O Level Computer Science 2210 Paper 12, Oct/Nov 2025

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2210/12 · Oct/Nov 2025

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1

A toy store gives each of the toys it sells a unique code. The codes are 3-digit hexadecimal codes, for example A4B. A computer is used to store a database of the codes. The computer has 12-bit registers.

a

Give the largest hexadecimal number that can be stored in a 12-bit register.

[1]
b

Give the largest denary number that can be stored in a 12-bit register.

[1]
c

Two toys have the hexadecimal codes 429 and 1A3. Convert the two hexadecimal codes to 12-bit binary numbers. 429 ............................................................................................................................................ 1A3 ...........................................................................................................................................

[2]
d

Two binary numbers that are stored in the registers are 100010100001 and 011100001011. Convert the two binary numbers to hexadecimal numbers. 100010100001 .......................................................................................................................... 011100001011 ..........................................................................................................................

[2]
e(i)

The hexadecimal code for each toy is stored in a barcode that is displayed on each toy. Each time a customer buys a toy, the barcode is scanned and the amount of stock stored in the database for that toy is reduced by 1. An item of hardware is used in this system to receive the hexadecimal code from the barcode scanner and find it in the database. The item of hardware is built into a single chip. Identify the name of the item of hardware.

[1]
e(ii)

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 D storage

[1]
e(iii)

The barcode scanner contains a sensor. Identify the type of sensor that the barcode scanner could contain.

[1]
e(iv)

A backup of the database is made at the end of each day using optical storage. Describe how the database is written to the optical storage.

[4]
2

Two binary numbers are stored in a computer.

a

Add the two binary numbers using binary addition. Give your answer in binary. Show all of your working. 11110101 + 00111001

[4]
b

A logic right shift of three places is performed on the binary number 11110101. Give the denary number for the binary number that would be stored after the logical shift of three places has occurred. Show all of your working.

[3]
3

A programmer uses assembly language to create a program for a coffee machine.

a

Describe what is meant by assembly language.

[2]
b

Identify the translator needed for assembly language.

[1]
c

Tick (✓) one box to show which statement is an advantage of using assembly language. A It is close to human language. B It is memory efficient. C It is easy to debug. D It is machine independent.

[1]
4

A computer with a Von Neumann architecture has a central processing unit (CPU) that performs the fetch–decode–execute (FDE) cycle.

a

Complete and annotate the diagram to show how instructions are decoded and executed.

[5]
b

The CPU is dual core and has a processor speed of 2.4GHz. Describe what is meant by a core.

[2]
c

Explain two ways that the performance of the CPU could be increased.

[4]
5

A computer system has a mouse. An interrupt is sent to the CPU every time a button on the mouse is clicked.

a

Identify the name of this type of interrupt.

[1]
b

The interrupt is placed in a queue. Explain how the interrupt is serviced after it is placed in the queue.

[4]
c(i)

The mouse is connected using a universal serial bus (USB) connection. Explain how data is sent using the USB connection.

[2]
c(ii)

Give two benefits of using a USB connection for this purpose.

[2]
c(iii)

Give one drawback of using a USB connection for this purpose.

[1]
6

An online clothing company has a homepage at the uniform resource locator (URL) https://www.cieclothes.com/index.html

a

Write down the three different parts of the URL shown by the labels a, b and c. https://www.cieclothes.com/index.html a ..................................... b ........................................ c ................................

[3]
b

The web pages are stored on a web server. A proxy server is used to stop distributed denial of service (DDoS) attacks on the web server. Describe how the proxy server can stop a DDoS attack reaching a web server.

[3]
c

Customers use the website to buy clothing from the company. Complete the table with the missing terms and descriptions about retrieving and displaying web pages.

[5]
d

The clothing company uses cookies to store customer details. Complete the statements about cookies. Use terms from the list. Not all terms need to be used. You should only use a term once. asymmetric DNS dynamic persistent session static symmetric user utility software web browser Cookies are stored and managed by the ................................................................................ . ................................................................................ cookies are temporary files that are created when a user visits a web page. ................................................................................ cookies are permanent files that are created when a user visits a web page.

[3]
7

A house has a smart speaker that can take voice commands as input. A person in the house can tell the smart speaker to play music or audio books.

a

The smart speaker cannot be described as a robot. Explain why the smart speaker is not a robot.

[3]
b

Identify the input device that allows voice commands to be used as input.

[1]
c

The smart speaker has machine learning capabilities. Explain how the smart speaker can use machine learning to improve the voice command input.

[4]
d

The smart speaker is an example of an embedded system. Explain why the smart speaker is an embedded system.

[2]
e

The music and audio books that are played by the smart speaker are stored in cloud storage. Give two advantages of storing the music and audio books in cloud storage.

[2]
f(i)

The data for the music and audio books needs to be checked for errors after being transmitted from the cloud. Explain how errors may occur in the data during transmission.

[2]
f(ii)

Give two error detection methods that could be used to check for errors in the data after transmission.

[2]

Mark scheme

2210/12 · Oct/Nov 2025

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1a · 1 mark

  • 1 mark

    FFF

1b · 1 mark

  • 1 mark

    4095

1c · 2 marks

  • 1 mark

    0100 0010 1001

  • 1 mark

    0001 1010 0011

1d · 2 marks

  • 1 mark

    8A1

  • 1 mark

    70B

1e(i) · 1 mark

  • 1 mark

    Microprocessor

1e(ii) · 1 mark

  • 1 mark

    A

1e(iii) · 1 mark

  • 1 mark

    Light

1e(iv) · 4 marks

  • 1 mark

    The disk is spun

  • 1 mark

    A laser is shone onto the disk

  • 1 mark

    Pits are burnt into the disk

  • 1 mark

    Pits are in a (spiral) track

  • 1 mark

    Pits and lands represent binary values

2a · 4 marks

  • 2 marks

    One mark for each correct nibble (2)

  • 1 mark

    One mark for a correct method of working for example 4 or 5 correct carries

  • 1 mark

    One mark for showing an overflow error

2b · 3 marks

  • 1 mark

    showing the binary number after the shift: 00011110

  • 1 mark

    valid method of working to convert to denary: 16 + 8 + 4 + 2

  • 1 mark

    correct denary number: 30

3a · 2 marks

  • 1 mark

    Low-level language

  • 1 mark

    Uses mnemonics

  • 1 mark

    Used to communicate directly with the computer hardware

3b · 1 mark

  • 1 mark

    Assembler

3c · 1 mark

  • 1 mark

    B

4a · 5 marks

  • 1 mark

    CIR is built into CU

  • 1 mark

    CIR stores instruction

  • 1 mark

    CU decodes the instruction

  • 1 mark

    Instruction is decoded using an instruction set // Instruction is separated into opcode and operand

  • 1 mark

    Signal is sent from CIR to ALU (to execute)

  • 1 mark

    CU sends signal to RAM to fetch any data needed for instruction

  • 1 mark

    ACC is built into ALU

  • 1 mark

    ACC stores any data needed for instruction

  • 1 mark

    ALU executes the instruction // ALU performs the mathematic/logical operation (needed by the instruction)

4b · 2 marks

  • 1 mark

    Independent/self-contained processing unit

  • 1 mark

    It executes/processes instructions // It performs the FDE cycle

  • 1 mark

    It contains registers/units (to process data)

4c · 4 marks

  • 1 mark

    The number of cores could be increased // by example …

  • 1 mark

    … this means that more instructions can be processed simultaneously

  • 1 mark

    The clock speed could be increased // by example …

  • 1 mark

    … this means that more instructions can be processed (by a core) per second

  • 1 mark

    The cache could be increased // by example …

  • 1 mark

    … this means that more frequently used data/instructions can be stored (to be accessed faster than RAM)

5a · 1 mark

  • 1 mark

    Hardware (interrupt)

5b · 4 marks

  • 1 mark

    Checks the priority of the interrupt

  • 1 mark

    If priority is higher, it halts the current process

  • 1 mark

    … stores it on a stack

  • 1 mark

    … fetches the interrupt

  • 1 mark

    … checks the source of the interrupt

  • 1 mark

    … calls the interrupt service routine (ISR) / interrupt handler to process the interrupt

  • 1 mark

    If priority is not higher, it continues with current process

5c(i) · 2 marks

  • 1 mark

    It is sent one bit at a time

  • 1 mark

    It is sent down a single wire

5c(ii) · 2 marks

  • 1 mark

    The mouse can be powered by the device

  • 1 mark

    It is a universal connection

  • 1 mark

    It is backward compatible

  • 1 mark

    Less chance of skewing // Less chance of errors

  • 1 mark

    Supports different data transmission speeds

  • 1 mark

    Adequate transmission speeds

  • 1 mark

    The cable cannot be inserted incorrectly

  • 1 mark

    The device is automatically detected // Driver is automatically installed when device is connected

5c(iii) · 1 mark

  • 1 mark

    Slower transmission than a parallel connection

  • 1 mark

    Wire may get in the way // wire may limit movement of mouse

6a · 3 marks

  • 1 mark

    Protocol

  • 1 mark

    Domain name

  • 1 mark

    Web page name // file name

6b · 3 marks

  • 1 mark

    It examines each request/incoming transmission

  • 1 mark

    It can slow down the rate at which/limits the number of requests sent to the server

  • 1 mark

    It can use caching …

  • 1 mark

    … to respond to the request (rather than forwarding it to the server)

  • 1 mark

    It can stop any requests from a certain IP

6c · 5 marks

  • 1 mark

    hypertext markup language (HTML): It is the language that is often used to write/author web pages.

  • 1 mark

    domain name server (DNS): It is a system that stores URLs/domain names and their matching/corresponding IP addresses // It is a system that provides the matching IP address for a webpage to the web browser.

  • 1 mark

    IP address: It is a numerical address used to locate the web server.

  • 1 mark

    SSL/TLS/HTTPS: It is a secure protocol that can be used to transmit data sent to and from a web server.

  • 1 mark

    web browser: It is a piece of software that is used to display web pages.

6d · 3 marks

  • 1 mark

    web browser

  • 1 mark

    Session cookies

  • 1 mark

    Persistent cookies

7a · 3 marks

  • 1 mark

    It does not have a mechanical structure

  • 1 mark

    It does not have any actuators

  • 1 mark

    … so it cannot move itself

7b · 1 mark

  • 1 mark

    Microphone

7c · 4 marks

  • 1 mark

    Gather data from the same/different voices // It can ask a user to say lots of different words

  • 1 mark

    Analyse/identify patterns in a user’s voice

  • 1 mark

    It can adapt its own processes

  • 1 mark

    It can learn to identify a user’s voice

  • 1 mark

    Stores successful/unsuccessful voice commands

  • 1 mark

    It can learn different ways of making the same request

  • 1 mark

    It can learn the different pronunciations // It can learn different accents

  • 1 mark

    It can learn by listening to lots of different voices

  • 1 mark

    It can learn to ignore any background/environmental noise if a user is speaking

7d · 2 marks

  • 1 mark

    It has a single/limited function

  • 1 mark

    It has dedicated hardware

  • 1 mark

    It has a microprocessor

  • 1 mark

    Its function is not easily changed

7e · 2 marks

  • 1 mark

    The music/books can be easily accessed from any smart speaker

  • 1 mark

    The user doesn’t need to purchase a secondary storage device for the books/music // Smart speaker doesn’t need a large amount of secondary storage

  • 1 mark

    The user doesn’t need to maintain the storage needed for the books/music

  • 1 mark

    Smart speaker can be smaller in size (as it doesn’t need large amounts of secondary storage)

  • 1 mark

    Almost unlimited storage available for the books/music // Easy to increase storage capacity needed

7f(i) · 2 marks

  • 1 mark

    Data could be lost

  • 1 mark

    Data could be gained

  • 1 mark

    Data could be changed

  • 1 mark

    Skewing of data could occur

  • 1 mark

    Interference could occur

  • 1 mark

    Crosstalk could occur

  • 1 mark

    Data collisions could occur

  • 1 mark

    Data packets could time out/reach their hop count

7f(ii) · 2 marks

  • 1 mark

    Parity byte check

  • 1 mark

    Parity block check

  • 1 mark

    Checksum

  • 1 mark

    Echo check

  • 1 mark

    ARQ

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