Cambridge IGCSE Computer Science (9-1) 0984 — 2025 Oct/Nov Paper 1 · Variant 2

This document has 12 pages. Any blank pages are indicated. [Turn over DC (KAS) 366245/2 R © UCLES 2025 * 9 5 1 4 9 8 5 1 5 8 * COMPUTER SCIENCE 0984/12 Paper 1 Computer Systems October/November 2025 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. Cambridge IGCSE™(9–1) ,










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2 0984/12/O/N/25 © UCLES 2025 1 A toy store gives each of the toys it sells a unique code. The codes are 3-digit hexadecimal codes, for example A4B. A computer is used to store a database of the codes. The computer has 12-bit registers. (a) Give the largest hexadecimal number that can be stored in a 12-bit register. … [1] (b) Give the largest denary number that can be stored in a 12-bit register. … [1] (c) Two toys have the hexadecimal codes 429 and 1A3. Convert the two hexadecimal codes to 12-bit binary numbers. 429 … 1A3 … [2] Working space … … … … … (d) Two binary numbers that are stored in the registers are 100010100001 and 011100001011. Convert the two binary numbers to hexadecimal numbers. 100010100001 … 011100001011 … [2] Working space … … … … … * 0000800000002 * ,










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3 0984/12/O/N/25 © UCLES 2025 [Turn over (e) The hexadecimal code for each toy is stored in a barcode that is displayed on each toy. Each time a customer buys a toy, the barcode is scanned and the amount of stock stored in the database for that toy is reduced by 1. An item of hardware is used in this system to receive the hexadecimal code from the barcode scanner and find it in the database. The item of hardware is built into a single chip. (i) Identify the name of the item of hardware. … [1] (ii) Tick (✓) one box to show whether a barcode scanner is a type of input, output, process or storage device. A input B output C process D storage [1] (iii) The barcode scanner contains a sensor. Identify the type of sensor that the barcode scanner could contain. … [1] (iv) A backup of the database is made at the end of each day using optical storage. Describe how the database is written to the optical storage. … … … … … … … … [4] * 0000800000003 * ,










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4 0984/12/O/N/25 © UCLES 2025 2 Two binary numbers are stored in a computer. (a) Add the two binary numbers using binary addition. Give your answer in binary. Show all of your working. 11110101 + 00111001 [4] (b) A logic right shift of three places is performed on the binary number 11110101. Give the denary number for the binary number that would be stored after the logical shift of three places has occurred. Show all of your working. Working space … … … … … Denary number … [3] 3 A programmer uses assembly language to create a program for a coffee machine. (a) Describe what is meant by assembly language. … … … … [2] (b) Identify the translator needed for assembly language. … [1] (c) Tick (✓) one box to show which statement is an advantage of using assembly language. A It is close to human language. B It is memory efficient. C It is easy to debug. D It is machine independent. [1] * 0000800000004 * ,










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5 0984/12/O/N/25 © UCLES 2025 [Turn over 4 A computer with a Von Neumann architecture has a central processing unit (CPU) that performs the fetch–decode–execute (FDE) cycle. (a) Complete and annotate the diagram to show how instructions are decoded and executed. control unit (CU) arithmetic logic unit (ALU) [5] (b) The CPU is dual core and has a processor speed of 2.4 GHz. Describe what is meant by a core. … … … … [2] (c) Explain two ways that the performance of the CPU could be increased. … … … … … … … … [4] * 0000800000005 * ,










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6 0984/12/O/N/25 © UCLES 2025 5 A computer system has a mouse. An interrupt is sent to the CPU every time a button on the mouse is clicked. (a) Identify the name of this type of interrupt. … [1] (b) The interrupt is placed in a queue. Explain how the interrupt is serviced after it is placed in the queue. … … … … … … … … [4] (c) The mouse is connected using a universal serial bus (USB) connection. (i) Explain how data is sent using the USB connection. … … … … [2] (ii) Give two benefits of using a USB connection for this purpose. 1 … … 2 … … [2] (iii) Give one drawback of using a USB connection for this purpose. … … [1] * 0000800000006 * ,










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7 0984/12/O/N/25 © UCLES 2025 [Turn over 6 An online clothing company has a homepage at the uniform resource locator (URL) https://www.cieclothes.com/index.html (a) Write down the three different parts of the URL shown by the labels a, b and c. https://www.cieclothes.com/index.html a b c a … c … b … [3] (b) The web pages are stored on a web server. A proxy server is used to stop distributed denial of service (DDoS) attacks on the web server. Describe how the proxy server can stop a DDoS attack reaching a web server. … … … … … … [3] * 0000800000007 * ,










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8 0984/12/O/N/25 © UCLES 2025 (c) Customers use the website to buy clothing from the company. Complete the table with the missing terms and descriptions about retrieving and displaying web pages. Term Description hypertext markup language (HTML) … … … domain name server (DNS) … … … … It is a numerical address used to locate the web server. … It is a secure protocol that can be used to transmit data sent to and received from a web server. … It is a piece of software that is used to display web pages. [5] * 0000800000008 * ,










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9 0984/12/O/N/25 © UCLES 2025 [Turn over (d) The clothing company uses cookies to store customer details. Complete the statements about cookies. Use terms from the list. Not all terms need to be used. You should only use a term once. asymmetric DNS dynamic persistent session static symmetric user utility software web browser Cookies are stored and managed by the … . … cookies are temporary files that are created when a user visits a web page. … cookies are permanent files that are created when a user visits a web page. [3] 7 A house has a smart speaker that can take voice commands as input. A person in the house can tell the smart speaker to play music or audio books. (a) The smart speaker cannot be described as a robot. Explain why the smart speaker is not a robot. … … … … … … [3] (b) Identify the input device that allows voice commands to be used as input. … [1] * 0000800000009 * ,










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10 0984/12/O/N/25 © UCLES 2025 (c) The smart speaker has machine learning capabilities. Explain how the smart speaker can use machine learning to improve the voice command input. … … … … … … … … [4] (d) The smart speaker is an example of an embedded system. Explain why the smart speaker is an embedded system. … … … … [2] (e) The music and audio books that are played by the smart speaker are stored in cloud storage. Give two advantages of storing the music and audio books in cloud storage. 1 … … 2 … … [2] * 0000800000010 * ,










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11 0984/12/O/N/25 © UCLES 2025 (f) The data for the music and audio books needs to be checked for errors after being transmitted from the cloud. (i) Explain how errors may occur in the data during transmission. … … … … [2] (ii) Give two error detection methods that could be used to check for errors in the data after transmission. 1 … 2 … [2] * 0000800000011 * ,









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12 0984/12/O/N/25 © UCLES 2025 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 * 0000800000012 * ,









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This document consists of 13 printed pages. © Cambridge University Press & Assessment 2025 [Turn over Cambridge IGCSE™ (9–1) COMPUTER SCIENCE 0984/12 Paper 1 Computer Systems October/November 2025 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 October/November 2025 series for most Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level components.

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 2 of 13 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alon gside 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 October/November 2025 © Cambridge University Press & Assessment 2025 Page 3 of 13 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 thre sholds or grade descriptors in mind.

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 4 of 13 Annotations guidance for centres Examiners use a system of annotations as a shorthand for communicating their marking decisions to one another. Examiners are trained during the standardisation process on how and when to use annotations. The purpose of annotations is to inform the standard isation and monitoring processes and guide the supervising examiners when they are checking the work of examiners within their team. The meaning of annotations and how they are used is specific to each component and is understood by all examiners who mark the component. We publish annotations in our mark schemes to help centres understand the annotations they may see on copies of scripts. Note that there may not be a direct correlation between the number of annotations on a script and the mark awarded. Similarly, the use of an annotation may not be an indication of the quality of the response. The annotations listed below were available to examiners marking this component in this series. Annotations Annotation Meaning Correct point Incorrect point Unclear response Follow through Repetition Ignore Benefit of doubt given Content of response too vague Not answered question Omission

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 5 of 13 Annotation Meaning Section not relevant Section incorrect Highlighter Information copied from the text Page or response seen by examiner 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) 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 October/November 2025 © Cambridge University Press & Assessment 2025 Page 6 of 13 Question Answer Marks 1(a) FFF 1 1(b) 4095 1 1(c) 0100 0010 1001 0001 1010 0011 2 1(d) 8A1 70B 2 1(e)(i) Microprocessor 1 1(e)(ii) A 1 1(e)(iii) Light 1 1(e)(iv) Any four from: • The disk is spun • A laser is shone onto the disk • Pits are burnt into the disk • Pits are in a (spiral) track • Pits and lands represent binary values 4

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 7 of 13 Question Answer Marks 2(a) One mark for each correct nibble (2) One mark for a correct method of working for example 4 or 5 correct carries One mark for showing an overflow error (1) 111 1 11110101 + 00111001 1 0010 1110 4 2(b) One mark for showing the binary number after the shift One mark for valid method of working to convert to denary One mark for correct denary number • 00011110 • 16 + 8 + 4 + 2 • 30 3 Question Answer Marks 3(a) Any two from: • Low-level language • Uses mnemonics • Used to communicate directly with the computer hardware 2 3(b) Assembler 1 3(c) B 1

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 8 of 13 Question Answer Marks 4(a) One mark for each correct part of the diagram. The diagram shows: • CIR is built into CU • CIR stores instruction • CU decodes the instruction • Instruction is decoded using an instruction set // Instruction is separated into opcode and operand • Signal is sent from CIR to ALU (to execute) • CU sends signal to RAM to fetch any data needed for instruction • ACC is built into ALU • ACC stores any data needed for instruction • ALU executes the instruction // ALU performs the mathematic/logical operation (needed by the instruction) Example: 5 4(b) Any two from: • Independent/self-contained processing unit • It executes/processes instructions // It performs the FDE cycle • It contains registers/units (to process data) 2 control unit (CU) arithmetic logic unit (ALU) CIR ACC Instruction is stored in CIR CU uses an instruction set to decode instruction and sends a signal to ALU to execute the instruction ACC stores data needed to execute instruction

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 9 of 13 Question Answer Marks 4(c) Four from (MAX 2 if no expansion given): • The number of cores could be increased // by example … • … this means that more instructions can be processed simultaneously • The clock speed could be increased // by example … • … this means that more instructions can be processed (by a core) per second • The cache could be increased // by example … • … this means that more frequently used data/instructions can be stored (to be accessed faster than RAM) 4 Question Answer Marks 5(a) Hardware (interrupt) 1 5(b) Any four from: • Checks the priority of the interrupt • If priority is higher, it halts the current process • … stores it on a stack • … fetches the interrupt • … checks the source of the interrupt • … calls the interrupt service routine (ISR) / interrupt handler to process the interrupt • If priority is not higher, it continues with current process 4 5(c)(i) • It is sent one bit at a time • It is sent down a single wire 2

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 10 of 13 Question Answer Marks 5(c)(ii) Any two from: • The mouse can be powered by the device • It is a universal connection • It is backward compatible • Less chance of skewing // Less chance of errors • Supports different data transmission speeds • Adequate transmission speeds • The cable cannot be inserted incorrectly • The device is automatically detected // Driver is automatically installed when device is connected 2 5(c)(iii) Any one from: • Slower transmission than a parallel connection • Wire may get in the way // wire may limit movement of mouse 1 Question Answer Marks 6(a) One mark for each correct label • Protocol • Domain name • Web page name // file name 3 6(b) Any three from: • It examines each request/incoming transmission • It can slow down the rate at which/limits the number of requests sent to the server • It can use caching … • … to respond to the request (rather than forwarding it to the server) • It can stop any requests from a certain IP 3

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 11 of 13 Question Answer Marks 6(c) One mark for each correct missing term or definition. Term Description hypertext markup language (HTML) It is the language that is often used to write/author web pages. domain name server (DNS) It is a system that stores URLs/domain names and their matching/corresponding IP addresses // It is a system that provides the matching IP address for a webpage to the web browser. IP address It is a numerical address used to locate the web server. SSL/TLS/HTTPS It is a secure protocol that can be used to transmit data sent to and from a web server. web browser It is a piece of software that is used to display web pages. 5 6(d) One mark for each correct missing term in the correct place. Cookies are stored and managed by the web browser. Session cookies are temporary files that are created when a user visits a web page. Persistent cookies are permanent files that are created when a user visits a web page. 3

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 12 of 13 Question Answer Marks 7(a) • It does not have a mechanical structure • It does not have any actuators • … so it cannot move itself 3 7(b) Microphone 1 7(c) Any four from: For example: • Gather data from the same/different voices // It can ask a user to say lots of different words • Analyse/identify patterns in a user’s voice • It can adapt its own processes • It can learn to identify a user’s voice • Stores successful/unsuccessful voice commands • It can learn different ways of making the same request • It can learn the different pronunciations // It can learn different accents • It can learn by listening to lots of different voices • It can learn to ignore any background/environmental noise if a user is speaking 4 7(d) Any two from: • It has a single/limited function • It has dedicated hardware • It has a microprocessor • Its function is not easily changed 2

0984/12 Cambridge IGCSE (9–1) – Mark Scheme PUBLISHED October/November 2025 © Cambridge University Press & Assessment 2025 Page 13 of 13 Question Answer Marks 7(e) Any two from: For example: • The music/books can be easily accessed from any smart speaker • The user doesn’t need to purchase a secondary storage device for the books/music // Smart speaker doesn’t need a large amount of secondary storage • The user doesn’t need to maintain the storage needed for the books/music • Smart speaker can be smaller in size (as it doesn’t need large amounts of secondary storage) • Almost unlimited storage available for the books/music // Easy to increase storage capacity needed 2 7(f)(i) Any two from: • Data could be lost • Data could be gained • Data could be changed • Skewing of data could occur • Interference could occur • Crosstalk could occur • Data collisions could occur • Data packets could time out/reach their hop count 2 7(f)(ii) Any two from: • Parity byte check • Parity block check • Checksum • Echo check • ARQ 2