← IGCSE Computer Science Paper 1

Read only memory (ROM)

Read only memory: non-volatile primary storage whose contents are fixed. It keeps the start-up (boot) instructions, so data stays when power is off. Also used in embedded devices.

Part of: IGCSE Computer Science 0478 — 3.3 Data Storage — Module 4, IGCSE Computer Science 0478 — 4.1 Types of Software and Interrupts — Module 35

Understanding Read only memory (ROM) in IGCSE Computer Science Paper 1

What it does: Non-volatile means data stays without power, which is why ROM can hold the start-up instructions. Embedded devices use ROM to store a fixed program that the device runs every time it is switched on. ROM holds the boot instructions the computer needs to start up. Open files and programs in use are held in RAM. ROM is read only in normal use. Its contents are fixed, so the user cannot save new data onto it. ROM is primary storage because the CPU can access it directly. Secondary storage such as an HDD is not directly accessed by the CPU. ROM is non-volatile, so its contents are not lost when power is removed.

Common mistakes: ROM keeps fixed contents, mainly the start-up (boot) instructions. It does not hold open browser tabs, which live in RAM. Line 3 should be holds ← "boot instructions". ROM is non-volatile, so it keeps its data when the power is off. Line 1 should set romVolatile to FALSE.

Class: _____________________ · Name: _____________________ · Date: _________

Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

🖨 Print worksheet + answer key Add Read only memory (ROM) to a class →

This module's key terms are also in a printable crossword (Modules 293–303) and word search (Modules 283–303).

Take this worksheet further — free with Cloodit

Each concept is reinforced from every angle — learned, then applied, then tested.

Learning

Duo

Which statement about ROM is correct?

ROM is volatile, so its contents are lost when the power is offROM is non-volatile, so its contents stay when the power is off

Matches

ROM is volatile, so it loses its contents when the power is off

↓

ROM is non-volatile, not volatile. It keeps its contents when the power is off. It is RAM that is volatile.

Applying

Meanings

Term

ROM

Meaning

Read only memory: non-volatile primary storage whose contents are fixed. It keeps the start-up (boot) instructions, so data stays when power is off. Also used in embedded devices.

Practice

SWITCH ON computer

Testing

Gaps

ROM is memory: it keeps data

Check Answer

Spots

2volatile ← FALSE

3holds ← "open browser tabs"

Cloodit turns curriculum-aligned coding content into journeys students work through one biome at a time.

Students earn collectable badges

Over 100 of them, across seven natural biomes.

Study Buddy

Students build a real study resource

Turns their work into revision material ready for Flash Cards and Exam study.

Diamond Dash — one of Cloodit's live, competitive Sprint games

Students lock in with Sprints

Live, competitive practice for the start of the lesson or a teacher-led lesson finisher.

A Cloodit certificate of achievement, ready to personalise and print

Custom printable certificates

Honour your top performers, or encourage a student who's trying hard — ready to print in seconds.

Add to class →

Quick Questions

1. Which statement about ROM is correct?

A. ROM is non-volatile, so its contents stay when the power is off ✓

B. ROM is volatile, so its contents are lost when the power is off

ROM is non-volatile primary storage. Its contents are kept without power. RAM is the volatile one.

2. What is ROM mainly used to store in a computer?

A. The start-up (boot) instructions ✓

B. The documents the user is currently editing

ROM holds the boot instructions the computer needs to start up. Open files and programs in use are held in RAM.

3. In normal use, what can the user do with the contents of ROM?

A. Read them, but not change them ✓

B. Read them and freely overwrite them

ROM is read only in normal use. Its contents are fixed, so the user cannot save new data onto it.

4. A computer is switched on. Where does it first find the instructions to start up?

A. RAM, because it was saved there last time

B. ROM ✓

RAM is empty when the power is off. The start-up instructions are kept in ROM, which keeps its data without power.

5. Is ROM a type of primary storage?

A. No, it is secondary storage like an HDD

B. Yes, the CPU can access it directly ✓

ROM is primary storage because the CPU can access it directly. Secondary storage such as an HDD is not directly accessed by the CPU.

Match the Pairs

ROM → Read only memory: non-volatile primary storage whose contents are fixed and stay when the power is off

boot instructions → The start-up program a computer runs when switched on, kept in ROM so it is always available

ROM is non-volatile, so its contents are not lost when the power is switched off → power = OFF → ROM contents = KEPT

ROM is also found in embedded devices, such as a washing machine, holding the fixed program that controls it → washing_machine.ROM = "wash program"

ROM is volatile, so it loses its contents when the power is off → ROM is non-volatile, not volatile. It keeps its contents when the power is off. It is RAM that is volatile.

The user saves their homework files into ROM → ROM is read only in normal use, so its contents are fixed and users cannot save files to it. Files are saved to secondary storage.

Key Term

ROM

Read only memory: non-volatile primary storage whose contents are fixed. It keeps the start-up (boot) instructions, so data stays when power is off. Also used in embedded devices.

Fill in the Blanks

1. ROM is non-volatile memory: it keeps data

Hint: Type the word describing memory that keeps its data when the power is switched off.

2. ROM stores the boot instructions at start-up

Hint: Type the word for the start-up instructions the computer needs to get going.

3. ROM contents are fixed in normal use

Hint: Type the word that describes data that cannot normally be changed.

4. ROM is also found in embedded devices

Hint: Type the word for devices like washing machines, with a computer built in to do one job.

5. ROM is a type of primary storage

Hint: Type the word for storage the CPU can access directly, like RAM.

Spot the Error

Question 1

A memory ← "ROM"

B volatile ← FALSE

C holds ← "open browser tabs"

Line C — ROM keeps fixed contents, mainly the start-up (boot) instructions. It does not hold open browser tabs, which live in RAM. Line 3 should be holds ← "boot instructions".

Question 2

A romVolatile ← TRUE

B powerOff ← TRUE

C IF powerOff = TRUE THEN

D OUTPUT "ROM data kept"

E ENDIF

Line A — ROM is non-volatile, so it keeps its data when the power is off. Line 1 should set romVolatile to FALSE.

Question 3

A device ← "washing machine"

B storedIn ← "RAM"

C OUTPUT device, storedIn

Line B — An embedded device such as a washing machine keeps its fixed program in ROM. RAM is volatile and would lose the program when switched off. Line 2 should be storedIn ← "ROM".

Question 4

A mode ← "normal use"

B romAccess ← "read and write"

C OUTPUT mode, romAccess

Line B — ROM contents are fixed and are read only in normal use. They are not freely written to like RAM. Line 2 should be romAccess ← "read only".

Question 5

A powerOn ← TRUE

B IF powerOn THEN

C bootCode ← READ(ROM)

D ERASE(bootCode)

E ENDIF

Line D — At start-up the computer reads the boot instructions from ROM and runs them. Erasing them would stop the computer starting, and ROM contents are fixed anyway. Line 4 should be RUN(bootCode).

Student with a class code? Join your class →