← IGCSE Computer Science Paper 1

Primary storage

Memory the CPU can access directly, so it is fast. It is made up of RAM (temporary, holds running programs and data) and ROM (permanent, holds start-up instructions).

Part of: IGCSE Computer Science 0478 — 3.3 Data Storage — Module 1

Understanding Primary storage in IGCSE Computer Science Paper 1

What it does: The list shows that primary storage is made up of exactly two parts, RAM and ROM. Because the CPU reads primary storage directly without another device in between, access is fast. RAM and ROM are the two kinds of primary storage. HDDs and SSDs are secondary storage devices. RAM holds running programs and data temporarily. ROM holds the start-up instructions permanently. ROM is permanent, so its start-up instructions are still there when the computer is switched on.

Common mistakes: Primary storage is made up of RAM and ROM. An SSD is secondary storage, so the list should be ['RAM', 'ROM']. A hard disk drive is secondary storage, not primary storage. Only RAM and ROM are primary. It should be hdd_kind = 'secondary'.

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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 statement describes primary storage?

Memory that the CPU can only access through an input deviceMemory that the CPU can access directly

Matches

primary storage = HDD + SSD

↓

HDD and SSD are secondary storage, not primary storage. Primary storage is RAM and ROM.

Applying

Meanings

Term

primary storage

Meaning

Memory the CPU can access directly, so it is fast. It is made up of RAM (temporary, holds running programs and data) and ROM (permanent, holds start-up instructions).

Practice

PRIMARY_STORAGE ← RAM + ROM

Testing

Gaps

Primary storage is made of RAM and

Check Answer

Spots

1primary = ['RAM', 'SSD']

2for part in primary:

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Quick Questions

1. Which statement describes primary storage?

A. Memory that the CPU can only access through an input device

B. Memory that the CPU can access directly ✓

Primary storage is directly accessed by the CPU. This is what makes it different from secondary storage.

2. Primary storage is made up of which two types of memory?

A. RAM and ROM ✓

B. HDD and SSD

RAM and ROM are the two kinds of primary storage. HDDs and SSDs are secondary storage devices.

3. Why is primary storage fast to access?

A. The CPU can access it directly ✓

B. It is always stored on a spinning magnetic disk

Direct access means the CPU does not need to go through another device, so data is read quickly. Spinning disks are slower secondary storage.

4. Which of these is part of primary storage?

A. USB flash drive

B. ROM ✓

ROM is primary storage and the CPU accesses it directly. A USB flash drive is secondary storage.

5. Which part of primary storage holds the programs and data currently being used?

A. RAM ✓

B. ROM

RAM holds running programs and data temporarily. ROM holds the start-up instructions permanently.

Match the Pairs

primary storage → Memory the CPU can access directly, made up of RAM and ROM

CPU <-> RAM + ROM → The CPU accesses both kinds of primary storage directly

Primary storage has two kinds: RAM and ROM → primary_storage = [RAM, ROM]

Direct access by the CPU makes primary storage fast → CPU -> primary storage (direct, fast)

primary storage = HDD + SSD → HDD and SSD are secondary storage, not primary storage. Primary storage is RAM and ROM.

The CPU can only reach primary storage through the hard drive → The CPU accesses primary storage directly. It does not need to go through a secondary storage device.

Key Term

primary storage

Memory the CPU can access directly, so it is fast. It is made up of RAM (temporary, holds running programs and data) and ROM (permanent, holds start-up instructions).

Fill in the Blanks

1. Primary storage is made of RAM and ROM

Hint: Type the name of the permanent memory type that holds start-up instructions

2. The CPU accesses primary storage directly

Hint: Type the word describing how the CPU reaches primary storage, with no middle step

3. RAM is temporary primary storage

Hint: Type the name of the temporary memory that holds running programs and data

4. ROM stores the start-up instructions

Hint: Type the word for the kind of instructions needed when the computer is switched on

5. Direct CPU access makes primary storage fast

Hint: Type the word that describes the speed of primary storage

Spot the Error

Question 1

A primary = ['RAM', 'SSD']

B for part in primary:

C print(part)

Line A — Primary storage is made up of RAM and ROM. An SSD is secondary storage, so the list should be ['RAM', 'ROM'].

Question 2

A ram_kind = 'primary'

B rom_kind = 'primary'

C hdd_kind = 'primary'

D print(ram_kind, rom_kind)

Line C — A hard disk drive is secondary storage, not primary storage. Only RAM and ROM are primary. It should be hdd_kind = 'secondary'.

Question 3

A ram_volatile = False

B rom_volatile = False

C print(ram_volatile)

Line A — RAM is volatile because it loses its contents when the power is off. It should be ram_volatile = True.

Question 4

A ram = 'temporary'

B rom = 'temporary'

C print(ram, rom)

Line B — ROM is permanent (non-volatile) memory and keeps its contents without power. It should be rom = 'permanent'.

Question 5

A # Primary storage contents

B ram = 'running programs'

C rom = 'start-up instructions'

D print('ROM holds', ram)

Line D — The variable ram describes what RAM holds, so the label must say 'RAM holds'. Mixing up ROM and RAM gives a wrong statement.

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