Cambridge A Level Computer Science 9618 — 2024 Oct/Nov Paper 1 · Variant 1

This document has 16 pages. Any blank pages are indicated. [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9618/11 Paper 1 Theory Fundamentals October/November 2024 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. * 7 7 3 6 5 0 3 5 8 3 * DC (LK) 337419/3 © UCLES 2024 ,










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2 9618/11/O/N/24 © UCLES 2024 1 (a) State one difference between a tebibyte and a gigabyte. … … [1] (b) (i) Convert the unsigned binary integer into hexadecimal. 110001100111 Answer … [1] (ii) Convert the two’s complement binary number into denary. 100110010111 Answer … [1] (iii) Convert the Binary Coded Decimal (BCD) into denary. 010101110011 Answer … [1] (c) Subtract the denary number 23 from the two’s complement binary number 01001010 Perform this calculation using binary subtraction. Show your working. Working … … … … … … Answer … [2] * 0000800000002 * ,










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3 9618/11/O/N/24 © UCLES 2024 [Turn over (d) State one reason why binary addition and subtraction can result in overflow. … … [1] * 0000800000003 * ,










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4 9618/11/O/N/24 © UCLES 2024 2 A shop repairs electronic devices, for example mobile phones and tablet computers. The shop owner stores the data about the repairs using a file-based approach. (a) Give one limitation of using a file-based approach to store the data and explain how a relational database addresses this limitation. Limitation … … Explanation … … … … [3] (b) The shop owner creates a relational database called FIXIT. The database stores data about the customers and the devices for repair. Some devices need new parts that are ordered from suppliers. The database FIXIT is designed to include the following tables: PART(PartID, Description, Price, SupplierID) CUSTOMER(CustomerID, FirstName, LastName, ContactNumber) REPAIR(RepairNumber, StartDate, EndDate, CustomerID, Device) REPAIR_PART(PartID, RepairNumber, Quantity) (i) Complete the entity-relationship (E-R) diagram for the given tables. REPAIR_PART CUSTOMER REPAIR PART [3] * 0000800000004 * ,










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5 9618/11/O/N/24 © UCLES 2024 [Turn over (ii) The table shows sample data for the table REPAIR_PART. PartID RepairNumber Quantity ACD128SA 0022 3 PPOR543DWW 0022 1 TR453 0023 1 PPOR543DWW 0023 2 WED5 0024 5 Write a Structured Query Language (SQL) script to define the table REPAIR_PART. Include constraints (restrictions) on the data that can be entered into each field where appropriate. … … … … … … … … … … [5] * 0000800000005 * ,










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6 9618/11/O/N/24 © UCLES 2024 (iii) Suppliers send invoices to the company for the parts that are used. A new table, INVOICE, stores the data about each invoice and whether it has been paid or not. The design for the table INVOICE is shown: INVOICE(InvoiceID, SupplierID, AmountDue, Paid, DatePaid) The table shows sample data for the table INVOICE. InvoiceID SupplierID AmountDue Paid DatePaid 000001 JK675 22.50 TRUE 01/01/2024 000002 WR443 358.99 FALSE 000003 JK675 10.21 FALSE Write an SQL script to return the total amount due to the supplier with the ID of JK675 for all the invoices that have not currently been paid. … … … … … … [3] (c) Complete the table by writing a definition for each of the database terms. Term Definition Referential integrity … … Candidate key … … Tuple … … [3] * 0000800000006 * ,










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7 9618/11/O/N/24 © UCLES 2024 [Turn over 3 A computer system has a dual-core Central Processing Unit (CPU). (a) State the purpose of the system clock and the Control Unit (CU) in a CPU. System clock … … CU … … [2] (b) (i) The number of cores in the processor affects the performance of the computer system. Identify one other feature of a processor that can affect the performance of a computer system and state why it affects the performance. Feature … … Reason … … [2] (ii) A solid state (flash) memory drive is automatically recognised by the computer when it is plugged into a port in the computer. Identify an appropriate type of port to connect the solid state memory drive to the computer. Explain how this port provides an automatic connection. Port … Explanation … … … … [3] * 0000800000007 * ,










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8 9618/11/O/N/24 © UCLES 2024 (c) Identify two disadvantages of using Dynamic RAM (DRAM) instead of Static RAM (SRAM) in a computer system. 1 … … 2 … … [2] (d) The computer system is used to store data received from a temperature sensor every five seconds. The data is stored on an optical disc using an optical disc reader/writer. (i) Describe the principal operation of an optical disc reader/writer. … … … … … … … … [4] (ii) The computer uses a buffer when writing data to the optical disc. Explain the use of a buffer when writing data to the optical disc. … … … … … … [3] * 0000800000008 * ,










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9 9618/11/O/N/24 © UCLES 2024 [Turn over 4 A student uses a laptop to write a program that is saved as a text file. (a) The laptop has utility software and an Operating System (OS). (i) Describe the file management tasks carried out by an OS. … … … … [2] (ii) Explain the need for back-up software. … … … … [2] (b) The student compresses the file before it is emailed to their teacher as an attachment. (i) Explain the benefits to the teacher of the attachment being a compressed file. … … … … … … [3] (ii) Describe one lossless method of compressing a text file. … … … … … … [3] * 0000800000009 * ,










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10 9618/11/O/N/24 © UCLES 2024 (c) The student used a program library when writing their program. Explain the benefits to the student of using library files when writing a program. … … … … … … [3] (d) The program code is written using an Integrated Development Environment (IDE). (i) One presentation feature found in a typical IDE is prettyprint. Identify and describe one other presentation feature found in a typical IDE. Feature … Description … … … [2] (ii) One debugging feature found in a typical IDE is single stepping. Identify and describe one other debugging feature found in a typical IDE. Feature … Description … … … [2] * 0000800000010 * ,










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11 9618/11/O/N/24 © UCLES 2024 [Turn over 5 A security system has both a floodlight (very bright light) and an audio alarm. The data from multiple sensors is analysed and used to: • turn on the floodlight • sound the audio alarm. Sensors can be used to detect: • if doors are open • the external daylight level • if people are detected within a set distance. (a) Complete the table to identify the most appropriate type of sensor for each scenario. Scenario Type of sensor A door is open. The external daylight level is below a set amount. A person is detected within 2 metres. [1] * 0000800000011 * ,









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12 9618/11/O/N/24 © UCLES 2024 (b) The floodlight (X) and audio alarm (Y) operate according to the following criteria: Parameter Description of parameter Binary value Condition A external daylight level 1 Low 0 High B front door 1 Open 0 Closed C person is within 2 m 1 Detected 0 Not detected D back door 1 Open 0 Closed E security system 1 Switched on 0 Switched off The floodlight turns on (X = 1) if: • the security system is switched on and • the external daylight level is low and • a person is detected within 2 m. The audio alarm turns on (Y = 1) if: • the security system is switched on and • one or more doors are open, or a person is detected within 2 m. Write logic expressions for the security system. X = … … Y = … … [2] (c) Explain whether the security system is an example of a monitoring system or a control system. … … … … … … [3] * 0000800000012 * ,









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13 9618/11/O/N/24 © UCLES 2024 [Turn over 6 A car park system uses a camera to record the registration number of each car as it enters and leaves the car park. Explain how artificial intelligence is used in the car park system to identify the car’s registration number. … … … … … … … … [4] 7 Software is distributed with a licence. (a) Give two benefits of distributing software using a shareware software licence. 1 … … 2 … … [2] (b) Give two benefits of distributing software using a commercial software licence. 1 … … 2 … … [2] * 0000800000013 * ,









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14 9618/11/O/N/24 © UCLES 2024 8 A computer designed using the Von Neumann model for a computer system contains general purpose registers and special purpose registers. (a) Describe the purpose of the Status Register (SR). … … … … [2] (b) Identify two differences between general purpose registers and special purpose registers. 1 … … … 2 … … … [2] * 0000800000014 * ,









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15 9618/11/O/N/24 © UCLES 2024 BLANK PAGE * 0000800000015 * ,









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16 9618/11/O/N/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 * 0000800000016 * ,









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This document consists of 9 printed pages. © Cambridge University Press & Assessment 2024 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9618/11 Paper 1 Theory Fundamentals October/November 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 October/November 2024 series for most Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level components.

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 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 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.

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 Page 3 of 9 Question Answer Marks 1(a) 1 mark for: • A tebibyte = 1024 gibibytes / 1 048 576 kibibytes / 240 bytes whereas a gigabyte = 1000 megabytes / 1 000 000 kilobytes / 109 bytes • Tebi is binary prefix giga is denary prefix 1 1(b)(i) 1 mark for: C67 1 1(b)(ii) 1 mark for: −1641 1 1(b)(iii) 1 mark for: 573 1 1(c) 1 mark for working 1 mark for answer. Working Using the two’s complement and adding: 23 in binary = 00010111 so minus 23 is 11101001 0100 1010 + 1110 1001 (1)0011 0011 Direct subtraction: 0100 1010 – 0001 0111 0011 0011 Answer: 0011 0011 2 1(d) 1 mark from: • The answer cannot be represented in the number of bits available • The answer is larger than the maximum positive number that can be stored in the register • The answer is smaller than the most negative number that can be stored in the register 1

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 Page 4 of 9 Question Answer Marks 2(a) 1 mark for limitation and 2 marks for corresponding explanation e.g. Data redundancy // data duplication • Separate linked tables are used • Data items are stored once so reduces data duplication / data redundancy Data inconsistency / Poor data integrity • Data changed once in one place will automatically update elsewhere • Linked data cannot be entered differently in two tables • Referential integrity can be enforced The data structure used depends on the application • Changes to the data structure are managed by the DBMS • … and queries are not dependent on the structure of the data • … and changes to the data do not require programs to be re-written 3 2(b)(i) 1 mark for each correct relation 3 2(b)(ii) 1 mark for each bullet point • Create table REPAIR_PART with opening and closing brackets, all statements inside the brackets • PartID and RepairNumber as varchar (or equivalent) • Quantity as integer • At least 1 appropriate constraint • Dual primary key For example: CREATE TABLE REPAIR_PART( PartID VARCHAR(20) NOT NULL, RepairNumber VARCHAR(4) NOT NULL, Quantity INT NOT NULL, PRIMARY KEY (PartID, RepairNumber) ); 5

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 Page 5 of 9 Question Answer Marks 2(b)(iii) 1 mark for each bullet point • Select SUM of AmountDue • From the correct table and one correct condition • Second correct condition SELECT SUM(AmountDue) FROM INVOICE WHERE SupplierID = "JK675" AND Paid = FALSE; 3 2(c) 1 mark for each correct definition Database Term Definition Referential Integrity All duplicate entries of data between tables are consistent // all foreign keys are matched to an appropriate primary key Candidate Key A field that could be a primary key but is not // an attribute or smallest set of attributes in a table where no tuple has the same value Tuple A row / record in a table // one instance of an entity in a table 3 Question Answer Marks 3(a) 1 mark for system clock and 1 mark for Control Unit System clock • To synchronise operations • ... by creating and transmitting timing signals on the control bus Control Unit • Sends/receives control signals along control bus • Reads an instruction from the contents of the memory location whose address is stored in PC • Coordinates/synchronises the activity of other components in the CPU • Manages the execution of instructions • Controls communication between the components in the CPU 2 3(b)(i) 1 mark for the feature, 1 mark max for the matching reason e.g. Feature: clock speed • Higher clock speed means that more F-E cycles are executed per second // Higher clock speed results in more throughput Feature: bus width • Larger bus width means that more data transferred at the same time 2

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 Page 6 of 9 Question Answer Marks 3(b)(ii) 1 mark for correct port. 2 marks for explanation Port: USB / Universal Serial Bus Explanation: • A voltage change occurs when the drive is plugged in • The computer detects this voltage change • The code of the device is transferred to computer • … the OS finds the code of the device in the list of devices • … and loads the appropriate device driver 3 3(c) 1 mark for each bullet point (max 2) e.g. • DRAM requires constant refresh cycles unlike SRAM • DRAM has lower access speed than SRAM 2 3(d)(i) 1 mark for each bullet point (max 4) • The disc is spun at high speed • A laser is shone onto the disc to read / write • … using optical head to move it into position • … it follows the spiral track from the centre outwards • When writing the laser burns pits to represent the data • When reading the laser reflects from pits and lands • The reflection from a pit and a land is different • ... the differences are interpreted as 1 or 0 4 3(d)(ii) 1 mark for each bullet point (max 3) • The computer and optical disc reader/writer send and receive at different speeds • A buffer allows temporary storage of the data • … so that the computer can transfer data to the buffer at the higher speed • ... and is not held up waiting for data to transfer // so the computer can carry on with other tasks • ... so the optical disc reader/writer is not overloaded • … and so that data is transferred to optical disc reader/writer from the buffer at the slower rate 3

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 Page 7 of 9 Question Answer Marks 4(a)(i) 1 mark for each bullet point (max 2) e.g. • Secondary storage space is divided into file allocation units • Space on secondary storage is allocated to particular files • Maintains/creates directory structures • Specifies the logical method of file storage e.g. FAT or NTFS • Provides file naming conventions • Controls user access // implements access rights //implements password protection // Makes file sharing possible • Controls access to the file by other software • Specifies tasks that can be performed on a file e.g. open, close, delete, copy, create, move, etc • Allows searching for a file 2 4(a)(ii) 1 mark for each bullet point (max 2) • To allow data to be retrieved / restored when lost • To automatically make a duplicate copy of data… • …so the user does not have to remember to backup data • To make regular duplicate copies of data 2 4(b)(i) 1 mark for each bullet point (max 3) e.g. • Less of the teacher’s storage space is used • ... so more student work can be stored • Transmission time is reduced • … so the teacher does not have to wait as long for it to arrive • Bandwidth usage is reduced • … so other transmissions are not adversely affected • Less data allowance is used on the teacher’s email system 3 4(b)(ii) 1 mark for each bullet point (max 3) • Run-Length Encoding // RLE • Repeated sequences of the same characters are replaced by • ... a single copy of the character • ... and a count of the number of characters 3 4(c) 1 mark for each bullet point (max 3) e.g. • It saves development time for the student • … by using pre-written code • There is less testing to do // the routines are more likely to work correctly • … because they have already been tested and are error-free • It results in a more robust program • Subroutines can be used that they do not have the skill to write • … which enables a more complex program to be written 3

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 Page 8 of 9 Question Answer Marks 4(d)(i) 1 mark for correct name, 1 mark for matching description • Expand/collapse code blocks… • … sections of source code that are part of the same block can be expanded to see the content or collapsed so that the overall code is seen • Auto-indentation // auto-formatting... • ... automatically indents/formats code as the user types so that the structure is clear // aids readability 2 4(d)(ii) 1 mark for correct name, 1 mark for matching description • Breakpoints … • … stops the code running on a set line to view the current status/variable contents/program flow • Report window // variable watch window … • … shows the values in variables/data structures and how they change when each line is run 2 Question Answer Marks 5(a) 1 mark for all 3 appropriate sensors Scenario Type of sensor A door is open. Pressure sensor // Infra-red The external daylight-level is below a set amount. Light sensor A person is detected within 2 metres. Infra-red 1 5(b) 1 mark for each correct expression X = E AND A AND C Y = E AND (B OR C OR D) 2 5(c) 1 mark for each bullet point (max 3) for a correct justification No marks for the identification of the system Monitoring system • There is no use of feedback // The light and the alarm are just warnings • The output of the floodlight or the audio alarm does not affect the input of data from the sensors • The system does not have any actuators 3

9618/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2024 © Cambridge University Press & Assessment 2024 Page 9 of 9 Question Answer Marks 6 1 mark for each bullet point (max 4) e.g. • It uses image recognition • The pixels of each image from the camera are stored • … and matched to the expected shape/size/colour of registration number • It uses optical character recognition • The pixels within the registration number area identified are analysed • … and compared to expected characters/letters/numbers 4 Question Answer Marks 7(a) 1 mark for each bullet point (max 2) • The user can test/trial the program before purchasing to see whether it meets needs • There is no initial cost • Users who try the software may spread the word so the developer gets more custom • The developer can get feedback to improve the program 2 7(b) 1 mark for each bullet point (max 2) • The owner/developer can earn a fee • Comprehensive support is usually offered so problems can be easily solved • The software is usually well tested so few bugs 2 Question Answer Marks 8(a) 1 mark for each bullet point (max 2) • To store the value of flags/bits • … that can be changed/set/cleared after arithmetic / logical operations • To allow flags to be checked • … to change instruction sequence 2 8(b) 1 mark for each bullet point (max 2) • Special purpose registers have a specified role in the machine whereas general purpose registers can be used for all purposes defined by the programmer • Special purpose registers hold the state of the program’s execution while general purpose registers hold the program’s data during operations 2