AQA · GCSE · Computer Science
Course version: 8525 · Version from Sept 2020
Systems architecture: Understand the differences between RAM and ROM.
RAM and ROM differ in purpose, writability and volatility.
Checked against the AQA 8525 specification (opens in a new tab) on .
- Point 22 of 30
Study notes
From the checked teaching notes for this specification point.
The idea
RAM and ROM differ in purpose, writability and volatility. RAM is the main memory that holds the programs and data currently in use; it is read from and written to while the computer runs, and it is volatile, so its contents are lost when power is removed. ROM holds start-up instructions such as the bootstrap loader; it is read only in normal use, its contents are fixed at manufacture, and it is non-volatile, so it keeps its data without power. A clear comparison covers all three axes: what each stores, whether it can be written to, and what happens on power loss.
For example: The operating system is loaded into RAM to run, while the firmware that begins the boot process sits in ROM.
What earns the marks
- RAM holds the programs and data currently being used by the processor.
- RAM can be read from and written to while the computer is running.
- RAM is volatile, so its contents are lost when power is removed.
- ROM holds fixed start-up instructions such as the bootstrap loader or firmware.
- ROM is read only in normal operation and its contents are not changed by the user.
- ROM is non-volatile, so it retains its contents when power is removed.
- A full comparison addresses purpose, writability and volatility for both types.
Common mistakes and how to put them right
Saying RAM stores files permanently.
Put it right by explaining that RAM is volatile and holds only the programs and data in current use.
Claiming ROM can be freely written to like RAM.
Put it right by stating that ROM is read only in normal use and holds fixed start-up instructions.
Confusing ROM with secondary storage such as a hard disk.
Put it right by describing ROM as internal memory holding firmware used at start-up.
Exam tips
- Structure your answer around three contrasts: purpose, whether it can be written to, and volatility.
- Name a concrete role for each, such as RAM holding the running program and ROM holding the bootstrap loader.
- Use the word 'volatile' explicitly for RAM and 'non-volatile' for ROM to show the difference in power behaviour.
Try the lesson
The start of the Systems architecture: Understand the differences between RAM and ROM. lesson, made from checked teaching notes for this specification point.
Have a go first
Which statement correctly describes a difference between RAM and ROM in a typical computer?
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Systems architecture: Understand the differences between RAM and ROM.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge