ExamPal

A Level Computer Science 9618 Paper 12, May/June 2025

Question paper and mark scheme75 marks7 questions

Solve it on ExamPal

Practise

Untimed. Write on the paper and check as you go.

Start

Exam

Timed, with a clock you set, like sitting the real paper.

Start

Opens full screen.

Download PDFMark scheme
100%

Opening the question paper

Read as textThe questions and the mark scheme as plain text. Easier to read on a phone.

Question paper

9618/12 · May/June 2025

Download PDF
1
a

The table has six statements about the Von Neumann model for a computer system. Three of the statements are incorrect. Statement number | Statement 1 | The Program Counter (PC) stores the next instruction to be fetched from memory. 2 | The Arithmetic and Logic Unit (ALU) performs mathematical and logical operations. 3 | The Control Unit (CU) sends signals to other components on the data bus. 4 | The Memory Data Register (MDR) transfers data to the memory address stored in the Memory Address Register (MAR). 5 | The MAR stores an address from memory. 6 | The Accumulator (ACC) stores the result of calculations. Complete the table by writing the three incorrect statement numbers and the corrected statements.

[3]
b

Registers that are used in the Fetch-Execute (F-E) cycle include the PC, MAR, MDR and the ACC. Identify one other register and describe its role in the Fetch-Execute (F-E) cycle. Register .................................................................................................................................... Role .......................................................................................................................................... ...................................................................................................................................................

[2]
c

Explain how an interrupt from an input device will be detected and handled in the F-E cycle.

[4]
2
a

Convert the denary integer 558 into 12-bit binary and hexadecimal. Binary ....................................................................................................................................... Hexadecimal .............................................................................................................................

[2]
b(i)

Convert the two’s complement binary integer 11100010 into denary.

[1]
b(ii)

Write the smallest and the largest two’s complement binary integers that can be represented in 8 bits. Smallest ............................................................................................................................ Largest ..............................................................................................................................

[2]
c

Give one application where Binary Coded Decimal (BCD) is used and justify its use. Application ................................................................................................................................ Justification ............................................................................................................................... ...................................................................................................................................................

[2]
3

A computer program uses a digital camera to read the words on an item. The program can read the words that are written on the item, translate the words to a chosen language and then output the words as audio. For example, when used in a supermarket, the program can output the words written on the labels on products. The program uses Artificial Intelligence (AI).

a

Explain how AI is used in the computer program described.

[4]
b

State two social benefits of the use of AI in the computer program described. 1 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... ...................................................................................................................................................

[2]
c(i)

The computer program is released under a commercial software licence. Describe the features of a commercial software licence.

[3]
c(ii)

Explain the reasons why an open source software licence might not be appropriate for the computer program described.

[3]
4
Figure 1 of 1 for question 4
a

Write the logic expressions for the following logic circuit. X = ............................................................................................................................................ Y = ............................................................................................................................................

[2]
b

Complete the truth table for the logic expression: X = NOT (A AND (B XOR C))

[2]
5

An online game has a database that stores data about users and the characters each user creates in the game. Each user can create multiple characters and purchase multiple items for each character. The normalised database has the following design: USER(Username, Password, DateOfBirth) CHARACTER(CharacterName, CharacterID, Username, Level, Money) ITEM(ItemName, MinimumLevel, Cost) CHARACTER_ITEM(CharacterID, ItemName)

a

Explain the purpose of the table CHARACTER_ITEM in the database.

[2]
b

Underline the attribute, or attributes, that form the primary key in each of the tables. USER(Username, Password, DateOfBirth) CHARACTER(CharacterName, CharacterID, Username, Level, Money) ITEM(ItemName, MinimumLevel, Cost) CHARACTER_ITEM(CharacterID, ItemName)

[2]
c(i)

A Database Management System (DBMS) provides data security. Identify two methods the DBMS can use to protect the data in the table USER from unauthorised access. Explain how each method protects the data. Method 1 ........................................................................................................................... Explanation ....................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... Method 2 ........................................................................................................................... Explanation ....................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................

[4]
c(ii)

The DBMS also supports data integrity. Give two ways that a DBMS can support data integrity. 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ...........................................................................................................................................

[2]
d(i)

Write a Structured Query Language (SQL) script to count the number of items purchased by the user with the username "KAT123".

[3]
d(ii)

The following changes need to be made to the character with the ID "0002": • level changed to 3 • money changed to 10000.00 Write an SQL script to change the character’s data.

[3]
6

A company has multiple sites in different cities. The company has drivers who deliver products to customers. Each driver can connect to the company’s WAN (Wide Area Network) whilst out of the office using a smartphone.

a

State two ways that a WAN is different to a LAN (Local Area Network). 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ...................................................................................................................................................

[2]
b

The smartphones use the cell phone network to connect to the WAN. Explain how data is transmitted using the cell phone network.

[4]
c

Devices that connect to the WAN have an IP address. Complete the following description of IP addresses by writing the missing words. IPv4 is displayed as four groups of 8-bit numbers separated by ........................................ . Each IPv4 address is 32 bits. IPv6 is made of eight groups of 4 ........................................ numbers separated by colons. Multiple consecutive groups of ........................................ can be replaced with a double colon. Each IPv6 address is ........................................ bits. A ........................................ IP address can change each time the computer connects to a network. A ........................................ IP address can only be accessed by other devices in the same LAN and is assigned by the router within the LAN.

[6]
d

The main office for the company has four wired computers, one server, two printers, one central switch and a device providing a single point of access for the internet. The network is set up as a star topology. Draw the topology for the main office network. Label all devices.

[4]
e

Describe the role of a switch in a network.

[3]
7
a(i)

The following table shows part of the instruction set for a processor. The processor has one register: the Accumulator (ACC). Instruction | Explanation Opcode | Operand | LDD | <address> | Direct addressing. Load the contents of the location at the given address to ACC LDM | #n | Immediate addressing. Load the number n to ACC STO | <address> | Store the contents of ACC at the given address ADD | #n/Bn/&n | Add the number n to the ACC ADD | <address> | Add the contents of the given address to the ACC INC | <register> | Add 1 to the contents of the register (ACC) CMP | <address> | Compare the contents of ACC with the contents of <address> CMP | #n | Compare the contents of ACC with number n JPE | <address> | Following a compare instruction, jump to <address> if the compare was True JMP | <address> | Jump to the given address END | | Return control to the operating system ACC denotes Accumulator <address> can be an absolute or a symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A The current contents of memory are: Address | Instruction 10 | 12 11 | 11 12 | 10 13 | 22 14 | 22 ... 100 | LDD 10 101 | ADD 12 102 | STO 11 103 | CMP 14 104 | JPE 107 105 | INC ACC 106 | JMP 101 107 | STO 10 108 | END Trace the program currently in memory using the following trace table.

[3]
a(ii)

State the effect of changing instruction LDD 10 in address 100 to LDM #10

[1]
a(iii)

Identify and describe one mode of addressing not given in the table of instructions in part (a). Mode of addressing ........................................................................................................... Description ........................................................................................................................ ........................................................................................................................................... ...........................................................................................................................................

[2]
b(i)

The table shows part of the instruction set for a processor. The processor has one register: the Accumulator (ACC). Instruction | Explanation Opcode | Operand | AND | #n/Bn/&n | Bitwise AND operation of the contents of ACC with the operand AND | <address> | Bitwise AND operation of the contents of ACC with the contents of <address> XOR | #n/Bn/&n | Bitwise XOR operation of the contents of ACC with the operand XOR | <address> | Bitwise XOR operation of the contents of ACC with the contents of <address> OR | #n/Bn/&n | Bitwise OR operation of the contents of ACC with the operand OR | <address> | Bitwise OR operation of the contents of ACC with the contents of <address> <address> can be an absolute or symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A The ACC currently contains the following binary value. 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 Write the result after the instruction OR B00001111 is run.

[1]
b(ii)

The ACC currently contains the following binary value. 0 | 0 | 0 | 1 | 1 | 1 | 0 | 1 Write the result after the instruction XOR #30 is run.

[1]

Mark scheme

9618/12 · May/June 2025

Download PDF

1a · 3 marks

  • 1 mark

    1: The Program Counter (PC) stores the address of the next instruction to be fetched from memory.

  • 1 mark

    3: The Control Unit (CU) sends signals to other components on the control bus.

  • 1 mark

    4: The Memory Data Register (MDR) holds data to be stored in the memory address in the MAR. // The Memory Data Register (MDR) holds data read from the memory address in the MAR

1b · 2 marks

  • 1 mark

    Current Instruction Register // CIR (and corresponding role: To store the instruction to be decoded / executed next) // Status register // SR (and corresponding role: To contain bits that can be referenced individually to indicate a state or event) // Interrupt register (and corresponding role: To store details of any interrupts that have occurred)

  • 1 mark

    Corresponding role for the named register

1c · 4 marks

  • 1 mark

    At the start / end of FE cycle the interrupt register is checked

  • 1 mark

    The priority of any interrupts waiting is checked

  • 1 mark

    if the priority of the interrupt is higher than the current process

  • 1 mark

    the contents of the registers are stored on the stack

  • 1 mark

    The relevant Interrupt Service Routine (ISR) / interrupt handler is called to process the interrupt

  • 1 mark

    When the ISR has finished, a further check is made for higher priority interrupts

  • 1 mark

    if no more interrupts of higher priority, the register contents are restored and the next FE cycle continues

2a · 2 marks

  • 1 mark

    0010 0010 1110

  • 1 mark

    22E

2b(i) · 1 mark

  • 1 mark

    -30

2b(ii) · 2 marks

  • 1 mark

    Smallest: 1000 0000

  • 1 mark

    Largest: 0111 1111

2c · 2 marks

  • 1 mark

    Application: an application that performs financial / banking calculations // electronic displays // The storage of the date and time in the BIOS of a PC // Barcode systems

  • 1 mark

    Corresponding justification: because financial transactions use only two decimal places and must be accurate, no accumulating / rounding errors and it is difficult to represent decimal values exactly in normal binary // because visual displays only need to show individual digits / because conversion between denary and BCD is straightforward // because conversion between denary and BCD is more straightforward // because conversion between denary and BCD can be accurately completed

3a · 4 marks

  • 1 mark

    Uses image recognition // optical character recognition

  • 1 mark

    to analyse a photograph/pixels to identify the location of characters within an image

  • 1 mark

    in order to convert the pattern of pixels into individual characters

  • 1 mark

    Uses natural language

  • 1 mark

    to combine the characters into words

  • 1 mark

    and compare the words to database to identify a match in the language of the writing

  • 1 mark

    it may also predict what is missing / incomplete / from what has been read

  • 1 mark

    then compare the words to a database of the user's chosen language to find a match and translate

  • 1 mark

    Uses text-to-speech

  • 1 mark

    to generate the audio waveforms corresponding to the words

3b · 2 marks

  • 1 mark

    It can help people with visual impairment to identify which products to purchase

  • 1 mark

    It can help people who cannot understand the language

  • 1 mark

    It can help to overcome learning / reading difficulties

3c(i) · 3 marks

  • 1 mark

    The program is usually sold for a fee

  • 1 mark

    Users have no access to source code

  • 1 mark

    It protects the intellectual rights of the programmer / developer

  • 1 mark

    Users cannot legally alter or share the program

  • 1 mark

    There are limitations on the use of the software e.g. number of times it can be installed

  • 1 mark

    Support and maintenance is usually provided e.g. updates, bug fixes etc.

3c(ii) · 3 marks

  • 1 mark

    The source code would be accessible therefore it could be changed

  • 1 mark

    which might lead to the program outputting an incorrect response

  • 1 mark

    so people could purchase the wrong item

  • 1 mark

    which might have serious consequences // by example e.g. allergies

4a · 2 marks

  • 1 mark

    X = (R NOR S) XOR T

  • 1 mark

    Y = (T AND U) OR U

4b · 2 marks

  • 1 mark

    First four rows: X = 1, 1, 1, 1

  • 1 mark

    Second four rows: X = 1, 0, 0, 1

5a · 2 marks

  • 1 mark

    To remove the many-to-many relationship

  • 1 mark

    between CHARACTER and ITEM tables

  • 1 mark

    To allow each character to have many items // to allow each item to be purchased for many characters

  • 1 mark

    by creating a linking table

  • 1 mark

    between the characters and the items purchased for each one

5b · 2 marks

  • 1 mark

    The three single Primary Keys: Username in USER, CharacterID in CHARACTER, ItemName in ITEM underlined

  • 1 mark

    The composite key: CharacterID and ItemName in CHARACTER_ITEM underlined

5c(i) · 4 marks

  • 1 mark

    Method 1

  • 1 mark

    Matching explanation 1

  • 1 mark

    Method 2

  • 1 mark

    Matching explanation 2

5c(ii) · 2 marks

  • 1 mark

    Validation

  • 1 mark

    Enforce referential integrity

  • 1 mark

    Cascade update / delete

  • 1 mark

    Ensuring the database is normalised

5d(i) · 3 marks

  • 1 mark

    Select COUNT

  • 1 mark

    FROM (using correct tables) and joining

  • 1 mark

    WHERE (or AND) condition for correct username

5d(ii) · 3 marks

  • 1 mark

    UPDATE character

  • 1 mark

    SET level and money

  • 1 mark

    WHERE condition

6a · 2 marks

  • 1 mark

    In a WAN devices can connect over a larger geographical area in a LAN devices connect over a smaller geographical area

  • 1 mark

    A WAN may use non-dedicated hardware the hardware in a LAN is usually dedicated

  • 1 mark

    A WAN uses external / not company owned transmission media // the transmission media for a LAN is usually company owned

6b · 4 marks

  • 1 mark

    Land is split into cells designed for maximum line of sight

  • 1 mark

    Each cell has a tower with an antenna which receives and transmits data

  • 1 mark

    Data is transmitted between the tower and the phone

  • 1 mark

    Data transmission is wireless using low power radio signals/frequencies

  • 1 mark

    Multiple devices can communicate simultaneously with the same tower

6c · 6 marks

  • 1 mark

    full stops

  • 1 mark

    hexadecimal

  • 1 mark

    zeros

  • 1 mark

    128

  • 1 mark

    dynamic

  • 1 mark

    private

6d · 4 marks

  • 1 mark

    Server directly connected to the switch

  • 1 mark

    Four labelled computers all connected directly to the switch

  • 1 mark

    Two printers each directly connected to the switch / server / a computer

  • 1 mark

    Router / modem directly connected to the switch / server for internet access

6e · 3 marks

  • 1 mark

    To store the MAC addresses of devices connected to it

  • 1 mark

    To receive packets from devices

  • 1 mark

    To forward packets directly to the intended recipient

  • 1 mark

    To provide a central point of connection for the network

  • 1 mark

    to enable connected devices to communicate

7a(i) · 3 marks

  • 1 mark

    First shaded section: ACC values 12 and 22 for instructions 100 and 101

  • 1 mark

    Second shaded section: Memory address 11 value 22 for instruction 102

  • 1 mark

    Third shaded section: Memory address 10 value 22 for instruction 107

7a(ii) · 1 mark

  • 1 mark

    The number 10 will be loaded into the ACC instead of 12 / contents of address 10 // The addition will give 20 not 22 so the comparison will fail and result in an infinite loop

7a(iii) · 2 marks

  • 1 mark

    Name of mode: Indirect // Indexed // Relative

  • 1 mark

    Matching description: The operand points to the memory location that contains the address of the data // The address of the data is formed by adding the contents of the Index Register (IX) to the operand // The address is calculated using its distance from a base address

7b(i) · 1 mark

  • 1 mark

    1111 1111

7b(ii) · 1 mark

  • 1 mark

    0000 0011

Questions

  1. 1
    Question 19 marks
    Mark scheme ›
  2. 2
    Question 27 marks
    Mark scheme ›
  3. 3
    Question 312 marks
    Mark scheme ›
  4. 4
    Question 44 marks
    Mark scheme ›
  5. 5
    Question 516 marks
    Mark scheme ›
  6. 6
    Question 619 marks
    Mark scheme ›
  7. 7
    Question 78 marks
    Mark scheme ›

More 9618 papers

Other papers from May/June 2025

Solve it on ExamPalStart