A Level Computer Science 9618 Paper 12, Oct/Nov 2025

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9618/12 · Oct/Nov 2025

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2
a

Complete the table by describing each term. Term | Description Copyright | Open Source (Initiative) | Shareware | Software Licence |

[4]
b

Describe the purpose of a code of conduct.

[2]
3
a(i)

State what is meant by relative addressing.

[1]
a(ii)

Registers such as the Accumulator (ACC) and the Index Register (IX) are used in the CPU. Identify two special purpose registers used in the CPU. Do not include the ACC or IX in your answers. 1 2

[2]
b

The following table shows part of the instruction set for a processor. The processor has two registers: the ACC and an IX. Instruction Opcode | Operand | Explanation LDM | #n | Immediate addressing. Load the number n to ACC LDD | <address> | Direct addressing. Load the contents of the location at the given address to ACC LDI | <address> | Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC LDX | <address> | Indexed addressing. Form the address from <address> + the contents of the index register. Copy the contents of this calculated address to ACC LDR | #n | Immediate addressing. Load the number n to IX <address> can be an absolute or symbolic address # denotes a denary number, e.g. #127 The current contents of the main memory and the index register are shown. Address | Instruction 98 | 8 99 | 16 100 | 3 101 | 98 102 | 32 IX | 2 Write the contents of the ACC after each instruction is executed. Instruction | Value in ACC LDM #98 | LDI 101 | LDX 100 |

[3]
c

A student buys a new computer. The table shows the specifications of the old computer and the new computer. Old computer | New computer 1.8GHz dual core processor | 2.3GHz dual core processor 16MB cache | 32MB cache Explain why increasing the clock speed and increasing the cache memory will improve the performance of the computer. Clock speed Cache memory

[4]
4

A relational database, SHIPPING, stores data about the ships in a company and the containers that are carried on the ships. The database has the following tables: CONTAINER(ContainerID, Type, Weight, OwnerName, ShipID) SHIP(ShipID, Type, Capacity, ShipName)

a

Describe the relationship between the two tables. Refer to the primary and foreign keys in your answer.

[2]
b

The table CONTAINER needs an additional field to store the data for the last inspection date. Write a Structured Query Language (SQL) script to add one field to the table CONTAINER to store the date of last inspection of the container, for example 08/07/2019.

[2]
c

Write an SQL script to return the number of containers stored in the database for the ship with the name Caledonia.

[4]
d

Describe the purpose of a developer interface in a Database Management System (DBMS).

[2]
5

A local area network (LAN) has five computers, one switch and one server.

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a

Describe the characteristics of a LAN.

[2]
b

Complete the following diagram to show how these devices are connected in a star topology.

[2]
c

Describe how packets are transmitted between two hosts using a star topology.

[3]
d

Another type of network is a bus network. Ethernet is used to transmit and receive data between the devices on the bus network. Describe how collisions are detected and managed on this network.

[3]
e

Complete the table by identifying one threat to computer and data security posed by networks and the internet. Describe the threat and give a method of prevention. Threat | Description | Prevention

[3]
6
a

A sound file is compressed by reducing the sampling rate. State whether this is lossless or lossy compression. Justify your choice. Type of compression Justification

[1]
b

The following table shows some words and corresponding denary values. Word | Denary value Computing | 55 Science | 56 Computers | 57 are | 58 Brilliant! | 59 is | 60 Fun! | 61 Amazing! | 62 The following table shows three bytes of data that have been received. Use the table to find the corresponding words from the binary values received. Binary value | 00111000 | 00111100 | 00111110 Word | | | Working

[1]
c(i)

A computer system uses even parity. The least significant (rightmost) bit of each byte is the parity bit. Complete the byte by writing the missing parity bit:

[1]
c(ii)

The computer also uses parity block check. The parity block check uses even parity. Computer A transmits four bytes of data to computer B, followed by a parity byte. Computer B receives the following sequence of bytes. 1 0 1 1 0 1 1 1 0 1 1 1 0 0 0 0 0 0 0 1 1 0 1 1 0 1 1 1 0 1 0 0 parity byte: 1 0 1 0 0 0 0 0 Following transmission, one of the four bytes of data has an error in one of the bits. Circle the bit that has been altered during the data transfer.

[1]
d

A bitmap image has a resolution of 1000 pixels wide by 2000 pixels high. The colour depth is 16 bits. Calculate an estimate of the file size in megabytes. Show your working. File size .......................... megabytes

[2]
7
a

The following binary addition is performed using 8‑bit registers. Complete the calculation using binary addition. 1 0 0 0 0 1 1 1 + 0 0 1 1 1 0 0 1

[1]
b

A computer uses the Unicode character set. State the number of bits used to store one character from the Unicode character set.

[1]
c(i)

ASCII is another character set. The ASCII value for the character ‘h’ has the denary value 104. Write the Binary Coded Decimal (BCD) value for the ASCII character ‘h’.

[1]
c(ii)

Write the hexadecimal value for the ASCII character ‘h’.

[1]
8

A restaurant accesses software and stores data using cloud computing.

a(i)

Give two benefits of storing data using cloud computing. 1 2

[2]
a(ii)

Give two drawbacks of using cloud computing. 1 2

[2]
b(i)

The restaurant uses touchscreens as input devices to allow staff to select items from a menu. Explain how a touchscreen converts the point of touch to a selection from the menu.

[4]
b(ii)

The image files that are displayed on the touchscreen have been corrupted. Identify two examples of utility software that could be used to recover the images. 1 2

[2]
9
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a

Consider the following logic circuit: Write the logic expression for the logic circuit. Do not simplify the expression. X =

[2]
b

Consider the following logic expression: X = NOT ((A NAND B) XOR (NOT A OR NOT C)) A truth table for the logic expression is given: Row number | A | B | C | X 1 | 0 | 0 | 0 | 1 2 | 0 | 0 | 1 | 0 3 | 0 | 1 | 0 | 1 4 | 0 | 1 | 1 | 0 5 | 1 | 0 | 0 | 1 6 | 1 | 0 | 1 | 0 7 | 1 | 1 | 0 | 1 8 | 1 | 1 | 1 | 1 There are three errors in the truth table. Identify the three errors in the truth table by writing the row numbers with an incorrect output. Error 1 Row number Error 2 Row number Error 3 Row number

[2]
10

A programmer is developing a computer program.

a

Explain how the programmer can first use an interpreter and then a compiler to develop the computer program. Interpreter Compiler

[4]
b

The programmer releases the program as Free Software. Describe what is meant by Free Software.

[2]
c

A user downloads the computer program from the internet. State what should be included as part of the download to make sure the program is authentic.

[1]
11

An automated system opens doors when a person is detected within 2 metres. The system closes the doors when there is no longer a person within 2 metres. Identify whether the automated system is an example of a monitoring system or a control system. Justify your choice. Monitoring or Control..................................................... Justification

[3]

Mark scheme

9618/12 · Oct/Nov 2025

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2a · 4 marks

  • 1 mark

    Copyright: Gives the holder the legal right of ownership of intellectual property

  • 1 mark

    Open Source (Initiative): Software can be freely copied, distributed or adapted

  • 1 mark

    Shareware: Gives the user a trial period / limited functionality before a payment/sign up may be required

  • 1 mark

    Software Licence: A (legal) agreement that defines the rights and terms of usage for the software

2b · 2 marks

  • 1 mark

    to create a safe, respectable and professional working environment for all employees

  • 1 mark

    to ensure that employees understand the expectations

  • 1 mark

    ... and the consequences of their actions

  • 1 mark

    to provide a clear outline of what is considered good practice

  • 1 mark

    so there are clear rules to follow in certain situations

  • 1 mark

    to protect the reputation of the organisation // maintain public trust

3a(i) · 1 mark

  • 1 mark

    The value of the operand is an offset value which is added to another base value to give the address from which the contents are loaded to the accumulator

3a(ii) · 2 marks

  • 1 mark

    Program counter (PC)

  • 1 mark

    Memory Data Register (MDR)

  • 1 mark

    Memory Address Register (MAR)

  • 1 mark

    Current Instruction Register (CIR)

  • 1 mark

    Status Register

3b · 3 marks

  • 1 mark

    LDM #98: 98

  • 1 mark

    LDI 101: 8

  • 1 mark

    LDX 100: 32

3c · 4 marks

  • 1 mark

    Clock Speed: Processor can perform more F-E cycles per second

  • 1 mark

    Clock Speed: ... so more instructions / data can be processed each second

  • 1 mark

    Cache Memory: Can store more of the most frequently used instructions

  • 1 mark

    Cache Memory: … which reduces the need to access slower RAM

4a · 2 marks

  • 1 mark

    The relationship between SHIP and CONTAINER is one-to-many (1:M)

  • 1 mark

    The primary key ShipID in the SHIP table is linked to the foreign key ShipID in the CONTAINER table

4b · 2 marks

  • 1 mark

    ALTER TABLE statement

  • 1 mark

    Including the additional field with a suitable field name and suitable field type

4c · 4 marks

  • 1 mark

    SELECT COUNT statement

  • 1 mark

    Using the correct tables

  • 1 mark

    Joining the tables

  • 1 mark

    The condition for the name

4d · 2 marks

  • 1 mark

    To allow the user to create / modify / delete tables // maintain the database

  • 1 mark

    To allow the user to set up / modify relationships

  • 1 mark

    To allow the user to create a form for data input

  • 1 mark

    To allow a user to add tools to a form // for example, drop-down boxes / buttons etc.

  • 1 mark

    To allow a user to design a report (to show the output in an organised manner)

  • 1 mark

    To allow a user to add a menu to enable a choice of different actions

  • 1 mark

    To allow a user to inspect the database contents and metadata

  • 1 mark

    ... by creating and/or running different SQL queries

5a · 2 marks

  • 1 mark

    Covers a small geographical area

  • 1 mark

    Normally privately owned / dedicated infrastructure

  • 1 mark

    Can use wired or wireless communication

5b · 2 marks

  • 1 mark

    All computers directly connected to switch and no other connections

  • 1 mark

    Switch connected directly to server

5c · 3 marks

  • 1 mark

    The sending device sends the packets to the switch

  • 1 mark

    The switch checks the destination address on each packet

  • 1 mark

    … and sends them only to the intended receiver

5d · 3 marks

  • 1 mark

    The use of CSMA/CD // Carrier Sense Multiple Access with Collision Detection

  • 1 mark

    The workstations listen to the communication channel

  • 1 mark

    ... and send data only when there is no data being transmitted / the line is idle

  • 1 mark

    If a collision is detected, transmission is aborted

  • 1 mark

    …and a jamming signal is sent

  • 1 mark

    The workstation calculates a random wait time before trying to re-transmit

  • 1 mark

    The random time is increased if there are multiple collisions

5e · 3 marks

  • 1 mark

    1 mark for correct threat

  • 1 mark

    1 mark corresponding description

  • 1 mark

    1 mark for correct method of prevention

6a · 1 mark

  • 1 mark

    Type of compression: lossy Justification: There will be fewer samples per second, so data will be permanently lost // There will be fewer samples per second, so the original sound cannot be re-created

6b · 1 mark

  • 1 mark

    Science is Amazing!

6c(i) · 1 mark

  • 1 mark

    parity bit is 0 (0 1 0 1 1 1 0 0)

6c(ii) · 1 mark

  • 1 mark

    Identifying error at row 2, column 5 (circled 0)

6d · 2 marks

  • 1 mark

    Working: (1000 * 2000 * 16) / (8 * 1000 * 1000) // (1000 * 2000 * 2 / (1000 * 1000)

  • 1 mark

    Answer: 4 megabytes

7a · 1 mark

  • 1 mark

    1100 0000

7b · 1 mark

  • 1 mark

    8 // 16 // 32 // 64

7c(i) · 1 mark

  • 1 mark

    0001 0000 0100

7c(ii) · 1 mark

  • 1 mark

    68

8a(i) · 2 marks

  • 1 mark

    Cloud storage can be free of charge for a limited amount

  • 1 mark

    There is no need for personal storage devices

  • 1 mark

    The data can be accessed from any computer with an internet connection

  • 1 mark

    Cloud data services usually include data backup and recovery services

  • 1 mark

    It is easier to share data / collaborate with colleagues

  • 1 mark

    Cloud storage capacity can be quickly and easily increased if needed

8a(ii) · 2 marks

  • 1 mark

    The storage/cloud can only be accessed with an internet connection

  • 1 mark

    There may be no backups // possibly no control over backups // reliance on third party for backups

  • 1 mark

    Uploading / downloading data could take a long time

  • 1 mark

    Potential issues with the cloud storage company impacting access e.g. downtime or technical problems

  • 1 mark

    Potential compatibility issues if wanting to move the data

  • 1 mark

    Limited storage availability without paying extra

  • 1 mark

    … meaning (possibly) more expensive in the long term

  • 1 mark

    Possibly security issues

8b(i) · 4 marks

  • 1 mark

    Resistive // two layers of material make contact and complete a circuit

  • 1 mark

    Capacitive // contact with the screen creates a change in charge

  • 1 mark

    Infrared // the beams are broken by the pointing device

  • 1 mark

    Optical imaging // a shadow is created when the surface is touched

  • 1 mark

    Acoustic pulse // the acoustic wave is absorbed by the pointing device

  • 1 mark

    The point of touch is used to determine the x and y coordinates

  • 1 mark

    The menu item corresponding to the coordinate position is recognised and the menu item is added to the order

8b(ii) · 2 marks

  • 1 mark

    Disk repair / disk contents analysis

  • 1 mark

    Back-up software

9a · 2 marks

  • 1 mark

    NOT (A XOR B)

  • 1 mark

    NAND ((B AND C) OR A)

9b · 2 marks

  • 1 mark

    1 or 2 row numbers correct (Row 2, Row 4, Row 7)

  • 1 mark

    All three row numbers correct (Row 2, Row 4, Row 7)

10a · 4 marks

  • 1 mark

    Interpreter: Use an interpreter while writing/coding the program

  • 1 mark

    Interpreter: … to test / debug the partially completed program

  • 1 mark

    Interpreter: … because errors can be corrected and processing continue from where the execution stopped // errors can be corrected in real time // errors are identified one at a time

  • 1 mark

    Compiler: Use the compiler after the program is complete

  • 1 mark

    Compiler: … to create an executable file so source code not seen

  • 1 mark

    Compiler: Use the compiler to repeatedly test the same completed section without having to re-interpret every time

10b · 2 marks

  • 1 mark

    The software is free of restrictions

  • 1 mark

    The software is not necessarily free of charge

  • 1 mark

    The source code comes with the program // A user can edit the source code to add functionality / suit their needs

  • 1 mark

    Users can share the software with others

10c · 1 mark

  • 1 mark

    Digital Signature

11 · 3 marks

  • 1 mark

    The system uses an actuator to open or close the doors

  • 1 mark

    The output / opening the doors allows people to move, which changes the input to the sensor

  • 1 mark

    The system acts autonomously on the feedback from a sensor

Questions

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  2. 3
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  3. 4
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  4. 5
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  5. 6
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  6. 7
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  7. 8
    Question 810 marks
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  8. 9
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  9. 10
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  10. 11
    Question 113 marks
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