Skip to content
Cambridge IGCSE0417

Storage devices and media

Information Communication Technology 0417 Chapter Notes

What this chapter covers

Storage devices and media
ShareWhatsAppPost
Storage devices and media notes

Read online free. Download a watermarked copy with a free account.

Read the notes

The full Storage devices and media notes as text: skim, search, and jump between subtopics.

~7 min read

In this chapter

  1. 1Internal memory and backing storage
  2. 2Magnetic, optical and solid-state
  3. 3Magnetic hard disks and tape
  4. 4Solid-state drives and media
  5. 5Optical discs and readers
  6. 6Cloud storage
  7. 7Comparing storage in an answer

1. Internal memory and backing storage

ROM and RAM are internal memory. ROM stores the start-up instructions and is non-volatile. RAM stores the data and instructions currently in use and is volatile.

Backing storage is secondary storage. It is non-volatile and stores large amounts of data. Internal memory is directly accessed by the CPU and its speed of access is faster.

Examples of backing storage are a magnetic hard disk, magnetic tape, a CD, a DVD, a Blu-ray disc, flash memory and cloud storage.

Examiner insight

“There were some good answers like backing storage is non-volatile and it is permanent.” “Some candidates thought that backing storage was storage used in backing up data.”

Worked example 13 marks

Computers have internal memory and backing storage. State three differences between internal memory and backing storage.

  1. 1

    Backing storage is non-volatile only. Internal memory can be volatile or non-volatile. [1]

  2. 2

    Backing storage stores large amounts of data. [1]

  3. 3

    Internal memory is directly accessed by the CPU. [1]

2. Magnetic, optical and solid-state

The syllabus groups storage devices and media into three types.

Magnetic: hard disks (fixed or portable) and magnetic tape. Optical: CD, DVD and Blu-ray discs. Solid-state: SSD, pen drive, flash drive and memory cards (SD, xD, CFast).

A DVD or a Blu-ray disc is a storage medium. A DVD reader or a Blu-ray reader is a storage device. Read the question to see which one it asks for.

Examiner insight

“Most candidates were able to gain two marks on this question but over half the candidates thought the hard disk was solid state and that the SD card was magnetic storage.” “Some mixed up magnetic and solid state.”

Worked example 14 marks

State whether each of these is magnetic, optical or solid-state storage: hard disk, DVD, SD card, magnetic tape.

  1. 1

    hard disk: magnetic [1]

  2. 2

    DVD: optical [1]

  3. 3

    SD card: solid-state [1]

  4. 4

    magnetic tape: magnetic [1]

3. Magnetic hard disks and tape

A hard disk is magnetic storage, not solid-state. It can be fixed or portable.

Magnetic tape is also a magnetic medium. Compared with flash memory, its data access time is slower. It is larger, so it is not as easily lost.

A magnetic stripe on a credit card is not magnetic tape. Do not mix the two up.

Examiner insight

“This question was misread by some candidates who mixed up magnetic tape with magnetic stripes from credit cards.” “To achieve a mark a candidate should write ‘Data access time is slower’.”

Worked example 12 marks

Give two differences between magnetic tape and flash memory.

  1. 1

    Magnetic tape has a slower data access time. [1]

  2. 2

    Magnetic tape is larger, so it is not as easily lost. [1]

4. Solid-state drives and media

A portable solid-state drive (SSD) is robust. Its seek / access / transfer times are fast, so data can be restored or backed up quickly. It is not affected by a magnetic field and can store a lot of data.

Once the backup is finished, the drive can be stored securely. The owner keeps control of the data.

A solid-state drive can be fixed or portable. Read the question to see which. An SSD that is an integral part of a laptop is not a memory stick.

Examiner insight

“Candidates tended not to expand on their answers giving answers like faster without saying what it was that was faster.” “In order to improve the answering of this question candidates need to carefully read the question, as some candidates confused SSD with flash memory sticks, even though the question stated that the SSD was an integral part of the laptop.”

Worked example 14 marks

A headteacher is planning to set up a backup of the confidential data stored on her office computer. Discuss the reasons why the headteacher should use a portable solid state drive for her backup.

  1. 1

    Once the backup is finished it could be stored securely. [1]

  2. 2

    The headteacher keeps control of the data. [1]

  3. 3

    The SSD is robust. [1]

  4. 4

    The seek / access / transfer times on the SSD are fast so data can be restored / backed up quickly. [1]

5. Optical discs and readers

CD, DVD and Blu-ray are optical media. A disc is read in a reader: a DVD reader or a Blu-ray reader.

Write Blu-ray disc, not Blu-ray alone. A Blu-ray disc is more portable than an internal hard disk.

Do not write that a Blu-ray disc has more storage than a hard disk. To play a Blu-ray disc, a computer needs a Blu-ray reader, not a CD or DVD player.

Examiner insight

“Blu-ray on its own is the technology rather than the medium.” “Some candidates realised that additional hardware was needed or a Blu-ray player, but some candidates referred to this as a CD or DVD player.”

Worked example 12 marks

State two examples of optical storage media.

  1. 1

    CD disc [1]

  2. 2

    DVD disc (or Blu-ray disc) [1]

6. Cloud storage

Cloud storage is also backing storage. Write cloud storage, not a brand name.

Compared with a portable SSD, there is no need to carry a drive. A portable SSD, and the data on it, could be lost or damaged by the environment. Data on the cloud is easier to share and can be accessed from other locations.

Cloud storage has drawbacks. Control of the data is with a third party. It requires a stable internet connection. More storage has to be paid for.

Examiner insight

“Some candidates wrote that the cloud is faster without giving any explanation.” “Many candidates also gave a generic-type answer saying that the cloud can be used on any device at any time which is also true for the SSD.”

Worked example 13 marks

The data collected from the sensors can be stored on the cloud. State why the data is stored on the cloud rather than being stored on a portable solid-state drive.

  1. 1

    The SSD / data could be damaged by the environment. [1]

  2. 2

    No need to carry the SSD with you. [1]

  3. 3

    Can access data from various / other locations. [1]

7. Comparing storage in an answer

A question that asks for advantages or disadvantages is a comparison question. Name both things and say how one differs from the other: write ‘slower’, not ‘slow’, and ‘more portable’, not ‘portable’. A question that asks for benefits and drawbacks is not a comparison.

On an explain question, add the reason to the point: the transfer times are fast, so data can be restored quickly.

Examiner insight

“Questions that ask for advantages and/or disadvantages are comparison questions whereas questions that ask for benefits and drawbacks are not.” “An advantage/disadvantage type question requires the candidate to give a comparison between the memory stick and cloud storage.”

Worked example 12 marks

A company stores its files on the cloud instead of on a memory stick. Give two advantages of using the cloud rather than a memory stick.

  1. 1

    There is no need to carry the memory stick with you. [1]

  2. 2

    The memory stick, and the data on it, could be lost or damaged by the environment. [1]

Recap

  • Internal memory: ROM and RAM. Backing storage is secondary storage and non-volatile.
  • Three technologies: magnetic, optical, solid-state.
  • Magnetic tape has a slower data access time. It is not the same as a magnetic stripe.
  • A portable SSD is robust, fast and not affected by a magnetic field.
  • Write Blu-ray disc, not Blu-ray. A DVD or Blu-ray reader reads the disc.
  • Cloud: no drive to carry, but control is with a third party and it needs an internet connection.
  • Advantages and disadvantages are comparisons. Give the reason every time.

End-of-chapter exercise

Test yourself on the whole chapter. Work through these before moving on.

  1. A student writes ‘USB’ as an example of a storage device. Explain why this does not earn the mark.1 mark
  2. State three examples of backing storage.3 marks
  3. A student writes ‘Backing storage is the storage used for backing up data.’ This earns no mark. State two characteristics of backing storage.2 marks
  4. State whether each is magnetic, optical or solid-state storage: (a) a hard disk, (b) an SD card, (c) a CD ROM, (d) a memory stick.4 marks
  5. A customer buys a film on a Blu-ray disc. State the hardware needed to play it on a computer.1 mark
  6. A student gives ‘Blu-ray’ as an example of an optical storage medium. Explain why this is not enough.2 marks
  7. A photographer backs up her photographs to a portable solid-state drive. A student says she uses it because ‘it is quicker, smaller and better’. This earns no marks. Give three reasons for using the SSD that would earn marks.3 marks
  8. State three drawbacks of using cloud storage for a backup.3 marks
  9. A film crew records video on SD cards (flash memory). Each evening the video is copied to magnetic tape. A crew member is asked for the disadvantages and advantages of the tape compared with the SD cards and writes: Statement 1: ‘Data access time is slow.’ Statement 2: ‘Tape is big.’ Statement 3: ‘Tape is the stripe on the back of a credit card.’ (a) State the type of storage of an SD card and of magnetic tape. [2] (b) Rewrite statements 1 and 2 so that each would earn a mark. [2] (c) State what is wrong with statement 3. [1]5 marks
  10. A vet visits farms and types confidential animal health records into a tablet computer. Many of the farms have no internet connection. She can store the records on a portable solid-state drive or on cloud storage. A colleague says: ‘Use the cloud. It is faster, and it can be used on any device at any time.’ (a) Explain why neither of the colleague's reasons would earn a mark. [2] (b) Give two reasons for using the cloud rather than the SSD that would earn marks. [2] (c) Discuss why the portable SSD suits this vet better than cloud storage. [4]8 marks

Go deeper

Practise and revise with member-only material for this chapter.

Workbook

Exam-style practice questions with full worked solutions.

Unlock with a plan

Chapter at a Glance

A single-page summary of every key idea for fast revision.

Unlock with a plan

Free notes are just the start.

Unlock every Workbook and Chapter at a Glance, and generate your own worksheets and predicted papers.

Explore plans

Related chapters

Hardware and softwareInput devices and their usesNetworksMicroprocessor-controlled devicesCommunicationAnalysis