AQA · GCSE · Computer Science
Course version: 8525 · Version from Sept 2020
Students should be able to explain the terms volatile and non-volatile.
Full specification wording
Systems architecture: Students should be able to explain the terms volatile and non-volatile.
Volatility describes what happens to stored data when power is removed.
Checked against the AQA 8525 specification (opens in a new tab) on .
- Point 21 of 30
Study notes
From the checked teaching notes for this specification point.
The idea
Volatility describes what happens to stored data when power is removed. Volatile memory loses its contents when the power supply is switched off, so it needs a continuous supply to hold data; RAM is the everyday example, which is why unsaved work disappears in a power cut. Non-volatile memory keeps its contents when the power is removed, so data survives being switched off; ROM, flash memory and a hard disk are examples. A good explanation links the term to the power state and to the consequence for the data, not just to a named component. For instance, a USB flash drive keeps a saved file after the computer is shut down because it is non-volatile, whereas the program currently running in RAM is lost because RAM is volatile.
What earns the marks
- Volatile means the contents are lost when the power is switched off or interrupted.
- Volatile memory requires a continuous power supply to retain its data.
- RAM is the standard example of volatile storage in a computer.
- Non-volatile means the contents are retained when the power is removed.
- ROM, flash memory and magnetic or optical storage are examples of non-volatile storage.
- A full explanation states the effect on the stored data, not merely the name of a component.
Common mistakes and how to put them right
Saying volatile means 'fast' or 'temporary' without linking it to loss of power.
Put it right by defining volatility in terms of what happens to data when power is removed.
Claiming ROM is volatile because it is 'read only'.
Put it right by stating that ROM keeps its contents without power and is therefore non-volatile.
Describing non-volatile as 'permanent' data that can never change.
Put it right by explaining that non-volatile storage retains data without power but can still be rewritten, as with a flash drive.
Exam tips
- Always include the power condition in your definition: state what happens when power is removed.
- Pair each term with a named example, such as RAM for volatile and ROM or flash for non-volatile.
- When comparing, write one sentence for volatile and one for non-volatile so both halves of the idea are visible to the examiner.
Try the lesson
The start of the Systems architecture: Students should be able to explain the terms volatile and non-volatile. lesson, made from checked teaching notes for this specification point.
Have a go first
A computer is switched off at the wall and loses the contents of one of its stores. Which term describes a store that loses its contents when power is removed?
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