The IA-32 architecture allows a segment to be as large as 4 GB,and the maximum number of segments per process is 16 K.
The logical address space of a process is divided into two partitions. The first partition consists of up to 8 Ksegments that are private to that process.
The second partition consists of up to 8 K segments that are shared among all the processes.
Information about the first partition is
kept in the local descriptor table (LDT); information about the second partition is kept in the global descriptor table (GDT).
Each entry in the LDT and GDT consists of an 8-byte segment descriptor with detailed information about a
particular segment, including the base location and limit of that segment.
The logical address is a pair (selector, offset), where the selector is a 16-bit
number: