Register indirect addressing mode in 8085 Microprocessor

Microcontroller Microprocessor 8085

In this mode, the data is transferred from one register to another by using the address pointed by the register. Register indirect addressing mode also used to call as indirect addressing mode. For example MOV A, M: means data is transferred from the memory address pointed by the register pair HLto the register A.

MOV E, M

It occupies only 1-Byte in memory. MOV E, M is an example instruction of this type. It is a 1-Byte instruction. Suppose E register content is DBH, H register content is 40H, and L register content is 50H. Letus say location 4050H has the data value AAH. When the 8085 executes this instruction, the contents of E register will change to AAH, as shown below –

	Before	After
(E)	DBH	AAH
(HL)	4050H	4050H
(4050H)	AAH	AAH

Address	Hex Codes	Mnemonic	Comment
2008	2A	MOV E, M	E ← Content of the memory location pointed by HL register pair

The timing diagram for this MOV E, M instruction is as follows –

Summary: So this instruction MOV E, M requires1-Byte, 2-Machine Cycles (Opcode Fetch, Memory Read) and 7 T-States for execution as shown in the timing diagram.

Ankith Reddy

Published on 04-Jan-2019 13:02:59

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