In 8085 Instruction set, MOV r, M is an instruction where the 8-bit data content of the memory location as pointed by HL register pair will be moved to the register r. Thus this is an instruction to load register r with the 8-bit value from a specified memory location whose 16-bit address is in HL register pair.
As r can have any of the seven values, there are seven opcodes for this type of instruction.
r = A, B, C, D, E, H, or L
|MOV A, M||7E||1|
|MOV B, M||46||1|
|MOV C, M||4E||1|
|MOV D, M||56||1|
|MOV E, M||5E||1|
|MOV H, M||66||1|
|MOV L, M||6E||1|
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. Let us 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.
|2008||2A||MOV E, M||Comment 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 requires 1-Byte, 2-Machine Cycles (Opcode Fetch, Memory Read) and 7 T-States for execution as shown in the timing diagram.