AQA · GCSE · Computer Science
Course version: 8525 · Version from Sept 2020
Systems architecture: ROM
ROM (Read-Only Memory) is non-volatile memory whose contents are retained when the power is switched off.
Checked against the AQA 8525 specification (opens in a new tab) on .
- Point 16 of 30
Study notes
From the checked teaching notes for this specification point.
The idea
ROM (Read-Only Memory) is non-volatile memory whose contents are retained when the power is switched off. It is used to store the start-up instructions (often called the bootstrap or BIOS/firmware) that a computer runs when it is first switched on, so the computer can begin loading the operating system. The contents of ROM are not normally changed during ordinary use, which is why it is described as read-only. Watch for distractors that describe RAM (volatile working memory holding running programs) or secondary storage (long-term user files). Choose the option that matches ROM's role as permanent memory holding start-up instructions.
What earns the marks
- ROM is non-volatile, so its contents are retained when the power is switched off.
- ROM stores the start-up instructions (bootstrap/firmware) used when the computer is first switched on.
- ROM contents are not normally changed during ordinary use, hence 'read-only'.
- ROM is distinct from RAM, which is volatile and holds currently running programs and data.
- ROM enables the computer to begin the process of loading the operating system.
Common mistakes and how to put them right
Confusing ROM with RAM.
Put it right: ROM is non-volatile and holds start-up instructions, whereas RAM is volatile working memory.
Thinking ROM holds the user's documents and files.
Put it right: Those belong in secondary storage; ROM holds firmware/start-up instructions.
Believing ROM is wiped when the computer is switched off.
Put it right: ROM retains its contents without power.
Exam tips
- Look for the word 'non-volatile' or 'start-up' as a clue pointing to ROM.
- Reject options describing running programs or data in use, which describe RAM.
- Confirm the option is true of ROM generally, not of a specific device only.
Try the lesson
The start of the Systems architecture: ROM lesson, made from checked teaching notes for this specification point.
Have a go first
Which statement best describes the role of ROM in a computer system?
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