9618 Computer Science June 2025 Question Paper 31

1 short_answer p. 2

A programmer is writing a program to manage bookings for a small taxi company. The programmer requires some user-defined data types.

1a 2 marks short_answer p. 2 13.1

Write a pseudocode statement to declare the enumerated data type, \texttt{Vehicle}, to hold the identity code of each of the company's taxis:

M100, M230, T101, T102, T120, T150

1b 4 marks short_answer p. 2 13.1

Write pseudocode statements to declare the composite data type, \texttt{Booking}, to hold data about taxi bookings. The data required includes:

\begin{itemize} \item booking number (any combination of letters and numbers) \item destination \item client name \item client telephone number \item date of departure \item address for pick-up \item the identity code of the taxi used. \end{itemize}

Use the most appropriate data type in each case, including the enumerated data type from part (a).

2 short_answer p. 3

Numbers are stored in a computer 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 2 marks calculation p. 3 13.3

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

0.00000011010111

\textbf{Mantissa} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \textbf{Exponent}

\framebox{$\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square$} \quad \framebox{$\square\,\square\,\square\,\square\,\square\,\square$}

2b 4 marks calculation p. 3 13.3

Calculate the normalised binary floating-point representation of $-25.3125$ in this system. Show your working.

\textbf{Mantissa} \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \quad \textbf{Exponent}

\framebox{$\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square\,\square$} \quad \framebox{$\square\,\square\,\square\,\square\,\square\,\square$}

Working \hrulefill

3 short_answer p. 4

The Application Layer and Transport Layer are two layers of the TCP/IP protocol suite.

3a 5 marks long_answer p. 4 14.1

Describe the purpose of the Application Layer \textbf{and} the purpose of the Transport Layer.

Purpose of Application Layer \hrulefill

Purpose of Transport Layer \hrulefill

3b 4 marks long_answer p. 4 14.2

Describe packet switching as a method of transmitting messages across the internet.

4 short_answer p. 5

A linked list of nodes is used to store an ordered list of integers. Each node consists of the data, a left pointer and a right pointer, for example:

\begin{tabular}{ccc} Left pointer & Data & Right pointer \ \framebox{$\square$} & \framebox{20} & \framebox{$\square$} \ \end{tabular}

4a 4 marks short_answer p. 5 10.4

The linked list will be organised as a binary tree.

$-1$ is used to represent a null pointer.

Complete the binary tree, including null pointers, to show how the data will be organised after the following integers have been added:

6, 15, 41, 66

4b 2 marks short_answer p. 5 19.2

Describe what is meant by recursion.

4c 1 mark short_answer p. 6 10.4

A binary tree is a suitable Abstract Data Type (ADT) that a designer can implement using recursive algorithms.

Identify \textbf{one other} ADT that a designer can implement using recursive algorithms.

5 short_answer p. 6

This truth table represents a logic circuit.

\begin{tabular}{|cccc|c|} \hline \multicolumn{4}{|c|}{\textbf{INPUT}} & \textbf{OUTPUT} \ \hline \textbf{A} & \textbf{B} & \textbf{C} & \textbf{D} & \textbf{Z} \ \hline 0 & 0 & 0 & 0 & 1 \ \hline 0 & 0 & 0 & 1 & 0 \ \hline 0 & 0 & 1 & 0 & 0 \ \hline 0 & 0 & 1 & 1 & 0 \ \hline 0 & 1 & 0 & 0 & 0 \ \hline 0 & 1 & 0 & 1 & 1 \ \hline 0 & 1 & 1 & 0 & 0 \ \hline 0 & 1 & 1 & 1 & 1 \ \hline 1 & 0 & 0 & 0 & 1 \ \hline 1 & 0 & 0 & 1 & 0 \ \hline 1 & 0 & 1 & 0 & 0 \ \hline 1 & 0 & 1 & 1 & 0 \ \hline 1 & 1 & 0 & 0 & 0 \ \hline 1 & 1 & 0 & 1 & 1 \ \hline 1 & 1 & 1 & 0 & 0 \ \hline 1 & 1 & 1 & 1 & 1 \ \hline \end{tabular}

5a 2 marks short_answer p. 6 3.2

Write the Boolean logic expression that corresponds to the given truth table as the sum-of-products.

\textbf{Z} = \hrulefill

5b short_answer p. 7

(no root text)

5bi 2 marks short_answer p. 7 15.2

Complete the Karnaugh map (K-map) for the given truth table.

\begin{tabular}{cc|c|c|c|c|} & \multicolumn{1}{c}{} & \multicolumn{4}{c}{\textbf{AB}} \ & \multicolumn{1}{c}{} & \multicolumn{1}{c}{\textbf{00}} & \multicolumn{1}{c}{\textbf{01}} & \multicolumn{1}{c}{\textbf{11}} & \multicolumn{1}{c}{\textbf{10}} \ \cline{3-6} \textbf{CD} & \textbf{00} & & & & \ \cline{3-6} & \textbf{01} & & & & \ \cline{3-6} & \textbf{11} & & & & \ \cline{3-6} & \textbf{10} & & & & \ \cline{3-6} \end{tabular}

5bii 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.

5biii 2 marks short_answer p. 7 15.2

Write the Boolean logic expression from your answer to part (b)(ii) as the simplified sum-of-products.

\textbf{Z} = \hrulefill

6 4 marks long_answer p. 7 16.2

Describe the process of executing a program using an interpreter.

7 short_answer p. 8

Several syntax diagrams are shown.

\textbf{uppercase} \begin{itemize} \item A \item C \item E \item G \item J \end{itemize}

\textbf{lowercase} \begin{itemize} \item b \item d \item f \item h \item k \end{itemize}

\textbf{symbol} \begin{itemize} \item $ \item @ \item # \item & \item % \end{itemize}

\textbf{digit} \begin{itemize} \item 0 \item 1 \item 2 \item 3 \item 4 \item 5 \item 6 \item 7 \item 8 \item 9 \end{itemize}

\textbf{passcode} \begin{itemize} \item uppercase \item lowercase \item symbol \item digit \end{itemize}

7a 2 marks short_answer p. 9 16.2

State why each \textbf{passcode} is invalid for the given syntax diagrams.

\texttt{#Jd7}

Reason \hrulefill

\texttt{C%6A}

Reason \hrulefill

7b 4 marks short_answer p. 9 16.2

Complete the Backus-Naur Form (BNF) for \texttt{} and \texttt{}.

\texttt{ ::= } \hrulefill

8 short_answer p. 10

(no root text)

8a 2 marks short_answer p. 10 16.1

Describe what is meant by \textbf{multi-tasking} and how it benefits process management.

8b 4 marks long_answer p. 10 16.1

Explain the function of the shortest remaining time scheduling routine \textbf{and} give a benefit of this routine.

Function \hrulefill

Benefit \hrulefill

9 short_answer p. 10

Secure Socket Layer (SSL) and Transport Layer Security (TLS) are two protocols.

9a 2 marks short_answer p. 10 17.1

State \textbf{two} functions of SSL/TLS.

\hrulefill
\hrulefill

9b 2 marks short_answer p. 10 17.1

Give \textbf{two} examples of situations where the use of SSL/TLS would be appropriate.

\hrulefill
\hrulefill

10 short_answer p. 11

(no root text)

10a 2 marks short_answer p. 11 18.1

Describe the purpose of a graph when used in an Artificial Intelligence (AI) system.

10b 4 marks long_answer p. 11 18.1

Explain the use of artificial neural networks in Deep Learning.

11 short_answer p. 12

(no root text)

11a 5 marks short_answer p. 12 13.1

A medical centre uses objects of the class \texttt{Appointment} to record treatments given and medication prescribed during each doctor's appointment. Some of the attributes required in the class are listed in the table.

\begin{tabular}{|l|l|l|} \hline \textbf{Attribute} & \textbf{Data type} & \textbf{Description} \ \hline \texttt{DateSeen} & \texttt{DATE} & date of treatment \ \hline \texttt{Treatments} & \texttt{STRING} & treatments given \ \hline \texttt{Medications} & \texttt{STRING} & medications prescribed \ \hline \end{tabular}

Patients are identified by a unique 8-digit number, beginning with the patient's year of birth, for example, 20108989. Doctors are identified by their name, for example, A N Other.

Complete the class diagram for \texttt{Appointment}, to include: \begin{itemize} \item attribute and data type for the identification of the patient \item attribute and data type for the identification of the doctor \item methods to assign date seen, treatments given and medications prescribed \item method to return the date seen and the attributes for the patient and the doctor. \end{itemize}

\begin{tabular}{|l|} \hline \multicolumn{1}{|c|}{\textbf{Appointment}} \ \hline \texttt{DateSeen : DATE} \ \hrulefill : \hrulefill \ \hrulefill : \hrulefill \ \texttt{Treatments : STRING} \ \texttt{Medications : STRING} \ \hline \ \texttt{SetPatientID(PatientNumber : INTEGER)} \ \texttt{SetDoctor(DoctorID : STRING)} \ \ \ \ \ \ \texttt{GetTreatments()} \ \texttt{GetMedications()} \ \hline \end{tabular}

11b short_answer p. 13

(no root text)

11bi 1 mark short_answer p. 13 20.1

Identify the object-oriented programming (OOP) feature whose function includes restricting external access to the data.

11bii 2 marks short_answer p. 13 20.1

Describe what is meant by the OOP feature \textbf{inheritance}.

12 5 marks short_answer p. 13 10.313.2

The pseudocode algorithm checks whether a location in a stock file \texttt{StockList.dat} is empty or not. The location is given by the user. If the location is empty, a suitable message is displayed, otherwise the item stored at that location is displayed.

Complete this file-handling pseudocode algorithm.

\begin{alltt} DECLARE Location : INTEGER DECLARE Item : STRING DECLARE Continue : BOOLEAN DECLARE Answer : CHAR Continue <- TRUE

OPENFILE \hrulefill WHILE Continue OUTPUT "Enter a location between 1 and 500: " INPUT Location

\hrulefill

GETRECORD \hrulefill IF Item = "" THEN OUTPUT "This record is missing." ELSE OUTPUT "The item in stock is ", \hrulefill ENDIF OUTPUT "Another location (Y or N)?" INPUT Answer IF Answer <> 'Y' THEN Continue <- FALSE ENDIF ENDWHILE

\hrulefill OUTPUT "End of program" \end{alltt}

9618 Computer Science June 2025 Question Paper 31

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