MVI Instruction in 8085 - Move Immediate Data into Registers

MVI Instruction in 8085 - Move Immediate Data into Registers

Introduction

Need to load a specific value directly into a register? That’s where MVI (Move Immediate) comes in! Unlike MOV, which transfers data between registers, MVI allows you to assign a fixed value directly to a register or memory location.

In this guide, we’ll break down how MVI works, explore its execution at the pin level, and provide hands-on examples so you can see it in action!

Syntax & Operand Details

Mnemonic: MVI
Operands: Destination, 8-bit Data
Syntax: MVI D, XX

• D = Destination Register (where data is loaded)

• XX = 8-bit Immediate Data

Addressing Modes

MVI uses immediate addressing mode, meaning data is directly provided in the instruction.

Hex Code Representation

Instruction	Opcode	Example
MVI A, 32H	3E 32	Loads 32H into A
MVI B, 45H	06 45	Loads 45H into B
MVI C, FFH	0E FF	Loads FFH into C
MVI D, 10H	16 10	Loads 10H into D
MVI E, 77H	1E 77	Loads 77H into E
MVI H, 2AH	26 2A	Loads 2AH into H
MVI L, 99H	2E 99	Loads 99H into L

Execution & Pin-Level Breakdown (T-Cycle Analysis)

T-Cycle Breakdown:

T-State	Operation	Affected Pins
T1	Fetch opcode	AD0-AD7 (Multiplexed Address/Data)
T2	Fetch immediate data	AD0-AD7 (Data Transfer)
T3	Load data into register	Control signals (ALE, WR)

Example with Step-by-Step Execution

Example: Load 45H into Register B

MVI B, 45H  ; Load 45H into register B

Step-by-Step Execution:

1. The processor fetches the instruction opcode (06).

2. The next byte (45H) is fetched and stored in register B.

3. Register B now holds 45H.

Try It in Live 8085 Simulator!