Cambridge A Level Computer Science 9618 — 2025 May/June Paper 1 · Variant 2

[Turn over Cambridge International AS & A Level This document has 16 pages. Any blank pages are indicated. DC (WW/SG) 341016/3 © UCLES 2025 * 3 1 1 0 8 7 2 2 9 1 * COMPUTER SCIENCE 9618/12 Paper 1 Theory Fundamentals May/June 2025 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. ,










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2 9618/12/M/J/25 © UCLES 2025 1 (a) The table has six statements about the Von Neumann model for a computer system. Three of the statements are incorrect. Statement number Statement 1 The Program Counter (PC) stores the next instruction to be fetched from memory. 2 The Arithmetic and Logic Unit (ALU) performs mathematical and logical operations. 3 The Control Unit (CU) sends signals to other components on the data bus. 4 The Memory Data Register (MDR) transfers data to the memory address stored in the Memory Address Register (MAR). 5 The MAR stores an address from memory. 6 The Accumulator (ACC) stores the result of calculations. Complete the table by writing the three incorrect statement numbers and the corrected statements. Incorrect statement number Corrected statement … … … … … … … … … … … … [3] * 0000800000002 * ,










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3 9618/12/M/J/25 © UCLES 2025 [Turn over (b) Registers that are used in the Fetch-Execute (F-E) cycle include the PC, MAR, MDR and the ACC. Identify one other register and describe its role in the Fetch-Execute (F-E) cycle. Register … Role … … [2] (c) Explain how an interrupt from an input device will be detected and handled in the F-E cycle. … … … … … … … … [4] * 0000800000003 * ,










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4 9618/12/M/J/25 © UCLES 2025 2 (a) Convert the denary integer 558 into 12-bit binary and hexadecimal. Binary … Hexadecimal … [2] (b) (i) Convert the two’s complement binary integer 11100010 into denary. … … … [1] (ii) Write the smallest and the largest two’s complement binary integers that can be represented in 8 bits. Smallest … Largest … [2] (c) Give one application where Binary Coded Decimal (BCD) is used and justify its use. Application … Justification … … [2] * 0000800000004 * ,










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5 9618/12/M/J/25 © UCLES 2025 [Turn over 3 A computer program uses a digital camera to read the words on an item. The program can read the words that are written on the item, translate the words to a chosen language and then output the words as audio. For example, when used in a supermarket, the program can output the words written on the labels on products. The program uses Artificial Intelligence (AI). (a) Explain how AI is used in the computer program described. … … … … … … … … [4] (b) State two social benefits of the use of AI in the computer program described. 1 … … … 2 … … … [2] * 0000800000005 * ,










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6 9618/12/M/J/25 © UCLES 2025 (c) The computer program is released under a commercial software licence. (i) Describe the features of a commercial software licence. … … … … … … [3] (ii) Explain the reasons why an open source software licence might not be appropriate for the computer program described. … … … … … … [3] 4 (a) Write the logic expressions for the following logic circuit. R S X Y T U X = … Y = … [2] * 0000800000006 * ,










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7 9618/12/M/J/25 © UCLES 2025 [Turn over (b) Complete the truth table for the logic expression: X = NOT (A AND (B XOR 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] * 0000800000007 * ,










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8 9618/12/M/J/25 © UCLES 2025 5 An online game has a database that stores data about users and the characters each user creates in the game. Each user can create multiple characters and purchase multiple items for each character. The normalised database has the following design: USER(Username, Password, DateOfBirth) CHARACTER(CharacterName, CharacterID, Username, Level, Money) ITEM(ItemName, MinimumLevel, Cost) CHARACTER_ITEM(CharacterID, ItemName) (a) Explain the purpose of the table CHARACTER_ITEM in the database. … … … … [2] (b) Underline the attribute, or attributes, that form the primary key in each of the tables. USER(Username, Password, DateOfBirth) CHARACTER(CharacterName, CharacterID, Username, Level, Money) ITEM(ItemName, MinimumLevel, Cost) CHARACTER_ITEM(CharacterID, ItemName) [2] * 0000800000008 * ,










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9 9618/12/M/J/25 © UCLES 2025 [Turn over (c) A Database Management System (DBMS) provides data security. (i) Identify two methods the DBMS can use to protect the data in the table USER from unauthorised access. Explain how each method protects the data. Method 1 … Explanation … … … Method 2 … Explanation … … … [4] (ii) The DBMS also supports data integrity. Give two ways that a DBMS can support data integrity. 1 … … 2 … … [2] * 0000800000009 * ,










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10 9618/12/M/J/25 © UCLES 2025 (d) (i) Write a Structured Query Language (SQL) script to count the number of items purchased by the user with the username "KAT123". … … … … … … … [3] (ii) The following changes need to be made to the character with the ID "0002": • level changed to 3 • money changed to 10000.00 Write an SQL script to change the character’s data. … … … … … … [3] * 0000800000010 * ,










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11 9618/12/M/J/25 © UCLES 2025 [Turn over 6 A company has multiple sites in different cities. The company has drivers who deliver products to customers. Each driver can connect to the company’s WAN (Wide Area Network) whilst out of the office using a smartphone. (a) State two ways that a WAN is different to a LAN (Local Area Network). 1 … … 2 … … [2] (b) The smartphones use the cell phone network to connect to the WAN. Explain how data is transmitted using the cell phone network. … … … … … … … … [4] (c) Devices that connect to the WAN have an IP address. Complete the following description of IP addresses by writing the missing words. IPv4 is displayed as four groups of 8-bit numbers separated by … . Each IPv4 address is 32 bits. IPv6 is made of eight groups of 4 … numbers separated by colons. Multiple consecutive groups of … can be replaced with a double colon. Each IPv6 address is … bits. A … IP address can change each time the computer connects to a network. A … IP address can only be accessed by other devices in the same LAN and is assigned by the router within the LAN. [6] * 0000800000011 * ,









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12 9618/12/M/J/25 © UCLES 2025 (d) The main office for the company has four wired computers, one server, two printers, one central switch and a device providing a single point of access for the internet. The network is set up as a star topology. Draw the topology for the main office network. Label all devices. [4] (e) Describe the role of a switch in a network. … … … … … … [3] * 0000800000012 * ,









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13 9618/12/M/J/25 © UCLES 2025 [Turn over BLANK PAGE * 0000800000013 * ,









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14 9618/12/M/J/25 © UCLES 2025 7 (a) The following table shows part of the instruction set for a processor. The processor has one register: the Accumulator (ACC). Instruction Explanation Opcode Operand LDD <address> Direct addressing. Load the contents of the location at the given address to ACC LDM #n Immediate addressing. Load the number n to ACC STO <address> Store the contents of ACC at the given address ADD #n/Bn/&n Add the number n to the ACC ADD <address> Add the contents of the given address to the ACC INC <register> Add 1 to the contents of the register (ACC) CMP <address> Compare the contents of ACC with the contents of <address> CMP #n Compare the contents of ACC with number n JPE <address> Following a compare instruction, jump to <address> if the compare was True JMP <address> Jump to the given address END Return control to the operating system ACC denotes Accumulator <address> can be an absolute or a symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A The current contents of memory are: Address Instruction 10 12 11 11 12 10 13 22 14 22 … 100 LDD 10 101 ADD 12 102 STO 11 103 CMP 14 104 JPE 107 105 INC ACC 106 JMP 101 107 STO 10 108 END * 0000800000014 * ,









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15 9618/12/M/J/25 © UCLES 2025 [Turn over (i) Trace the program currently in memory using the following trace table. Instruction address ACC Memory address 10 11 12 13 14 12 11 10 22 22 [3] (ii) State the effect of changing instruction LDD 10 in address 100 to LDM #10 … … … [1] (iii) Identify and describe one mode of addressing not given in the table of instructions in part (a). Mode of addressing … Description … … … [2] * 0000800000015 * ,









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16 9618/12/M/J/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. (b) The table shows part of the instruction set for a processor. The processor has one register: the Accumulator (ACC). Instruction Explanation Opcode Operand AND #n/Bn/&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/Bn/&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/Bn/&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 symbolic address # denotes a denary number, e.g. #123 B denotes a binary number, e.g. B01001010 & denotes a hexadecimal number, e.g. &4A (i) The ACC currently contains the following binary value. 1 1 1 1 0 0 0 0 Write the result after the instruction OR B00001111 is run. [1] (ii) The ACC currently contains the following binary value. 0 0 0 1 1 1 0 1 Write the result after the instruction XOR #30 is run. [1] * 0000800000016 * ,









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This document consists of 12 printed pages. © Cambridge University Press & Assessment 2025 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9618/12 Paper 1 Theory Fundamentals May/June 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 May/June 2025 series for most Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level components.

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 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. 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 2025 © Cambridge University Press & Assessment 2025 Page 3 of 12 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 standardisation 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 Incorrect To indicate where a key word/phrase/code is missing. Not relevant or used to separate parts of an answer. Indicates a part of the answer that is incorrect. Highlighter To draw attention to a particular aspect or to indicate where parts of an answer have been combined. Too vague. Repetition No examples or not enough. Benefit of Doubt. Not Answered Question. Indicates that work or a page has been seen including blank answer spaces and blank pages. Follow through. Ignore

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 4 of 12 Question Answer Marks 1(a) 1 mark for each correct row Incorrect statement number Corrected statement 1 The Program Counter (PC) stores the address of the next instruction to be fetched from memory. 3 The Control Unit (CU) sends signals to other components on the control bus. 4 The Memory Data Register (MDR) holds data to be stored in the memory address in the MAR. // The Memory Data Register (MDR) holds data read from the memory address in the MAR 3 1(b) 1 mark for name, 1 mark for corresponding role e.g. • Current Instruction Register // CIR • To store the instruction to be decoded / executed next • Status register // SR • To contain bits that can be referenced individually to indicate a state or event • Interrupt register • To store details of any interrupts that have occurred 2 1(c) 1 mark each to max 4 • At the start / end of FE cycle the interrupt register is checked • The priority of any interrupts waiting is checked • if the priority of the interrupt is higher than the current process • the contents of the registers are stored on the stack • The relevant Interrupt Service Routine (ISR) / interrupt handler is called to process the interrupt • When the ISR has finished, a further check is made for higher priority interrupts • if no more interrupts of higher priority, the register contents are restored and the next FE cycle continues 4

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 5 of 12 Question Answer Marks 2(a) 1 mark for: 0010 0010 1110 1 mark for: 22E 2 2(b)(i) 1 mark for: -30 1 2(b)(ii) 1 mark for smallest, 1 mark for largest Smallest: 1000 0000 Largest: 0111 1111 2 2(c) 1 mark for application and 1 mark for corresponding justification e.g. • an application that performs financial / banking calculations • because financial transactions use only two decimal places and must be accurate, no accumulating / rounding errors and it is difficult to represent decimal values exactly in normal binary. Or • electronic displays • because visual displays only need to show individual digits • because conversion between denary and BCD is straightforward Or • The storage of the date and time in the BIOS of a PC • because conversion between denary and BCD is more straightforward Or • Barcode systems • because conversion between denary and BCD can be accurately completed 2

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 6 of 12 Question Answer Marks 3(a) 1 mark each to max 4 e.g. • Uses image recognition // optical character recognition • to analyse a photograph/pixels to identify the location of characters within an image • in order to convert the pattern of pixels into individual characters • Uses natural language • to combine the characters into words • and compare the words to database to identify a match in the language of the writing • it may also predict what is missing / incomplete / from what has been read • then compare the words to a database of the user’s chosen language to find a match and translate • Uses text-to-speech • to generate the audio waveforms corresponding to the words 4 3(b) 1 mark each to max 2 e.g. • It can help people with visual impairment to identify which products to purchase • It can help people who cannot understand the language • It can help to overcome learning / reading difficulties 2 3(c)(i) 1 mark each to max 3 • The program is usually sold for a fee • Users have no access to source code • It protects the intellectual rights of the programmer / developer • Users cannot legally alter or share the program • There are limitations on the use of the software e.g. number of times it can be installed • Support and maintenance is usually provided e.g. updates, bug fixes etc. 3 3(c)(ii) 1 mark each to max 3 e.g. • The source code would be accessible therefore it could be changed • which might lead to the program outputting an incorrect response • so people could purchase the wrong item • which might have serious consequences // by example e.g. allergies 3

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 7 of 12 Question Answer Marks 4(a) 1 mark each: • X = (R NOR S) XOR T • Y = (T AND U) OR U 2 4(b) 1 mark for first four rows, 1 mark for second four rows A B C Working space X 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 1 2

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 8 of 12 Question Answer Marks 5(a) 1 mark each to max 2 • To remove the many-to-many relationship • between CHARACTER and ITEM tables • To allow each character to have many items // to allow each item to be purchased for many characters • by creating a linking table • between the characters and the items purchased for each one 2 5(b) 1 mark for the three single Primary Keys 1 mark for the composite key USER(Username, Password, DateOfBirth) CHARACTER(CharacterName, CharacterID, Username, Level, Money) ITEM(ItemName, MinimumLevel, Cost) CHARACTER_ITEM(CharacterID, ItemName) 2 5(c)(i) 1 mark for method 1 mark for matching explanation e.g. • Access rights • appropriate permissions for the table USER are needed to read or edit the data • A password for the database or the USER table • prevents users without the password from accessing the data • Encrypting the database • stops users without the decryption key from decoding / understanding the data • Views • users can be given a view to the database that does not include the data in the table USER 4 5(c)(ii) 1 mark each to max 2 e.g. • Validation • Enforce referential integrity • Cascade update / delete • Ensuring the database is normalised 2

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 9 of 12 Question Answer Marks 5(d)(i) 1 mark for each point • Select COUNT • FROM (using correct tables) and joining • WHERE (or AND) condition for correct username Example 1: SELECT COUNT(ItemName) FROM CHARACTER_ITEM INNER JOIN CHARACTER ON CHARACTER.CharacterID = CHARACTER_ITEM.CharacterID WHERE CHARACTER.Username = "KAT123"; Example 2: SELECT COUNT(ItemName) FROM CHARACTER_ITEM, CHARACTER WHERE CHARACTER.CharacterID = CHARACTER_ITEM.CharacterID AND CHARACTER.Username = "KAT123"; 3 5(d)(ii) 1 mark for each point • UPDATE character • SET level and money • WHERE condition e.g. UPDATE CHARACTER SET Level = 3, Money = 10000.00 WHERE CharacterID = "0002"; 3

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 10 of 12 Question Answer Marks 6(a) 1 mark each to max 2 • In a WAN devices can connect over a larger geographical area in a LAN devices connect over a smaller geographical area • A WAN may use non-dedicated hardware the hardware in a LAN is usually dedicated • A WAN uses external / not company owned transmission media // the transmission media for a LAN is usually company owned 2 6(b) 1 mark each to max 4 e.g. • Land is split into cells designed for maximum line of sight • Each cell has a tower with an antenna which receives and transmits data • Data is transmitted between the tower and the phone • Data transmission is wireless using low power radio signals/frequencies • Multiple devices can communicate simultaneously with the same tower 4 6(c) 1 mark for each correct word • full stops • hexadecimal • zeros • 128 • dynamic • private IPv4 is made of four groups of 8-bit numbers separated by full stops. Each IPv4 address is 32 bits. IPv6 is made of eight groups of 4 hexadecimal numbers separated by colons. Multiple consecutive groups of zeros can be replaced with a double colon. Each IPv6 address is 128 bits. A dynamic IP address can change each time the computer connects to a network. A private IP address can only be accessed by other devices in the same LAN and is assigned by the router within the LAN. 6

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 11 of 12 Question Answer Marks 6(d) 1 mark each • Server directly connected to the switch • Four labelled computers all connected directly to the switch • Two printers each directly connected to the switch / server / a computer • Router / modem directly connected to the switch / server for internet access e.g. Example only 4 6(e) 1 mark each to max 3 e.g. • To store the MAC addresses of devices connected to it • To receive packets from devices • To forward packets directly to the intended recipient • To provide a central point of connection for the network • to enable connected devices to communicate 3

9618/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2025 © Cambridge University Press & Assessment 2025 Page 12 of 12 Question Answer Marks 7(a)(i) 1 mark for each shaded section Instruction address ACC Memory address 10 11 12 13 14 12 11 10 22 22 100 12 101 22 102 22 103 104 107 22 3 7(a)(ii) 1 mark from: • The number 10 will be loaded into the ACC instead of 12 / contents of address 10 • The addition will give 20 not 22 so the comparison will fail and result in an infinite loop 1 7(a)(iii) 1 mark for name of mode, 1 mark for matching description e.g. • Indirect • The operand points to the memory location that contains the address of the data • Indexed • The address of the data is formed by adding the contents of the Index Register (IX) to the operand • Relative • The address is calculated using its distance from a base address 2 7(b)(i) 1 mark for: 1111 1111 1 7(b)(ii) 1 mark for: 0000 0011