3.3

Memory and storage

Cambridge IGCSE Computer Science (0478)  · Unit 3: Hardware  · 9 flashcards

Memory and storage is topic 3.3 in the Cambridge IGCSE Computer Science (0478) syllabus , positioned in Unit 3 — Hardware , alongside Computer architecture, Input and output devices and Logic gates.  In one line: RAM (Random Access Memory) is volatile primary storage used to hold data and instructions that the CPU is currently using. It allows for fast access and modification of data, unlike ROM which is read-only.

This topic is examined in Paper 1 (computer systems theory) and Paper 2 (algorithms, programming and logic).

The deck below contains 9 flashcards — 4 definitions and 5 key concepts — covering the precise wording mark schemes reward.  Use the 4 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

RAM and explain its role in a computer system

RAM (Random Access Memory) is volatile primary storage used to hold data and instructions that the CPU is currently using. It allows for fast access and modification of data, unlike ROM which is read-only.

Example: storing the program and data when a game is running.

What the Cambridge 0478 syllabus says

Official 2026-2028 spec

These are the exact learning objectives Cambridge sets for this topic. Match the command word (Describe, Explain, State, etc.) in your answer to score full marks.

  1. Understand Understand what is meant by primary storage including the role of RAM and ROM
  2. Understand Understand what is meant by secondary storage
  3. Describe Describe the operation of magnetic, optical and solid-state (flash memory) storage and give examples of each
  4. Describe Describe what is meant by virtual memory, how it is created and used and why it is necessary
  5. Understand Understand what is meant by cloud storage
  6. Explain Explain the advantages and disadvantages of storing data on the cloud in comparison to storing it locally
Definition Flip

Define RAM and explain its role in a computer system.

Answer Flip

RAM (Random Access Memory) is volatile primary storage used to hold data and instructions that the CPU is currently using. It allows for fast access and modification of data, unlike ROM which is read-only.

Example: storing the program and data when a game is running.
Key Concept Flip

Explain the difference between volatile and non-volatile memory, providing an example of each.

Answer Flip

Volatile memory requires power to maintain stored information, like RAM (data lost when power is off). Non-volatile memory retains information even when power is off, like a hard disk drive (HDD) or solid state drive (SSD).

Key Concept Flip

Describe the key differences between primary and secondary storage.

Answer Flip

Primary storage (RAM, ROM) is directly accessible by the CPU and is faster but more expensive and has lower capacity. Secondary storage (HDD, SSD) is used for long-term storage, is slower and less expensive, but offers higher capacity.

Key Concept Flip

State two advantages and two disadvantages of using a Solid State Drive (SSD) compared to a Hard Disk Drive (HDD).

Answer Flip

Advantages of SSD: faster access times, more durable. Disadvantages of SSD: generally more expensive per GB, potentially limited write cycles. HDD's are cheaper and have high capacity.

Definition Flip

Explain the purpose of ROM (Read-Only Memory) in a computer system.

Answer Flip

ROM stores essential boot-up instructions (BIOS) that the computer needs to start. The data in ROM cannot be easily modified or erased, ensuring the computer can reliably initialize its hardware components.

Key Concept Flip

Describe how magnetic storage devices, such as Hard Disk Drives (HDDs), store data.

Answer Flip

HDDs store data by magnetizing areas on a spinning disk. A read/write head moves across the disk to access and modify the magnetic orientation of these areas, representing bits of data.

Definition Flip

What are optical storage devices? Give two examples

Answer Flip

Optical storage devices use lasers to read and write data to a reflective surface. Examples include CDs, DVDs, and Blu-ray discs.

Definition Flip

Explain how flash memory is used in storage devices and give two examples of where it is used.

Answer Flip

Flash memory is a type of non-volatile memory that can be electrically erased and reprogrammed. Examples include USB drives, SSDs, and memory cards used in digital cameras and smartphones.

Key Concept Flip

Describe the advantages and disadvantages of using cloud storage compared to local storage.

Answer Flip

Advantages of Cloud Storage: Accessibility from anywhere, data backup and recovery. Disadvantages: Requires internet connection, security and privacy concerns, potential cost over time.

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Practice with MCQ questions to check your understanding.

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3.2 Input and output devices 3.4 Logic gates

Key Questions: Memory and storage

Define RAM and explain its role in a computer system.

RAM (Random Access Memory) is volatile primary storage used to hold data and instructions that the CPU is currently using. It allows for fast access and modification of data, unlike ROM which is read-only.

Example: storing the program and data when a game is running.
Explain the purpose of ROM (Read-Only Memory) in a computer system.

ROM stores essential boot-up instructions (BIOS) that the computer needs to start. The data in ROM cannot be easily modified or erased, ensuring the computer can reliably initialize its hardware components.

What are optical storage devices? Give two examples

Optical storage devices use lasers to read and write data to a reflective surface. Examples include CDs, DVDs, and Blu-ray discs.

Explain how flash memory is used in storage devices and give two examples of where it is used.

Flash memory is a type of non-volatile memory that can be electrically erased and reprogrammed. Examples include USB drives, SSDs, and memory cards used in digital cameras and smartphones.

More topics in Unit 3 — Hardware

Memory and storage sits alongside these Computer Science decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.

3.1 Computer architecture

10 flashcards
3.2 Input and output devices

10 flashcards
3.4 Logic gates

10 flashcards

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 0478 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

RAM ROM primary storage secondary storage volatile non-volatile hard disk SSD optical magnetic flash cloud storage

Key terms covered in this Memory and storage deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

RAM and explain its role in a computer system
Explain the purpose of ROM (Read-Only Memory) in a computer system
Optical storage devices? Give two examples
Explain how flash memory is used in storage devices and give two examples of where it is used

How to study this Memory and storage deck

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