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IGCSE Computer Science 0478 Paper 12, May/June 2024

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0478/12 · May/June 2024

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1

Data can be measured in bits.

a

Give the name of the data storage measurement that is equal to 8 bits.

[1]
b

State how many bits there are in a kibibyte (KiB).

[1]
c

Give the name of the data storage measurement that is equal to 1024 gibibytes (GiB).

[1]
d

A 16-bit colour image has a resolution of 512 pixels wide by 512 pixels high. Calculate the file size of the image in kibibytes (KiB). Show all your working. Answer ......................................................... KiB

[3]
2

Data can be transmitted from one device to another.

a

Tick (✓) one box to show which of the terms is not a method for transmitting data. A serial B simplex C parallel D parity

[1]
b

Data is broken down into smaller units to be transmitted from one device to another. Give the name of the unit that data is broken down into.

[1]
c(i)

Data is often encrypted when it is transmitted from one device to another. Explain how data is encrypted using symmetric encryption.

[4]
c(ii)

Give the purpose of encryption.

[1]
3

Binary is a base 2 number system.

a

Give the name of the number system that is base 16.

[1]
b(i)

Three denary numbers are entered into a computer. The computer converts the numbers and stores them as binary. Give the binary number that would be stored for each of the denary numbers. 10 ...................................................................................................................................... 50 ...................................................................................................................................... 201 .................................................................................................................................... Working space

[3]
b(ii)

Explain why the data is converted to binary by the computer.

[2]
c

The two binary integers 00110000 and 01100110 are added together. Add the binary integers using binary addition and show your answer in binary. Show all your working.

[3]
d

The denary integer –32 is stored as a two’s complement integer. Calculate the two’s complement integer that would be stored. Show all your working.

[2]
4

A student uses both system software and application software on their computer.

a

Give one example of system software.

[1]
b

Give two examples of application software. 1 ................................................................................................................................................ 2 ................................................................................................................................................

[2]
c

Describe the difference between system software and application software.

[2]
5

Instructions are processed by a central processing unit (CPU) in a computer.

a

Complete the paragraph about fetching an instruction into the CPU to be processed. Use the terms from the list. Some of the terms in the list will not be used. You should only use a term once. address arithmetic logic unit (ALU) binary control unit (CU) current instruction register (CIR) data denary driver fetch interrupt memory address register (MAR) memory data register (MDR) random access memory (RAM) read only memory (ROM) secondary storage signal The program counter contains the ……………………………………………………… of the next instruction to be processed; this is then sent to the ……………………………………………………… using the address bus. The address is then sent to the ……………………………………………………… . Once the address is received, the instruction stored at the location is sent to the ………………………………………………………, using the ……………………………………………………… bus. The instruction is then sent to the ……………………………………………………… that is built into the ……………………………………………………… .

[7]
b

The CPU uses an instruction set to decode the instruction. State what is meant by an instruction set.

[1]
6

The table contains statements about error detection methods. Complete the table by giving the correct error detection method for each statement.

error detection methodstatement
An odd or even process can be used.
A value is calculated from the data, using an algorithm. This happens before and after the data is transmitted.
A copy of the data is sent back to the sender by the receiver.
Acknowledgement and timeout are used.
A value is appended to data that has been calculated using the data. This value is checked on data entry.
[5]
7

A computer has both a media access control (MAC) address and an internet protocol (IP) address.

a

Tick (✓) one box to show which of the statements is correct about the MAC address. A It is assigned by the manufacturer. B It is assigned by a router. C It can be static or dynamic. D It is made up of three different parts.

[1]
b(i)

An IP address can have an IPv4 or IPv6 format. Give an example of an IP address that has an IPv4 format.

[1]
b(ii)

Give two characteristics of the IPv6 format. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ...........................................................................................................................................

[2]
8

A company has a website that is suffering a distributed denial of service (DDoS) attack.

a

Draw and annotate a diagram to show the process of the DDoS.

[5]
b

Identify a solution that can be used to help prevent the DDoS attack being successful.

[1]
9

A company uses both solid-state and optical secondary storage.

a

Explain why a computer needs secondary storage.

[2]
b

Describe three differences between solid-state and optical storage. 1 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... 3 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................

[6]
10

A garage uses an expert system to help diagnose any problems with cars that need repair.

a

The expert system is an example of artificial intelligence (AI). Describe what is meant by AI.

[2]
b

A car has a problem with its braking system, so it is brought into the garage. Explain how the expert system operates and how it is used to help diagnose the problem.

[5]
11

A company has a website. Users use the internet and the world wide web to access the website.

a

Describe the difference between the internet and the world wide web.

[2]
b

The website has a uniform resource locator (URL). The URL has three different parts. Identify the three different parts that are included in the URL. 1 ................................................................................................................................................ 2 ................................................................................................................................................ 3 ................................................................................................................................................

[3]
c

One function of a web browser is to provide an address bar for a user to enter a URL. Give three other functions of a web browser. 1 ................................................................................................................................................ 2 ................................................................................................................................................ 3 ................................................................................................................................................

[3]

Mark scheme

0478/12 · May/June 2024

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1a · 1 mark

  • 1 mark

    (1) byte

1b · 1 mark

  • 1 mark

    8192

1c · 1 mark

  • 1 mark

    (1) Tebibyte // TiB

1d · 3 marks

  • 1 mark

    512 × 512

  • 1 mark

    262 144 * 2 // multiplied by 16 and divided by 8 // 524 288/1024

  • 1 mark

    512 (KiB)

2a · 1 mark

  • 1 mark

    D

2b · 1 mark

  • 1 mark

    Packet

2c(i) · 4 marks

  • 1 mark

    Data is encrypted and decrypted using the same key

  • 1 mark

    Plain text is encrypted into cipher text // cipher text is decrypted into plain text

  • 1 mark

    Data is encrypted using an algorithm … … that uses a key

  • 1 mark

    The key can be generated using an algorithm // The key is transmitted to the receiver

2c(ii) · 1 mark

  • 1 mark

    To help keep the data secure // To make the data meaningless

3a · 1 mark

  • 1 mark

    Hexadecimal

3b(i) · 3 marks

  • 1 mark

    1010

  • 1 mark

    110010

  • 1 mark

    11001001

3b(ii) · 2 marks

  • 1 mark

    Computers use logic gates/switches …

  • 1 mark

    … that only process the values 1 and 0 // that only have two states

3c · 3 marks

  • 1 mark

    Evidence of working, for example 2 carries

  • 1 mark

    Correct first nibble (1 0 0 1)

  • 1 mark

    Correct second nibble (0 1 1 0)

3d · 2 marks

  • 1 mark

    Evidence of working, for example, flip and add

  • 1 mark

    11100000

4a · 1 mark

  • 1 mark

    Operating system // Utility software // by example

4b · 2 marks

  • 1 mark

    Word processor // Spreadsheet // Database // Web browser

  • 1 mark

    Image/photo-editor // Video-editor // Email client // Game // Social media app

4c · 2 marks

  • 1 mark

    System software manages/maintains the hardware/software

  • 1 mark

    Applications software allows the user to perform tasks

5a · 7 marks

  • 1 mark

    address

  • 1 mark

    memory address register // MAR

  • 1 mark

    random access memory // RAM

  • 1 mark

    memory data register // MDR

  • 1 mark

    data

  • 1 mark

    current instruction register // CIR

  • 1 mark

    control unit // CU

5b · 1 mark

  • 1 mark

    A list of (machine code) commands that can be processed by the CPU

6 · 5 marks

  • 1 mark

    parity (check/bit/byte/block) - An odd or even process can be used.

  • 1 mark

    checksum - A value is calculated from the data using an algorithm. This happens before and after the data is transmitted.

  • 1 mark

    echo check - A copy of the data is sent back to the sender by the receiver.

  • 1 mark

    automatic repeat query/request // ARQ - Acknowledgement and timeout are used.

  • 1 mark

    check digit - A value is appended to data that has been calculated using the data. This value is checked on data entry.

7a · 1 mark

  • 1 mark

    A

7b(i) · 1 mark

  • 1 mark

    An IP address that has numerical values separated by dots that follows the format with a max value of 255 in any xxx / xxx.xxx.xxx.xxx / Example: 10.245.3.99

7b(ii) · 2 marks

  • 1 mark

    128-bit // 16 bytes // Hexadecimal // Separated by colons

  • 1 mark

    Characters in groups of 4 // Has 8 groups of characters // Double colons can be used for sets of (consecutive) zeros (only once)

8a · 5 marks

  • 1 mark

    A perpetrator/third party sending malware // user downloads/installs malware

  • 1 mark

    Each computer is turned into a bot… … to create a botnet

  • 1 mark

    Third party initiates the attack

  • 1 mark

    All the bots send a request at once to a web server

  • 1 mark

    … crashing the webserver

8b · 1 mark

  • 1 mark

    Proxy server

9a · 2 marks

  • 1 mark

    To store data/files permanently (… otherwise, data/programs would need to be downloaded/entered/installed every time the computer was used)

  • 1 mark

    To allow software to be installed on the computer // For the creation of virtual memory

9b · 6 marks

  • 1 mark

    Solid-state has no moving parts // … optical does have moving parts

  • 1 mark

    Solid-state is faster to access data // … optical is slower to access data

  • 1 mark

    Solid-state uses less power to operate // … optical uses more power to operate

  • 1 mark

    Solid-state runs quietly // … optical makes more noise

  • 1 mark

    Solid state is more durable/robust // … optical is less durable/robust // Solid state storage has a large storage capacity // … optical has a much smaller limit to its storage capacity

  • 1 mark

    Solid-state is more expensive per GB of data // … optical is cheaper per GB of data // Solid-state stores data onto silicon chips/transistors using logic (floating/control/NAND/NOR) gates to control the movement of electrons // … optical stores data by using lasers to burning pits and lands onto a disk

10a · 2 marks

  • 1 mark

    The simulation of intelligent behaviours by computers // A collection of data and the rules for using that data

  • 1 mark

    Has the ability to reason // Has the ability to learn/adapt

10b · 5 marks

  • 1 mark

    The user will enter data into the interface // The user will plug the car into an interface // The user is given questions using the interface

  • 1 mark

    The inference engine will decide which questions to ask (… by using the previous answers given)

  • 1 mark

    The inference engine will decide on a diagnosis

  • 1 mark

    … by comparing the data/answers entered to the knowledge base and rule base (… by calculating which option is most likely if there are multiple)

  • 1 mark

    The interface will output the diagnosis/result // The explanation system shows how the diagnosis was reached

11a · 2 marks

  • 1 mark

    The internet is the infrastructure

  • 1 mark

    The world wide web is a collection of web pages

11b · 3 marks

  • 1 mark

    Protocol

  • 1 mark

    Domain name

  • 1 mark

    File name // web page name

11c · 3 marks

  • 1 mark

    Displays a web page // Storing bookmarks/favourites

  • 1 mark

    Recording user history // Allowing use of multiple tabs

  • 1 mark

    Storing cookies // Providing navigation tools // Can set a home page

Questions

  1. 1
    Question 16 marks
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  2. 2
    Question 27 marks
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  3. 3
    Question 311 marks
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  4. 4
    Question 45 marks
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  5. 5
    Question 58 marks
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  6. 6
    Question 65 marks
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  7. 7
    Question 74 marks
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  8. 8
    Question 86 marks
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  9. 9
    Question 98 marks
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  10. 10
    Question 107 marks
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  11. 11
    Question 118 marks
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