Instruction type MVI r, d8 in 8085 Microprocessor


MVI is a mnemonic, which actually means “Move Immediate”. With this instruction,we can load a register with an 8-bitsor 1-Bytevalue. This instruction supports immediate addressing mode for specifying the data in the instruction. In the instruction “d8” stands for any 8-bit data, and ‘r’ stands for any one of the registers e.g. A, B, C, D, E, H or L. So this r can replace any one of the seven registers.

As ‘r’ can have any of the seven register names, so there are seven opcodes for this type of instruction. It occupies 2-Bytes in the memory.

Mnemonics, Operand Opcode Bytes
MVI A, Data 3E 2
MVI B, Data 06 2
MVI C, Data 0E 2
MVI D, Data 16 2
MVI E, Data 1E 2
MVI H, Data 26 2
MVI L, Data 2E 2

As example, if we consider instruction MVI E, ABH then it means that ABH will be moved or copied to the register E. And as a result the previous value of E will get over written.

Address Hex Codes Mnemonic Comment
2000 1E MVI E, ABH E <- ABH
2001 AB ABH as operand

This instruction will have seven T-states as shown below.


Summary − So this instruction MVI E, ABH requires 2-Bytes, 2-Machine Cycles (Opcode Fetch and Memory Read) and 7 T-States for execution as shown in the timing diagram.

Published on 30-Nov-2018 06:39:16