Register Indirect Addressing : Content of register pair points to the address of operand.A register pair (H-L pair) is specified for addressing 16-bit address of memory location.These generally are single byte instructions.Д®xample : MOV M,BThis instruction transfers the content of register B to memory location whose address is placed in HL register pair without modifying the content of BД®xample : MOV A,MThis instruction transfers the content of memory location whose address is placed in HL register pair to accumulator without modifying the content of memory locationД®xample : ADD MThis instruction will add the content of memory location whose address is placed in HL register pair to accumulator without modifying the content of memory locationImmediate Addressing : Data (8 or 16-bit) appears immediately after opcode of instruction.In these instructions actual data is specified within the instruction.These may be 2 to 3 byte instructions.Д®xample : MVI A,99HThis instruction will load the accumulator with 8-bit immediate data 99H which is specified within second byte of instruction.Д®xample : LXI D,8C50HThis instruction will load DE register pair with 16-bit immediate data 8C50H. All actions occur within CPUД®xample : MOV A,BThis instruction transfers the content of register B to accumulator without modifying the content of BД®xample : INR BThis instruction will increment the content of register B by 1Д®xample : ADD CThis instruction will add the content of register C to accumulator without modifying the content of C InstructionByte 1Byte 2Byte 3LDA D500 HLDA00D5InstructionByte 1Byte 2Byte 3STA 95FF HSTAFF95Register Addressing : Register appears after opcodeOperands are general purpose registers specified within instructionThese are single byte instructions. Byte 1 is opcode while byte 2 & 3 are of address.Д®xample : LDA D500 HThis instruction will load accumulator with content of memory location D500 H.Д®xample : STA 95FF HThis instruction will store the content of accumulator to memory location 95FF H Microprocessor has five addressing modesAddressing Modes of Microprocessor 8085Direct AddressingRegister AddressingRegister Indirect AddressingImmediate AddressingImplied AddressingDirect Addressing : Address appears after opcode of instructionThe address of operand is specified within instructionThese are 3 byte instructions. Opcode tells about the type of operation while operand can be data (8 or 16 bit), address, registers, register pair, etc.Addressing mode is format of specifying on operands INSTRUCTION SET OF MICROPROCESSOR 80858085 has 246 instructionsД®ach instruction of microprocessor 8085 consists of opcode & operand.

8085 microprocessor instruction set