Learn Extracted exam questions A-Level Computer Science 9618 Computer Science November 2025 Question Paper 32
9618 Computer Science November 2025 Question Paper 32
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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}
The composite data type, \texttt{Car}, is defined.
Write the \textbf{pseudocode} statement to set up a variable for one record of the composite data type, \texttt{Car}.
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}
The data type for \texttt{BodyStyle} is changed to an enumerated type, \texttt{Body}.
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}
Write the new \textbf{pseudocode} statement required to update the declaration of \texttt{BodyStyle} in the definition of \texttt{Car}.
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}
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
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{$\square\,\square\,\square\,\square\,\square\,\square$}
HTTP and IMAP are examples of protocols used in the Application Layer of the TCP/IP protocol suite.
State the purpose of the HTTP and IMAP protocols.
HTTP \hrulefill IMAP \hrulefill
Describe how files are shared using the BitTorrent protocol.
Identify one benefit of circuit switching and one benefit of packet switching.
Circuit switching \hrulefill Packet switching \hrulefill
Identify two differences between circuit switching and packet switching.
- \hrulefill
- \hrulefill
Describe how interrupt handling is used in low-level scheduling.
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}
The diagram shows a logic circuit.
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}
Complete the Karnaugh map (K-map) for the Boolean expression:
\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}
Draw loop(s) around appropriate group(s) in the K-map to produce an optimal sum-of-products.
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.
Asymmetric encryption is a type of cryptography.
Identify \textbf{one} other type of cryptography.
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.
State the purpose of the optimisation stage in the compilation of a program.
Convert this Reverse Polish Notation (RPN) back to its original infix form:
\texttt{a b - c + c a - * d /}
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}
Deep Learning is a form of Machine Learning.
State \textbf{one} example where Deep Learning is used.
Identify how Deep Learning can be made more effective.
Describe the back propagation of errors method in Machine Learning.
An exception is an error that may cause a program to halt unexpectedly.
Describe how program termination due to an exception can be avoided.
Identify \textbf{two} possible causes of exceptions.
- \hrulefill
- \hrulefill
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{The following table shows the global variables used to implement a stack.
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.
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}
Write \textbf{pseudocode} to input a new data item and add it to the stack using \texttt{Push()}.
Explain the reasons why a stack is used when a recursive algorithm is executed.