← IGCSE Computer Science Paper 1

Differences between RAM and ROM

RAM is volatile, read/write and holds running programs; ROM is non-volatile, read only and holds start-up instructions. RAM is larger.

Part of: IGCSE Computer Science 0478 — 3.3 Data Storage — Module 5

Understanding Differences between RAM and ROM in IGCSE Computer Science Paper 1

What it does: The CPU can change what is stored in RAM, unlike ROM, which is read only. ROM stores the bootstrap and cannot normally be changed by the CPU, while RAM holds programs and data currently in use. RAM is volatile, so its data is lost when power is removed. ROM is non-volatile and keeps its contents. ROM is non-volatile. That is why the start-up instructions are still there when the computer is switched on again. RAM is usually measured in gigabytes. ROM only needs to store a small set of start-up instructions, so it is much smaller. The second row describes ROM, not RAM. RAM is volatile, read/write and holds the programs in use.

Common mistakes: RAM is larger than ROM, so ram_size should be "large", not "small". ROM is usually much smaller than RAM, so the line should say "Smaller than RAM".

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

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Learning

Duo

Which type of memory loses its contents when the power is switched off?

RAMROM

Matches

ROM is volatile and loses its data when the power is off

↓

ROM is non-volatile, so it keeps its data without power. RAM is the volatile memory.

Applying

Meanings

Term

RAM vs ROM

Meaning

RAM is volatile, read/write and holds running programs; ROM is non-volatile, read only and holds start-up instructions. RAM is larger.

Practice

RAM: volatile, read/write, holds running programs, larger

Testing

Gaps

RAM.volatile ←

Check Answer

Spots

3ram_holds = "open programs"

4ram_size = "small"

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Quick Questions

1. Which type of memory loses its contents when the power is switched off?

A. RAM ✓

B. ROM

RAM is volatile, so its data is lost when power is removed. ROM is non-volatile and keeps its contents.

2. Which statement about ROM is correct?

A. ROM is non-volatile and keeps its data without power ✓

B. ROM is volatile and loses its data without power

ROM is non-volatile. That is why the start-up instructions are still there when the computer is switched on again.

3. Can the CPU normally write new data to RAM?

A. No, RAM is read only

B. Yes, RAM is read/write ✓

RAM is read/write. The CPU can both read from it and save new data to it while programs run.

4. Can the CPU normally change the data stored in ROM?

A. Yes, ROM is read/write

B. No, ROM is read only ✓

ROM is read only. Its contents are set when it is made and cannot normally be changed by the CPU.

5. Where is the data and program you are currently using stored?

A. RAM ✓

B. ROM

RAM holds the programs and data currently in use. ROM does not hold the programs you open and use.

Match the Pairs

RAM: volatile → RAM loses all of its contents when the power is turned off

ROM: non-volatile → ROM keeps its contents when the power is turned off

RAM is read/write, so the CPU can both read data from it and save new data to it while programs run → RAM: read and write

ROM holds the start-up instructions (bootstrap) the computer needs to begin working, and the CPU can only read them → ROM: read only, boot instructions

ROM is volatile and loses its data when the power is off → ROM is non-volatile, so it keeps its data without power. RAM is the volatile memory.

RAM stores the start-up instructions and ROM stores the open programs → The roles are swapped. RAM stores programs and data in use, and ROM stores the start-up instructions.

Key Term

RAM vs ROM

RAM is volatile, read/write and holds running programs; ROM is non-volatile, read only and holds start-up instructions. RAM is larger.

Fill in the Blanks

1. RAM.volatile ← TRUE ROM.volatile ← FALSE

Hint: Type the Boolean value showing that RAM loses its data when the power is off.

2. ROM.access ← READ_ONLY RAM.access ← READ_WRITE

Hint: Type the constant describing how the CPU can use ROM.

3. ROM.holds ← startup_instructions RAM.holds ← programs_in_use

Hint: Type what ROM stores so the computer can start up.

4. IF RAM.size > ROM.size THEN OUTPUT "RAM is larger" ENDIF

Hint: Type the comparison operator that shows RAM is bigger than ROM.

5. RAM.holds ← programs_in_use ROM.holds ← startup_instructions

Hint: Type what RAM holds while the computer is running.

Spot the Error

Question 1

A ram_volatile = True

B ram_writable = True

C ram_holds = "open programs"

D ram_size = "small"

Line D — RAM is larger than ROM, so ram_size should be "large", not "small".

Question 2

A if memory == "ROM":

B print("Non-volatile")

C print("Read only")

D print("Larger than RAM")

Line D — ROM is usually much smaller than RAM, so the line should say "Smaller than RAM".

Question 3

A if memory == "ROM":

B print("Data is lost")

C print("Volatile")

Line A — It is RAM that is volatile and loses its data when the power is off. ROM is non-volatile, so the condition should test for "RAM".

Question 4

A memory = "ROM"

B can_cpu_write = False

C holds = "open programs"

Line C — ROM holds the start-up (boot) instructions. Programs that are currently in use are held in RAM.

Question 5

A memory = "RAM"

B can_cpu_write = False

C holds = "open programs"

Line B — RAM is read/write, so the CPU can write to it. can_cpu_write should be True.

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