8085 Microprocessor Data Transfer Instructions

8085 Microprocessor Data Transfer Instructions – An instruction is a command in a binary pattern. Whenever an instruction is applied, the microprocessor performs a specific task. The collection of instructions is known as the instruction set of the microprocessor. The instruction set is fixed for the particular microprocessor by design and can not be altered.

Any other type of operation that is not a part of the instruction set can not be performed directly. Such operations can be performed by the combination of the instructions written and executed in sequence. The sequence of instructions to perform a specific task is known as a program. The 8085 microprocessor has 74 opcodes and 246 instructions. All the instructions in the 8085 microprocessor will be either 1-byte, or 2-bytes, or 3-bytes in length. All the instructions of the 8085 microprocessor instruction set can be classified into the following five functional categories: data transfer (move/copy) instructions, arithmetic instructions, logical instructions, branching instructions, and machine/processor control instructions.

Let’s first understand the notations used in the instructions of the 8085 microprocessor, and then we will learn about the instructions in detail. Here are the following notations used in the description of the instructions.

Notation	Meaning
R	Any 8-bit register (A, B, C, D, E, H, L)
Rd	Destination register (A, B, C, D, E, H, L)
Rs	Source register (A, B, C, D, E, H, L)
Rp	Register pair (BC, DE, HL, SP)
M	Memory location whose address is specified by the HL register pair
[ ]	Data stored in a memory address specified within brackets.

Data Transfer (Move/Copy) Instructions

The data transfer instructions copy data from a source into a destination without modifying the contents of the source. The contents of the destination are replaced by the new contents from the source. It is important to note that the data transfer instructions do not affect the flag register. These instructions are used to copy data

• between registers
• Immediate data (8-bit or 16-bit) to a register/register pair or a memory location.
• between a memory location and a register.
• between an input/output device and the accumulator.

MOV Rd, Rs	Move (Copy) data from source register (Rs) into destination register (Rd)
Operation	Rd ← Rs
Length	1 byte
Addressing mode	Register address mode
Flags	Flags are not affected

MOV M, Rs	Move (Copy) data from the source register (Rs) into the memory location given by the HL register pair.
Operation	[HL] ← Rs
Length	1 byte
Addressing mode	Indirect addressing
Flags	Flags are not affected

MOV Rd, M	Move (Copy) the data from the memory location pointed by the HL register pair into register Rd
Operation	Rd ← [HL]
Length	1 byte
Addressing mode	Indirect addressing
Flags	Flags are not affected

MVI Rd, data (8-bit)	Move (Copy) the 8-bit immediate data into the destination register Rd
Operation	Rd ← data (8-bit)
Length	2 byte
Addressing mode	Immediate addressing
Flags	Flags are not affected

MVI M, data (8-bit)	Move (Copy) the 8-bit immediate data into the memory location pointed by the HL register pair.
Operation	[HL] ← data (8-bit)
Length	2 byte
Addressing mode	Indirect addressing
Flags	Flags are not affected

LXI Rp, data (16-bit)	Load 16-bit immediate data into the register pair Rp
Operation	Rd ← data (16-bit)
Length	3 byte
Addressing mode	Immediate addressing mode
Flags	Flags are not affected

LDA Address (16-bit)	Load the data byte into the accumulator from the specified memory location.
Operation	A ← [Address]
Length	3 byte
Addressing mode	Direct addressing mode
Flags	Flags are not affected

STA Address (16-bit)	Store the data byte into the specified memory location from the accumulator.
Operation	[Address] ← A
Length	3 byte
Addressing mode	Direct addressing mode
Flags	Flags are not affected

LDAX Rp	Load the accumulator with the data stored at the location pointed to by register pair Rp
Operation	A ← [Rp]
Length	1 byte
Addressing mode	Indirect addressing mode
Flags	Flags are not affected

STAX Rp	Store the contents of the accumulator into the memory location pointed to by register pair Rp
Operation	[Rp] ← A
Length	1 byte
Addressing mode	Indirect addressing mode
Flags	Flags are not affected

IN Address (8-bit)	Copy the data from the 8-bit port address into the accumulator.
Operation	A ← [Address]
Length	2 byte
Addressing mode	Direct addressing mode
Flags	Flags are not affected

OUT Address (8-bit)	Copy the data from the accumulator into the 8-bit port address.
Operation	[Address] ← [A]
Length	2 byte
Addressing mode	Direct addressing mode
Flags	Flags are not affected

SHLD Address (16-bit)	Store contents of HL register pair directly into two conjugative memory locations.
Operation	[Address + 1] ← H
Length	3 bytes
Addressing mode	Direct addressing mode
Flags	Flags are not affected

LHLD Address (16-bit)	Load HL register pair from two conjucative memory locations.
Operation	[L] ← [Address] H ← [Address + 1]
Length	3 bytes
Addressing mode	Direct addressing mode
Flags	Flags are not affected

XCHG	Exchange H and L with D and E
Operation	H ↔ D L ↔ E
Length	1 bytes
Addressing mode	Register addressing mode
Flags	Flags are not affected

XTHL	Exchange H and L with the top of the stack
Operation	L ↔ [SP] H ↔ [SP + 1]
Length	1 bytes
Addressing mode	Register addressing mode
Flags	Flags are not affected

SPHL	Copy the contents of the register pair HL to the stack pointer.
Operation	SP ← HL
Length	1 bytes
Addressing mode	Register addressing mode
Flags	Flags are not affected

PCHL	Copy the contents of the register pair to the program counters.
Operation	PC ← HL
Length	1 bytes
Addressing mode	Register addressing mode
Flags	Flags are not affected