IGCSE Computer Science (9–1) 0984 · Topic 3

Describe how a check digit is used to detect: past paper questions

58 real questionsasked in 7 of the last 10 exam series2019–2026usually: Identify, Give, Explain, Describe, State

Real questions on describe how a check digit is used to detect

The newest 20 of 58 written questions. Open one to see it on the real paper.

0984/11 · May/June 2026 · Q2a(i)[1]
The first register used in the FDE cycle stores the location in random access memory (RAM) of the next instruction. Identify the name of this register.
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0984/11 · May/June 2026 · Q2b[2]
Explain the advantages of the smartphone having a quad-core processor instead of a dual-core processor.
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0984/11 · May/June 2026 · Q2c(i)[2]
Identify two input devices that could be built into the smartphone.
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0984/11 · May/June 2026 · Q2c(ii)[2]
Identify two output devices that could be built into the smartphone.
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0984/11 · May/June 2026 · Q4a[1]
State the purpose of the optical mouse.
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0984/11 · May/June 2026 · Q7a[1]
Give one suitable sensor that the robot animal could use to identify a clapping sound.
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0984/11 · May/June 2026 · Q7b[2]
Give two suitable sensors that the robot animal could use to identify if an object is nearby.
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0984/12 · May/June 2026 · Q1a[1]
Tick (“) one box to show whether a microphone is an input, output, process or storage device. A_ input B_ output C_ process D_ storage
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0984/12 · May/June 2026 · Q1d[1]
Identify one example of a sensor that would be built into the smartwatch.
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0984/12 · May/June 2026 · Q2a[1]
State the role of the CPU.
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0984/12 · May/June 2026 · Q2b[2]
The memory address register (MAR) and the memory data register (MDR) are two registers built into the CPU. Give two other registers that are built into the CPU.
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0984/12 · May/June 2026 · Q2c[3]
Avalue is fetched from random access memory (RAM) to the CPU. Explain how the MAR and MDR are used in this process.
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0984/12 · May/June 2026 · Q2d[3]
The CPU has a clock speed of 3 GHz. Describe what is meant by a 3 GHz clock speed.
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0984/12 · May/June 2026 · Q3f(i)[2]
One feature of magnetic storage is that it has moving parts. Give two other features of magnetic storage.
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0984/12 · May/June 2026 · Q3f(ii)[1]
The video streaming service wants faster read and write speeds for their videos than is provided by magnetic storage. State which type of storage they should use.
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0984/12 · May/June 2026 · Q6c(i)[1]
Give one advantage to the user of the app storing data in cloud storage instead of locally on the smartphone.
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0984/12 · May/June 2026 · Q6c(ii)[2]
Give two disadvantages to the user of the app storing data in cloud storage instead of locally on the smartphone.
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0984/12 · October/November 2025 · Q1e(i)[1]
Identify the name of the item of hardware.
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0984/12 · October/November 2025 · Q1e(ii)[1]
Tick (✓) one box to show whether a barcode scanner is a type of input, output, process or storage device. A input B output C process
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0984/12 · October/November 2025 · Q1e(iii)[1]
The barcode scanner contains a sensor. Identify the type of sensor that the barcode scanner could contain.
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What examiners said

Most candidates were able to identify the appropriate output device.
— Examiner report, May/June 2025, 0984/11 Q2(a) (Cambridge)

Many candidates were able to identify the role of a core. Some candidates were able to identify the definition of an instruction set. Many candidates were able to give a definition for a current instruction register, cache and the accumulator. Some candidates incorrectly stated that the cache stores the data and instructions that have just been used or are just about to be used. This was not an ac...
— Examiner report, May/June 2025, 0984/11 Q5(a) (Cambridge)

Many candidates were able to identify that the control unit is responsible for decoding an instruction.
— Examiner report, May/June 2025, 0984/11 Q5(b) (Cambridge)

Practise this topic

Answer these questions online and get each one marked against the official mark scheme, with what you missed and how to fix it.

Download 0984 papers

In the syllabus

1 0478.3.0.01 — Describe how an automatic repeat query (ARQ) • Including the use of:

Describe how an automatic repeat query (ARQ) • Including the use of:
– positive/negative acknowledgements
– timeout
Explain the purpose and functions of a web • The main purpose of a web browser is to
render hypertext markup language (HTML) and display web pages • Functions include: – storing bookmarks and favourites – recording user history – allowing use of multiple tabs – storing cookies – providing navigation tools – providing an address bar
(a) Understand and use the concept of
Understand and use the concept of • Including:
– IF statements – CASE statements
Understand and use the concept of • Including:
– count-controlled loops – pre-condition loops – post-condition loops
Understand and use the concepts of
Understand and use the concept of string • Including:

2 0478.3.0.02 — – positive/negative acknowledgements

– positive/negative acknowledgements

3 0478.3.0.03 — – timeout

– timeout

4 0478.3.0.04 — Explain the purpose and functions of a web • The main purpose of a web browser is to

Explain the purpose and functions of a web • The main purpose of a web browser is to

5 0478.3.0.05 — render hypertext markup language (HTML) and display web pages • Functions include: – storing bookmarks and favourites – recording user histo

render hypertext markup language (HTML) and display web pages • Functions include: – storing bookmarks and favourites – recording user history – allowing use of multiple tabs – storing cookies – providing navigation tools – providing an address bar

6 0478.3.0.06 — (a) Understand and use the concept of

(a) Understand and use the concept of

7 0478.3.0.07 — Understand and use the concept of • Including:

Understand and use the concept of • Including:

8 0478.3.0.08 — – IF statements – CASE statements

– IF statements – CASE statements

9 0478.3.0.09 — Understand and use the concept of • Including:

Understand and use the concept of • Including:

10 0478.3.0.10 — – count-controlled loops – pre-condition loops – post-condition loops

– count-controlled loops – pre-condition loops – post-condition loops

11 0478.3.0.11 — Understand and use the concepts of

Understand and use the concepts of

12 0478.3.0.12 — Understand and use the concept of string • Including:

Understand and use the concept of string • Including:

13 0478.3.0.13 — – length – substring – upper – lower • The first character of the string can be position zero or one

– length – substring – upper – lower • The first character of the string can be position zero or one

14 0478.3.0.14 — Read, understand and complete structured • Limited to:

Read, understand and complete structured • Limited to:

15 0478.3.0.15 — – SELECT

– SELECT

16 0478.3.0.16 — – FROM – WHERE – ORDER BY DESCENDING – ORDER BY ASCENDING – SUM – COUNT – AND – OR • Identifying the output given by an SQL statement that w

– FROM – WHERE – ORDER BY DESCENDING – ORDER BY ASCENDING – SUM – COUNT – AND – OR • Identifying the output given by an SQL statement that will query the given contents of a database table

17 0478.3.1.01 — (a) Understand the role of the central • The CPU processes instructions and data that

(a) Understand the role of the central • The CPU processes instructions and data that
are input into the computer so that the result can be output
Understand what is meant by a • A microprocessor is a type of integrated circuit
on a single chip
(a) Understand the purpose of the • Including:
– units: arithmetic logic unit (ALU) and control
unit (CU) – registers: program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR) and accumulator (ACC) – buses: address bus, data bus and control bus
Describe the process of the • How instructions and data are fetched from
random access memory (RAM) into the CPU,
how they are processed using each component
and how they are then executed • Storing data and addresses into specific registers • Using buses to transmit data, addresses and signals • Using units to fetch, decode and execute data and instructions
Understand what is meant by a core, cache • The number of cores, size of the cache and

18 0478.3.1.02 — are input into the computer so that the result can be output

are input into the computer so that the result can be output

19 0478.3.1.03 — Understand what is meant by a • A microprocessor is a type of integrated circuit

Understand what is meant by a • A microprocessor is a type of integrated circuit

20 0478.3.1.04 — on a single chip

on a single chip

21 0478.3.1.05 — (a) Understand the purpose of the • Including:

(a) Understand the purpose of the • Including:

22 0478.3.1.06 — – units: arithmetic logic unit (ALU) and control

– units: arithmetic logic unit (ALU) and control

23 0478.3.1.07 — unit (CU) – registers: program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR) a

unit (CU) – registers: program counter (PC), memory address register (MAR), memory data register (MDR), current instruction register (CIR) and accumulator (ACC) – buses: address bus, data bus and control bus

24 0478.3.1.08 — Describe the process of the • How instructions and data are fetched from

Describe the process of the • How instructions and data are fetched from

25 0478.3.1.09 — random access memory (RAM) into the CPU,

random access memory (RAM) into the CPU,

26 0478.3.1.10 — how they are processed using each component

how they are processed using each component

27 0478.3.1.11 — and how they are then executed • Storing data and addresses into specific registers • Using buses to transmit data, addresses and signals •

and how they are then executed • Storing data and addresses into specific registers • Using buses to transmit data, addresses and signals • Using units to fetch, decode and execute data and instructions

28 0478.3.1.12 — Understand what is meant by a core, cache • The number of cores, size of the cache and

Understand what is meant by a core, cache • The number of cores, size of the cache and

29 0478.3.1.13 — speed of the clock can affect the performance

speed of the clock can affect the performance

30 0478.3.1.14 — of a CPU

of a CPU

31 0478.3.1.15 — Understand the purpose and use of an • An instruction set is a list of all the commands

Understand the purpose and use of an • An instruction set is a list of all the commands

32 0478.3.1.16 — that can be processed by a CPU, and the commands are machine code

that can be processed by a CPU, and the commands are machine code

33 0478.3.1.17 — Describe the purpose and characteristics of • An embedded system is used to perform a

Describe the purpose and characteristics of • An embedded system is used to perform a

34 0478.3.1.18 — dedicated functions

dedicated functions

35 0478.3.1.19 — For example in, domestic

For example in, domestic

36 0478.3.1.20 — appliances, cars, security systems, lighting systems or vending machines

appliances, cars, security systems, lighting systems or vending machines

37 0478.3.1.21 — This is different to a general purpose computer that is used to perform many different functions

This is different to a general purpose computer that is used to perform many different functions

38 0478.3.1.22 — For example in, a personal computer (PC) or a laptop

For example in, a personal computer (PC) or a laptop

39 0478.3.2.01 — Understand what is meant by an input device • Including:

Understand what is meant by an input device • Including:
– barcode scanner – digital camera – keyboard – microphone – optical mouse – QR code scanner – touch screen (resistive, capacitive and infra-red) – two-dimensional (2D) and three-dimensional (3D) scanners
Understand what is meant by an output device • Including:
– actuator – digital light processing (DLP) projector – inkjet printer – laser printer – light emitting diode (LED) screen – liquid crystal display (LCD) projector – liquid crystal display (LCD) screen – speaker – 3D printer
(a) Understand what is meant by a sensor and • Limited to:
– acoustic – accelerometer – flow – gas – humidity – infra-red – level – light – magnetic field – moisture – pH – pressure – proximity – temperature
Identify the type of data captured by each

40 0478.3.2.02 — – barcode scanner – digital camera – keyboard – microphone – optical mouse – QR code scanner – touch screen (resistive, capacitive and infra

– barcode scanner – digital camera – keyboard – microphone – optical mouse – QR code scanner – touch screen (resistive, capacitive and infra-red) – two-dimensional (2D) and three-dimensional (3D) scanners

41 0478.3.2.03 — Understand what is meant by an output device • Including:

Understand what is meant by an output device • Including:

42 0478.3.2.04 — – actuator – digital light processing (DLP) projector – inkjet printer – laser printer – light emitting diode (LED) screen – liquid crystal

– actuator – digital light processing (DLP) projector – inkjet printer – laser printer – light emitting diode (LED) screen – liquid crystal display (LCD) projector – liquid crystal display (LCD) screen – speaker – 3D printer

43 0478.3.2.05 — (a) Understand what is meant by a sensor and • Limited to:

(a) Understand what is meant by a sensor and • Limited to:

44 0478.3.2.06 — – acoustic – accelerometer – flow – gas – humidity – infra-red – level – light – magnetic field – moisture – pH – pressure – proximity – tem

– acoustic – accelerometer – flow – gas – humidity – infra-red – level – light – magnetic field – moisture – pH – pressure – proximity – temperature

45 0478.3.2.07 — Identify the type of data captured by each

Identify the type of data captured by each

46 0478.3.3.01 — Understand what is meant by primary storage • Primary storage is directly accessed by the CPU • Including the role of: – random access memor

Understand what is meant by primary storage • Primary storage is directly accessed by the CPU • Including the role of: – random access memory (RAM) – read only memory (ROM) • Including why a computer needs both RAM and ROM, and the difference between them
Understand what is meant by secondary • Secondary storage is not directly accessed by
the CPU and is necessary for more permanent storage of data
Describe the operation of magnetic, optical • Magnetic storage uses platters which are
divided into tracks and sectors
Data is read
and written using electromagnets
Including hard disk drive (HDD) • Optical storage uses lasers to create and read pits and lands
Including: CD, DVD and Blu-ray • Solid-state (flash memory) uses NAND or NOR technology
Transistors are used as control gates and floating gates
Including: solid-state drive (SSD), SD card and USB drive
Describe what is meant by virtual memory, how • Pages of data are transferred between RAM

47 0478.3.3.02 — Understand what is meant by secondary • Secondary storage is not directly accessed by

Understand what is meant by secondary • Secondary storage is not directly accessed by

48 0478.3.3.03 — the CPU and is necessary for more permanent storage of data

the CPU and is necessary for more permanent storage of data

49 0478.3.3.04 — Describe the operation of magnetic, optical • Magnetic storage uses platters which are

Describe the operation of magnetic, optical • Magnetic storage uses platters which are

50 0478.3.3.05 — divided into tracks and sectors

divided into tracks and sectors

51 0478.3.3.06 — Data is read

Data is read

52 0478.3.3.07 — and written using electromagnets

and written using electromagnets

53 0478.3.3.08 — Including hard disk drive (HDD) • Optical storage uses lasers to create and read pits and lands

Including hard disk drive (HDD) • Optical storage uses lasers to create and read pits and lands

54 0478.3.3.09 — Including: CD, DVD and Blu-ray • Solid-state (flash memory) uses NAND or NOR technology

Including: CD, DVD and Blu-ray • Solid-state (flash memory) uses NAND or NOR technology

55 0478.3.3.10 — Transistors are used as control gates and floating gates

Transistors are used as control gates and floating gates

56 0478.3.3.11 — Including: solid-state drive (SSD), SD card and USB drive

Including: solid-state drive (SSD), SD card and USB drive

57 0478.3.3.12 — Describe what is meant by virtual memory, how • Pages of data are transferred between RAM

Describe what is meant by virtual memory, how • Pages of data are transferred between RAM

58 0478.3.3.13 — and virtual memory when needed

and virtual memory when needed

59 0478.3.3.14 — Understand what is meant by cloud storage • Cloud storage can be accessed remotely in comparison to storing data locally

Understand what is meant by cloud storage • Cloud storage can be accessed remotely in comparison to storing data locally

60 0478.3.3.15 — Explain the advantages and disadvantages • Physical servers and storage are needed to

Explain the advantages and disadvantages • Physical servers and storage are needed to

61 0478.3.3.16 — store data in cloud storage

store data in cloud storage

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