One of the key aspects of assembly language programming is the notion of addressing modes, the techniques used to specify the location of an operand using by an instruction. The three fundamental addressing modes are:

1.    Literal addressing: the actual value of an operand is used in an instruction.

2.    Direct or absolute addressing: the instruction specifies the location of the operand. In this case, the operand is a variable.

3.    Register indirect addressing. The instruction specified a register (called a pointer) that contains the address of the operand in memory.

This tutorial demonstrates the operation of register indirect addressing because it is the most powerful addressing mode. It allows you to access data structures such as arrays, lists and tables.