IGCSE Computer Science 0478 Paper 11, Oct/Nov 2025

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Question paper

0478/11 · Oct/Nov 2025

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1

A student has an electronic calculator. The calculator has a screen that displays the result of calculations. The calculator has 8-bit registers.

a

State the highest denary number that could be stored in a single 8-bit register.

[1]
b

Denary numbers are typed into the calculator. They are converted to binary numbers and stored in the 8-bit registers. The student types in the denary number 23 and the denary number 168. Give the 8-bit binary numbers that are stored in the registers for these two denary numbers. 23 168 Working space

[2]
c

The result of a calculation that is stored in a register is the binary number 00001011 Give the denary number that will be displayed on the screen for this binary number. 00001011 Working space

[1]
d

Another result of a calculation that is stored in a register is the binary number 01000010 Give the denary number that will be displayed on the screen for this binary number. 01000010 Working space

[1]
e

Two binary numbers stored in the registers are 01110110 and 00110000 Add the binary numbers using binary addition. Show all your working. Give your answer in binary. 0 1 1 1 0 1 1 0 + 0 0 1 1 0 0 0 0

[3]
f

The result of a calculation could be a negative denary number. State how the calculator could represent a negative denary number as a binary number.

[1]
g

The electronic calculator is an example of an embedded system. Explain why it is an example of an embedded system.

[2]
2

An employee of a company sells houses. He sends images of the houses to his company.

a

The employee compresses the image files using lossy compression before sending them. Lossy compression reduces the size of the image files. Give two other reductions that lossy compression makes to the images.

[2]
b(i)

The image data is broken down into packets to be sent across a network to the company. The destination internet protocol (IP) address is read by a device in the network. The device uses the IP address to forward the packet towards its correct destination. State the name of the device that reads the destination IP address.

[1]
b(ii)

Identify the part of the packet where the destination IP address is found.

[1]
c

The IP address has an IPv6 format. Give three characteristics of the IPv6 format.

[3]
d

An echo check is used to check for errors after the image has been transmitted. Draw and annotate a diagram to show how the echo check would detect any errors.

[3]
e(i)

The image data is encrypted using symmetric encryption. Tick (✓) one box to show the correct statement about symmetric encryption. A Encrypted text is known as plain text. B The most secure form of encryption. C The encryption key is shared with any device receiving the encrypted data. D Two different keys are used.

[1]
e(ii)

Give one other type of encryption that could be used.

[1]
3

A student has a portable device. He uses an on-screen keyboard to write messages to his friend.

a

Explain how the text the student writes is converted to binary to be processed.

[3]
b(i)

The device has 4 gibibytes (GiB) of random access memory (RAM). State the amount of RAM the device has in mebibytes (MiB).

[1]
b(ii)

State the amount of RAM the device has in tebibytes (TiB). Your answer can be given rounded to 3 decimal places. Working space

[1]
c

Explain why the portable device needs RAM.

[3]
d

The device has a fingerprint scanner to allow the student to unlock the portable device. Circle only three terms that can be used to describe the fingerprint scanner. authentication biometric malware parity check firewall input device output device storage device

[3]
4

A computer game development company are reviewing their current security solutions. The company wants employees to be aware of how they can identify phishing.

a

Describe the process of phishing.

[4]
b

Give two ways an employee could identify phishing.

[2]
c

The company has installed anti-malware software on all employees' computers. Give three examples of malware that anti-malware software can detect.

[3]
d(i)

The computer game developers use a high-level language to create a computer game. State what is meant by a high-level language.

[1]
d(ii)

One benefit of using a high-level language is that the code is easy to debug. Give two other benefits of using a high-level language.

[2]
d(iii)

One drawback of using a high-level language is that it must be converted to a low-level language before it can be run. Give one other drawback of using a high-level language.

[1]
d(iv)

The computer game developers use an interpreter instead of a compiler when developing the computer game. Explain why an interpreter would be more appropriate for developing the computer game.

[3]
5

A supermarket wants to start delivering groceries to local elderly people, using robots.

Figure 1 of 1 for question 5
a

Describe the characteristics of a robot.

[3]
b

Explain one benefit to the supermarket of using robots to deliver groceries to elderly customers.

[2]
c

Explain one drawback to the elderly customers of robots being used to deliver their groceries.

[2]
d

Each robot has a media access control (MAC) address. Tick (✓) one box to show the correct statement about a MAC address. A It is assigned by the manufacturer. B It is assigned by the product. C It is assigned by the router. D It is assigned by the user.

[1]
e

The robots have artificial intelligence (AI). Give three ways the robots could make use of AI.

[3]
6

A computer with a Von Neumann architecture has a central processing unit (CPU).

a

Complete the statements about the operation of the CPU. Use the terms from the list. Not all terms will need to be used. You should only use each term once. accumulator arithmetic logic unit character set control unit current instruction register cipher decoding set instruction counter instruction set memory address register memory data register memory instruction register next instruction register program counter program register The ............................................................... stores the address of the next instruction to be fetched. This address is then sent to the ............................................................... . This address is the location in RAM where the instruction can be found. The instruction is retrieved from RAM and immediately stored in the ............................................................... . The instruction is then sent to the ............................................................... where it is decoded by the ............................................................... . The instruction is decoded using an ............................................................... .

[6]
b(i)

Handling interrupts is one function of an operating system. An interrupt is sent to the CPU every time a key is pressed on the keyboard. Give the name of this type of interrupt.

[1]
b(ii)

Give the name of the program that services the interrupt.

[1]
b(iii)

Give one other function of an operating system.

[1]
7

A theatre has a microphone on stage that is connected by cables to several speakers around the theatre. A person speaks into the microphone and their voice is output from the speakers. Identify the most appropriate data transmission method for this purpose. Explain your choice. Data transmission method ............................................................................................................... Explanation ......................................................................................................................................

[5]

Mark scheme

0478/11 · Oct/Nov 2025

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1a · 1 mark

  • 1 mark

    255

1b · 2 marks

  • 1 mark

    00010111

  • 1 mark

    10101000

1c · 1 mark

  • 1 mark

    11

1d · 1 mark

  • 1 mark

    66

1e · 3 marks

  • 1 mark

    Correct first nibble (1010)

  • 1 mark

    Correct second nibble (0110)

  • 1 mark

    Correct method of working, for example carries

1f · 1 mark

  • 1 mark

    Using two’s complement

1g · 2 marks

  • 1 mark

    It has a single/limited function

  • 1 mark

    It has dedicated hardware

  • 0 marks

    It has a microprocessor

  • 0 marks

    Its function is not easily changed

2a · 2 marks

  • 1 mark

    Resolution // number of pixels

  • 1 mark

    Colour depth // bit depth

  • 0 marks

    Quality // detail

  • 0 marks

    Metadata

2b(i) · 1 mark

  • 1 mark

    Router

2b(ii) · 1 mark

  • 1 mark

    (Packet) header

2c · 3 marks

  • 1 mark

    It has 128 bits

  • 1 mark

    Hexadecimal

  • 1 mark

    Separated by colons

  • 0 marks

    8 groups of digits

  • 0 marks

    Each group is 4 digits

  • 0 marks

    Consecutive groups of 0s can be represented by :: once

2d · 3 marks

  • 1 mark

    (Data being sent to the receiver) and a copy sent back from the receiver to the sender

  • 1 mark

    Sending device comparing the original data and the copy

  • 1 mark

    If original data and copy don’t match an error is detected

2e(i) · 1 mark

  • 1 mark

    C

2e(ii) · 1 mark

  • 1 mark

    Asymmetric

3a · 3 marks

  • 1 mark

    A character set is used

  • 1 mark

    … such as ASCII/Unicode

  • 1 mark

    Each character has a unique binary value that it is converted to

3b(i) · 1 mark

  • 1 mark

    4096

3b(ii) · 1 mark

  • 1 mark

    0.004 // 0.0039(0625)

3c · 3 marks

  • 1 mark

    To store data/instructions that are currently in use

  • 1 mark

    To store software/programs that are currently in use

  • 1 mark

    For volatile storage // to store data temporarily

  • 0 marks

    To allow data to be accessed directly by the CPU/processor // To allow data to be stored closer to the CPU/processor

3d · 3 marks

  • 1 mark

    Authentication

  • 1 mark

    Biometric

  • 1 mark

    Input device

4a · 4 marks

  • 1 mark

    A legitimate looking email is sent to the user

  • 1 mark

    The user clicks a link in the email // the user replies to the email

  • 1 mark

    The user is directed to a fake website

  • 1 mark

    The user enters their personal data …

  • 0 marks

    … that is stolen/used by a third party (for malicious purposes)

4b · 2 marks

  • 1 mark

    Check the email address that the email has been sent from

  • 1 mark

    Check the tone/spelling of the email

  • 0 marks

    Check the URL that is attached to the link

4c · 3 marks

  • 1 mark

    Virus

  • 1 mark

    Worm

  • 1 mark

    Trojan horse

  • 0 marks

    Spyware // keylogger

  • 0 marks

    Ransomware

  • 0 marks

    Adware

4d(i) · 1 mark

  • 1 mark

    A language that uses English-like statements

  • 0 marks

    It is a language that needs to be converted to machine code (to be processed by a computer)

  • 0 marks

    It is a portable language (that can be used on any computer)

4d(ii) · 2 marks

  • 1 mark

    Easy/quick to read/write/understand

  • 1 mark

    Machine independent

  • 0 marks

    Less likely to make errors

  • 0 marks

    Programmer can focus on the problem instead of the manipulation of memory/hardware

4d(iii) · 1 mark

  • 1 mark

    Cannot directly manipulate the hardware

  • 0 marks

    Takes longer to convert (than low level-language)

  • 0 marks

    Cannot use specialised hardware

  • 0 marks

    Uses more memory // less efficient memory use

4d(iv) · 3 marks

  • 1 mark

    The code is translated and executed line by line

  • 1 mark

    … stopping when an error is found (showing the error location)

  • 1 mark

    … meaning errors can be corrected in real time

  • 0 marks

    No need to retranslate each time an error is fixed

  • 0 marks

    … making it easier to debug

  • 0 marks

    Sections of code can be easily tested

  • 0 marks

    … meaning the whole program doesn’t need to be written for testing

5a · 3 marks

  • 1 mark

    A mechanical structure/framework

  • 1 mark

    Electrical components

  • 1 mark

    … such as sensors/microprocessor/actuators

  • 0 marks

    Programmable

  • 0 marks

    Has the ability to move

5b · 2 marks

  • 1 mark

    Supermarket may gain more customers / Supermarket can serve customers more efficiently (benefit)

  • 1 mark

    … as elderly people who could not previously make it to the store can now shop there / … which will increase their sales/profits / … as multiple orders can be delivered at the same time (matching explanation)

5c · 2 marks

  • 1 mark

    They may get less exercise / They may struggle to use technology // may mistrust technology // would prefer an employee/person to deliver it (drawback)

  • 1 mark

    … as they no longer need to walk to/round the store to get their shopping / … that could negatively affect their health / … and this may cause additional stress/anxiety / … leading to making mistakes in receiving the delivery (matching explanation)

5d · 1 mark

  • 1 mark

    A

5e · 3 marks

  • 1 mark

    It could learn the route to a customer’s house

  • 1 mark

    It could learn where there are obstacles on a route

  • 1 mark

    It could learn to deal with obstacles more effectively

  • 0 marks

    It could reason which parts of the route are paths and which are roads

  • 0 marks

    It can use machine learning

  • 0 marks

    To identify patterns in the route data

6a · 6 marks

  • 1 mark

    program counter

  • 1 mark

    memory address register

  • 1 mark

    memory data register

  • 1 mark

    current instruction register

  • 1 mark

    control unit

  • 1 mark

    instruction set

6b(i) · 1 mark

  • 1 mark

    Hardware (interrupt)

6b(ii) · 1 mark

  • 1 mark

    Interrupt handler // Interrupt service routine

6b(iii) · 1 mark

  • 1 mark

    managing files

  • 0 marks

    providing an interface

  • 0 marks

    managing peripherals and drivers

  • 0 marks

    managing memory

  • 0 marks

    managing multitasking

  • 0 marks

    providing a platform for running applications

  • 0 marks

    providing system security

  • 0 marks

    managing user accounts

7 · 5 marks

  • 1 mark

    Serial

  • 1 mark

    Simplex

  • 1 mark

    Serial: Data will need to travel long distances

  • 1 mark

    Serial: One wire is used // bits are sent in order // sent one bit at a time

  • 1 mark

    Serial: Less chance of data being skewed // less chance of error

  • 0 marks

    Serial: Transmission speed would be adequate

  • 0 marks

    Simplex: Data only needs to be sent in one direction

  • 0 marks

    Simplex: Data does not need to be sent back from the speakers to the microphone

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