Microprocessor Tutorial

8085 Microprocessor

8086 Microprocessor

Difference between

8085 Addressing Mode

An addressing mode for an instruction implies the way an operand is presented for execution by the instruction.

Addressing modes available are:

  1. Register addressing mode
  2. Direct addressing mode
  3. Indirect addressing mode
  4. Immediate addressing mode

Register addressing mode

In this mode, both source and destination are registers.

MOV A, B    (content of B is copied to A)
MOV A, C    (content of C is copied to A)

Direct addressing mode

In this mode, Data is directly copied from the given location to the register

LDA 4000H    (content at location 4000H is copied to A)
STA 1700H    (content of accumulator is stored at 1700H)

Indirect addressing mode

In this mode, data is transferred from the address pointed by the data in a register to other register.

MOV C, M    (Here memory M contains the address of the data and from there it is transferred to register C)

Immediate addressing mode

In this mode, data is written in the instruction itself.

MOV A, 90H    (Copy 90H to A)
LXI H, 2022H    (HL pair is loaded with 2022H immediately)