9618 Computer Science November 2025 Question Paper 31

1 short_answer p. 2

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

\begin{alltt} TYPE ClubMember DECLARE Code : INTEGER DECLARE LastName : STRING DECLARE FirstName : STRING DECLARE Telephone : STRING DECLARE JoinDate : DATE DECLARE Fees : REAL DECLARE FeesPaid : BOOLEAN ENDTYPE \end{alltt}

1a short_answer p. 2

1ai 1 mark short_answer p. 2 13.1

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

1aii 2 marks short_answer p. 2 10.1

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

\begin{itemize} \item 984632 to \texttt{Code} \item \texttt{TRUE} to \texttt{FeesPaid} \end{itemize}

1b short_answer p. 2

An enumerated data type, \texttt{Activity}, is required, so that a new field, \texttt{Choice}, can be added to the composite data type, \texttt{ClubMember}, to allow members to choose an activity.

1bi 2 marks short_answer p. 2 13.1

Write the pseudocode statement for the type declaration of \texttt{Activity} to hold the names of the available activities:

Badminton, Football, Golf, Snooker, Swimming, Tennis.

1bii 1 mark short_answer p. 2 13.1

Write the new pseudocode statement required to update the declaration of \texttt{Choice} in the definition of \texttt{ClubMember}.

2 short_answer p. 3

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. \end{itemize}

2a 2 marks calculation p. 3 13.3

Write the normalised floating-point representation of the following positive binary number using this system.

$$0.00000001110101101$$

\textbf{Mantissa} \hfill \textbf{Exponent}

\framebox{$\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square$} \hfill \framebox{$\square\,\square\,\square\,\square$}

2b 4 marks calculation p. 3 13.3

Calculate the normalised binary floating-point representation of $-76.1875$ in this system. Show your working.

\textbf{Mantissa} \hfill \textbf{Exponent}

\framebox{$\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square$} \hfill \framebox{$\square\,\square\,\square\,\square$}

3 short_answer p. 4

3a 2 marks short_answer p. 4 14.1

Explain why protocols are essential for communication between computer systems.

3b 4 marks short_answer p. 4 14.1

POP3 is an email communication protocol.

Identify and describe \textbf{two} other communication protocols that are used when sending or receiving emails.

Protocol 1 \hrulefill

Description \hrulefill

Protocol 2 \hrulefill

Description \hrulefill

3c 4 marks short_answer p. 4 14.2

Describe \textbf{two} ways in which packet switching ensures a complete message is received when passing messages across a network.

\hrulefill
\hrulefill

4 short_answer p. 5

A scheduling routine determines how processes are managed by the operating system.

4a 2 marks short_answer p. 5 16.1

Identify \textbf{two} scheduling routines.

\hrulefill
\hrulefill

4b 4 marks short_answer p. 5 16.1

Describe \textbf{two} ways in which the complexities of the computer hardware are hidden from the user.

\hrulefill
\hrulefill

5 short_answer p. 5

(no root text)

5a 2 marks short_answer p. 5 17.1

Identify \textbf{two} items commonly found within a digital certificate.

\hrulefill
\hrulefill

5b 3 marks short_answer p. 5 17.1

Explain why a digital certificate is required to validate a digital signature.

6 short_answer p. 6

(no root text)

6a 3 marks short_answer p. 6 3.2

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}

6b short_answer p. 7

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

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

6bi 2 marks short_answer p. 7 15.2

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

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

\begin{tabular}{cc|c|c|c|c|} & \multicolumn{5}{c}{\textbf{BC}} \ \textbf{A} & & \textbf{00} & \textbf{01} & \textbf{11} & \textbf{10} \ \cline{2-6} & \textbf{0} & & & & \ \cline{2-6} & \textbf{1} & & & & \ \cline{2-6} \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

Identify one Artificial Intelligence (AI) algorithm to find the shortest distance between two points on a graph.

7a 1 mark short_answer p. 7 18.1

Identify one Artificial Intelligence (AI) algorithm to find the shortest distance between two points on a graph.

7b 5 marks long_answer p. 7 18.1

Describe Deep Learning.

8 short_answer p. 8

8a 2 marks short_answer p. 8 16.2

Outline the purpose of lexical analysis during the compilation of a program.

8b 2 marks short_answer p. 8 16.2

Write the Reverse Polish Notation (RPN) for the given infix expression:

$(2 - 6) * (13 + 7) / 5$

8c 4 marks short_answer p. 8 16.2

The RPN expression:

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

is to be evaluated, where:

$a = 6$, $b = 12$, $c = 15$ and $d = 5$.

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

\begin{tabular}{ccccccccc} \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} \ \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} \ \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} \ \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} \ \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} & \framebox{\quad} \end{tabular}

9 short_answer p. 9

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

9a short_answer p. 9

\begin{tabular}{|c|c|c|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 every time a data item is removed.

9ai 5 marks short_answer p. 9 10.4

Complete the \textbf{pseudocode} for the function to remove a data item from the stack.

\begin{alltt} FUNCTION Pop() \hrulefill DECLARE DataItem : STRING DataItem <- ""

IF \hrulefill THEN

    DataItem <- \hrulefill

    Top <- \hrulefill
ELSE
    DataItem <- "You cannot remove data; the stack is empty"
ENDIF

\hrulefill

ENDFUNCTION \end{alltt}

9aii 1 mark short_answer p. 9 10.4

Write the \textbf{pseudocode} to output the data item removed from the stack with an appropriate message.

9b 3 marks short_answer p. 10 19.2

A stack is used to implement recursion.

State the \textbf{three} essential features of recursion.

\hrulefill
\hrulefill
\hrulefill

10 3 marks short_answer p. 10 20.2

Explain what is meant by \textbf{exception handling}. Include an example of a possible cause of an exception in your answer.

Explanation \hrulefill

Example \hrulefill

11 short_answer p. 11

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

\begin{tabular}{|l|l|l|l|} \hline \textbf{Label} & \textbf{Opcode} & \textbf{Operand} & \textbf{Explanation} \ \hline & LDM & #n & Load the number n to ACC \ \hline & LDD & \texttt{

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

} & The address to be used is at the given address. Load the contents of this second address to the ACC \ \hline & ADD & \texttt{

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

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

# denotes a denary number, e.g. #123 \texttt{} can be used in place of \texttt{

}

11a 6 marks short_answer p. 11 4.2

Write \textbf{assembly language} code, using \textbf{only} the given instruction set to:

\begin{itemize} \item store the denary value 100 as a named constant \item subtract the constant from the value contained in address 632 \item store the result in variable \texttt{Answer}. \end{itemize}

Show the initialisation of the constant and \texttt{Answer} in the table provided.

\begin{tabular}{|c|c|} \hline \textbf{Label} & \textbf{Contents} \ \hline & \ \hline & \ \hline & \ \hline & \ \hline \end{tabular}

11b 1 mark short_answer p. 11 4.2

The address 632 contains the value 45.

State the value of \texttt{Answer} after the code described in part \textbf{(a)} has executed.

9618 Computer Science November 2025 Question Paper 31

Sign in

Log in or create account