Cambridge A Level Computer Science 9618 — 2023 Oct/Nov Paper 1 · Variant 3

This document has 16 pages. Any blank pages are indicated. [Turn over Cambridge International AS & A Level DC (EF/CT) 318311/1 © UCLES 2023 * 4 6 7 3 9 4 4 9 5 0 * COMPUTER SCIENCE 9618/13 Paper 1 Theory Fundamentals October/November 2023 1 hour 30 minutes You must answer on the question paper. No additional materials are needed. INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use an HB pencil for any diagrams, graphs or rough working. ● Calculators must not be used in this paper. INFORMATION ● The total mark for this paper is 75. ● The number of marks for each question or part question is shown in brackets [ ]. ● No marks will be awarded for using brand names of software packages or hardware.

2 9618/13/O/N/23 © UCLES 2023 1 (a) State what is meant by analogue data. … [1] (b) Draw one line from each term to its most appropriate description. Term Description sampling the number of samples taken per second sampling rate taking measurements at regular intervals and storing the values sampling resolution the number of bits used to store each sample [2]

3 9618/13/O/N/23 © UCLES 2023 [Turn over 2 (a) Describe the impact of increasing the image resolution on the quality of a bitmap graphic. … … … … [2] (b) Calculate the file size of a bitmap image using the following information: • image resolution of 2048 pixels wide and 1024 pixels high • bit depth of 16 bits. Give your answer in kibibytes. Show your working. Working … … … … … Answer in kibibytes … [2]

4 9618/13/O/N/23 © UCLES 2023 3 A company sells online Computer Science courses to students in different countries. The courses are stored on a public cloud. (a) (i) Explain why the company uses a public cloud to store these courses. … … … … [2] (ii) Describe two disadvantages of storing data on a public cloud compared to storing data on a server in a Local Area Network (LAN). 1 … … … … 2 … … … … [4] (iii) State how the following security measures can be used to protect computer systems. Firewall … … Encryption … … Passwords … … [3]

5 9618/13/O/N/23 © UCLES 2023 [Turn over (b) The company uses a database, COURSES, to store data about the courses and their tutors. Each course starts at different times of the year and may have a different tutor. The database has the following structure: COURSE_INFORMATION(CourseID, Description, Cost) TUTOR(TutorID, TelephoneNumber, EmailAddress, TutorName) COURSE_SCHEDULE(CourseID, DateStarted, TutorID) (i) Complete the entity‑relationship (E‑R) diagram for the database COURSES. COURSE_SCHEDULE TUTOR COURSE_INFORMATION [1] (ii) Write the Structured Query Language (SQL) script to return the total number of courses that have started after 9 September 2023. The value returned must have an appropriate field name. … … … … … … [4]

6 9618/13/O/N/23 © UCLES 2023 (c) An example of a tutor ID is NK16C6. An administrative officer enters the tutor ID into the TUTOR table. Explain how data verification can be used when the tutor ID is entered. … … … … … … … … [4]

7 9618/13/O/N/23 © UCLES 2023 [Turn over 4 (a) Complete the truth table for the logic expression: Y = ((P AND Q) XOR ((NOT Q) OR R)) AND NOT P P Q R Working space Y 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] (b) Draw a logic circuit for the logic expression: Y = ((P AND Q) XOR ((NOT Q) OR R)) AND NOT P P Q Y R [2]

8 9618/13/O/N/23 © UCLES 2023 5 A programmer uses an Integrated Development Environment (IDE) to develop a program that monitors air quality. (a) Describe the following features of a typical IDE. Context‑sensitive prompts … … … … Single stepping … … … … … [4] (b) The program is distributed by downloading the source code and its library files from a web server. (i) Explain the reasons for compressing the files. … … … … [2] (ii) The program files are stored on a new hard disk after they have been downloaded. Describe the reasons why a hard disk formatter is needed for the new hard disk. … … … … … … [3]

9 9618/13/O/N/23 © UCLES 2023 [Turn over 6 (a) State two benefits to a programmer of distributing a program using a shareware licence. 1 … … 2 … … [2] (b) Explain why it is important for a programmer to join a professional ethical body. … … … … … … … … [4]

10 9618/13/O/N/23 © UCLES 2023 7 A laptop computer has Static RAM (SRAM). A virtual reality headset and a laser printer are connected to the laptop. (a) Explain why Static RAM is used in the laptop instead of Dynamic RAM. … … … … [2] (b) Identify two reasons for using Electrically Erasable Programmable ROM (EEPROM) in a virtual reality headset. 1 … … 2 … … [2] (c) Describe how the laser printer makes use of a buffer. … … … … … … … … [4]

11 9618/13/O/N/23 © UCLES 2023 [Turn over (d) Identify one port that could be used to connect the virtual reality headset to the laptop. Justify your choice. Port … Justification … … … … [3]

12 9618/13/O/N/23 © UCLES 2023 8 (a) Data verification is one method of protecting the integrity of data. Describe one other method of protecting the integrity of data. … … … … [2] (b) State one difference and one similarity between pharming and phishing. Difference … … Similarity … … [2] (c) Explain how the data security risks of malware can be restricted. … … … … … … [3]

13 9618/13/O/N/23 © UCLES 2023 [Turn over 9 A computer system is designed using the basic Von Neumann model. Registers and buses are components in the Von Neumann model. (a) (i) Identify three other components in the Von Neumann model of a computer system. Do not include registers or buses in your answers. 1 … 2 … 3 … [3] (ii) Identify two differences between special purpose registers and general purpose registers. 1 … … 2 … … [2]

14 9618/13/O/N/23 © UCLES 2023 (b) The following incomplete table contains steps of the Fetch‑Execute (F‑E) cycle and their descriptions. Complete the table by writing the missing steps using register transfer notation and the missing descriptions. Step Description … The address in PC is incremented. MDR [[MAR]] … … … MAR [PC] … … … … The contents of MDR are copied into CIR. [4] (c) Interrupts can be caused by software programs or hardware devices. State one cause of a software interrupt. … … [1]

15 9618/13/O/N/23 © UCLES 2023 (d) The following statements describe the stages that the CPU performs when an interrupt is detected. There are three missing statements. Write the letter of the missing statements from the table in the correct place to complete the description. 1 At the end of each Fetch‑Execute (F‑E) cycle, the processor checks if an interrupt flag is set. 2 … 3 If the interrupt priority is high enough, the processor saves the current contents of the registers. 4 … 5 When servicing of the interrupt is complete, the processor restores the registers. 6 … Letter Stage A The address of the Interrupt Service (ISR) handling routine is loaded into the Program Counter (PC). B Lower priority interrupts are re‑enabled. C The device causing the interrupt transfers data to the CPU. D The processor identifies the source of the interrupt and checks the priority of the interrupt. E The ISR is incremented. [3]

16 9618/13/O/N/23 © UCLES 2023 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 10 printed pages. © UCLES 2023 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9618/13 Paper 1 Theory Fundamentals October/November 2023 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 2023 series for most Cambridge IGCSE, Cambridge International A and AS Level components, and some Cambridge O Level components.

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 2 of 10 Generic Marking Principles These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these marking principles. GENERIC MARKING PRINCIPLE 1: Marks must be awarded in line with: • the specific content of the mark scheme or the generic level descriptors for the question • the specific skills defined in the mark scheme or in the generic level descriptors for the question • the standard of response required by a candidate as exemplified by the standardisation scripts. GENERIC MARKING PRINCIPLE 2: Marks awarded are always whole marks (not half marks, or other fractions). GENERIC MARKING PRINCIPLE 3: Marks must be awarded positively: • marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the scope of the syllabus and mark scheme, referring to your Team Leader as appropriate • marks are awarded when candidates clearly demonstrate what they know and can do • marks are not deducted for errors • marks are not deducted for omissions • answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the question as indicated by the mark scheme. The meaning, however, should be unambiguous. GENERIC MARKING PRINCIPLE 4: Rules must be applied consistently, e.g. in situations where candidates have not followed instructions or in the application of generic level descriptors. GENERIC MARKING PRINCIPLE 5: Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may be limited according to the quality of the candidate responses seen). GENERIC MARKING PRINCIPLE 6: Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or grade descriptors in mind.

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 3 of 10 Question Answer Marks 1(a) 1 mark for: • data values that are continuously changing // variable // any value 1 1(b) 1 mark for 1 correct line 2 marks for 3 correct lines Term Description sampling the number of samples taken per second sampling rate taking measurements at regular intervals and storing the values sampling resolution the number of bits used to store each sample 2 Question Answer Marks 2(a) 1 mark for each bullet point: • more pixels can be stored / are available • the image is sharper / less pixelated 2 2(b) 1 mark for answer. 1 mark for working Answer: 4096 kibibytes Working: File size = (2048  1024  16) / (8  1024) 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 4 of 10 Question Answer Marks 3(a)(i) 1 mark for each bullet point (max 2). • Courses must be available to anyone who wishes to follow them • Courses must be available on the internet • Company is willing to share infrastructure with other companies (public) • …which is more economic for the company 2 3(a)(ii) 1 mark for each bullet point (max 2 for each disadvantage). • There could be a possible loss of control unlike the LAN • …because the data is stored on a remote infrastructure / someone else’s infrastructure • …reliance on external agency to complete tasks, e.g. backups, security • Requires reliable internet connection • …to ensure access to the remote data, more likely with LAN • Increased recurring costs • ...as cloud provider charges must be paid, costs for LAN once only. 4 3(a)(iii) 1 mark each for firewall, encryption and passwords. Firewall: • Monitors incoming and outgoing traffic and rejects any traffic that does not meet the set rules Encryption: • Ensures that if data is intercepted / obtained it cannot be understood without the decryption key Passwords: • Ensures only users with the correct password can access the resources // prevents unauthorised access 3 3(b)(i) 1 mark for both 1:M relationships as follows: 1

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 5 of 10 Question Answer Marks 3(b)(ii) 1 mark for each bullet point. • SELECT Count(CourseID) • AS NumOfCourses • FROM COURSE_SCHEDULE • WHERE DateStarted > "09/09/23"; SELECT Count(CourseID) AS NumOfCourses FROM COURSE_SCHEDULE WHERE DateStarted > "09/09/23"; 4 3(c) 1 mark for each bullet point. • The administrator completes a visual check / checks by eye • …that the tutor identifier input matches the tutor identifier on the original document • Double entry check // the administrator (or a second person) enters the number a second time • …and the system compares it with the first entry 4 Question Answer Marks 4(a) 1 mark for each set of highlighted rows P Q R Y 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 0 2 4(b) 1 mark for P AND Q and NOT Q OR R 1 mark for NOT gate and AND gate and XOR gate 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 6 of 10 Question Answer Marks 5(a) 1 mark for each bullet point (max 2 for each feature). Context-sensitive prompts: • As the code is being written • …the options to complete the statement are shown Single stepping: • allows the programmer to execute the program one line at a time • …so that the effects of each statement can be seen 4 5(b)(i) 1 mark for each bullet point (max 2). • To reduce the time it takes to download the program files from the web server // to upload them to the server in the first place • To reduce the amount of storage space used on the web server // user’s device 2 5(b)(ii) 1 mark for each bullet point (max 3). • Disk needs to be prepared for initial use • Disk needs to be checked for errors • A new file system needs to be generated on the disk • The file allocation table needs to be set up 3 Question Answer Marks 6(a) 1 mark for each bullet point (max 2). • Users are able to trial the program and may offer the programmer constructive feedback • More people might try the program because the trial is free of charge • Allows bugs to be found and corrected on a wide range of computer system configurations improving the programmer’s original program • Users that find the trial useful will buy the program so programmer gets income • Allows the program to be copyrighted and so protects the programmer’s intellectual property rights // no illegal modification allowed 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 7 of 10 Question Answer Marks 6(b) 1 mark for each bullet point (max 4). • The programmer has ethical guidelines to follow • …so purchasers of programs know the standards being applied • …so programmer does not have to decide what is ethical or not • Clients know programmer is reputable • …recognition of programmer’s skills/knowledge • There may be an entry requirement / exam • … so clients know that the programmer is competent • Professional ethical body provides help and support • Such as legal advice // by appropriate example • Enables programmer to attend the ethical body’s training courses • …to keep skills up to date // to develop skills 4 Question Answer Marks 7(a) 1 mark for each bullet point (max 2). • Static RAM has faster access time • …because it does not need to be refreshed • …used on the CPU for improvement of CPU cache speed • Static RAM has lower 2 7(b) 1 mark for each bullet point (max 2) • EEPROM allows frequent / multiple read / write / erase operations • …which means that the contents of the firmware in the headset can be changed easily • …without fully erasing the contents of the firmware in the headset first 2 7(c) 1 mark for each bullet point (max 4) • The print instructions and data are sent by the laptop to a buffer (at laptop speed) • The data is transferred from the buffer to the printer (at printer speed) • …allowing user to continue using the laptop // and allowing processor to continue processing • …instead of waiting for relatively slower printer • When the buffer is empty an interrupt is sent to the laptop • …requesting more data 4

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 8 of 10 Question Answer Marks 7(d) 1 mark for naming a correct port 2 marks for matching justification • USB • …has fast data transfer speeds for data (to the headset) • …is a universal/popular cable // universal standard • HDMI • …allows video and audio to be transferred (on the same cable) • …convenience of HDMI as no need for two cables 3 Question Answer Marks 8(a) 1 mark for each bullet point (max 2) • Validation // a validation method named or described • …protects the data by ensuring that the data is reasonable / sensible and within specified bounds 2 8(b) 1 mark for difference 1 mark for similarity Difference: • Pharming is malicious code that redirects to a fake website. Phishing uses an email to prompt user action. • Pharming is automatic. Phishing requires user action. Similarity: • Both try to obtain financial or personal information • Both are a false representation of an official organisation, e.g. a bank • Both make use of fake websites 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 9 of 10 Question Answer Marks 8(c) 1 mark for each bullet point (max 3). • Download programs from reputable websites / sources • …as these are less likely to contain malware • Backup / archive computer systems • …so they can be restored in case of data loss from malware program installation • Install and run anti-malware program • …so that regular scans can be made for known malware • …and if malware is found it can be quarantined / removed • …and computer’s anti-malware definitions are regularly updated • Using a firewall to block unused ports • …so that malware cannot enter the computer system • Deny administrator privileges to everyday users • …so that malware cannot be downloaded by everyday users • Avoid the use of / access to removable devices • …so that malware cannot be installed from these devices 3 Question Answer Marks 9(a)(i) 1 mark for each bullet point (max 3). • Control unit (CU) • Arithmetic and Logic Unit (ALU) • Immediate Access Store (IAS) • (System clock) 3 9(a)(ii) 1 mark for each bullet point (max 2). • Special purpose registers hold the status of a program whereas general purpose registers hold the temporary data while performing operations. • Special purpose registers are specialised for a specific use, whereas general purpose registers are used for any purpose. • General purpose registers can be used by most instructions, whereas special purpose can only be used by certain instruction 2

9618/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED October/November 2023 © UCLES 2023 Page 10 of 10 Question Answer Marks 9(b) 1 mark for each correct answer (shaded cells) Step Description PC  [PC] + 1 The address in PC is incremented. MDR  [[MAR]] The data in the location pointed to by the MAR is copied to the MDR. MAR  [PC] The contents of PC are copied to the MAR. CIR  [MDR] The contents of MDR are copied into CIR. 4 9(c) 1 mark for an appropriate example. Examples: • Division by zero • Runtime error • Out of memory bounds • Program requesting an external device / input • Buffer overflow 1 9(d) 1 mark for each letter in the correct position (2, 4 and 6) D A B 3