Cambridge IGCSE Computer Science (9-1) 0984 — 2024 May/June Paper 1 · Variant 2

This document has 12 pages. Any blank pages are indicated. [Turn over Cambridge IGCSE™(9–1) DC (JP) 341460 © UCLES 2024 * 4 6 6 7 5 4 1 8 6 9 * COMPUTER SCIENCE 0984/12 Paper 1 Computer Systems May/June 2024 1 hour 45 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. ● 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. ● 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 0984/12/M/J/24 © UCLES 2024 1 Data can be measured in bits. (a) Give the name of the data storage measurement that is equal to 8 bits. … [1] (b) State how many bits there are in a kibibyte (KiB). … [1] (c) Give the name of the data storage measurement that is equal to 1024 gibibytes (GiB). … [1] (d) A 16-bit colour image has a resolution of 512 pixels wide by 512 pixels high. Calculate the file size of the image in kibibytes (KiB). Show all your working. … … … … … Answer … KiB [3] 2 Data can be transmitted from one device to another. (a) Tick (3) one box to show which of the terms is not a method for transmitting data. A serial B simplex C parallel D parity [1] (b) Data is broken down into smaller units to be transmitted from one device to another. Give the name of the unit that data is broken down into. … [1]

3 0984/12/M/J/24 © UCLES 2024 [Turn over (c) Data is often encrypted when it is transmitted from one device to another. (i) Explain how data is encrypted using symmetric encryption. … … … … … … … … [4] (ii) Give the purpose of encryption. … … [1]

4 0984/12/M/J/24 © UCLES 2024 3 Binary is a base 2 number system. (a) Give the name of the number system that is base 16. … [1] (b) Three denary numbers are entered into a computer. The computer converts the numbers and stores them as binary. (i) Give the binary number that would be stored for each of the denary numbers. 10 … 50 … 201 … [3] Working space … … … … … (ii) Explain why the data is converted to binary by the computer. … … … … [2] (c) The two binary integers 00110000 and 01100110 are added together. Add the binary integers using binary addition and show your answer in binary. Show all your working. … … … … … [3]

5 0984/12/M/J/24 © UCLES 2024 [Turn over (d) The denary integer –32 is stored as a two’s complement integer. Calculate the two’s complement integer that would be stored. Show all your working. … … … … … [2] 4 A student uses both system software and application software on their computer. (a) Give one example of system software. … [1] (b) Give two examples of application software. 1 … 2 … [2] (c) Describe the difference between system software and application software. … … … … … [2]

6 0984/12/M/J/24 © UCLES 2024 5 Instructions are processed by a central processing unit (CPU) in a computer. (a) Complete the paragraph about fetching an instruction into the CPU to be processed. Use the terms from the list. Some of the terms in the list will not be used. You should only use a term once. address arithmetic logic unit (ALU) binary control unit (CU) current instruction register (CIR) data denary driver fetch interrupt memory address register (MAR) memory data register (MDR) random access memory (RAM) read only memory (ROM) secondary storage signal The program counter contains the ……………………………………………………… of the next instruction to be processed; this is then sent to the ……………………………………………………… using the address bus. The address is then sent to the ……………………………………………………… . Once the address is received, the instruction stored at the location is sent to the ………………………………………………………, using the ……………………………………………………… bus. The instruction is then sent to the ……………………………………………………… that is built into the ……………………………………………………… . [7] (b) The CPU uses an instruction set to decode the instruction. State what is meant by an instruction set. … … [1]

7 0984/12/M/J/24 © UCLES 2024 [Turn over 6 The table contains statements about error detection methods. Complete the table by giving the correct error detection method for each statement. error detection method statement …………………………………………… An odd or even process can be used. …………………………………………… A value is calculated from the data, using an algorithm. This happens before and after the data is transmitted. …………………………………………… A copy of the data is sent back to the sender by the receiver. …………………………………………… Acknowledgement and timeout are used. …………………………………………… A value is appended to data that has been calculated using the data. This value is checked on data entry. [5] 7 A computer has both a media access control (MAC) address and an internet protocol (IP) address. (a) Tick (3) one box to show which of the statements is correct about the MAC address. A It is assigned by the manufacturer. B It is assigned by a router. C It can be static or dynamic. D It is made up of three different parts. [1] (b) An IP address can have an IPv4 or IPv6 format. (i) Give an example of an IP address that has an IPv4 format. … [1] (ii) Give two characteristics of the IPv6 format. 1 … … 2 … … [2]

8 0984/12/M/J/24 © UCLES 2024 8 A company has a website that is suffering a distributed denial of service (DDoS) attack. (a) Draw and annotate a diagram to show the process of the DDoS. [5] (b) Identify a solution that can be used to help prevent the DDoS attack being successful. … [1]

9 0984/12/M/J/24 © UCLES 2024 [Turn over 9 A company uses both solid-state and optical secondary storage. (a) Explain why a computer needs secondary storage. … … … … [2] (b) Describe three differences between solid-state and optical storage. 1 … … … … 2 … … … … 3 … … … … [6]

10 0984/12/M/J/24 © UCLES 2024 10 A garage uses an expert system to help diagnose any problems with cars that need repair. (a) The expert system is an example of artificial intelligence (AI). Describe what is meant by AI. … … … … [2] (b) A car has a problem with its braking system, so it is brought into the garage. Explain how the expert system operates and how it is used to help diagnose the problem. … … … … … … … … … … [5]

11 0984/12/M/J/24 © UCLES 2024 11 A company has a website. Users use the internet and the world wide web to access the website. (a) Describe the difference between the internet and the world wide web. … … … … [2] (b) The website has a uniform resource locator (URL). The URL has three different parts. Identify the three different parts that are included in the URL. 1 … 2 … 3 … [3] (c) One function of a web browser is to provide an address bar for a user to enter a URL. Give three other functions of a web browser. 1 … 2 … 3 … [3]

12 0984/12/M/J/24 © UCLES 2024 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 12 printed pages. © Cambridge University Press & Assessment 2024 [Turn over Cambridge IGCSE™ (9–1) COMPUTER SCIENCE 0984/12 Paper 1 Theory May/June 2024 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 2024 series for most Cambridge IGCSE, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 2 of 12 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 descriptions 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.

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 3 of 12 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. Mark scheme abbreviations / separates alternative words/phrases within a marking point // separates alternative answers within a marking point underline actual word given must be used by candidate (grammatical variants accepted) bold means that some notion of that term needs to be present max indicates the maximum number of marks that can be awarded ( ) the word/phrase in brackets is not required, but sets the context Note: No marks are awarded for using brand names of software packages or hardware.

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 4 of 12 Question Answer Marks 1(a) (1) byte 1 1(b) 8192 1 1(c) (1) Tebibyte // TiB 1 1(d) One mark for each correct stage of working (max 2):  512  512  262 144 * 2 // multiplied by 16 and divided by 8  524 288/1024 One mark for the correct answer: 512 (KiB) 3 Question Answer Marks 2(a) D 1 2(b) Packet 1 2(c)(i) Data is encrypted and decrypted using the same key (1 mark) Any three from:  Plain text is encrypted into cipher text // cipher text is decrypted into plain text  Data is encrypted using an algorithm …  … that uses a key  The key can be generated using an algorithm  The key is transmitted to the receiver 4 2(c)(ii) Any one from:  To help keep the data secure  To make the data meaningless 1

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 5 of 12 Question Answer Marks 3(a) Hexadecimal 1 3(b)(i) 1010 110010 11001001 3 3(b)(ii) Two from:  Computers use logic gates/switches …  … that only process the values 1 and 0 // that only have two states 2 3(c) One mark for evidence of working, for example 2 carries One mark for each correct nibble (Max 2) 1 1 0 0 1 1 0 0 0 0 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 3 3(d) One marking for evidence of working For example, flip and add One mark for correct binary 11100000 2 Question Answer Marks 4(a) Any one from:  Operating system  Utility software // by example 1

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 6 of 12 Question Answer Marks 4(b) Any two from.: Example:  Word processor  Spreadsheet  Database  Web browser  Image/photo-editor  Video-editor  Email client  Game  Social media app 2 4(c) Any two from:  System software manages/maintains the hardware/software  Applications software allows the user to perform tasks 2

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 7 of 12 Question Answer Marks 5(a) One mark for each correct term in the correct place:  address  memory address register // MAR  random access memory // RAM  memory data register // MDR  data  current instruction register // CIR  control unit // CU 7 5(b) A list of (machine code) commands that can be processed by the CPU 1 Question Answer Marks 6 One mark for each correct method. error detection method statement parity (check/bit/byte/block) An odd or even process can be used. checksum A value is calculated from the data using an algorithm. This happens before and after the data is transmitted. echo check A copy of the data is sent back to the sender by the receiver. automatic repeat query/request // ARQ Acknowledgement and timeout are used. check digit A value is appended to data that has been calculated using the data. This value is checked on data entry. 5

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 8 of 12 Question Answer Marks 7(a) A 1 7(b)(i) An IP address that has numerical values separated by dots that follows the format with a max value of 255 in any xxx xxx.xxx.xxx.xxx Example: 10.245.3.99 1 7(b)(ii) Any two from:  128-bit // 16 bytes  Hexadecimal  Separated by colons  Characters in groups of 4  Has 8 groups of characters  Double colons can be used for sets of (consecutive) zeros (only once) 2

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 9 of 12 Question Answer Marks 8(a) One mark for each part of the diagram that shows:  A perpetrator/third party sending malware // user downloads/installs malware  Each computer is turned into a bot…  … to create a botnet  Third party initiates the attack  All the bots send a request at once to a web server  … crashing the webserver Example: 5 8(b) Proxy server 1 third party bot bot bot bot web server Third party sends malware. Malware turns computers into bots. Botnet Requests Web server cannot handle all the requests and crashes.

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 10 of 12 Question Answer Marks 9(a) Any two from:  To store data/files permanently  … otherwise, data/programs would need to be downloaded/entered/installed every time the computer was used  To allow software to be installed on the computer  For the creation of virtual memory 2 9(b) Any six from (Max 3 for one type only):  Solid-state has no moving parts  … optical does have moving parts  Solid-state is faster to access data  … optical is slower to access data  Solid-state uses less power to operate  … optical uses more power to operate  Solid-state runs quietly  … optical makes more noise  Solid state is more durable/robust  … optical is less durable/robust  Solid state storage has a large storage capacity  … optical has a much smaller limit to its storage capacity  Solid-state is more expensive per GB of data  … optical is cheaper per GB of data  Solid-state stores data onto silicon chips/transistors using logic (floating/control/NAND/NOR) gates to control the movement of electrons  … optical stores data by using lasers to burning pits and lands onto a disk 6

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 11 of 12 Question Answer Marks 10(a) Any two from:  The simulation of intelligent behaviours by computers  A collection of data and the rules for using that data  Has the ability to reason  Has the ability to learn/adapt 2 10(b) Any five from:  The user will enter data into the interface // The user will plug the car into an interface // The user is given questions using the interface  The inference engine will decide which questions to ask  … by using the previous answers given  The inference engine will decide on a diagnosis  … by comparing the data/answers entered to the knowledge base and rule base  … by calculating which option is most likely if there are multiple  The interface will output the diagnosis/result  The explanation system shows how the diagnosis was reached 5

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED May/June 2024 © Cambridge University Press & Assessment 2024 Page 12 of 12 Question Answer Marks 11(a) Any two from:  The internet is the infrastructure  The world wide web is a collection of web pages 2 11(b) Protocol Domain name File name // web page name 3 11(c) Any three from: Example:  Displays a web page  Storing bookmarks/favourites  Recording user history  Allowing use of multiple tabs  Storing cookies  Providing navigation tools  Can set a home page 3