Swapping and Memory Sharing In classical swapping systems, what does swapping allow regarding use of main memory?

Introduction / Context:
Swapping is an early memory-management technique where entire processes are moved between main memory and secondary storage to share limited RAM among multiple programs.

Given Data / Assumptions:

• Memory is insufficient to hold all processes at once.
• CPU scheduling determines which process runs.
• Whole-process images can be written to disk and restored.

Concept / Approach:
Swapping enables time-sharing by loading a process into memory to run and writing it back to disk when it is not scheduled, freeing memory for others. This differs from paging, which moves fixed-size pages instead of entire processes.

Step-by-Step Solution:
Scheduler selects a ready process.If not resident, the OS swaps it in (reads its image into RAM).The process executes for a quantum.When descheduled and memory is needed, the OS may swap it out.

Verification / Alternative check:
Historically, systems with limited RAM relied on swapping to provide multi-user interactivity; performance improved with paging and demand-paged virtual memory, but the principle of using memory “in turn” remains accurate for swapping.

Why Other Options Are Wrong:
Option A: Partition count alone does not make swapping “best”.Option B: “Simultaneously” is misleading; swapped-out programs are not in RAM.Option D: Overlaying (manually managing code segments) can be used with or without swapping; they are not mutually exclusive.Option E: Not applicable because Option C is correct.

Common Pitfalls:

• Equating swapping with paging—they are distinct mechanisms.
• Assuming swapping implies concurrent residency; it does not.

Final Answer:
Each program to use memory in turn by being swapped in when scheduled.