8 bit number–
