16 Bit Data Transfer Instructions | 8085 Microprocessor

Rp = Register pair

1. LXI   Rp, 16 Bit data

Rp 

BC ≡ B

DE ≡ D

HL ≡ H

SP

Instruction word size  ⇒   3 Byte

Operation ⇒ When this instruction will execute the 16-bit data will store in register pair Rp.

[Rp ] ← 16-bit data

Addressing Mode ⇒ Immediate Addressing Mode

For example:

LXI  D  2059 H

[D] = 20 H [E] = 59 H

2. LDA   16-bit address

Instruction word size  ⇒   3 Byte

Operation ⇒ When this instruction will execute the 8-bit data available in the memory at the 16-bit address given in the instruction will load in the accumulator.

[A] ← [16-bit address]

Addressing Mode ⇒ Direct Addressing Mode

For example:

LDA  5029 H

[A] = [ [ 5029 ] ] [A] = 2D H

3. STA   16-bit address

Instruction word size  ⇒   3 Byte

Operation ⇒ When this instruction will execute the content of accumulator will store at the 16-bit address in memory that is given in the instruction.

[A] → [16-bit address]

Addressing Mode ⇒ Direct Addressing Mode

For example:

[A] = 21 H

STA  3089 H

[ [ 3089 ] ] = 21 H

4. LDAX    Rp

Instruction word size  ⇒   1 Byte

Operation ⇒ When this instruction will execute the 8-bit data available at the 16-bit address in memory that is given in the form of content of register pair Rp will load in the accumulator.

[A] ← [ [Rp] ]

Addressing Mode ⇒ Indirect register Addressing Mode

For example:

[B] = 50 H [C] = 8F H [BC] = [508F] = 92 H

 

LDAX   B

[A] = 92 H

5. STAX    Rp

Instruction word size  ⇒   1 Byte

Operation ⇒ When this instruction will execute the content of accumulator will store at a 16-bit address in memory that is given in the form of content of register pair Rp.

[A] → [ [Rp] ]

Addressing Mode ⇒ Indirect register Addressing Mode

For example:

[A] = 12 H [D] = 50 H [E] = 89 H

STAX  D

[DE] = [5089] = 12 H

 

Note: All above instructions are data transfer instructions, so the status of the flag will not affect.

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