These addressing modes are:
With immediate addressing, no lookup of data is essentially required. The data is located in the operands of the instruction itself, not in a different memory location. This is the fastest of the addressing modes to execute, but the least flexible. For itself it is the least used of the three in practice.
• Direct addressing
for direct addressing, the operands of the instruction contain the memory address where the data involved for execution is stored. For the instruction to be processed the involved data must be first fetched from that location.
• Indirect addressing
When using indirect addressing, the operands provide a location in memory likewise to direct addressing. although, rather than the data being at this location, there is instead another memory address given where the data in reality is located. This is the most flexible of the modes, but also the slowest as two data lookups are necessary.