Learn Extracted exam questions A-Level Computer Science 9618 Computer Science November 2025 Question Paper 33
9618 Computer Science November 2025 Question Paper 33
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An enumerated data type, \texttt{Spectrum}, is required to hold the names of colours.
An enumerated data type, \texttt{Spectrum}, is required to hold the names of colours.
Write the \textbf{pseudocode} statement for the type declaration of \texttt{Spectrum} to hold the names of the colours available:
Red, Orange, Yellow, Green, Blue, Indigo, Violet.
Identify \textbf{two} characteristics of the list of values given in an enumerated data type declaration.
- \hrulefill
- \hrulefill
\texttt{ColourData} is a composite data type to store definitions of colours.
Write \textbf{pseudocode} statements to declare \texttt{ColourData} to hold the following fields:
\begin{tabular}{|l|l|} \hline \textbf{Field} & \textbf{Example data} \ \hline ColourCode & XYZ12345 \ \hline Colour & Red \ \hline Wavelength & 650 \ \hline Frequency & 4.62 \ \hline PrimaryColour & Yes \ \hline \end{tabular}
Use the most appropriate data type in each case, including the enumerated data type \texttt{Spectrum} from part a(i).
Numbers are stored in a computer system using binary floating-point representation with:
\begin{itemize} \item 12 bits for the mantissa \item 4 bits for the exponent \item two's complement form for both the mantissa and the exponent \item 2 bytes in total. \end{itemize}
Outline the effect of changing the number of bits used to store the mantissa to 10 bits, in this system.
Describe \textbf{one} example of a situation that could cause an overflow to occur and the consequences of such an overflow.
Describe how packet switching is used to pass messages across a network. Do \textbf{not} include checking for completeness and resending packets in your answer.
Identify \textbf{and} describe \textbf{three} protocols that are used in the Application Layer of the TCP/IP protocol suite.
Protocol 1 \hrulefill
Description \hrulefill
Protocol 2 \hrulefill
Description \hrulefill
Protocol 3 \hrulefill
Description \hrulefill
State the purpose of multi-tasking.
Explain how an operating system ensures that multi-tasking operates efficiently.
The Karnaugh map (K-map) represents a logic circuit with four inputs.
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{a(i)} as a simplified sum-of-products. Do \textbf{not} carry out any further simplification.
Simplify the following expression using De Morgan’s laws and Boolean algebra.
Show all the stages in your simplification.
Outline the process of optimisation during the compilation of a program.
Write the Reverse Polish Notation (RPN) for the given infix expression:
The RPN expression
is to be evaluated, where:
Show the changing contents of the stack as the RPN expression is evaluated.
\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|c|c|c|} \hline & & & & & & & & & & & & \ \hline & & & & & & & & & & & & \ \hline & & & & & & & & & & & & \ \hline & & & & & & & & & & & & \ \hline & & & & & & & & & & & & \ \hline \end{tabular}
Calculate the shortest distance between the \textbf{Start} node and each of the nodes in the graph using Dijkstra's algorithm.
Show your working on the graph or in the working space. Write your answers in the table provided.
Answers:
\begin{tabular}{|c|c|c|c|c|c|} \hline \textbf{T} & \textbf{V} & \textbf{W} & \textbf{X} & \textbf{Y} & \textbf{Z} \ \hline & & & & & \ \hline \end{tabular}
A company requires a digital certificate to ensure the authenticity of its online communications.
Outline the process followed to acquire a digital certificate.
A stack, \texttt{StackArray}, is to be implemented using pseudocode, to store a maximum of 100 string items in an appropriate array. Declarations are required so that the stack has a beginning, an end and a maximum size. An array is also required to store the data.
Write \textbf{pseudocode} to declare the variables, constant and array required to implement the stack.
Write \textbf{pseudocode} for a procedure to initialise the top and bottom pointers of the stack to appropriate values.
Describe when the use of recursion would be beneficial \textbf{and} give an example.
Description \hrulefill Example \hrulefill
An exception can occur when running a program.
Explain what is meant by an exception.
Identify \textbf{one} example of an exception and give \textbf{one} reason why the exception may cause a problem.
Example \hrulefill Reason \hrulefill
The table shows assembly language instructions for a processor that has one register, the Accumulator (ACC).
\begin{tabular}{|c|c|l|p{7.5cm}|} \hline \textbf{Label} & \multicolumn{2}{c|}{\textbf{Instruction}} & \multicolumn{1}{c|}{\textbf{Explanation}} \ \cline{2-3} & \textbf{Opcode} & \textbf{Operand} & \ \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 the ACC \ \hline & \texttt{LDI} & \texttt{} & The address to be used is at the given address. \newline Load the contents of this second address to the ACC \ \hline & \texttt{ADD} & \texttt{} & Add the contents of the given address to the ACC \ \hline & \texttt{ADD} & \texttt{#n} & Add the number n to the ACC \ \hline & \texttt{SUB} & \texttt{} & Subtract the contents of the given address from the ACC \ \hline & \texttt{SUB} & \texttt{#n} & Subtract the number n from the ACC \ \hline & \texttt{STO} & \texttt{} & Store the contents of the ACC at the given address \ \hline \texttt{