After some time, the system becomes slow, but it does NOT crash. The hard disk activity light keeps blinking continuously even th…

Question

A student is using a computer with 8 GB RAM. He opens:

A web browser with 25 tabs

A video editing software

A music player

A code editor

After some time, the system becomes slow, but it does NOT crash. The hard disk activity light keeps blinking continuously even though he is not saving or opening files. Which of the following is the most accurate explanation?

1. A. The operating system has stopped multitasking and is running programs one by one.
2. B. The CPU cache memory is full, so the system is waiting for space to free up.
3. C. The operating system is using virtual memory and swapping data between RAM and disk. (Correct answer)
4. D. The BIOS is reallocating hardware resources dynamically.

Correct Answer

Option C — The operating system is using virtual memory and swapping data between RAM and disk.

Detailed Solution & Explanation

The correct answer is The operating system is using virtual memory and swapping data between RAM and disk.

Key Points

• The three symptoms together point unambiguously to virtual memory in use:
  • The system slows but does not crash — the operating system has found more memory rather than running out of it.
  • Continuous hard disk activity with no file being saved or opened — the disk is being used as memory, which is exactly what swapping means.
  • Many memory-hungry applications open at once — 25 browser tabs plus video editing software easily exceed 8 GB of physical RAM.
• How virtual memory works: when physical RAM is exhausted, the operating system moves inactive pages from RAM to a reserved area of the disk — the page file on Windows or the swap partition on Linux — and brings them back when needed. Because disk access is orders of magnitude slower than RAM, performance degrades sharply while the system remains functional.

Additional Information

• Why the other options are wrong:
  • Option A — an operating system does not abandon multitasking; the scheduler continues to time-slice among processes throughout.
  • Option B — CPU cache is managed entirely in hardware and never generates disk activity. A full cache causes a cache miss, not disk I/O.
  • Option D — the BIOS runs only at boot time and plays no part in resource allocation once the operating system has loaded.
• Thrashing is the extreme case, in which the system spends more time swapping pages than executing programs, and throughput collapses. The characteristic sign is a continuously active disk with an almost idle CPU.
• The memory hierarchy, fastest and smallest first: CPU registers → L1/L2/L3 cache → main memory (RAM) → solid-state or hard disk → tertiary storage. Cost per byte falls and capacity rises at each step down.
• Paging versus segmentation: paging divides memory into fixed-size blocks, while segmentation uses variable-size logical divisions. Modern systems generally use paging, often with segmentation layered above it.
• Why an SSD helps: swapping to a solid-state drive is far faster than to a mechanical disk, which is why the same memory pressure feels much less severe on modern hardware.