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J277 1.2.1 Virtual memory

Part 2 of 6 · J277 1.2.1-1.2.3 · Memory and storage

What happens when RAM runs short, and why the fix costs performance.

Students will:

  • explain why virtual memory may be needed
  • identify where virtual memory is located
  • describe how data moves between RAM and secondary storage
  • explain why virtual memory is slower than RAM
  • decide whether a given system can use it

Inside: 6 explanation cells, 4 multiple-choice questions, 1 fill-in-the-blanks cell and 4 written answers. 29 marks, about 60 minutes.

Series: J277 1.2.1-1.2.3 · Memory and storage, part 2 of 6.

Shared by Coding PathwayVerified teacher

  • 15 cells
  • About 60 minutes
  • CC BY-SA 4.0
  • Shared 17 Aug 2026
  • Updated 9 Sept 2026

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The whole resource, exactly as a class sees it. Answers and marking are held back.

Memory and storage 2: virtual memory

RAM has a fixed capacity. If too many programs and data items need RAM at once, the computer may run short of space. Virtual memory allows part of secondary storage to be used temporarily when this happens.

By the end of this worksheet, you should be able to:

  • explain why virtual memory may be needed
  • identify where virtual memory is located
  • describe the movement of data between RAM and secondary storage
  • explain why virtual memory is slower than RAM
  • decide whether virtual memory can be used in a given system

Work through the explanation, checks and applications in order. Use the final challenge to connect several ideas.

Multiple choice1 mark

Which statement about RAM is accurate?

  • AIt is non-volatile storage for all user files
  • BIt stores only the computer's start-up instructions
  • CIt stores data and instructions currently in use
  • DIt is a type of optical secondary storage

1. Why virtual memory is used

When RAM is full or nearly full, the operating system can use a section of secondary storage as virtual memory.

The basic process is:

  1. data not currently needed is moved from RAM to virtual memory
  2. this creates space in RAM for data needed now
  3. if the moved data is needed again, it is transferred from virtual memory back to RAM

The CPU still needs the data in RAM before it can use it. Virtual memory is not a new piece of RAM and it is not stored in ROM.

Data movement between RAM and secondary storage when virtual memory is used When RAM is full, currently unneeded data is moved from RAM to an area of secondary storage. When it is needed again, it is moved back to RAM. Secondary storage is slower than RAM. RAMfast working memory programs and data in use Secondary storageslower than RAM virtual-memoryarea RAM full: move unneeded data out needed again: move data back to RAM Frequent movement slows performance because secondary storage is slower.
Fill in the blanks4 marks
Virtual memory is a section of label 1. It may be used when label 2 is full or nearly full. Data not currently needed moves from RAM to label 3. When required again, the data moves back into label 4.
  • the CPU
  • virtual memory
  • secondary storage
  • RAM
  • cache
  • ROM
Multiple choice1 mark

What is the immediate purpose of moving some data from RAM into virtual memory?

  • ATo make ROM volatile
  • BTo create space in RAM for data and instructions needed now
  • CTo permanently back up every user file
  • DTo increase the CPU clock speed

2. Follow the data

Imagine that RAM is like a small work surface. Several items are already open, and a new application needs space.

  • Data for a background application is not needed immediately.
  • The operating system moves that data from RAM to a reserved section of secondary storage.
  • The new application's data is loaded into the free space in RAM.
  • Later, when the background application is used again, its data is copied back into RAM.

The analogy helps with capacity, but use the technical terms RAM, secondary storage and transfer in an exam answer.

Written answer5 marks

Explain how virtual memory works when RAM becomes full.

Write the process in order. Include where virtual memory is located, the first transfer and the return transfer.

Students type their answer here.

3. Virtual memory affects performance

Secondary storage is slower to access than RAM. Moving data between RAM and virtual memory therefore takes extra time.

Virtual memory can allow more applications to remain open, but a computer that relies on it heavily may respond slowly because data is repeatedly transferred to and from secondary storage.

Do not write only “virtual memory is slow”. State what is slower and why:

Accessing data in virtual memory is slower than accessing it in RAM because virtual memory uses secondary storage.

Multiple choice1 mark

Why can heavy use of virtual memory reduce system performance?

  • ASecondary storage is slower to access than RAM, and data must be transferred
  • BVirtual memory permanently deletes instructions
  • CROM has to be rewritten every time
  • DThe CPU loses all of its cores
Written answer4 marks

Correct both statements: (1) “Virtual memory is a section of primary storage.” (2) “Data is moved from ROM into virtual memory and then returned to primary storage.”

Use the exact terms secondary storage and RAM. Make the direction of each transfer clear.

Students type their answer here.

4. Can every system create virtual memory?

Virtual memory requires secondary storage. A small embedded system may have enough RAM for its fixed task but no suitable secondary storage. In that case, it cannot create virtual memory.

This is a useful application point: do not assume that virtual memory is always present or always needed. Check the hardware and the scenario.

Multiple choice1 mark

A simple embedded controller has sufficient RAM for its single task and has no secondary storage. Which conclusion is best?

  • AIt must transfer its RAM into cache
  • BIt automatically gains more physical RAM
  • CIt must use ROM as virtual memory
  • DIt cannot create virtual memory because it has no secondary storage, and it may not need it
Written answer6 marks

A laptop becomes noticeably slower when a student opens a video editor, a game and many browser tabs at the same time. Explain how a shortage of RAM and the use of virtual memory could cause this.

Link the number of running applications to RAM filling, then describe the transfers and the slower access to secondary storage.

Students type their answer here.

Written answer6 marks

Challenge: evaluate the claim, “Virtual memory is just as good as adding more RAM.”

Explain one similarity in what each allows the computer to do, then explain the important performance and hardware differences before reaching a judgement.

Students type their answer here.

Closed-book review

Complete these prompts without looking back:

  1. Virtual memory may be needed when...
  2. Virtual memory is located...
  3. First, data moves from...
  4. When required again, data moves...
  5. Heavy virtual-memory use can reduce performance because...
  6. A system without secondary storage...

Check that you have used RAM rather than the broader phrase “primary storage” when describing the transfers.