GATE CS 1995 Q1.7 — Memory Management and Virtual Memory

In a paged segmentation scheme, the virtual address space is divided into segments, and each segment is further divided into pages. This requires a Segment Table where each entry points to a Page Table for that specific segment.

However, if a process has a large number of segments, the segment table itself can become extremely large. Requiring a large, contiguous block of physical memory to store this entire segment table defeats the purpose of paging (which avoids external fragmentation).

To solve this, the segment table itself is paged (i.e., it has its own page table). This allows the segment table to be stored in non-contiguous physical memory pages.

Therefore, the segment table itself must have a page table because the segment table is often too large to fit in one page (Option A).

Analysis of other options:

• Option B: Explains why segments are paged, not why the segment table itself is paged.
• Option C: Describes the standard translation mechanism (segment table entries pointing to page tables), but does not explain the necessity of paging the segment table itself.
• Option D: The Segment Table Base Register (STBR) typically points to the segment table, not a generic processor description base register pointing to a page table.