Segmentation unit: The segmentation unit plays a vital role in the 80836 microprocessor.Providing protection to the data or code inside the system is the most advantageous factor that was first given by the 80386 microprocessor.So, for protection purposes, the main part of the OS is stored in PL0 while PL3 holds the user programs.It offers a protection mechanism in order to protect the code or data present in the memory from application programs.Suppose a file (either data or code) is needed to be accessed is stored in the memory at PL0.