ExamPal

A Level Computer Science 9618 Paper 32, Oct/Nov 2024

Question paper and mark scheme75 marks11 questions

Solve it on ExamPal

Practise

Untimed. Write on the paper and check as you go.

Start

Exam

Timed, with a clock you set, like sitting the real paper.

Start

Opens full screen.

Papers open in
Download PDFMark scheme
100%

Opening the question paper

Read as textThe questions and the mark scheme as plain text. Easier to read on a phone.

Question paper

9618/32 · Oct/Nov 2024

Download PDF
1
a

Describe how packet switching is used to transmit messages across a network.

[3]
b

State two benefits and two drawbacks of packet switching as a method of transmitting messages across a network. Benefit 1 ................................................................................................................................... ................................................................................................................................................... Benefit 2 ................................................................................................................................... ................................................................................................................................................... Drawback 1 ............................................................................................................................... ................................................................................................................................................... Drawback 2 ............................................................................................................................... ...................................................................................................................................................

[4]
2
a

Describe serial file organisation as a method of storing data records in a file.

[2]
b

State one example of a use for serial file organisation.

[1]
3
a

Describe the user‑defined data type record.

[3]
b

A programmer defines a record, Order, to store the following data: • account number • order number • order price • order date. Write pseudocode statements to define this record.

[4]
4

Numbers are stored in a computer using binary floating‑point representation with: • 12 bits for the mantissa • 4 bits for the exponent • two’s complement form for both the mantissa and the exponent.

Figure 1 of 2 for question 4
Figure 2 of 2 for question 4
a

Calculate the denary value of the given normalised binary floating‑point number. Show your working. Mantissa 0 1 0 0 0 1 1 1 0 1 1 1 Exponent 0 1 1 1 Working ..................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... Answer ......................................................................................................................................

[2]
b

Calculate the normalised binary floating‑point representation of – 49.1875 in this system. Show your working. Mantissa Exponent Working ..................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... ...................................................................................................................................................

[4]
5
a

Name and describe two protocols used by the Application Layer of the TCP/IP protocol suite. Protocol 1 ................................................................................................................................. Description ................................................................................................................................ ................................................................................................................................................... ................................................................................................................................................... Protocol 2 ................................................................................................................................. Description ................................................................................................................................ ................................................................................................................................................... ...................................................................................................................................................

[4]
b

Explain the purpose and function of the Application Layer in the TCP/IP protocol suite.

[3]
6

The truth table for a logic circuit is shown. INPUT A B C D 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1 OUTPUT X 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0

Figure 1 of 1 for question 6
a

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

[3]
b

Complete the Karnaugh map (K‑map) for the given truth table. AB CD 00 01 11 10 00 01 11 10

[2]
c

Draw loop(s) around appropriate group(s) in the K‑map to produce an optimal sum‑of‑products.

[2]
d

Write the Boolean logic expression from your answer to part (c) as the simplified sum‑of‑products. X = ............................................................................................................................................ .............................................................................................................................................

[2]
7

Several syntax diagrams are shown.

Figure 1 of 4 for question 7
Figure 2 of 4 for question 7
Figure 3 of 4 for question 7
Figure 4 of 4 for question 7
a

State why each number is invalid for the given syntax diagrams. 21 Reason ..................................................................................................................................... ................................................................................................................................................... 123 Reason ..................................................................................................................................... ...................................................................................................................................................

[2]
b

Complete the Backus‑Naur Form (BNF) for the given syntax diagrams. <symbol> ::= ........................................................................................................................ ................................................................................................................................................... <number> ::= ........................................................................................................................ ...................................................................................................................................................

[2]
c(i)

A new syntax rule, code, is required. It must begin with a letter, followed by one or two numbers, and end with a symbol. Draw a syntax diagram for code.

[3]
c(ii)

Write the BNF for code.

[2]
8

Complex Instruction Set Computer (CISC) is a type of processor. Identify four features of a CISC processor. 1 ....................................................................................................................................................... .......................................................................................................................................................... 2 ....................................................................................................................................................... .......................................................................................................................................................... 3 ....................................................................................................................................................... .......................................................................................................................................................... 4 ....................................................................................................................................................... ..........................................................................................................................................................

[4]
9
a

The kernel is the central component of an Operating System (OS). Outline how the kernel of an OS acts as an interrupt handler.

[2]
b(i)

State what is meant by the term multi‑tasking in an Operating System.

[1]
b(ii)

Describe how multi‑tasking is implemented in an Operating System.

[2]
10

Objects and classes form the basic structure of Object‑Oriented Programming (OOP).

a

Outline the structure of a class.

[3]
b

Give three differences between an object and a class. 1 ................................................................................................................................................ ................................................................................................................................................... 2 ................................................................................................................................................ ................................................................................................................................................... 3 ................................................................................................................................................ ...................................................................................................................................................

[3]
11

This binary tree shows an ordered list of integers.

Figure 1 of 2 for question 11
Figure 2 of 2 for question 11
a

A linked list of nodes is used to store the data. Each node consists of a left pointer, the data and a right pointer. –1 is used to represent a null pointer. Complete this linked list to represent the given binary tree organisation.

[4]
b

A 2D array is used to store the nodes of the linked list in part (a). Complete the diagram using your answer for part (a).

[4]
c

The linked list in part (a) is implemented using a 1D array of records. Each record contains a left pointer, data and a right pointer. The following pseudocode represents a function that searches for an element in the array of records LinkList. It returns the index of the record if the element is found, or it returns a null pointer if the element is not found. Complete the pseudocode for the function. FUNCTION SearchList(Item : INTEGER)........................................................................ NullPtr ← −1 .................................................................... ← RootPtr WHILE NowPtr <> NullPtr IF LinkList[NowPtr].Data < Item THEN NowPtr ← LinkList[NowPtr].RightPtr ELSE IF .............................................................................................................. THEN NowPtr ← ..................................................................................................... ELSE RETURN NowPtr ENDIF ENDIF ENDWHILE RETURN NullPtr ENDFUNCTION

[4]

Mark scheme

9618/32 · Oct/Nov 2024

Download PDF

1a · 3 marks

  • 1 mark

    The data to be transmitted is divided into equal sized packets

  • 1 mark

    A packet header is attached to each packet containing key information

  • 1 mark

    … such as source/destination IP addresses, packet number, etc

1b · 4 marks

  • 1 mark

    Benefit: Packets are more likely to arrive because they can be re-routed if a problem occurs with one of the routes//Packets are more likely to arrive because if a packet is lost, it can be re-transmitted

  • 1 mark

    Benefit: Bandwidth can be shared allowing packets from different messages to share the same path

  • 1 mark

    Drawback: Time delay because packets need to be re-ordered/reassembled at the destination//Time delay caused by missing packets needing to be re-sent//Time delay because it has to share the bandwidth of the circuit / channel with other packets

  • 1 mark

    Drawback: Requires a complex algorithm to function

2a · 2 marks

  • 1 mark

    Records are stored one after the other as they are collected // records are stored in chronological order

  • 1 mark

    New records are appended to the end of the file.

2b · 1 mark

  • 1 mark

    Creating unsorted / temporary transaction files // Creating data logging files

3a · 3 marks

  • 1 mark

    A user-defined record data type is a composite data type

  • 1 mark

    It uses other data types in its definition to form a single new data type

  • 1 mark

    The data types referenced may be primitive data types from a programming language or they may be other user-defined data types.

3b · 4 marks

  • 1 mark

    TYPE Order and ENDTYPE correct

  • 1 mark

    Correct use of DECLARE in all declarations seen

  • 1 mark

    The two shaded declarations

  • 1 mark

    The two unshaded declarations

4a · 2 marks

  • 1 mark

    application of exponent to mantissa to go from 0.10001110111 to 01000111.0111 // moving the binary point 7 places // multiplying by 2^7/128 in the fractions method // 64 + 4 + 2 +1 + .25+ .125 + .0625 seen

  • 1 mark

    71.4375 // 71 7/16

4b · 4 marks

  • 1 mark

    correct mantissa – exact answer only (1 0 0 1 1 1 0 1 1 0 1 0)

  • 1 mark

    correct exponent – exact answer only (0 1 1 0)

  • 1 mark

    number converted to binary e.g., positive binary version of 49.1875 = 0110001.0011 // two’s complement version bits flipped and 1 added = 1001110.1101 // –64 + 8 + 4 + 2 + .5 + .25 + .0625 // –64 + 14.8125

  • 1 mark

    use of the exponent e.g. moving the binary point 6 places /  2^6

5a · 4 marks

  • 1 mark

    First correct name

  • 1 mark

    Corresponding expansion for first name

  • 1 mark

    Second correct name

  • 1 mark

    Corresponding expansion for second name

5b · 3 marks

  • 1 mark

    The application layer provides access to all the programs that exchange data // Interacts directly with user.

  • 1 mark

    … used by, for example, web browsers, server software.

  • 1 mark

    Communicates/enables data transfer to/from Transport layer // It allows applications to access the services used in other TCP/IP layers.

6a · 3 marks

  • 3 marks

    All eight correct products and no additional products: (X =) Ā.B̄.C̄.D + Ā.B̄.C.D̄ + Ā.B.C̄.D + Ā.B.C.D̄ + A.B̄.C̄.D + A.B̄.C.D̄ + A.B.C̄.D + A.B.C.D̄

6b · 2 marks

  • 2 marks

    Correct Karnaugh map: Row 00: 0 0 0 0; Row 01: 1 1 1 1; Row 11: 0 0 0 0; Row 10: 1 1 1 1

6c · 2 marks

  • 1 mark

    Correct loop around row 01

  • 1 mark

    Correct loop around row 10

6d · 2 marks

  • 1 mark

    Any correct relevant Boolean term

  • 1 mark

    Boolean terms with correct operator + and no other terms present ((X =) C.D̄ + C̄.D // C̄.D + C.D̄)

7a · 2 marks

  • 1 mark

    21 - a number must begin with an odd digit, 2 is even

  • 1 mark

    123 - a number can only be one or two digits in length not three

7b · 2 marks

  • 1 mark

    <symbol> ::= % | £ | # | @ | $

  • 1 mark

    <number> ::= <odd>|<odd><even>|<odd><odd>

7c(i) · 3 marks

  • 1 mark

    letter, number and symbol all included in correct order: letter first, followed by number, finishing with symbol

  • 1 mark

    provision for one or two numbers including relevant connectors

  • 1 mark

    all other connections and label correct and no additional data

7c(ii) · 2 marks

  • 1 mark

    First correct line in BNF rule definition

  • 1 mark

    Second correct line in BNF rule definition

8 · 4 marks

  • 1 mark

    many instruction formats possible

  • 1 mark

    large instruction set

  • 1 mark

    many addressing modes available

  • 1 mark

    uses variable length/multi-operation instructions

9a · 2 marks

  • 1 mark

    the kernel receives a signal when an interrupt is generated

  • 1 mark

    the kernel checks the priority and reviews the status/priority of the current interrupts

9b(i) · 1 mark

  • 1 mark

    multi-tasking allows computers to carry out / seem to carry out more than one process at a time

9b(ii) · 2 marks

  • 1 mark

    processor time/common hardware and resources is/are shared between tasks

  • 1 mark

    scheduling is used to decide on the processes to be carried out to ensure multi-tasking operates correctly / efficiently / without clashes

10a · 3 marks

  • 1 mark

    Attributes/properties … … with their data types // … are variables bound to the class

  • 1 mark

    Methods … … that are subroutines / functions / procedures that act upon the attributes

  • 1 mark

    Getters/setters … … are methods that can fetch / update the contents of attributes // A constructor … … that is used to create instances / objects of this class.

10b · 3 marks

  • 1 mark

    A class is only defined once but many objects can be created from that class // A class is a template / blueprint from which objects are created // An object is an instance of a class

  • 1 mark

    No memory is allocated when a class is defined, but objects are allocated memory space whenever they are created

  • 1 mark

    A class cannot be manipulated as it is not available in the memory, but objects can be manipulated

11a · 4 marks

  • 1 mark

    Five additional nodes with correct data values

  • 1 mark

    Correct null pointers in all nodes (7) – no extra null pointers where the arrow points to the next node

  • 1 mark

    Correct arrows to represent pointers joining parent nodes to child nodes – must come from the correct left or right pointer not the middle

  • 1 mark

    All nodes in correct order and no additional data in left/right pointer boxes.

11b · 4 marks

  • 3 marks

    First eight rows of table correct (Three marks for all eight correct rows; Two marks for six or seven correct rows; One mark for three, four or five correct rows)

  • 1 mark

    Correct FreePtr (8) with last row of table completely blank

11c · 4 marks

  • 1 mark

    Initialisation / loop condition: NullPtr  -1 and NowPtr  RootPtr / WHILE NowPtr <> NullPtr

  • 1 mark

    IF LinkList[NowPtr].Data < Item THEN NowPtr  LinkList[NowPtr].RightPtr

  • 1 mark

    ELSE IF LinkList[NowPtr].Data > Item THEN NowPtr  LinkList[NowPtr].LeftPtr

  • 1 mark

    ELSE RETURN NowPtr / RETURN NullPtr

Questions

  1. 1
    Question 17 marks
    Mark scheme ›
  2. 2
    Question 23 marks
    Mark scheme ›
  3. 3
    Question 37 marks
    Mark scheme ›
  4. 4
    Question 46 marks
    Mark scheme ›
  5. 5
    Question 57 marks
    Mark scheme ›
  6. 6
    Question 69 marks
    Mark scheme ›
  7. 7
    Question 79 marks
    Mark scheme ›
  8. 8
    Question 84 marks
    Mark scheme ›
  9. 9
    Question 95 marks
    Mark scheme ›
  10. 10
    Question 106 marks
    Mark scheme ›
  11. 11
    Question 1112 marks
    Mark scheme ›

More 9618 papers

Other papers from Oct/Nov 2024

Solve it on ExamPalStart