Cambridge A Level Computer Science 9618 — 2022 May/June Paper 1 · Variant 2

This document has 16 pages. Any blank pages are indicated. [Turn over Cambridge International AS & A Level DC (KN) 301924/3 © UCLES 2022 * 4 7 0 8 7 1 2 3 9 8 * COMPUTER SCIENCE 9618/12 Paper 1 Theory Fundamentals May/June 2022 1 hour 30 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use an HB pencil for any diagrams, graphs or rough working. ● Calculators must not be used in this paper. INFORMATION ● The total mark for this paper is 75. ● The number of marks for each question or part question is shown in brackets [ ]. ● No marks will be awarded for using brand names of software packages or hardware.

2 9618/12/M/J/22 © UCLES 2022 1 (a) Draw one line from each image representation term to its correct definition. Term Definition Pixel Bit depth Image resolution File header The number of pixels wide by the number of pixels high The smallest identifiable component of an image Stores data about the image file, e.g. file format, number of bits per pixel, file size The number of bits used to represent each colour [3] (b) The following section of a bitmap image is 10 pixels wide and 5 pixels high. In this example, each colour is represented by a letter, e.g. B is blue. B B B B B B B B B B Y Y P Y Y Y P Y Y Y R R M R P K T T R R B O P Y Y Y P G P P R O R P P P R R R R The complete image can have up to 256 colours. (i) Identify the smallest number of bits that can be used to represent each colour in the complete bitmap image. … [1]

3 9618/12/M/J/22 © UCLES 2022 [Turn over (ii) Calculate an estimate for the file size of the section of the bitmap image shown, giving your answer in bytes. Use your answer from part (b)(i). Show your working. Working … … … … Answer … bytes [2] (c) Describe how changing the colour depth of an image affects its file size. … … … … [2] (d) The first row of pixels in the image from part (b) is shown: B B B B B B B B B B Explain how this row of pixels can be compressed using lossless compression. … … … … [2]

4 9618/12/M/J/22 © UCLES 2022 2 A car has several features. (a) One feature is a lane detection system. This system monitors the lines on either side of the lane. If the car gets too close to one line, the system automatically moves the car away from the line. Explain why the lane detection system is an example of an embedded system. … … … … [2] (b) Two other features: • record the number of miles travelled in the current journey, from when the engine is turned on to when it is turned off • record the total number of miles the car has travelled since it was built. Identify the data that will be stored in the primary and secondary storage of the car for these two features. Primary … … Secondary … … [2] (c) The car has a resistive touchscreen for the user to select options. Tick (3) one box in each row to show whether each statement about a resistive touchscreen is true or false. Statement True False The screen always has five different layers A processor determines the horizontal and vertical coordinates of the point of contact The touchscreen will work if any object touches the screen [1]

5 9618/12/M/J/22 © UCLES 2022 [Turn over 3 The table shows part of the instruction set for a processor. The processor has one general purpose register, the Accumulator (ACC). Instruction Explanation Opcode Operand AND #n Bitwise AND operation of the contents of ACC with the operand AND <address> Bitwise AND operation of the contents of ACC with the contents of <address> XOR #n Bitwise XOR operation of the contents of ACC with the operand XOR <address> Bitwise XOR operation of the contents of ACC with the contents of <address> OR #n Bitwise OR operation of the contents of ACC with the operand OR <address> Bitwise OR operation of the contents of ACC with the contents of <address> <address> can be an absolute or a symbolic address # denotes a denary number, e.g. #123 (a) The ACC currently contains the following positive binary integer: 0 1 1 0 0 1 0 1 Write the bit manipulation instruction that would change the binary integer in ACC to: 1 1 1 1 1 1 1 1 Opcode … Operand … [2] (b) The ACC currently contains the following positive binary integer: 0 1 1 0 0 1 0 1 Write the bit manipulation instruction that would change the binary integer in ACC to: 1 0 0 1 1 0 1 0 Opcode … Operand … [2]

6 9618/12/M/J/22 © UCLES 2022 (c) Convert the following positive binary integer into hexadecimal. 0 1 1 1 1 1 1 0 … [1] (d) A three-place logical shift to the left is performed on the following positive binary integer. Show the result of this logical shift. 0 1 1 1 1 1 1 0 … [1] (e) Convert the denary numbers 127 and 12 to 8-bit binary and then perform the subtraction 12 − 127 in binary. Show your working. 127 in binary … 12 in binary … 12 − 127 in binary … … … … … [3]

7 9618/12/M/J/22 © UCLES 2022 [Turn over 4 A school stores personal data about its staff and students on its computer system. (a) Explain why the school needs to keep both its data and its computer system secure from unauthorised access. Data … … Computer system … … [2] (b) Complete the table by identifying two security threats to the data on a computer. Describe each threat. Give a different prevention method for each threat. Threat Description Prevention method … … … … … … … … … … … … … … … … [6] (c) Data is encrypted when it is transmitted within the school network, or externally such as over the internet. Describe what is meant by encryption and explain why it is used. … … … … [2]

8 9618/12/M/J/22 © UCLES 2022 5 A database, FILMS, stores information about films and actors. Part of the database is shown: ACTOR(ActorID, FirstName, LastName, DateOfBirth) FILM_FACT(FilmID, FilmTitle, ReleaseDate, Category) FILM_ACTOR(ActorID, FilmID) (a) Complete the entity-relationship (E-R) diagram. ACTOR FILM_FACT FILM_ACTOR [2] (b) A composite primary key consists of two or more attributes that together form the primary key. Explain why the table FILM_ACTOR has a composite primary key. … … … … [2]

9 9618/12/M/J/22 © UCLES 2022 [Turn over (c) Complete the SQL script to return the IDs of all the actors in the film with the title Cinderella. SELECT … FROM FILM_ACTOR INNER JOIN … ON FILM_FACT.FilmID = … WHERE FILM_FACT.FilmTitle = … ; [4] (d) Write an SQL script to count the number of films that were released in January 2022. … … … … … … [3]

10 9618/12/M/J/22 © UCLES 2022 (e) A Database Management System (DBMS) is used to create and manipulate the database. Complete the descriptions of the features and tools found in a DBMS using the given terms. Not all terms will be used. Boolean data dictionary data redundancy field names input interface logical schema normalisation operating system output primary keys query structure A DBMS provides data management. This includes the development of a … that stores information about the data stored, such as … and … . The … uses methods, such as an E-R diagram, to show the structure of the database and its relationships. The … processor allows a user to perform searches to find specific data. The DBMS also provides a developer … that allows the user to create tables, forms and reports. [6]

11 9618/12/M/J/22 © UCLES 2022 [Turn over 6 A programmer uses language translators when writing and testing a program. (a) Describe the operation of a compiler. … … … … [2] (b) Describe the operation of an interpreter. … … … … [2] (c) Explain how a programmer can make use of a typical Integrated Development Environment (IDE) when writing and testing a program. Writing … … … … Testing … … … … [4]

12 9618/12/M/J/22 © UCLES 2022 7 Complete the truth table for the following logic expression: X = (A XOR B) AND NOT C A B C Working space X 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 [2] 8 Describe one application of Artificial Intelligence (AI). … … … … … … [3]

13 9618/12/M/J/22 © UCLES 2022 [Turn over 9 (a) The following incomplete table contains four network devices and their descriptions. Complete the table by writing the missing devices and missing descriptions. Device Description … Receives and sends data between two networks operating on the same protocol Wireless Network Interface Card (WNIC) … … … … Restores the digital signal so it can be transmitted over greater distances Wireless Access Point (WAP) … … … [4] (b) Describe three differences between fibre-optic cables and copper cables. 1 … … 2 … … 3 … … [3]

14 9618/12/M/J/22 © UCLES 2022 (c) Ethernet uses Carrier Sense Multiple Access/Collision Detection (CSMA/CD). Describe CSMA/CD. … … … … … … … … [4]

15 9618/12/M/J/22 © UCLES 2022 BLANK PAGE

16 9618/12/M/J/22 © UCLES 2022 Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity. To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series. Cambridge Assessment International Education is part of Cambridge Assessment. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which is a department of the University of Cambridge. BLANK PAGE

This document consists of 9 printed pages. © UCLES 2022 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9618/12 Paper 12 Theory Fundamentals May/June 2022 MARK SCHEME Maximum Mark: 75 Published This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the May/June 2022 series for most Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 2 of 9 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these marking principles. GENERIC MARKING PRINCIPLE 1: Marks must be awarded in line with:  the specific content of the mark scheme or the generic level descriptors for the question  the specific skills defined in the mark scheme or in the generic level descriptors for the question  the standard of response required by a candidate as exemplified by the standardisation scripts. GENERIC MARKING PRINCIPLE 2: Marks awarded are always whole marks (not half marks, or other fractions). GENERIC MARKING PRINCIPLE 3: Marks must be awarded positively:  marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate  marks are awarded when candidates clearly demonstrate what they know and can do  marks are not deducted for errors  marks are not deducted for omissions  answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the question as indicated by the mark scheme. The meaning, however, should be unambiguous. GENERIC MARKING PRINCIPLE 4: Rules must be applied consistently, e.g. in situations where candidates have not followed instructions or in the application of generic level descriptors. GENERIC MARKING PRINCIPLE 5: Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may be limited according to the quality of the candidate responses seen). GENERIC MARKING PRINCIPLE 6: Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or grade descriptors in mind.

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 3 of 9 Question Answer Marks 1(a) 1 mark for 1 correct line 2 marks for 2 or 3 correct lines 3 marks for all 4 correct lines Term Definition Pixel The number of pixels wide by the number of pixels high Bit depth The smallest identifiable component of an image Image resolution Stores data about the image file, e.g. file format, number of bits per pixel, file size File header The number of bits used to represent each colour 3 1(b)(i) 8 1 1(b)(ii) 1 mark for working  10 * 5 * 8 (bits) / 8 // = 50 (pixels) * 8 (bits) / 8 1 mark for answer  50 (bytes) 2 1(c) 1 mark per point  Increasing the colour depth results in increased file size // Decreasing the colour depth results in smaller file size  Increasing the colour depth means more bits per pixel and hence more data stored // Decreasing the colour depth means fewer bits per pixel and hence less data stored 2 1(d) 1 mark per point  Use run-length encoding // RLE  Record the colour Blue, and the number of times it occurs 10 2

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 4 of 9 Question Answer Marks 2(a) 1 mark per point to max 2  The lane detection system is built into / integrated into the car  The lane detection system only performs one task  The lane detection system is not easily changed/updated by the car owner 2 2(b) 1 mark for primary  e.g. Miles travelled in the current journey, before the engine is turned off 1 mark for secondary  e.g. Total miles travelled since the car was built // miles for most recent journey after engine switched off 2 2(c) 1 mark for all correct ticks Statement True False The screen always has five different layers  A processor determines the horizontal and vertical coordinates of the point of contact  The touchscreen will work if any object touches the screen  1 Question Answer Marks 3(a) 1 mark for correct opcode and 1 mark for corresponding operand OR #255 // OR #154 // XOR #154 e.g.  OR...  ... #255 2 3(b) 1 mark for correct opcode and 1 mark for corresponding operand XOR #255 e.g.  XOR...  ... #255 2 3(c) 7E 1 3(d) 11110000 1

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 5 of 9 Question Answer Marks 3(e) 1 mark per point  Correct conversion to binary 01111111 (127) and 00001100 (12)  Working e.g. turning 01111111 into two's complement 10000001  Answer: 1000 1101 3 Question Answer Marks 4(a) 1 mark per point, max 1 for data and max 1 for computer system Data  Data needs protecting from someone amending / deleting or taking it Computer System  Computer system need protecting to stop people for example, installing malware or damaging the system 2 4(b) 1 mark for each correct threat, matching description and prevention e.g. Threat Description Prevention method Virus Malicious software that replicates itself and can corrupt data Anti-virus / Firewall / Anti-malware Hacker Unauthorised access to the computer with malicious intent Firewall / strong or biometric passwords / user permissions 6 4(c) 1 mark per point to max 2  Data is turned into cipher text // Data is encoded  Used so that it cannot be understood if intercepted without the decryption key 2

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 6 of 9 Question Answer Marks 5(a) 1 mark for each correct relationship 2 5(b) 1 mark per point  Neither key uniquely identifies each tuple by itself  One actor cannot appear in the same film twice so together they are unique 2 5(c) 1 mark per correct entry SELECT FILM_ACTOR.ActorID / ActorID FROM FILM_ACTOR INNER JOIN FILM_FACT ON FILM_FACT.FilmID = FILM_ACTOR.FilmID WHERE FILM_FACT.FilmTitle = "Cinderella" ; 4 5(d) 1 mark per point  COUNT and correct fieldname  SELECT and FROM statements, including the table name in FROM  WHERE statement e.g. SELECT COUNT(FilmID) FROM FILM_FACT WHERE ReleaseDate >= #01/01/2022# AND ReleaseDate <= #31/01/2022#; // WHERE ReleaseDate BETWEEN #01/01/2022# AND #31/01/2022#; // WHERE ReleaseDate = “January 2022”; 3 ACTOR FILM_FACT FILM_ACTOR

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 7 of 9 Question Answer Marks 5(e) 1 mark for each correctly completed term  data dictionary  field names // primary keys  primary keys //field names  logical schema  query  interface A DBMS provides data management. This includes the development of a data dictionary that stores information about the data stored, such as field names and primary keys. The logical schema uses methods such as an E-R diagram to show the structure of the database and its relationships. The query processor allows a user to perform searches to find specific data. The DBMS also provides a developer interface that allows the user to create tables, forms and reports. 6 Question Answer Marks 6(a) 1 mark per point to max 2 e.g.  Attempts to translate the whole source code  Creates a separate error report at the end of the translation process  If translation successful / no errors creates an executable file 2 6(b) 1 mark per point to max 2 e.g.  Reads each line then translates it and executes it  Stops when an error is encountered // displays errors where it finds them 2 6(c) 1 mark per point, max 2 for writing, max 2 for testing Writing e.g.  Enter code into an editor  Pretty printing to identify key terms  Context-sensitive prompts to help complete statements  Expand and collapse code blocks  Auto-complete to suggest what to type next  Auto-formatting to indent code blocks  Dynamic syntax checking Testing e.g.  Single stepping to run the code line by line  Breakpoints to stop the code at set points to check values  Report window to see how variables change 4

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 8 of 9 Question Answer Marks 7 1 mark for first 4 rows, 1 mark for second 4 rows (shaded) A B C Working space X 0 0 0 0 0 0 1 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0 2 Question Answer Marks 8 1 mark for identification of an application Max 2 marks for relevant description e.g.  Police identifying wanted people  Uses image recognition  ... to identify features/characteristics/items in an image  Natural language interfaces  Use speech recognition to identify words that are spoken  ... and adapts to learn regional accents  Self-driving cars  Detects its position on the road and within the traffic  Follows a route // Collision avoidance // Self-parking etc.  Spoken Interfaces  Use natural language processing  ... to take a sentence and work out its meaning  Game playing  Models characters in a computer game  ... to allow computer characters to react according to the player's movements 3

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2022 © UCLES 2022 Page 9 of 9 Question Answer Marks 9(a) 1 mark for each completed name or description Device Description Router Receives and sends data between two networks operating on the same protocol Wireless Network Interface Card (WNIC) Hardware component that allows a device to connect to a wireless network // Provides a MAC address to the device to identify it on the wireless network Repeater Restores the digital signal so it can be transmitted over greater distances Wireless Access Point (WAP) Hardware component that provides radio communication from the central device to nodes on the network (and vice versa) 4 9(b) 1 mark for each difference e.g.  Fibre optic data is transmitted using light, copper cable through electrical signals  Fibre optic has higher bandwidth than copper cable // Fibre optic has higher transmission rates than copper cable  Fibre optic has smaller risk of (noise) interference than copper cable  Fibre optic can be used over longer distances than copper cable before repeaters are needed  Fibre optic is much more difficult to hack into than copper cable  Fibre optic is more prone to damage than copper cable 3 9(c) 1 mark per point to max 4  A workstation / node (wishing to transmit) listens to the communication channel  …data is only sent when the channel is free // ... if channel is free data is sent  Because there is more than one computer connected to the same transmission medium  ... two workstations can start to transmit at the same time, causing a collision  If a collision happens, the workstations send a (jamming) signal / abort transmission  …and each waits a random amount of time before attempting to resend 4