Addressing modes are used to specify the data to be operated with the help of instructions. Addressing Modes of 8085 are divided into five groups. The instructions are used to transfer the data from one register to another register, from the memory to the register, and from the register to the memory without any change in the content. Instructions are nothing but binary patterns which are designed to perform some specific functions. The microprocessor supports an entire group of instructions called an instruction set.
- The 8085 microprocessor has in total 246 instructions.
- An 8-bit binary value is assigned to each instruction.
- The 8-bit binary value assigned is called Op-code.
Addressing Modes of 8085 is divided into 5 groups −
Immediate addressing mode
Here, the 8/16-bit data is specified in the instruction itself as one of its operands. For example: MVI B, 40F means 40F is copied into register B.
Register addressing mode
Here, the data is copied from one register to another.
For example: MOV B, A: means data in register A is copied to register B.
Direct addressing mode
Here, the data is directly copied from the given address to the register.
For example: LDB 5008H: means the data at address 5008H is copied to register B.
Indirect addressing mode
In this case, the data is transferred from one register to another by using the address pointed by the register.
For example: MOV B, K: means data is transferred from the memory address pointed by the register K to the register B.
Implied addressing mode
In this case it doesn’t require any operand; the data is specified by the opcode itself.
For example: CMP.
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