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A Level Computer Science 9618 Paper 11, May/June 2023

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9618/11 · May/June 2023

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1

Images are being created to advertise holidays. Some of the images are bitmap images and some are vector graphics.

a

Complete the table by defining the image terms.

TermDefinition
Drawing list
Pixel
Colour depth
[3]
b(i)

The bitmap images are photographs of the holiday locations. Colour depth and image resolution are both included in the file header of a bitmap image. Identify two other items that could be included in the file header of each photograph. 1 ........................................................................................................................................ 2 ........................................................................................................................................

[2]
b(ii)

One of the photographs has a bit depth of 8 bytes and an image resolution of 1500 pixels wide and 3000 pixels high. Calculate the file size of the photograph in megabytes. Show your working. Working ............................................................................................................................. ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... File size ...........................MB

[2]
c(i)

The photographs are compressed before they are uploaded to a web server. Customers download the photographs from this web server. Explain the reasons why compressing the photographs will benefit the customers.

[3]
c(ii)

An image can be compressed using run-length encoding (RLE). Explain the reasons why RLE may not reduce the file size of a bitmap image. Give one example in your answer.

[3]
2

An organisation uses a database to store data about the types of bird that people have seen.

a(i)

The database is managed using a Database Management System (DBMS). State what is meant by a data dictionary and give one example of an item typically found in a data dictionary. Definition ........................................................................................................................... ........................................................................................................................................... Example ............................................................................................................................ ...........................................................................................................................................

[2]
a(ii)

State what is meant by data integrity and give one example of how this is implemented in a database. Definition ........................................................................................................................... ........................................................................................................................................... Example ............................................................................................................................ ...........................................................................................................................................

[2]
b(i)

The database, Birds, stores information about the types of bird and the people who have seen them. Data about each bird seen is stored with its location and data about the person who saw the bird. Database Birds has the following tables: BIRD_TYPE(BirdID, Name, Size) BIRD_SEEN(SeenID, BirdID, Date, Location, PersonID) PERSON(PersonID, FirstName, LastName, EmailAddress) Complete the table by identifying two foreign keys and the database table where each is found.

Foreign keyDatabase table
[2]
b(ii)

The database Birds has been normalised. Draw one line from each Normal Form to the most appropriate definition.

Normal FormDefinition
First Normal Form (1NF)All fields are fully dependent on the primary key.
Second Normal Form (2NF)There are no repeating groups of attributes.
Third Normal Form (3NF)There are no partial dependencies.
[1]
b(iii)

Part of the database table BIRD_TYPE is shown:

BirdIDNameSize
0123BlackbirdMedium
0035JayLarge
0004RavenLarge
0085RobinSmall

The database only supports these data types: • character • varchar • Boolean • integer • real • date • time Write a Structured Query Language (SQL) script to define the table Bird_Type.

[4]
b(iv)

The database tables are repeated here for reference: BIRD_TYPE(BirdID, Name, Size) BIRD_SEEN(SeenID, BirdID, Date, Location, PersonID) PERSON(PersonID, FirstName, LastName, EmailAddress) Complete the SQL script to return the number of birds of each size seen by the person with the ID of J_123. SELECT BIRD_TYPE.Size, ............................................ (BIRD_TYPE.BirdID) AS NumberOfBirds FROM BIRD_TYPE, ............................................ WHERE ...................................................... = "J_123" AND BIRD_TYPE.BirdID = ...................................................... ............................................ BIRD_TYPE.Size;

[5]
3

A computer has an Operating System (OS).

a

Describe how the Operating System manages the peripheral hardware devices of the computer.

[4]
b

Hardware management is one key management task carried out by the Operating System. Identify two other key management tasks carried out by the Operating System. 1 ................................................................................................................................................ 2 ................................................................................................................................................

[2]
c

The Operating System has utility software including defragmentation software. Explain how defragmentation can improve the performance of the computer.

[3]
d(i)

The computer stores data in binary form. State the difference between a kibibyte and a kilobyte.

[1]
d(ii)

Convert the denary number 964 into Binary Coded Decimal (BCD).

[1]
d(iii)

Convert the positive binary integer 11110010 into hexadecimal.

[1]
d(iv)

Give the smallest and largest two’s complement binary number that can be represented using 8 bits. Smallest ............................................................................................................................ Largest ..............................................................................................................................

[2]
d(v)

Add the following two binary integers using binary addition. Show your working.

10110000
+00011011
[2]
d(vi)

Show the result of a 3-place right logical shift on the binary number: 11001100

[1]
4

A networked closed-circuit television (CCTV) system in a house uses sensors and cameras to detect the presence of a person. It then tracks the person and records a video of their movements. Data from the CCTV cameras is transmitted to a central computer.

a(i)

This computer has both Read Only Memory (ROM) and Random Access Memory (RAM). Describe the contents of the ROM in the central computer.

[2]
a(ii)

The central computer has Dynamic RAM (DRAM). Identify two advantages of using DRAM instead of Static RAM (SRAM). 1 ........................................................................................................................................ ........................................................................................................................................... 2 ........................................................................................................................................ ...........................................................................................................................................

[2]
b

The central computer stores the video files on secondary storage. Describe two reasons why magnetic storage is more appropriate than solid state storage for this computer. 1 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................

[4]
c

The CCTV system uses Artificial Intelligence (AI) to identify the presence of a person in the house and to track their movements. Describe how AI is used in this system.

[3]
d(i)

The CCTV cameras are connected to a network and transfer their data wirelessly to the central computer. Each device on the network has an IP address. Complete the description of IP addresses. An IPv4 address contains ..................................... groups of digits. Each group is represented in ..................................... bits and the groups are separated by full stops. An IPv6 address contains ..................................... groups of digits. Each group is represented in ..................................... bits. Multiple groups that only contain zeros can be replaced with a ..................................... .

[5]
d(ii)

The network makes use of subnetting. Describe two benefits of subnetting a network. 1 ........................................................................................................................................ ........................................................................................................................................... ........................................................................................................................................... ........................................................................................................................................... 2 ........................................................................................................................................ ........................................................................................................................................... ........................................................................................................................................... ...........................................................................................................................................

[4]
5
a

Draw the logic circuit for this logic expression: T=(NOT A OR B) XOR (C NAND D)

[2]
b

Describe the function of the NAND and NOR logic gates. NAND ....................................................................................................................................... ................................................................................................................................................... NOR .......................................................................................................................................... ...................................................................................................................................................

[2]
6

An interrupt is generated when a key is pressed on a computer keyboard. Explain how the computer handles this interrupt.

[5]

Mark scheme

9618/11 · May/June 2023

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1a · 3 marks

  • 1 mark

    Drawing list: All the drawing objects in an image // a list that stores the commands required to draw each object

  • 1 mark

    Pixel: The smallest part of the image // one square / dot of one colour

  • 1 mark

    Colour depth: The number of bits per pixel // determines the number of colours that can be represented in the image

1b(i) · 2 marks

  • 1 mark

    Confirmation that it is a bitmap // file type

  • 1 mark

    Compression type // Location/offset of data within the file // Dimensions e.g. 100 × 100 pixels

1b(ii) · 2 marks

  • 1 mark

    Working: (1500 * 3000 * 8) / 1000 / 1000

  • 1 mark

    Answer: 36 MB

1c(i) · 3 marks

  • 1 mark

    The customers will be able to download the photographs in less time

  • 1 mark

    …and they will take less of the customer's bandwidth

  • 1 mark

    The photographs will take up less space on the customer's storage medium / …therefore the customers can store more images / …and will have more space for other files

1c(ii) · 3 marks

  • 1 mark

    RLE stores a colour and the number of times it occurs consecutively

  • 1 mark

    An image may not have many sequences of the same colour // It would need to store each colour and then the count/number 1 which adds data

  • 1 mark

    Example: Red-Green-Blue would become Red 1 Green 1 Blue 1

2a(i) · 2 marks

  • 1 mark

    Data about the data in the database // data about the structure of the database // metadata for a database

  • 1 mark

    Suitable example: table names / data types / field names

2a(ii) · 2 marks

  • 1 mark

    Methods of making sure the data is consistent

  • 1 mark

    Example: Enforcing referential integrity // If data in one table is deleted/edited all tables are updated // cascading update/delete // Validation/verification rules

2b(i) · 2 marks

  • 1 mark

    BirdID, BIRD_SEEN

  • 1 mark

    PersonID, BIRD_SEEN

2b(ii) · 1 mark

  • 1 mark

    All 3 correct lines: First Normal Form (1NF) connected to 'There are no repeating groups of attributes.', Second Normal Form (2NF) connected to 'There are no partial dependencies.', Third Normal Form (3NF) connected to 'All fields are fully dependent on the primary key.'

2b(iii) · 4 marks

  • 1 mark

    CREATE TABLE start and end bracket

  • 1 mark

    Bird ID as CHAR/VARCHAR

  • 1 mark

    Name and size as VARCHAR/CHAR

  • 1 mark

    Bird ID as primary key

2b(iv) · 5 marks

  • 1 mark

    COUNT(BIRD_TYPE.BirdID) (or COUNT(BirdID))

  • 1 mark

    BIRD_TYPE, BIRD_SEEN (or BIRD_SEEN)

  • 1 mark

    BIRD_SEEN.PersonID = "J_123"

  • 1 mark

    AND BIRD_TYPE.BirdID = BIRD_SEEN.BirdID

  • 1 mark

    GROUP BY BIRD_TYPE.Size;

3a · 4 marks

  • 1 mark

    Installs device drivers / … to allow communication between peripherals and computer

  • 1 mark

    Sends data and receives data to and from peripherals / … such as to an output device and from an input device/by example

  • 1 mark

    Handles buffers for transfer of data / … to ensure smooth transfer between devices that transmit and receive at different speeds

  • 1 mark

    Manages interrupts / signals from the device

3b · 2 marks

  • 1 mark

    Memory management / File management

  • 1 mark

    Security management / Process management / Error checking and recovery

3c · 3 marks

  • 1 mark

    Rearranges blocks of individual files (on the HDD) so they are contiguous // moves the free space together

  • 1 mark

    Accessing each file is faster

  • 1 mark

    …because there is no need to search for the next fragment / block of the file // …so less head movement is needed

3d(i) · 1 mark

  • 1 mark

    Kibibyte is 1024 bytes and kilobyte is 1000 bytes // Kibibyte is binary prefix and kilobyte is denary prefix

3d(ii) · 1 mark

  • 1 mark

    1001 0110 0100

3d(iii) · 1 mark

  • 1 mark

    F2

3d(iv) · 2 marks

  • 1 mark

    Smallest: 10000000

  • 1 mark

    Largest: 01111111

3d(v) · 2 marks

  • 1 mark

    Working

  • 1 mark

    Answer: 1 1 0 0 1 0 1 1

3d(vi) · 1 mark

  • 1 mark

    00011001

4a(i) · 2 marks

  • 1 mark

    Stores the bootstrap program // start-up instructions for the central computer // BIOS

  • 1 mark

    Stores the start-up instructions for the CCTV system/cameras // firmware for CCTV // Stores the kernel of the Operating System // stores parts of the Operating System

4a(ii) · 2 marks

  • 1 mark

    Costs less per unit

  • 1 mark

    Higher storage density // Simple design – uses fewer transistors

4b · 4 marks

  • 1 mark

    The computer will have a large number of read/write operations because it is working all the time

  • 1 mark

    .. magnetic storage has more longevity

  • 1 mark

    Magnetic storage costs less per storage unit

  • 1 mark

    … videos are large files and therefore very large storage capacity is required

4c · 3 marks

  • 1 mark

    Uses image recognition / Monitors every image taken to identify matching images/shapes/features to a 'person' …

  • 1 mark

    … starts recording to secondary storage/permanently when a person is identified

  • 1 mark

    System identifies direction of movement of person and uses this to decide where/how to move the camera/record / System identifies other cameras to start recording based on direction of movement

4d(i) · 5 marks

  • 1 mark

    4 (groups of digits in IPv4)

  • 1 mark

    8 (bits in IPv4 group)

  • 1 mark

    8 (groups of digits in IPv6)

  • 1 mark

    16 (bits in IPv6 group)

  • 1 mark

    :: // double colon

4d(ii) · 4 marks

  • 1 mark

    Reduce amount of traffic in a network // improve network speed

  • 1 mark

    Data stays in its subnet so it does not travel as far

  • 1 mark

    Improves network security // Allows for easier maintenance

  • 1 mark

    .. so that not all devices can access all areas of the network // … because only one subnetwork may need taking down/changing while the rest of the network can continue

5a · 2 marks

  • 1 mark

    2 correct gates (NOT gate on A, OR gate taking NOT A and B, AND gate taking C and D, XOR gate taking OR and AND outputs)

  • 1 mark

    All 4 correct gates

5b · 2 marks

  • 1 mark

    NAND: 0 is only output when both inputs are 1 // 1 is only output when none, or (either) one of the inputs is 1

  • 1 mark

    NOR: 1 is only output when both inputs are 0 // 0 is only output when (either) one or both inputs are 1

6 · 5 marks

  • 1 mark

    An interrupt flag is raised in the (interrupt) register

  • 1 mark

    At the end of the current FE cycle // at the start of the next FE cycle

  • 1 mark

    The system checks the interrupt register for higher priority interrupts than current process

  • 1 mark

    If true, it stores the current contents of the registers on the stack / The appropriate interrupt service routine (ISR) for the key press is called

  • 1 mark

    The input data from the keyboard is processed / The contents of the registers are restored from the stack / ... and control is passed back to previous process

Questions

  1. 1
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  2. 2
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  3. 3
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  4. 4
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  5. 5
    Question 54 marks
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  6. 6
    Question 65 marks
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