Page Table Present Bit

What this operating systems page table question tests

This is a foundational question about virtual memory management that appears in systems interviews at quantitative trading firms and other companies building high-performance infrastructure. It tests whether you understand the core mechanism that the OS uses to distinguish between memory that is physically resident versus memory that has been swapped or has never been allocated.

The question probes your grasp of how the page table—the kernel's data structure for translating virtual addresses to physical addresses—signals the validity and availability of a page. This is essential background for reasoning about page faults, memory protection, and the behaviour of systems under memory pressure.

• Page table structure and entry formats
• Valid vs. invalid memory references
• Hardware-software interaction in address translation
• Implications for fault handling and demand paging