All MCQs

Demand paging postpones page loading until an actual access requires the page.
Unused pages therefore consume neither initial I/O time nor physical frames.

Virtual memory separates the process's logical address space from the amount of installed physical memory.
Only the currently needed portions must be resident, allowing larger programs and more multiprogramming.

A process may define separated logical regions without allocating memory for the gaps between them.
This matches programs whose code, heap, stack, and modules occupy distinct ranges.

The combined scheme preserves logical segmentation while using paging for noncontiguous physical allocation.
It reduces external fragmentation associated with allocating whole variable-sized segments contiguously.

As variable-sized segments are allocated and removed, separated holes appear between them.
A new segment may fail to fit even when total free memory is sufficient.

Segmentation associates protection permissions with logical program units.
Hardware can enforce different read, write, and execute rights for each segment.

A library can occupy one segment with a defined base, limit, and access rights.
Different processes can reference the same physical segment through their own segment tables.

The offset violates the segment's bounds and therefore refers outside the legal logical object.
The processor traps to the operating system instead of accessing arbitrary memory.

The limit defines the valid range of offsets within the selected segment.
Hardware compares the logical offset with this bound before forming a physical address.

The segment base locates the first byte of the segment in physical memory.
The logical offset is added to this base after validation.

The segment-table entry defines where a segment begins in physical memory and how large it is.
These values support translation and bounds checking.

Segmentation reflects the programmer's logical view by dividing a process into meaningful variable-sized regions.
Each segment has an independent base, length, and often protection attributes.