9618 Computer Science November 2025 Question Paper 13

1 short_answer p. 2

A student creates sound recordings.

1a 3 marks short_answer p. 2 1.2

Making changes to a sound recording may impact the accuracy of the resulting sound file or the size of the file.

Draw \textbf{two} lines from each change to the impacts it has on the sound file.

\begin{tabular}{cc} \textbf{Change} & \textbf{Impact} \ & \ \framebox{increase the duration of the recording} & \framebox{the file size gets bigger} \ & \ & \framebox{no change in the file size} \ & \ \framebox{increase the sampling rate} & \framebox{the file size gets smaller} \ & \ & \framebox{the accuracy of the sound file improves} \ & \ \framebox{decrease the sampling resolution} & \framebox{no change to the accuracy of the sound file} \ & \ & \framebox{the accuracy of the sound file worsens} \ \end{tabular}

1b 2 marks long_answer p. 2 1.1

The file names of the sound recordings are stored using the ASCII character set.

Explain how text is represented by the ASCII character set.

1c 2 marks short_answer p. 2 1.1

Give \textbf{two} differences between the ASCII and UNICODE character sets.

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2 short_answer p. 3

Data in a computer system is represented in binary.

2a 3 marks short_answer p. 3 1.12.1

Put one tick ($\checkmark$) in each row to identify the minimum number of bits used to store each example of data.

\begin{tabular}{|l|c|c|c|c|c|c|c|} \hline \multicolumn{1}{|c|}{\textbf{Example of data}} & \multicolumn{7}{c|}{\textbf{Number of bits}} \ \cline{2-8} & \textbf{4} & \textbf{8} & \textbf{16} & \textbf{24} & \textbf{32} & \textbf{64} & \textbf{128} \ \hline the hexadecimal value F139 & & & & & & & \ \hline 16,000,000 unique amplitude values & & & & & & & \ \hline an IPv4 address & & & & & & & \ \hline 256 unique colours & & & & & & & \ \hline an IPv6 address & & & & & & & \ \hline the denary value 65,000 & & & & & & & \ \hline \end{tabular}

2b 1 mark calculation p. 3 1.1

Convert the denary number $-108$ into a 12-bit two's complement binary number.

2c 1 mark calculation p. 3 4.3

A three-place arithmetic shift to the right is performed on the following two's complement negative integer.

Show the result of this arithmetic shift.

10010011 \hrulefill

2d 1 mark calculation p. 3 1.1

Convert the following positive binary integer into hexadecimal.

1110001100111011 \hrulefill

3 short_answer p. 4

3a 2 marks short_answer p. 4 3.2

Complete the truth table for the following logic expression:

$$X = (A \text{ NOR } B) \text{ NAND } (C \text{ XOR } B)$$

\begin{tabular}{|c|c|c|p{5cm}|c|} \hline \textbf{A} & \textbf{B} & \textbf{C} & \textbf{Working space} & \textbf{X} \ \hline 0 & 0 & 0 & & \ \hline 0 & 0 & 1 & & \ \hline 0 & 1 & 0 & & \ \hline 0 & 1 & 1 & & \ \hline 1 & 0 & 0 & & \ \hline 1 & 0 & 1 & & \ \hline 1 & 1 & 0 & & \ \hline 1 & 1 & 1 & & \ \hline \end{tabular}

3b 2 marks short_answer p. 4 3.2

Draw a logic circuit for the logic expression:

$$X = \text{NOT } (((A \text{ AND } B) \text{ OR } C) \text{ AND } (C \text{ NOR } D))$$

4 short_answer p. 5

A network engineer is setting up a Local Area Network (LAN) in an office. The network uses both wired and wireless connectivity.

4a 3 marks short_answer p. 5 2.1

Give \textbf{three} advantages of a wireless network compared to a wired network.

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4b 1 mark short_answer p. 5 2.1

Give \textbf{one} drawback of using a wireless network.

4c 3 marks short_answer p. 5 3.1

Complete the table by writing the name of the type of memory technology for each description.

\begin{tabular}{|p{8cm}|p{6cm}|} \hline \multicolumn{1}{|c|}{\textbf{Description}} & \multicolumn{1}{c|}{\textbf{Memory technology}} \ \hline A read only memory where the contents can be erased using a voltage pulse. The contents can be changed multiple times without physically removing the memory. & \ \hline A read only memory where the contents are erased using ultraviolet (UV) light. The memory must be physically removed to be reprogrammed. & \ \hline A read only memory where the contents can be written only once after manufacture. & \ \hline \end{tabular}

5 short_answer p. 6

A company creates a relational database to store data about its customers.

The database, \texttt{REVIEWS}, stores data about the customers, products, complaints and staff.

The database has four tables:

\texttt{CUSTOMER(CustomerID, CustomerFirstName, CustomerLastName, CustomerEmail)}

\texttt{PRODUCT(ProductID, ProductName, ProductDetail, Price, Rating)}

\texttt{COMPLAINT(ComplaintID, ProductID, CustomerID, ComplaintDetails, StaffID)}

\texttt{STAFF(StaffID, StaffFirstName, StaffLastName, Department, RemoteWorker)}

5a 3 marks short_answer p. 6 8.1

Complete the entity-relationship (E-R) diagram for the database \texttt{REVIEWS}.

\begin{tabular}{cc} \framebox{\quad CUSTOMER \quad} & \framebox{\quad PRODUCT \quad} \ & \ & \ \framebox{\quad COMPLAINT \quad} & \framebox{\quad STAFF \quad} \ \end{tabular}

5b 4 marks short_answer p. 7 8.3

Some example data from the \texttt{STAFF} table is shown.

\begin{tabular}{|c|c|c|c|c|} \hline \textbf{StaffID} & \textbf{StaffFirstName} & \textbf{StaffLastName} & \textbf{Department} & \textbf{RemoteWorker} \ \hline 1 & Ralph & Jura & E & Yes \ \hline 2 & Luca & Emcee & A & Yes \ \hline 3 & Darwin & Acula & F & No \ \hline \end{tabular}

Write a Structured Query Language (SQL) script to define the table \texttt{STAFF}.

5c 5 marks short_answer p. 7 8.3

Products are given a rating between 1 and 10 inclusive.

Write an SQL script to return only the \texttt{ProductID}, \texttt{ProductName} and \texttt{ComplaintDetails} for all products with a rating of 5 or less. The results need to be displayed in descending order of rating.

5d 4 marks long_answer p. 8 8.2

A Database Management System (DBMS) is used to maintain and manage the database.

Describe \textbf{two} ways in which the DBMS can be used to ensure the security of the customer data.

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6 short_answer p. 10

The following table shows part of the instruction set for a processor. The processor has two registers: the Accumulator (ACC) and the Index Register (IX).

\begin{tabular}{|r|l|l|} \hline \multicolumn{2}{|c|}{\textbf{Instruction}} & \multicolumn{1}{c|}{\textbf{Explanation}} \ \cline{1-2} \textbf{Opcode} & \textbf{Operand} & \ \hline LDM & #n & Immediate addressing. Load the number n to the ACC \ \hline AND & #n / Bn / &n & Bitwise AND operation of the contents of the ACC with the operand \ \hline AND &

& Bitwise AND operation of the contents of the ACC with the contents of

\ \hline XOR & #n / Bn / &n & Bitwise XOR operation of the contents of the ACC with the operand \ \hline XOR &

& Bitwise XOR operation of the contents of the ACC with the contents of

\ \hline OR & #n / Bn / &n & Bitwise OR operation of the contents of the ACC with the operand \ \hline OR &

& Bitwise OR operation of the contents of the ACC with the contents of

\ \hline CMP & #n & Compare the contents of the ACC with number n \ \hline CMP &

& Compare the contents of the ACC with the contents of

\ \hline LSL & #n & Bits in the ACC are shifted logically n places to the left. Zeros are introduced on the right-hand end \ \hline LSR & #n & Bits in the ACC are shifted logically n places to the right. Zeros are introduced on the left-hand end \ \hline \end{tabular}

can be an absolute or symbolic address \# denotes a denary number, e.g. \#127 B denotes a binary number, e.g. B10010001 \& denotes a hexadecimal number, e.g. \&4A

The current contents of main memory are shown:

\begin{tabular}{rc} \textbf{Address} & \textbf{Data} \ 100 & \multicolumn{1}{|c|}{0000 0011} \ \cline{2-2} 101 & \multicolumn{1}{|c|}{1010 1110} \ \cline{2-2} 102 & \multicolumn{1}{|c|}{1100 1100} \ \cline{2-2} 103 & \multicolumn{1}{|c|}{1111 1111} \ \cline{2-2} 104 & \multicolumn{1}{|c|}{1100 1100} \ \cline{2-2} \end{tabular}

6a 4 marks short_answer p. 11 4.2

Complete the table by writing the contents of the ACC after the execution of each instruction.

\begin{tabular}{|c|c|c|} \hline \textbf{Current contents of the ACC} & \textbf{Instruction} & \textbf{Contents of the ACC after the execution of the instruction} \ \hline 0000 1111 & AND 101 & \ \hline 0000 0000 & LDM #100 & \ \hline 0000 0001 & XOR &F1 & \ \hline 0001 0001 & CMP 101 & \ \hline \end{tabular}

6b 4 marks long_answer p. 11 4.1

The Von Neumann model for a computer system uses registers.

Describe the role of the Memory Address Register (MAR) and Memory Data Register (MDR) in the fetch-execute (F-E) cycle.

6c 3 marks short_answer p. 11 4.2

Assembly language instructions are grouped.

Complete each statement by writing the name of the appropriate instruction group.

Loading data into the accumulator is an example of an instruction in the \underline{\hspace{1.5em}} group. Incrementing the index register is an example of an instruction in the \underline{\hspace{1.5em}} group. Branching to another address is an example of an instruction in the \underline{\hspace{1.5em}} group.

7 short_answer p. 12

A digital video camera records students in a classroom. The data is transferred from the digital video camera over the internet to a server. Artificial Intelligence (AI) is used to analyse the video on the server to identify when students are interacting with the lesson and the teacher.

7a 2 marks long_answer p. 12 7.1

Describe \textbf{one} ethical impact of this use of AI in the classroom.

7b 2 marks calculation p. 12 1.2

A video is made of many bitmap images called frames. 30 frames are recorded every second.

Each frame is 4000 pixels wide by 3000 pixels high. The video records using 16-bit colour depth.

Calculate an estimate for the file size for \textbf{one} second of the video in gigabytes.

Show your working.

File size \hrulefill gigabytes

7c 3 marks short_answer p. 12 6.2

Identify \textbf{and} describe \textbf{one} method of data verification that can be used when transferring data from the digital video camera to the server.

Method \hrulefill

Description \hrulefill

7d 4 marks long_answer p. 13 3.1

Describe \textbf{two} reasons why the server that stores the videos uses magnetic hard disks instead of solid state (flash) memory.

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7e 3 marks short_answer p. 14 6.2

The table contains three algorithms that perform data validation. The third algorithm uses the functions \texttt{MID} and \texttt{LENGTH}.

The functions \texttt{MID} and \texttt{LENGTH} are defined as follows:

\begin{itemize} \item \texttt{MID(ThisString : STRING, x : INTEGER, y : INTEGER) RETURNS STRING}\newline returns a string of length \texttt{y} starting at position \texttt{x} from \texttt{ThisString} \item \texttt{LENGTH(ThisString : STRING) RETURNS INTEGER}\newline returns the integer value representing the length of \texttt{ThisString} \end{itemize}

Complete the table to identify the method of data validation for each algorithm. Each method of data validation must be different.

\begin{tabular}{|p{9cm}|p{6cm}|} \hline \multicolumn{1}{|c|}{\textbf{Algorithm}} & \multicolumn{1}{c|}{\textbf{Method of data validation}} \ \hline \begin{alltt} INPUT x

IF x < 1 or x > 26 THEN

OUTPUT "Invalid"

ENDIF \end{alltt} & \ \hline \begin{alltt} INPUT x

IF x <> 'R' AND x <> 'G' AND x <> 'B' THEN

OUTPUT "Invalid"

ENDIF \end{alltt} & \ \hline \begin{alltt} INPUT x

FLAG <- FALSE

FOR INDEX <- 1 TO LENGTH(x)

IF MID(x, INDEX, 1) = "@" THEN

FLAG <- TRUE

ENDIF

NEXT INDEX

IF NOT FLAG THEN

OUTPUT "Invalid"

ENDIF \end{alltt} & \ \hline \end{tabular}

8 short_answer p. 15

Compilers and interpreters are used to translate programs written in a high-level language into a low-level language.

8a 2 marks short_answer p. 15 5.2

State \textbf{two} disadvantages of using a compiler compared to an interpreter during program development.

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8b 3 marks long_answer p. 15 5.1

Explain how a programmer benefits from using program libraries during program development.

8c 2 marks short_answer p. 15 7.1

A programmer is developing an Operating System (OS).

Identify \textbf{two} types of software licence the programmer can use to allow other people to edit and redistribute the OS.

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8d 3 marks short_answer p. 15 5.1

Memory management is one key management task performed by an OS.

Give \textbf{three} other key management tasks that are performed by an OS.

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9618 Computer Science November 2025 Question Paper 13

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