Cambridge A Level Computer Science 9608 — 2021 May/June Paper 1 · Variant 2

This document has 20 pages. Any blank pages are indicated. Cambridge International AS & A Level DC (CE/CGW) 205101/3 © UCLES 2021 [Turn over COMPUTER SCIENCE 9608/12 Paper 1 Theory Fundamentals May/June 2021 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. * 3 0 5 4 6 1 3 4 9 2 *

2 9608/12/M/J/21 © UCLES 2021 1 Consider the following logic circuit: Q A B C (a) Complete the truth table for the logic circuit. A B C Working space Q 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 [4] (b) Identify the three logic gates used in the given logic circuit. Gate 1 … Gate 2 … Gate 3 … [1]

3 9608/12/M/J/21 © UCLES 2021 [Turn over 2 The following diagram shows four register notations and seven descriptions. Draw one line from each register notation to its most appropriate description. Register notation Description MDR CIR MAR PC Holds the op code and operand of an instruction ready for it to be decoded Holds the address of the next instruction to be read Holds flags that are set when the Arithmetic and Logic Unit (ALU) executes instructions Holds data read from, or to be written to, memory Holds the current value in the Index Register Holds the address where data is to be written to or read from Holds the result of the last instruction executed by the ALU [4]

4 9608/12/M/J/21 © UCLES 2021 3 The table shows part of the instruction set for a processor. The processor has one general purpose register, the Accumulator (ACC), and an Index Register (IX). Instruction Explanation Op code Operand LDD <address> Direct addressing. Load the contents of the location at the given address to ACC. LDI <address> Indirect addressing. The address to be used is at the given address. Load the contents of this second address to ACC. STO <address> Store the contents of ACC at the given address. ADD <address> Add the contents of the given address to ACC. INC <register> Add 1 to the contents of the register (ACC or IX). JMP <address> Jump to the given address. CMP <address> Compare the contents of ACC with the contents of <address>. JPE <address> Following a compare instruction, jump to <address> if the compare was True. END Return control to the operating system. The current contents of the main memory are: Address Instruction 50 LDI 103 51 CMP 101 52 JPE 59 53 ADD 102 54 STO 102 55 LDD 100 56 INC ACC 57 STO 100 58 JMP 51 59 ADD 102 60 STO 102 61 END … 100 1 101 3 102 0 103 100

5 9608/12/M/J/21 © UCLES 2021 [Turn over (a) Trace the program currently in memory using the following trace table. Instruction address ACC Memory address 100 101 102 103 1 3 0 100 [5]

6 9608/12/M/J/21 © UCLES 2021 (b) The instruction in memory address 50 needs to be changed to use direct addressing to load the contents of the memory location at address 100. Give the new instruction to replace LDI 103. … [1] (c) Each instruction in the assembly language program is encoded in 16 bits (8-bit op code followed by an 8-bit operand). (i) The instruction JPE 59 has the operand 59. Convert the operand 59 into 8-bit binary. [1] (ii) Convert the denary value 59 into hexadecimal. … [1] (d) The assembly language program uses direct and indirect addressing. Identify two other modes of addressing used in an assembly language program. 1 … 2 … [2]

7 9608/12/M/J/21 © UCLES 2021 [Turn over 4 K2 Mountain Guiding is a company that runs courses teaching people how to climb mountains. The company uses a file-based approach to store and retrieve data. (a) Describe three drawbacks of a file-based approach compared to a relational database. Drawback 1 … … … … Drawback 2 … … … … Drawback 3 … … … … [6]

8 9608/12/M/J/21 © UCLES 2021 (b) Each course has a destination and a trip date, and is run by a guide. Customers can book a place on one or more courses. The following table shows part of the stored file: Customer name Customer date of birth Guide Destination Trip date Jay Patel 10/10/1976 Artem Elbrus 06/03/2023 Paul Schloss 10/04/1999 Kenton K2 01/03/2022 Mina Wang 03/03/2000 Kenton K2 01/03/2022 Paul Schloss 10/04/1999 Safia Mont Blanc 07/07/2024 Jay Patel 10/10/1976 Safia K2 04/04/2023 The company has decided to create a relational database to replace the current file-based approach. Identify three reasons why the data in this table is not in First Normal Form (1NF). 1 … … 2 … … 3 … … [3]

9 9608/12/M/J/21 © UCLES 2021 [Turn over (c) The table, GUIDE_TABLE, is created. Each guide has a unique guide ID. Part of the table GUIDE_TABLE is shown: GuideID Guide DateOfBirth Gender 1 Artem 07/03/1992 M 2 Kenton 08/04/1984 M 3 Safia 10/10/1999 F Write a Data Definition Language (DDL) statement to define the table GUIDE_TABLE. … … … … … … … … … … [5]

10 9608/12/M/J/21 © UCLES 2021 5 A web page includes HTML and JavaScript code. 01 <html> 02 <body> 03 04 Calculate area of a triangle: 05 <form name = "Triangle"> 06 <p>Base <input type = "number" name = "B" value = ""></p> 07 <p>Height <input type = "number" name = "H" value = ""></p> 08 <button onclick = "area()">Calculate</button> 09 </form> 10 11 <script> 12 function area() { 13 var base = document.forms["Triangle"]["B"].value; 14 var height = document.forms["Triangle"]["H"].value; 15 if (base == "" || height == "") { 16 alert("Both values must be entered"); 17 return false; 18 } 19 else { 20 area = 0.5 * height * base; 21 alert("The area is: " + area); 22 } 23 } 24 </script> 25 </body> 26 </html> (a) Give the three identifiers used in the JavaScript code. 1 … 2 … 3 … [2] (b) State the purpose of the code on line 08. … … [1]

11 9608/12/M/J/21 © UCLES 2021 [Turn over (c) The page is loaded and the values 2 and 8 are entered. State the output when the calculate button is clicked. … … [1] (d) State the meaning of the || operator in line 15 of the code. … [1] (e) Data validation has been used in line 15 of the JavaScript code. (i) Identify the type of data validation used in line 15. … [1] (ii) Identify two other data validation checks that could be used. 1 … 2 … [2] Question 5 continues on the next page.

12 9608/12/M/J/21 © UCLES 2021 Cambridge International Holidays allows customers to make holiday bookings on its website. (f) Bochen visits the Cambridge International Holidays website to book a holiday. The sequence (1 to 8) below describes the steps that take place when he submits a booking. Four of the statements A, B, C, D, E and F are used to complete the sequence. A Any errors found at the server side are flagged, and step 1 is repeated. B HTML code is used on the client’s web browser to validate the form data. C PHP code is executed to generate a confirmation (HTML) web page that is returned to the client’s web browser. D The form data is transmitted to Cambridge International Holidays’ web server. E JavaScript code is executed to generate a confirmation (HTML) web page that is returned to the client’s web browser. F JavaScript code is executed on the client’s web browser to validate the form data. Write one of the letters (A, B, C, D, E or F) in the appropriate row to complete the sequence. 1 Bochen completes the online booking and clicks ‘Submit’. 2 … 3 Any errors found are flagged, and step 1 is repeated. 4 … 5 PHP code is executed to perform extra data validation checks on the form data. 6 … 7 The booking details are added to the database. 8 … [4]

13 9608/12/M/J/21 © UCLES 2021 [Turn over 6 This question presents three scenarios. Tick (3) one box for each scenario to indicate whether you think the named person’s behaviour is ethical or unethical. Justify your choice. (a) Latifah has changed jobs and has started to work for a new company. The company uses an Integrated Development Environment (IDE) to develop code. Latifah decides not to use the IDE that the company has because she is familiar with a different IDE. Ethical Unethical Justification … … … … … [2] (b) Samid is in charge of a project to write a banking application. He is employing staff to work on the application. His daughter is a computer security expert. She is looking for a new job. Samid decides to employ his daughter. Ethical Unethical Justification … … … … … [2]

14 9608/12/M/J/21 © UCLES 2021 (c) Jason works for a social media company. He is concerned that users of the company’s social media website have not been told how their personal data is being used. Jason tells his manager his concerns. His manager tells him not to worry because there have been no complaints from the users. Jason takes no further action. Ethical Unethical Justification … … … … … [2]

15 9608/12/M/J/21 © UCLES 2021 [Turn over 7 Sam is a photographer. She has an image library of over 10 000 images. She stores the images on a high capacity magnetic hard disk. (a) Explain why Sam would use the following utility software. (i) Backup … … … … [2] (ii) Defragmenter … … … … [2] (iii) Disk repair … … … … [2] (b) The images are stored as bitmap files. Identify four items that will be stored in the header of a bitmap file. 1 … 2 … 3 … 4 … [4]

16 9608/12/M/J/21 © UCLES 2021 (c) The bitmap images are compressed for use on a website. Tick (3) one box to select the most appropriate type of compression for the images used on the website and justify your answer. Lossy Lossless Justification … … … … … … [3]

17 9608/12/M/J/21 © UCLES 2021 [Turn over 8 (a) Complete the following table by identifying the most appropriate term for each description. Each term must be different. Description Term Ensures data is accurate and up to date Prevents accidental or malicious data loss Prevents unauthorised access to data [3] (b) Describe what is meant by a digital signature. … … … … [2]

18 9608/12/M/J/21 © UCLES 2021 9 Networks can be either wired using cables or wireless using radio waves. (a) Describe one benefit of using a wireless network compared to using a wired network. … … … … [2] (b) Describe two drawbacks of using a wireless network compared to using a wired network. Drawback 1 … … … … Drawback 2 … … … … [4]

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20 9608/12/M/J/21 © UCLES 2021 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 the Cambridge Assessment Group. Cambridge Assessment is the brand name of the University of Cambridge Local Examinations Syndicate (UCLES), which itself is a department of the University of Cambridge. BLANK PAGE

This document consists of 10 printed pages. © UCLES 2021 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9608/12 Paper 1 Theory Fundamentals May/June 2021 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 2021 series for most Cambridge IGCSE™, Cambridge International A and AS Level components and some Cambridge O Level components.

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 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.

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 3 of 10 Question Answer Marks 1(a) 1 mark per pair of outputs (shaded) A B C Working space Q 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1 1 4 1(b) OR, AND, NOT 1 Question Answer Marks 2 1 mark for each register correctly described 4 Register Notation Description MDR Holds the op code and operand of an instruction ready for it to be decoded Holds the address of the next instruction to be read CIR Holds flags that are set when the Arithmetic and Logic Unit (ALU) executes instructions Holds data read from, or to be written to, memory MAR Holds the current value in the Index Register Holds the address where data is to be written to or read from PC Holds the result of the last instruction executed by the ALU

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 4 of 10 Question Answer Marks 3(a) 1 Mark for each set of shaded rows Instruction Address ACC Memory Address 100 101 102 103 1 3 0 100 50 1 51 52 53 1 54 1 55 1 56 2 57 2 58 51 52 53 3 54 3 55 2 56 3 57 3 58 51 52 59 6 60 6 61 5 3(b) LDD 100 1

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 5 of 10 Question Answer Marks 3(c)(i) 0011 1011 1 3(c)(ii) 3B 1 3(d) 1 mark each (max 2) • Immediate • Indexed • Relative 2 Question Answer Marks 4(a) 1 mark per drawback identified, 1 mark for related description (max 6) • There is data duplication // redundant data • …because the same data is stored multiple times // data changed in one file is not automatically changed in others // by example • There could be data inconsistency // reduced data integrity • … because duplicated data might be stored as different values // by example • There is program-data dependency • … if the data structure changes all the programs accessing that data must be changed too // by example • It is not easy to perform complex searches/queries • … a new program has to be written each time • Lack of privacy • …as access controls are usually to the system rather than the data // user views cannot easily be implemented 6 4(b) 1 mark per bullet point (max 3) • There is no unique primary key • Customer name is not atomic // Customer name needs to be split into first name and last name // by example • Customer name / Customer date of birth / Destination / Guide name / Trip have repeated groups of attributes 3

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 6 of 10 Question Answer Marks 4(c) 1 mark per bullet point • Create table GUIDE_TABLE with brackets and semi-colon • GuideID of suitable data type • Guide and Gender of suitable data type(s) • DateOfBirth of correct data type • Declaring GuideID as Primary Key Example answer: CREATE TABLE GUIDE_TABLE( GuideID INT, Guide VARCHAR(25), DateOfBirth DATE, Gender CHAR(1), PRIMARY KEY (GuideID) ); 5 Question Answer Marks 5(a) 1 mark for base and height, 1 mark for area • base and height • area 2 5(b) When the button is clicked the function area() is called 1 5(c) The area is: 8 1 5(d) (logical) OR 1 5(e)(i) Presence check 1 5(e)(ii) 1 mark for each (max 2) • range check • length check • type check 2

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 7 of 10 Question Answer Marks 5(f) 1 mark for each correct letter/statement in each space 1 Bochen completes the online booking form and clicks ‘Submit’. 2 F // JavaScript is executed on the client's web browser to validate the form data. 3 Any errors found are flagged, and step 1 is repeated. 4 D // The form data is transmitted to Cambridge International Holidays' webserver. 5 PHP code is executed to perform extra data validation checks on the form data. 6 A // Any errors found at the server side are flagged and step 1 is repeated. 7 The booking details are added to the database. 8 C // PHP is executed to generate a confirmation (HTML) web page that is returned to the client's web browser. 4 Question Answer Marks 6(a) 1 mark per bullet point for each justification, to max 2 e.g. Either Ethical • Latifah believes that her productivity is better using an IDE that she has experience of • … and the work is still compatible with other IDEs • …the IDE is open source so does not cost anything extra • Reference to IEEE standards in context Or Unethical • Latifah is knowingly using software that is not provided or supported by the company • …and this may lead to issues with future software compatibility/maintenance • Reference to IEEE standards in context 2

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 8 of 10 Question Answer Marks 6(b) 1 mark per bullet point for each justification, to max 2 e.g. Either Ethical • Samid believes his daughter is qualified and would be the best person for the job • …and believes that it is in the best interest of his client to secure a high- quality employee as soon as possible • … they may have interviewed her with a third party and she came out as the best candidate • Reference to IEEE standards in context Or Unethical • Samid shows poor judgement by favouring his daughter • …rather than using a fair and open recruitment process • there may be people with better qualifications that are being overlooked • Reference to IEEE standards in context 2 6(c) 1 mark per bullet point for each justification, to max 2 e.g. Either Ethical • Jason has already raised his concerns (to his manager) • …and has fulfilled his professional responsibilities by doing so. • Reference to IEEE standards in context Or Unethical • Jason should continue to raise any concerns he has with a higher level of management in the company • …because it may be against the public interest for users to have their data used in this way without them explicitly knowing it. • Reference to IEEE standards in context 2 Question Answer Marks 7(a)(i) 1 mark per bullet point to max 2 • The images on the hard disk can be lost or corrupted • To make a copy of her files (which can be stored elsewhere) • So that the images can be restored 2 7(a)(ii) 1 mark per bullet point to max 2 • Frequent changes to the images mean the data for each file is split across the disk • To rearrange the (fragmented) files into contiguous locations // to bring all the empty space together • To improve the time it takes to access and load the files 2

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 9 of 10 Question Answer Marks 7(a)(iii) 1 mark per bullet point to max 2 • Areas of the disk can become corrupt • To identify/mark the errors/bad sectors • ...so they can be repaired // so bad sectors are no longer used 2 7(b) 1 mark per bullet point to max 4 e.g. • Vertical height in pixels • Horizontal width in pixels • Bit depth/number of bits per pixel • Total file size in bytes • Offset in bytes where the image data is located • Type of compression used 4 7(c) Justification 1 mark per bullet point to max 3 Lossy: • Lossy compression will achieve a much higher compression ratio (than lossless) for photographic images... • ...so the images will load faster • There will be little identifiable change to the viewed images • It may not be important that the originals are not recoverable Lossless: • Images may be required in their original form // may need to be recovered completely • Images may already be a small file size so major reduction in file size is not needed... • ...as the files will load quickly 3 Question Answer Marks 8(a) 1 mark per term Description Term Ensures the data is accurate and up to date Data integrity Prevents accidental or malicious data loss Data security Prevents unauthorised access to data Data privacy 3 8(b) 1 mark per bullet point to max 2 • Mathematical algorithm // encrypted data • Attached to electronically transmitted document • …to verify its content/that it comes from a trusted source/ 2

9608/12 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 10 of 10 Question Answer Marks 9(a) 1 mark for identification, 1 mark for description (max 2) Benefits: • Less hard-wiring/hardware is required • Users and computers can be mobile • It is much more straightforward to connect other devices Descriptions: • Reduced cost of setting up the network • The network can be accessed from anywhere within range of an access point • No need to physically connect each device 2 9(b) 1 mark for identification, 1 mark for matching description (max 2 for each) • Transmissions may be less secure • …because data packets can be intercepted // easier connection by unauthorised user • Bandwidth may be limited // As more devices connect the bandwidth can be reduced • …so access may be slow • It is subject to interference from other signals or obstacles • …which can hinder transmission or corrupt data • Limited range // greater attenuation • …so there is a need for repeaters // users can easily move out of range • Higher latency • …so transmission will be slower 4