Operating System MCQs

The page-fault handler locates the page, obtains a frame, loads the data, and updates the mapping.
The interrupted instruction can then be restarted.

Pure demand paging relies entirely on first references to trigger page loading.
The initial instructions may therefore cause several compulsory page faults.

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

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 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.

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.

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

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.

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.

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 page-table base register tells the address-translation hardware where the active page table begins.
It is changed during an address-space switch unless an alternative tagged scheme is used.

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.