Register addressing mode in 8085 Microprocessor

MicrocontrollerMicroprocessor8085

In this mode, the data is copied from one register to another. For example, MOV A, B: means data in register B is copied to register A.

  • MOV E, H

It occupies only 1-Byte in memory. MOV E, H is an example instruction of this type. It is a 1-Byte instruction. Suppose E register content is AB H, and H register content is 9C H. When the 8085 executes this instruction, the contents of E register will change to 9C H.This is shown as follows.



Before
After
(E)
ABH
9CH
(H)
9CH
9CH


Address
Hex Codes
Mnemonic
Comment
2004
5C
MOV E, H
E ← H

Note that H register’s content has not been changed at all. Although Intel has called it a “move” instruction, but actually in reality it seems to be a “copy” instruction.

The timing diagram of MOVE, H instruction is as follows -

Summary − So this instruction MOV E, H requires 1-Byte, 1-Machine Cycles (Opcode Fetch) and 4 T-States for execution as shown in the timing diagram. 

raja
Published on 04-Jan-2019 17:24:30
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