Instruction format of 8085 , Addressing mode of 8085 microprocessor

Instruction Format of 8085 | Instruction Format | Types of Instruction | Addressing mode of microprocessor | Immediate addressing mode |Register addressing mode | Direct addressing mode | Indirect addressing mode | Implied addressing mode | 

                -: Instruction format :- 

Instruction format  is defined as - Instruction is the command given by the user to the microprocessor and need to be get executed by the processor the entire group of instruction are called instruction set and for properly working , these instruction sets are arranged in a proper way  which is known as instruction format .  
           Instruction format of 8085 has two fundamental fields.

(i) Opcode (information of operation)
(ii) Operand (address of location)

Type of instruction:- There are following three types of instructions formats used in microprocessor - 
(I)  1-byte instruction
(II)  2-byte instruction
(III) 3-byte instruction

(I) 1-byte instruction- A 1-byte instruction includes the opcode and a operand is the same byte.
Ex- INRC,ADD,MOVD etc.

(II) 2-byte instruction- In a two byte instruction have two field first byte specified the opcode or operation code and second byte is specified the operand.
Ex- MVI32H,SBI02H ,etc.

(III) 3- byte instruction- In a 3 byte instruction also have to filled first white specified the opcode for the following to bytes specified the 16 bit address / data (operand).
Ex- LXI D 1002H, LDA 4030H, JMP 2060H etc.

     -:Addressing Mode of 8085 Microprocessor:-

Addressing mode is defined as - The method of specify the data to be operated with instruction is called addressing mode.
             The different techniques provides the data address are referred to as addressing mode.

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   8085 has the following addressing mode-
I-Immediate addressing mode
II-Register addressing mode
III-Direct addressing mode
IV-Indirect addressing mode
V-Implied addressing mode

I-immediate addressing mode- In an immediate addressing mode 16 bit can be specified as a part of instruction. This is no need to specify the address of operand coma in 8085 the instruction having better for under this catching. I indicates immediate addressing mode.

in immediate addressing mode the data is stored along with the instruction and data directly transfer to the register.

Ex- MVIB20H(8-bit) , LXIDE 2040H(16-bit)


II-Register addressing mode- The addressing mode source operand,destination operand and both to be content in an 8085 registers. the result in the result in faster execution since it is not necessary to access memory locations for operands.
       In the Easter addressing mode that data is copied from one register and store another register or register pair.
Ex- MOV A, B ADD A, H

III-Direct addressing mode-  It is specify 16 bit address of operand within the instruction itself. Since this address is a part of instruction the second and third byte of instruction contains this 16 bit address.
Ex- LDA A, 2040H


IV-Indirect addressing mode- In indirect addressing mode the memory address operand located in a specified by the content of register pair.
Ex-LDAX B , MOV M,B

V- Implied (implicit) addressing mode- Implied addressing mode also known as "implicit"or Inherent addressing mode is the addressing mode in which, no operand(register or memory location or data) is specified in the instruction.

Ex-CMA , CLA

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