Cambridge A Level Computer Science 9608 — 2021 May/June Paper 1 · Variant 3

This document has 16 pages. Any blank pages are indicated. Cambridge International AS & A Level COMPUTER SCIENCE 9608/13 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. * 2 6 5 8 2 9 7 2 5 5 * DC (LK/CGW) 205099/1 © UCLES 2021 [Turn over

2 9608/13/M/J/21 © UCLES 2021 1 An adventure sports company has a website. (a) Customers can book courses using an online booking form. The booking form contains a number of fields. The following table gives a description of the validation for each field. Write the validation type for each validation description in the table. Field Validation description Validation type Name A name must be entered Date of Birth Entered as dd/mm/yyyy Telephone Number A limit of 15 characters can be entered Experience Level Only values between 1 and 5 can be entered [4] (b) (i) Validation is one way to protect the integrity of input data. Identify one other method to protect the integrity of input data. … [1] (ii) The data input will be transferred to a central server. Identify two measures to protect the integrity of the data during transfer. 1 … … 2 … … [2]

3 9608/13/M/J/21 © UCLES 2021 [Turn over 2 Consider the following logic circuit: A B Q 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 four logic gates used in the logic circuit above. 1 … 2 … 3 … 4 … [1]

4 9608/13/M/J/21 © UCLES 2021 3 The following 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 LDX <address> Indexed addressing. Form the address from <address> + the contents of the index register. Copy the contents of this calculated address to ACC. LDR #n Immediate addressing. Load the number n to IX. DEC <register> Subtract 1 from 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. OUT Output to the screen the character whose ASCII value is stored in ACC. END Return control to the operating system. The current contents of the main memory and selected values from the ASCII character set are: Address Instruction ASCII code table (selected codes only) 75 LDR #2 ASCII code Character 76 LDX 180 36 $ 77 CMP #0 40 ( 78 JPE 82 41 ) 79 OUT 43 + 80 DEC IX 69 E 81 JMP 76 70 F 82 END 71 G … 180 0 181 41 182 71 183 40 184 70 185 43 186 69

5 9608/13/M/J/21 © UCLES 2021 [Turn over (a) Complete a trace table for the execution of the program. Instruction address IX ACC Memory address Output 180 181 182 183 184 185 186 0 41 71 40 70 43 69 [5]

6 9608/13/M/J/21 © UCLES 2021 (b) Identify two modes of addressing that are not used in the assembly language program given. 1 … 2 … [2] (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 LDX 234 has the operand 234. Convert the operand 234 into 8-bit binary. [1] (ii) Convert the denary value 234 into hexadecimal. … [1] (iii) The contents of memory address 190 represent a two’s complement binary integer. Address 190 1 1 0 1 1 0 0 1 Convert the value in memory address 190 into denary. … [1] (d) The fetch-execute (FE) cycle is shown in register transfer notation. Complete the FE cycle using register transfer notation. … ← [PC] PC ← … + 1 MDR ← [[MAR]] … ← [MDR] [3]

7 9608/13/M/J/21 © UCLES 2021 [Turn over 4 An operating system (OS) is installed on a computer. (a) The OS performs a number of different tasks such as device management and error detection and recovery. (i) State three device management tasks the OS performs. 1 … 2 … 3 … [3] (ii) State three error detection and recovery management tasks the OS performs. 1 … 2 … 3 … [3] (iii) State two tasks, other than device management and error detection and recovery management that are carried out by an OS. 1 … 2 … [2]

8 9608/13/M/J/21 © UCLES 2021 (b) Utility programs are installed on a new computer. (i) The following table lists six programs. Tick (3) one box in each row to identify whether the program is a utility program or not a utility program. Program Utility Not utility Language translator Backup Integrated Development Environment (IDE) Graphics Defragmenter Spreadsheet [2] (ii) Identify two other utility programs. 1 … 2 … [2]

9 9608/13/M/J/21 © UCLES 2021 [Turn over 5 A web page staff.html contains the following HTML and PHP code. 01 <html> 02 <body> 03 <p><b>Current Staff</b></p> 04 05 <?php 06 echo "<h1>Staff list</h1>"; 07 echo "<p>"; 08 09 $first_name="Jason"; 10 $last_name="Chan"; 11 12 $result = $first_name." ".$last_name; 13 echo $result; 14 ?> 15 16 </body> 17 </html> (a) Give the identifier of two variables used in the PHP code. 1 … 2 … [2] (b) The PHP code produces multiple outputs. Give all the line numbers where the PHP code produces an output. … [1] (c) Describe the purpose of line 12 of the code. … … … … [2]

10 9608/13/M/J/21 © UCLES 2021 6 (a) A customer completes a booking form on a web page and clicks a submit button to submit the form. The following sequence (1 to 6) describes the steps that take place when the form is submitted. 1 … 2 The form data is transmitted to the web server 3 … 4 … 5 The HTML code is returned to the browser 6 … Write one of the letters A to D in each row (1, 3, 4 and 6) to complete the sequence. A The browser displays the web page B Server-side code is processed C Client-side code is processed D The web server produces the HTML code [3] (b) The web page 9608.html is accessed from the URL: https://www.cambridgeinternational.org/9608.html An employee of the company states, “A Domain Name and an IP address are exactly the same thing”. State whether this statement is true or false and justify your choice. … … … … … … … [3]

11 9608/13/M/J/21 © UCLES 2021 [Turn over 7 Patrick is writing a new software application. He is using a compiler to develop the software application. (a) Describe the drawbacks of using a compiler instead of an interpreter. … … … … … … [3] (b) Patrick has completed the application. He needs to choose whether to distribute the software application using an open source licence or a commercial licence. Describe open source and commercial software licensing. Open source … … … … Commercial … … … … [4] (c) Patrick works for a company that has a code of conduct for its employees. Explain the reasons why the company needs a professional code of conduct. … … … … … … [3]

12 9608/13/M/J/21 © UCLES 2021 8 A charity has a relational database, CHARITY_PROJECT. The database has three tables to store information about the charity’s employees, the projects and the project teams. EMPLOYEE(EmployeeID, FirstName, LastName, Salary, DOB) PROJECT(ProjectID, Name, Location, ProjectStartDate) PROJECT_TEAM(EmployeeID, ProjectID, JoinedProjectDate) (a) Complete the entity relationship (E-R) diagram to show the relationships between these tables. EMPLOYEE PROJECT PROJECT_TEAM [2] (b) Explain how primary and foreign keys are used to link the tables in CHARITY_PROJECT. … … … … … … … … [4]

13 9608/13/M/J/21 © UCLES 2021 [Turn over (c) The database needs to store the gender of each employee (either M for Male or F for Female). Write a Data Definition Language (DDL) statement to add the attribute Gender to the EMPLOYEE table. … … … … … … [2] (d) Part of the EMPLOYEE table is shown: EmployeeID FirstName LastName Salary DOB Gender 001 Jasmine Chen 25 000 25/12/2000 F 002 Kenton Archer 20 000 01/04/1993 M 003 Michael Roux 10 000 10/03/1990 M 004 Conrad Slavorski 15 000 30/03/1989 M Each employee is paid a salary in dollars ($). Write a Data Manipulation Language (DML) statement to return the first name, last name and salary of all employees that are paid more than $17 500. … … … … … … [3]

14 9608/13/M/J/21 © UCLES 2021 9 A website streams music and videos. (a) Two descriptions about how sound is encoded and represented on a computer are given. Give the correct term for each description. (i) “The number of samples taken per unit time” Term … [1] (ii) “The number of bits used to encode each sample” Term … [1] (b) Videos on the website are compressed. Compression algorithms can use spatial redundancy or temporal redundancy. Describe spatial redundancy and temporal redundancy. Spatial … … … … Temporal … … … … [4]

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16 9608/13/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 9 printed pages. © UCLES 2021 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9608/13 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.

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 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 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.

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 3 of 9 Question Answer Marks 1(a) 1 mark for each validation type Field Validation description Validation type Name A name must be entered Presence check Date of birth Entered as dd/mm/yyyy Format check Telephone number A limit of 15 characters can be entered Length check Experience level Only values between 1 and 5 can be entered Range check 4 1(b)(i) Verification // by example 1 1(b)(ii) 1 mark per bullet point: • Parity • Checksum 2 Question Answer Marks 2(a) 1 mark per pair of outputs (shaded) A B C Working space Q 0 0 0 0 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1 1 4 2(b) 1 mark for all four: NOT NAND OR XOR 1

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 4 of 9 Question Answer Marks 3(a) 1 mark per shaded section Instruction Address IX ACC Memory Address Output 180 181 182 183 184 185 186 0 41 71 40 70 43 69 75 2 76 71 77 78 79 G 80 1 81 76 41 77 78 79 ) 80 0 81 76 0 77 78 82 5 3(b) 1 mark per bullet point max 2 marks • Direct • Indirect • Relative 2 3(c)(i) 1110 1010 1

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 5 of 9 Question Answer Marks 3(c)(ii) EA 1 3(c)(iii) –39 1 3(d) 1 mark for each correctly completed item MAR ← [PC] PC ← [PC] + 1 MDR ← [[MAR]] CIR ← [MDR] 3 Question Answer Marks 4(a)(i) 1 mark per bullet point to max 3 • Install/manage device drivers • Control of hardware usage by processes // allocation of devices to processes // inter process communication • Device detection • Power Management • Keep track of device status (free or busy) • Buffer management 3 4(a)(ii) 1 mark per bullet point to max 3 • Deals with interrupts • Deal with run time errors generated by software • Deal with hardware faults • Error diagnostic messages • Deadlock detection and recovery • Safe-mode boot-up routines • System shutdown • Saves system restore points 3 4(a)(iii) 1 mark per bullet point to max 2 • Process / task/resource management • Main memory management • File/secondary storage management • Security management • Provision of a software platform/environment on which other programs can be run • Interrupt handling • Provision of a user interface NOT • Peripheral/hardware/device management • Error detection and recovery management 2

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 6 of 9 Question Answer Marks 4(b)(i) 1 mark for first 3 rows 1 mark for last 3 rows Program Utility Not utility Language translator  Backup  Integrated Development Environment (IDE)  Graphics  Defragmenter  Spreadsheet  2 4(b)(ii) 1 mark per bullet point to max 2 e.g. • Virus checker // anti-malware • Disk formatter • Disk contents analysis/disk repair • System clean-up • File compression • Firewall • Encryption 2 Question Answer Marks 5(a) 1 mark for each bullet point to max 2 • $first_name • $last_name • $result 2 5(b) 1 mark for all 3 06 07 13 1 5(c) 1 mark per bullet point • Concatenate the contents of $first_name and $last_name with a space in the middle... • …and store in $result 2

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 7 of 9 Question Answer Marks 6(a) 1 mark per bullet point • C in correct position • B and D in correct positions • A in correct position 1 C // The client-side code is processed 2 The form data is transmitted to the web server 3 B // The server-side code is processed 4 D // The web server produces the HTML code 5 The HTML code is returned to the browser 6 A // The browser displays the web page 3 6(b) 1 mark per bullet point for justification to max 3 • IP address is (physical) address of the server • A domain name is a memorable form for an IP address • cambridgeinternational.org is the domain name • An example of an IP address is 198.162.2.1 • Each domain name is linked to an IP address • A Domain Name Server/Service (DNS) is used to translate a domain name into its corresponding IP address • Domain name does not change but IP address could change (dynamic) • IP address can be used to address server directly, • The domain name needs translation before server can be assessed 3 Question Answer Marks 7(a) 1 mark per bullet point to max 3 • The program will not run if there are any errors • The program must be recompiled after every change // cannot correct errors in real-time • Part-programs cannot be tested • One error may result in other false errors being reported 3

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 8 of 9 Question Answer Marks 7(b) 1 mark per bullet point, max 2 marks per licence Open Source • The (source) code is distributed with the software • users can modify the software • The software is (usually) free of cost • Users must redistribute the modified software under the same terms Commercial • The software is (usually) purchased for a cost • A licence defines how it can be used • The source code is not distributed // users cannot change the software 4 7(c) 1 mark per bullet point to max 3 e.g. • To identify what employees can do • To identify what employees cannot do • To identify the repercussions of employees performing activities they should not • To identify the company's/employee's responsibilities • To identify the company's values/missions • To identify what behaviour/events/activities can be measured against • To identify how they will comply with legislation 3 Question Answer Marks 8(a) 1 mark for each correct join 2 8(b) 1 mark per bullet point • EmployeeID is the Primary Key in EMPLOYEE • …links to EmployeeID which is the Foreign Key in PROJECTTEAM • ProjectID is the Primary Key in PROJECT • …links to ProjectID which is the Foreign Key in PROJECTTEAM 4

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2021 © UCLES 2021 Page 9 of 9 Question Answer Marks 8(c) 1 mark per bullet point • ALTER TABLE EMPLOYEE • ADD Gender CHAR(1) Example: ALTER TABLE EMPLOYEE ADD Gender CHAR(1); 2 8(d) 1 mark per bullet point • SELECT FirstName, LastName, Salary • FROM EMPLOYEE • WHERE Salary > 17 500 Example: SELECT FirstName, LastName, Salary FROM EMPLOYEE WHERE Salary > 17 500; 3 Question Answer Marks 9(a)(i) Sampling rate 1 9(a)(ii) Sampling resolution // bit depth 1 9(b) 1 mark per bullet point, max 2 for each Spatial Redundancy • Intra-frame // Redundancy within a frame • Pixels in a single video frame have the same value • A description of an appropriate compression method e.g. RLE Temporal Redundancy • Inter-frame // Redundancy between frames • Pixels in a sequence of consecutive video frames have the same value in the same location • …records only the differences between the frames 4