Computer organization and architecture (Addressing Modes)

 Addressing Modes

The different ways in which the location of an operand is 

specified in an instruction are referred to as addressing 

modes. 

Computers use addressing mode techniques for the pur-

pose of accommodating the following provisions:

1. Facilitates pointers to memory.

2. Facilitates counters for loop control

3. Facilitates indexing of data

4. Facilitates program relocation.

5. Reduce the number of bits in the addressing field of 

the instruction.

The most common addressing techniques are

i. Implied mode

ii. Immediate mode

iii. Direct mode

iv. Indirect mode

v. Register mode

vi. Register Indirect mode

vii. Auto-increment or Auto-decrement mode

viii. Displacement mode

• PC relative mode

• Indexed mode

• Base register mode