The simplest form of addressing is immediate addressing, in which the operand is actually present in the instruction:
This mode can be used to define and use constants or set initial values of variables. The advantage of immediate addressing is that no memory reference other than the instruction fetch is required to obtain the operand. The disadvantage is that the size of the number is restricted to the size of the address field, which, in most instruction sets, is small compared with the world length.
Figure 4.1: Immediate Addressing Mode
The instruction format for Immediate Addressing Mode is shown in the Figure 4.1.