9618 Computer Science November 2025 Question Paper 32

1 short_answer p. 2

The composite data type, \texttt{Car}, is defined in pseudocode as:

\begin{alltt} TYPE Car DECLARE RegNumber : STRING DECLARE Make : STRING DECLARE Model : STRING DECLARE BodyStyle : STRING DECLARE Colour : STRING DECLARE IntoStock : DATE DECLARE Price : REAL ENDTYPE \end{alltt}

1a short_answer p. 2

The composite data type, \texttt{Car}, is defined.

1ai 1 mark short_answer p. 2 10.1

Write the \textbf{pseudocode} statement to set up a variable for one record of the composite data type, \texttt{Car}.

1aii 2 marks short_answer p. 2 10.1

Write the \textbf{pseudocode} statements to assign the following values to the variable set up in part (a)(i):

\begin{itemize} \item "Blue" to \texttt{Colour} \item 21/10/2025 to \texttt{IntoStock} \end{itemize}

1b short_answer p. 2

The data type for \texttt{BodyStyle} is changed to an enumerated type, \texttt{Body}.

1bi 2 marks short_answer p. 2 13.1

Write the \textbf{pseudocode} statement for the type declaration of \texttt{Body} to hold the names of the available choices:

\begin{center} Convertible, Hatchback, Saloon, SUV \end{center}

1bii 1 mark short_answer p. 2 13.1

Write the new \textbf{pseudocode} statement required to update the declaration of \texttt{BodyStyle} in the definition of \texttt{Car}.

2 short_answer p. 3

Numbers are stored in a computer system using binary floating-point representation with:

\begin{itemize} \item 10 bits for the mantissa \item 6 bits for the exponent \item two's complement form for both the mantissa and the exponent. \end{itemize}

2a 3 marks calculation p. 3 13.3

Calculate the denary value of the given normalised binary floating-point number. Show your working.

\textbf{Mantissa}

\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|} \hline 0 & 1 & 1 & 1 & 1 & 0 & 0 & 1 & 0 & 1 \ \hline \end{tabular}

\textbf{Exponent}

\begin{tabular}{|c|c|c|c|c|c|} \hline 0 & 0 & 1 & 0 & 1 & 1 \ \hline \end{tabular}

Denary value \hrulefill

2b 3 marks calculation p. 3 13.3

Calculate the normalised binary floating-point representation of +26.6875 in this system. Show your working.

\textbf{Mantissa} \qquad \qquad \qquad \qquad \qquad \qquad \textbf{Exponent}

\framebox{$\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square$} \qquad \framebox{$\square\,\square\,\square\,\square\,\square\,\square$}

3 short_answer p. 4

HTTP and IMAP are examples of protocols used in the Application Layer of the TCP/IP protocol suite.

3a 2 marks short_answer p. 4 14.1

State the purpose of the HTTP and IMAP protocols.

HTTP \hrulefill IMAP \hrulefill

3b 4 marks long_answer p. 4 14.1

Describe how files are shared using the BitTorrent protocol.

4 short_answer p. 4

Identify one benefit of circuit switching and one benefit of packet switching.

4a 2 marks short_answer p. 4 14.2

Circuit switching \hrulefill Packet switching \hrulefill

4b 2 marks short_answer p. 4 14.2

Identify two differences between circuit switching and packet switching.

\hrulefill
\hrulefill

5 short_answer p. 5

(no root text)

5a 2 marks short_answer p. 5 4.1

Describe how interrupt handling is used in low-level scheduling.

5b 3 marks short_answer p. 5 16.1

In process management, a process can be in one of three process states: running, ready or blocked.

Complete the table to identify \textbf{one} reason why a process could be in each of the three states.

\begin{tabular}{|c|p{8cm}|} \hline \textbf{Process state} & \textbf{Reason} \ \hline running & \newline\newline\newline \ \hline ready & \newline\newline\newline \ \hline blocked & \newline\newline\newline \ \hline \end{tabular}

6 short_answer p. 6

The diagram shows a logic circuit.

6a 3 marks short_answer p. 6 3.2

Complete the truth table for the given logic circuit. Show your working.

\begin{tabular}{|c|c|c|c|c|c|c|c|} \hline \multicolumn{3}{|c|}{} & \multicolumn{4}{c|}{\textbf{Working space}} & \ \hline \textbf{A} & \textbf{B} & \textbf{C} & \textbf{P} & \textbf{Q} & \textbf{R} & \textbf{S} & \textbf{Z} \ \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}

6b short_answer p. 7

6bi 2 marks short_answer p. 7 15.2

Complete the Karnaugh map (K-map) for the Boolean expression:

$$\mathbf{\bar{A}.\bar{B}.C + \bar{A}.B.C + A.\bar{B}.C + A.B.\bar{C}}$$

\begin{tabular}{r|c|c|c|c|} \multicolumn{1}{r}{\textbf{A} \textbackslash{} \textbf{BC}} & \multicolumn{1}{c}{\textbf{00}} & \multicolumn{1}{c}{\textbf{01}} & \multicolumn{1}{c}{\textbf{11}} & \multicolumn{1}{c}{\textbf{10}} \ \cline{2-5} \textbf{0} & & & & \ \cline{2-5} \textbf{1} & & & & \ \cline{2-5} \end{tabular}

6bii 2 marks short_answer p. 7 15.2

Draw loop(s) around appropriate group(s) in the K-map to produce an optimal sum-of-products.

6biii 2 marks short_answer p. 7 15.2

Write the Boolean expression from your answer to part \textbf{b(ii)} as a simplified sum-of-products. Do \textbf{not} carry out any further simplification.

7 short_answer p. 7

7a 1 mark short_answer p. 7 17.1

Asymmetric encryption is a type of cryptography.

Identify \textbf{one} other type of cryptography.

7b 4 marks long_answer p. 7 17.1

An organisation holds two asymmetric encryption keys, which they intend to use to receive secure transmissions.

Explain how the organisation makes use of the two keys to receive a secure transmission.

8 short_answer p. 8

8a 1 mark short_answer p. 8 16.2

State the purpose of the optimisation stage in the compilation of a program.

8b 3 marks short_answer p. 8 16.2

Convert this Reverse Polish Notation (RPN) back to its original infix form:

\texttt{a b - c + c a - * d /}

8c 4 marks short_answer p. 8 16.2

The RPN expression:

\texttt{c a / b d - * b +}

is to be evaluated, where:

$a = 3$, $b = 16$, $c = 9$ and $d = 6$.

Show the changing contents of the stack as the RPN expression is evaluated.

\begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular} \quad \begin{tabular}{|c|} \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \phantom{X} \ \hline \end{tabular}

9 short_answer p. 9

9a short_answer p. 9

Deep Learning is a form of Machine Learning.

9ai 1 mark short_answer p. 9 18.1

State \textbf{one} example where Deep Learning is used.

9aii 1 mark short_answer p. 9 18.1

Identify how Deep Learning can be made more effective.

9b 4 marks long_answer p. 9 18.1

Describe the back propagation of errors method in Machine Learning.

10 short_answer p. 9

An exception is an error that may cause a program to halt unexpectedly.

10a 2 marks short_answer p. 9 20.2

Describe how program termination due to an exception can be avoided.

10b 2 marks short_answer p. 9 20.2

Identify \textbf{two} possible causes of exceptions.

\hrulefill
\hrulefill

11 7 marks short_answer p. 10 4.2

The table shows assembly language instructions for a processor that has one register, the Accumulator (ACC).

\begin{tabular}{|c|c|l|l|} \hline \multicolumn{1}{|c|}{} & \multicolumn{2}{c|}{\textbf{Instruction}} & \multicolumn{1}{c|}{} \ \cline{2-3} \textbf{Label} & \textbf{Opcode} & \textbf{Operand} & \multicolumn{1}{c|}{\textbf{Explanation}} \ \hline & \texttt{LDM} & \texttt{#n} & Load the number n to the ACC \ \hline & \texttt{LDD} & \texttt{

} & Load the contents of the location at the given address to ACC \ \hline & \texttt{LDI} & \texttt{

} & \begin{tabular}[c]{@{}l@{}}The address to be used is at the given address.\ Load the contents of this second address to the ACC.\end{tabular} \ \hline & \texttt{ADD} & \texttt{

} & Add the contents of the given address to the ACC \ \hline & \texttt{SUB} & \texttt{

} & Subtract the contents of the given address from the ACC \ \hline & \texttt{STO} & \texttt{

} & Store the contents of the ACC at the given address \ \hline \texttt{:} & & \texttt{} & Gives a symbolic address \texttt{} to the memory location with the contents \texttt{} \ \hline \multicolumn{4}{|l|}{\begin{tabular}[c]{@{}l@{}}# denotes a denary number, e.g. \texttt{#123}\ \texttt{} can be used in place of \texttt{

}\end{tabular}} \ \hline \end{tabular}

The current contents of memory are:

\begin{tabular}{|r|c|} \hline \textbf{Address} & \textbf{Contents} \ \hline 150 & 26 \ \hline 300 & 86 \ \hline 420 & 150 \ \hline \end{tabular}

12 short_answer p. 12

The following table shows the global variables used to implement a stack.

12a short_answer p. 12

A stack has been implemented using pseudocode to store a maximum of 100 string items using the global variables in the following table:

\begin{tabular}{|c|c|l|c|} \hline \textbf{Identifier} & \textbf{Data type} & \textbf{Description} & \textbf{Initialisation value} \ \hline Base & INTEGER & pointer for the bottom of the stack & 0 \ \hline Top & INTEGER & pointer for the top of the stack & -1 \ \hline StackArray & STRING & 1D array to implement the stack & [0:99] \ \hline Max & INTEGER & maximum number of items in the stack & 100 \ \hline \end{tabular}

The value of \texttt{Top} is incremented each time a data item is added to the stack and decremented each time a data item is removed. If the stack is full, an appropriate error message is output.

12ai 4 marks short_answer p. 12 10.4

Complete the \textbf{pseudocode} for the procedure to add a data item onto the stack.

\begin{alltt} PROCEDURE Push(\underline{\hspace{1.5em}}) IF Top < Max - 1 THEN

    Top <- \underline{\hspace{1.5em}}

    \underline{\hspace{1.5em}} <- NewData
ELSE

    OUTPUT \underline{\hspace{1.5em}}
ENDIF

ENDPROCEDURE \end{alltt}

12aii 2 marks short_answer p. 12 10.4

Write \textbf{pseudocode} to input a new data item and add it to the stack using \texttt{Push()}.

12b 3 marks long_answer p. 12 19.2

Explain the reasons why a stack is used when a recursive algorithm is executed.

9618 Computer Science November 2025 Question Paper 32

Sign in

Log in or create account