9618 Computer Science November 2025 Question Paper 12

1 2 marks short_answer p. 2 6.2

Draw one line from each verification method to indicate whether it is used during data transfer or data entry.

\textbf{Verification Method}

\begin{itemize} \item Parity byte check \item Checksum \item Visual check \item Parity block check \end{itemize}

\textbf{Use}

\begin{itemize} \item Data transfer \item Data entry \end{itemize}

2 short_answer p. 2

Complete the table by describing each term.

2a 4 marks long_answer p. 2 7.1

\begin{tabular}{|l|p{10cm}|} \hline \textbf{Term} & \textbf{Description} \ \hline Copyright & \ & \ & \ \hline Open Source (Initiative) & \ & \ & \ \hline Shareware & \ & \ & \ \hline Software Licence & \ & \ & \ \hline \end{tabular}

2b 2 marks short_answer p. 3 7.1

Describe the purpose of a code of conduct.

3 short_answer p. 3

3a short_answer p. 3

3ai 1 mark short_answer p. 3 4.2

State what is meant by relative addressing.

3aii 2 marks short_answer p. 3 4.1

Registers such as the Accumulator (ACC) and the Index Register (IX) are used in the CPU.

Identify \textbf{two} special purpose registers used in the CPU. Do \textbf{not} include the ACC or IX in your answers.

\hrulefill
\hrulefill

3b 3 marks short_answer p. 4 4.2

The following table shows part of the instruction set for a processor. The processor has two registers: the ACC and an IX.

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

& Direct addressing. Load the contents of the location at the given address to ACC \ \hline LDI &

& Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC \ \hline LDX &

& Indexed addressing. Form the address from

+ the contents of the index register. Copy the contents of this calculated address to ACC \ \hline LDR & #n & Immediate addressing. Load the number n to IX \ \hline \end{tabular}

can be an absolute or symbolic address \# denotes a denary number, e.g. \#127

The current contents of the main memory and the index register are shown.

\begin{tabular}{r|c|} \multicolumn{1}{c}{\textbf{Address}} & \multicolumn{1}{c}{\textbf{Instruction}} \ \cline{2-2} 98 & 8 \ \cline{2-2} 99 & 16 \ \cline{2-2} 100 & 3 \ \cline{2-2} 101 & 98 \ \cline{2-2} 102 & 32 \ \cline{2-2} IX & 2 \ \cline{2-2} \end{tabular}

Write the contents of the ACC after each instruction is executed.

\begin{tabular}{|l|c|} \hline \textbf{Instruction} & \textbf{Value in ACC} \ \hline LDM #98 & \hrulefill \ \hline LDI 101 & \hrulefill \ \hline LDX 100 & \hrulefill \ \hline \end{tabular}

3c 4 marks long_answer p. 5 4.1

A student buys a new computer. The table shows the specifications of the old computer and the new computer.

\begin{tabular}{|c|c|} \hline \textbf{Old computer} & \textbf{New computer} \ \hline 1.8 GHz dual core processor & 2.3 GHz dual core processor \ \hline 16 MB cache & 32 MB cache \ \hline \end{tabular}

Explain why increasing the clock speed \textbf{and} increasing the cache memory will improve the performance of the computer.

Clock speed \hrulefill

Cache memory \hrulefill

4 short_answer p. 6

A relational database, \texttt{SHIPPING}, stores data about the ships in a company and the containers that are carried on the ships.

The database has the following tables:

\texttt{CONTAINER(\underline{ContainerID}, Type, Weight, OwnerName, ShipID)}

\texttt{SHIP(\underline{ShipID}, Type, Capacity, ShipName)}

4a 2 marks short_answer p. 6 8.1

Describe the relationship between the two tables. Refer to the primary and foreign keys in your answer.

4b 2 marks short_answer p. 6 8.3

The table \texttt{CONTAINER} needs an additional field to store the data for the last inspection date.

Write a Structured Query Language (SQL) script to add \textbf{one} field to the table \texttt{CONTAINER} to store the date of last inspection of the container, for example 08/07/2019.

4c 4 marks short_answer p. 6 8.3

Write an SQL script to return the number of containers stored in the database for the ship with the name Caledonia.

4d 2 marks short_answer p. 7 8.2

Describe the purpose of a developer interface in a Database Management System (DBMS).

5 short_answer p. 8

A local area network (LAN) has five computers, one switch and one server.

5a 2 marks short_answer p. 8 2.1

Describe the characteristics of a LAN.

5b 2 marks short_answer p. 8 2.1

Complete the following diagram to show how these devices are connected in a star topology.

5c 3 marks long_answer p. 8 2.1

Describe how packets are transmitted between two hosts using a star topology.

5d 3 marks long_answer p. 9 2.1

Another type of network is a bus network.

Ethernet is used to transmit and receive data between the devices on the bus network.

Describe how collisions are detected and managed on this network.

5e 3 marks short_answer p. 9 6.1

Complete the table by identifying \textbf{one} threat to computer and data security posed by networks and the internet.

Describe the threat and give a method of prevention.

\begin{tabular}{|p{3cm}|p{7cm}|p{3cm}|} \hline \centering \textbf{Threat} & \centering \textbf{Description} & \centering \textbf{Prevention} \tabularnewline \hline & & \ & & \ & & \ & & \ & & \ \hline \end{tabular}

6 short_answer p. 10

6a 1 mark short_answer p. 10 1.3

A sound file is compressed by reducing the sampling rate.

State whether this is lossless or lossy compression. Justify your choice.

Type of compression \hrulefill

Justification

6b 1 mark short_answer p. 10 1.1

The following table shows some words and corresponding denary values.

\begin{tabular}{|c|c|} \hline \textbf{Word} & \textbf{Denary value} \ \hline Computing & 55 \ \hline Science & 56 \ \hline Computers & 57 \ \hline are & 58 \ \hline Brilliant! & 59 \ \hline is & 60 \ \hline Fun! & 61 \ \hline Amazing! & 62 \ \hline \end{tabular}

The following table shows three bytes of data that have been received.

Use the table to find the corresponding words from the binary values received.

\begin{tabular}{|c|c|c|c|} \hline \textbf{Binary value} & 00111000 & 00111100 & 00111110 \ \hline \textbf{Word} & & & \ \hline \end{tabular}

6c short_answer p. 11

A computer system uses even parity. The least significant (rightmost) bit of each byte is the parity bit.

6ci 1 mark short_answer p. 11 1.1

Complete the byte by writing the missing parity bit:

\begin{tabular}{cc} & parity \ & bit \ & $\downarrow$ \ \hline \multicolumn{1}{|c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{\underline{\hspace{1.5em}}} \ \hline \end{tabular}

6cii 1 mark short_answer p. 11 6.2

The computer also uses parity block check. The parity block check uses even parity. Computer A transmits four bytes of data to computer B, followed by a parity byte. Computer B receives the following sequence of bytes.

\begin{tabular}{ccccccccc} & & & & & & & & parity \ & & & & & & & & bit \ & & & & & & & & $\downarrow$ \ \cline{2-9} & \multicolumn{1}{|c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} \ \cline{2-9} & \multicolumn{1}{|c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} \ \cline{2-9} & \multicolumn{1}{|c|}{0} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} \ \cline{2-9} & \multicolumn{1}{|c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} \ \cline{2-9} parity byte $\rightarrow$ & \multicolumn{1}{|c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{1} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} & \multicolumn{1}{c|}{0} \ \cline{2-9} \end{tabular}

Following transmission, one of the four bytes of data has an error in one of the bits.

Circle the bit that has been altered during the data transfer.

6d 2 marks calculation p. 11 1.2

A bitmap image has a resolution of 1000 pixels wide by 2000 pixels high. The colour depth is 16 bits.

Calculate an estimate of the file size in megabytes.

Show your working.

File size \underline{\hspace{1.5em}} megabytes

7 short_answer p. 12

(no root text)

7a 1 mark calculation p. 12 1.1

The following binary addition is performed using 8-bit registers.

Complete the calculation using binary addition.

$$\begin{array}{r} 10000111 \\ + 00111001 \\ \hline \end{array}$$

7b 1 mark short_answer p. 12 1.1

A computer uses the Unicode character set.

State the number of bits used to store \textbf{one} character from the Unicode character set.

7c short_answer p. 12

ASCII is another character set. The ASCII value for the character 'h' has the denary value 104.

7ci 1 mark short_answer p. 12 1.1

Write the Binary Coded Decimal (BCD) value for the ASCII character 'h'.

7cii 1 mark short_answer p. 12 1.1

Write the hexadecimal value for the ASCII character 'h'.

8 short_answer p. 13

A restaurant accesses software and stores data using cloud computing.

8a short_answer p. 13

8ai 2 marks short_answer p. 13 2.1

Give \textbf{two} benefits of storing data using cloud computing.

\hrulefill
\hrulefill

8aii 2 marks short_answer p. 13 2.1

Give \textbf{two} drawbacks of using cloud computing.

\hrulefill
\hrulefill

8b short_answer p. 13

The restaurant uses touchscreens as input devices to allow staff to select items from a menu.

8bi 4 marks long_answer p. 13 3.1

Explain how a touchscreen converts the point of touch to a selection from the menu.

8bii 2 marks short_answer p. 13 5.1

The image files that are displayed on the touchscreen have been corrupted.

Identify \textbf{two} examples of utility software that could be used to recover the images.

\hrulefill
\hrulefill

9 short_answer p. 14

9a 2 marks short_answer p. 14 3.2

Consider the following logic circuit:

Write the logic expression for the logic circuit. Do not simplify the expression.

X = \hrulefill

9b 2 marks short_answer p. 14 3.2

Consider the following logic expression:

$$X = \text{NOT } ((A \text{ NAND } B) \text{ XOR } (\text{NOT } A \text{ OR } \text{NOT } C))$$

A truth table for the logic expression is given:

\begin{tabular}{|c|c|c|c|c|} \hline \textbf{Row number} & \textbf{A} & \textbf{B} & \textbf{C} & \textbf{X} \ \hline 1 & 0 & 0 & 0 & 1 \ \hline 2 & 0 & 0 & 1 & 0 \ \hline 3 & 0 & 1 & 0 & 1 \ \hline 4 & 0 & 1 & 1 & 0 \ \hline 5 & 1 & 0 & 0 & 1 \ \hline 6 & 1 & 0 & 1 & 0 \ \hline 7 & 1 & 1 & 0 & 1 \ \hline 8 & 1 & 1 & 1 & 1 \ \hline \end{tabular}

There are \textbf{three} errors in the truth table.

Identify the \textbf{three} errors in the truth table by writing the row numbers with an incorrect output.

Error 1 Row number \hrulefill Error 2 Row number \hrulefill Error 3 Row number \hrulefill

10 short_answer p. 15

A programmer is developing a computer program.

10a 4 marks long_answer p. 15 5.2

Explain how the programmer can first use an interpreter \textbf{and} then a compiler to develop the computer program.

Interpreter \hrulefill

Compiler \hrulefill

10b 2 marks short_answer p. 15 7.1

The programmer releases the program as Free Software.

Describe what is meant by Free Software.

10c 1 mark short_answer p. 15 17.1

A user downloads the computer program from the internet.

State what should be included as part of the download to make sure the program is authentic.

11 3 marks short_answer p. 16 3.1

An automated system opens doors when a person is detected within 2 metres. The system closes the doors when there is no longer a person within 2 metres.

Identify whether the automated system is an example of a monitoring system or a control system.

Justify your choice.

Monitoring or Control \hrulefill

Justification

9618 Computer Science November 2025 Question Paper 12

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