Cambridge A Level Computer Science 9608 — 2020 May/June Paper 1 · Variant 3

Cambridge International AS & A Level * 2 8 4 6 0 9 3 3 7 7 * DC (LEG/FC) 183149/3 © UCLES 2020 [Turn over This document has 16 pages. Blank pages are indicated. COMPUTER SCIENCE 9608/13 Paper 1 Theory Fundamentals May/June 2020 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 9608/13/M/J/20 © UCLES 2020 1 Ana owns a small company with four employees. The office has a network containing several computers that run on a client-server model. There is one server that connects to the Internet using a router. (a) Networks transmit data using various types of connection shown in the following table. Complete the table. Type of connection Description Fibre-optic … … … … … … A communication device in Earth’s orbit that receives and transmits data Radio waves … … … … … … Carries data as electrical signals and can consist of a twisted pair [4] (b) Explain how the client-server model enables the employees to access the same files from different computers. … … … … … … [2]

3 9608/13/M/J/20 © UCLES 2020 [Turn over (c) Each computer in the network has a private IP address. Give two reasons why the computers do not have public IP addresses. 1 … … 2 … … [2]

4 9608/13/M/J/20 © UCLES 2020 2 Billy has a laser printer. (a) Complete the following description of the basic internal operation of a laser printer. The printer uses a … and a rotating … to draw the contents of the page on the photosensitive drum as … charge. The … is attracted to this charge. [4] (b) The laser printer has both RAM and ROM. Describe the purpose of RAM and ROM in the laser printer. RAM … … … … ROM … … … … [4] (c) Billy’s computer has several ports. (i) State the purpose of a port. … … [1] (ii) Identify one type of port. … … [1]

5 9608/13/M/J/20 © UCLES 2020 [Turn over 3 (a) The following is a logic expression. X = NOT(A OR B) OR (A AND (B XOR C)) Draw the logic circuit for the given expression, using a maximum of four logic gates. X B A C [4]

6 9608/13/M/J/20 © UCLES 2020 (b) Complete the truth table for the logic expression: X = NOT(A OR B) OR (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 [4] (c) The following is a logic expression. A AND B XOR C OR NOT A Identify one logic gate that would not be used in the logic circuit for this expression. Draw the symbol for the logic gate. Logic gate … Logic gate symbol: [2]

7 9608/13/M/J/20 © UCLES 2020 [Turn over 4 Annchi is writing a computer game with a group of friends. (a) One of her friends has suggested using Dynamic Link Library (DLL) files to help them develop the game. (i) Give three reasons why Annchi and her friends should use DLL files when developing the game. 1 … … 2 … … 3 … … [3] (ii) Give two reasons why Annchi and her friends should not use DLL files when developing the game. 1 … … 2 … … [2] (b) Each member of the group is creating a different part of the game. Each person needs to test their part of the game independently before they are combined. Identify the most appropriate type of translator that should be used to test each part of the game independently. Justify your choice. Translator … Justification … … … … … [3]

8 9608/13/M/J/20 © UCLES 2020 (c) Annchi needs to decide which type of software licence to use for the game. (i) Give two benefits to Annchi of using a commercial licence. 1 … … 2 … … [2] (ii) Give one benefit to the customers of the game being released using a commercial licence. … … [1] (iii) Describe one benefit to the customers of the game being released using a shareware licence. … … … … [2]

9 9608/13/M/J/20 © UCLES 2020 [Turn over 5 Wei is developing a program. (a) He wants to make sure the source code is secure on his laptop. Explain how encrypting the source code can keep it secure. … … … … … … [3] (b) Wei wants to compress the source code to transport it to another computer. Identify the most appropriate compression technique he should use. Justify your choice. Compression technique … Justification … … … … … [3]

10 9608/13/M/J/20 © UCLES 2020 6 Sheila creates a relational database for her hotel using a Database Management System (DBMS). (a) Draw one line from each database term to its most appropriate description. Database Term Description Attribute Primary key Foreign key Entity A field in one table that links to a primary key in another table A collection of records and fields The type of data that is being stored A unique identifier for each tuple A data item, represented as a field within a table The concept or object in the system that we want to model and store information about [4] (b) Identify three tasks that Sheila can perform using the DBMS developer interface. 1 … 2 … 3 … [3]

11 9608/13/M/J/20 © UCLES 2020 [Turn over (c) Sheila creates the database HOTEL with the following table structure: ROOM(RoomNumber, RoomType) BOOKING(BookingID, RoomNumber, CustomerID, StartDate) CUSTOMER(CustomerID, FirstName, LastName, Address, Tel_Num) (i) The following table shows some sample data for the table ROOM. RoomNumber RoomType 1 Standard 2 Double 3 Executive 4 Standard Complete the Data Definition Language (DDL) statement to create the table ROOM. … TABLE ROOM( RoomNumber Integer, RoomType …, … (RoomNumber) ); [3] (ii) Room number 5 is a Double room. Complete the Data Manipulation Language (DML) statement to add the details for room number 5 to the table ROOM. INSERT … ROOM VALUES(…); [2] (iii) The table BOOKING needs an additional field to store the number of nights (for example, 3) a customer is staying. Write a Data Definition Language (DDL) statement to add the new field to the table BOOKING. … … … … … [2]

12 9608/13/M/J/20 © UCLES 2020 7 Xiaoming created the following logo using bitmapped graphics software. PJF Interiors (a) Describe how one typical feature of bitmapped graphics software was used to create the logo. … … … … [2] (b) The finished logo is 160 pixels wide and 160 pixels high. The image has a colour depth of 3 bytes per pixel. Calculate an estimate of the file size for the logo. Give your answer in kilobytes. Show your working. Working … … … Answer … KB [3] (c) Xiaoming needs to use his logo on his business card, on his website and on large display boards. He is told that he should have created a vector graphic logo instead of a bitmapped graphic logo. Describe one benefit of creating a vector graphic logo instead of a bitmapped graphic logo. … … … … [2]

13 9608/13/M/J/20 © UCLES 2020 [Turn over (d) The hexadecimal colour value of the background of Xiaoming’s website is: 913C8E Complete the following table by converting each hexadecimal value to denary value. Red Green Blue Hexadecimal value 91 3C 8E Denary value [2]

14 9608/13/M/J/20 © UCLES 2020 (e) Part of Xiaoming’s website contains the JavaScript function performTask(). function performTask(){ var value1; value1 = document.getElementById("FirstBox").value; if (value1 == "Yes"){ document.getElementById("paragraph1").innerHTML = "Agreed"; } else if(value1 == "No"){ document.getElementById("paragraph1").innerHTML = "Sorry"; } else { alert("Error") } } Describe the purpose of the following JavaScript statements from the function performTask(). (i) alert("Error") … … [1] (ii) value1 = document.getElementById("FirstBox").value; … … … … [2] (iii) document.getElementById("paragraph1").innerHTML = "Agreed"; … … … … [2]

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16 9608/13/M/J/20 © UCLES 2020 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 2020 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9608/13 Paper 1 Written Paper May/June 2020 MARK SCHEME Maximum Mark: 75 Published Students did not sit exam papers in the June 2020 series due to the Covid-19 global pandemic. This mark scheme is published to support teachers and students and should be read together with the question paper. It shows the requirements of the exam. The answer column of the mark scheme shows the proposed basis on which Examiners would award marks for this exam. Where appropriate, this column also provides the most likely acceptable alternative responses expected from students. Examiners usually review the mark scheme after they have seen student responses and update the mark scheme if appropriate. In the June series, Examiners were unable to consider the acceptability of alternative responses, as there were no student responses to consider. Mark schemes should usually be read together with the Principal Examiner Report for Teachers. However, because students did not sit exam papers, there is no Principal Examiner Report for Teachers for the June 2020 series. Cambridge International will not enter into discussions about these mark schemes. Cambridge International is publishing the mark schemes for the June 2020 series for most Cambridge IGCSE™ and Cambridge International A & AS Level components, and some Cambridge O Level components.

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 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 2020 © UCLES 2020 Page 3 of 9 Question Answer Marks 1(a) 1 mark for each correctly completed media or description Type of connection Description Fibre-optic Transmits data as light // Uses (a bundle of) glass/plastic threads to transmit data Satellite A communication device in Earth’s orbit that receives and transmits data Radio Waves Carries data wirelessly, often known as Wi-Fi // Carries data in the form of electromagnetic waves Copper cable Carries data as electrical signals and can consist of a twisted pair 4 1(b) 1 mark per bullet point to max 2 • The employees’ computers are the clients • The server hosts the (shared) files • An employee can request a file (from the server) from any of the client computers • Several employees can access the same file (on the server) at the same time 2 1(c) 1 mark per bullet point • Improved security because the IP address is not visible outside the network • An internet presence is not required for each employee computer • Only the router needs a public IP address, as only the router needs to be externally visible • Reduces number of (public) IP addresses needed 2 Question Answer Marks 2(a) 1 mark for each appropriate term The printer uses a laser (beam) and a rotating mirror to draw the contents of the page on the photosensitive drum as an electrostatic charge. The toner is attracted to this charge. 4

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 4 of 9 Question Answer Marks 2(b) 1 mark per bullet point. Max 2 for RAM, max 2 for ROM RAM • Stores currently running parts of the printer software • Stores the data being printed // contents of buffer • Stores current progress of printing • Stores the data about the printer, e.g. toner levels ROM • Stores the printer operating software // OS for the printer • Stores the boot-up/start-up instructions for the printer • Printer fonts stored in ROM 4 2(c)(i) 1 mark • To provide the connection to peripheral devices • To provide an interface between the computer and other devices 1 2(c)(ii) 1 mark • USB • HDMI • SCSI • Firewire • Ethernet • Any other acceptable port 1 Question Answer Marks 3(a) 1 mark per correct gate • A NOR B • B XOR C • A AND (B XOR C) • Final OR 4

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 5 of 9 Question Answer Marks 3(b) 1 mark for each correct pair of answers (4 shaded sections) A B C Working Space X 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 1 1 1 0 1 1 1 1 0 4 3(c) 1 mark for name, 1 mark for symbol matching the name NAND NOR 2 Question Answer Marks 4(a)(i) 1 mark per reason to max 3 • DDL file is only loaded into memory when required • ... so the executable file for the game is smaller • Changes/improvements in the DLL file are independent of the main program • ... the game program will not need to be recompiled • ... the game program will get the benefit of the updates automatically • The same DDL file can be used in several game programs (at the same time) • (DLL) routines are pre-written saving the developers time • (DLL) routines are pre-tested so should be reliable • Developers can take advantage of other programmers’ expertise 3 4(a)(ii) 1 mark per reason to max 2 • Game will not work if DDL is corrupted • An external change to the DDL could stop the game working or change the way it works • The DDL file must be present at run-time otherwise there is an error 2

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 6 of 9 Question Answer Marks 4(b) 1 mark for interpreter 1 mark per bullet point for justification to max 2 • The interpreter translates and executes line by line • The interpreter stops translation when an error is found • …the error can be corrected, and the program continues running from where it stopped • There is no need for an executable file (at this stage) 3 4(c)(i) 1 mark per benefit to max 2 • She can charge a fee for the game • She retains the copyright • ... so, the game cannot be re-distributed by a third-party without her permission 2 4(c)(ii) 1 mark per benefit to max 1 • Potentially better support, as she is charging a fee • Likely to have fewer bugs / less prone to malware than if distributed under other licences e.g. open source • Redress available if the game does not function correctly 1 4(c)(iii) 1 mark per bullet point • They can check it works // check if it meets their requirements • ... without having to paying a fee if it does not 2 Question Answer Marks 5(a) 1 mark per bullet point to max 3 • Encryption scrambles the source code (so it is meaningless) • … using an encryption key / algorithm • If the file is accessed without authorisation it will be meaningless • It requires a decryption key / algorithm to unscramble 3 5(b) 1 mark for a lossless technique 1 mark per bullet point for justification to max 2 • Lossless does not lose any data • Any lost data will mean the program will not work 3

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 7 of 9 Question Answer Marks 6(a) 1 mark for each correct line Database Term Description 4 6(b) 1 mark per task to max 3 • Create a table • Set up relationships between tables • Create / design a form • Create / design a report • Create / design a query (NOT run a query) 3 6(c)(i) 1 mark for each completed line CREATE TABLE ROOM( RoomNumber Integer, RoomType Varchar, PRIMARY KEY (RoomNumber) ); 3 6(c)(ii) 1 mark for each completed line INSERT INTO ROOM VALUES (5,"Double"); 2 Primary key Attribute Foreign key Entity A field in one table that links to a primary key in another table A collection of records and tables The type of data that is being stored A unique identifier for each tuple A data item, represented as a field within a table The concept or object in the system that we want to model and store information about

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 8 of 9 Question Answer Marks 6(c)(iii) 1 mark per bullet point • Alter table booking • Add number of nights with appropriate field name and data type ALTER TABLE BOOKING ADD NumberNights Integer; 2 Question Answer Marks 7(a) 1 mark for each feature and 1 mark for further related expansion to max 2 • Colour select • Select all pixels of the same colour • Add text • To show the name of the company • Resize the star shape • To fit the space available in the box • Fill an area with colour • To shade the side of the box • Select • ‘Grab’ a number of pixels to perform a task with/to • Copy • Replicate a number of pixels 2 7(b) 1 mark per bullet point • 160 * 160 (= 25600 pixels) • 25600 * 3 (= 76800 bytes) • 75 KB (divide by 1024) or 76.8 KB (divide by 1000) 3 7(c) 1 mark per bullet point to max 2 • The logo can be enlarged without becoming pixelated • because the instructions to create the logo are stored or • (Usually) smaller file size • only coordinates and calculations stored instead of individual pixels 2

9608/13 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 9 of 9 Question Answer Marks 7(d) 1 mark for 1 or 2 correct answers 2 marks for 3 correct answers Red Green Blue Hexadecimal value 91 3C 8E Denary value 145 60 142 2 7(e)(i) 1 mark Displays a message box containing the text ‘Error’ 1 7(e)(ii) 1 mark per bullet point • Assigns to the variable Value • the contents of the object "FirstBox" 2 7(e)(iii) 1 mark per bullet point • Writes the text "Agreed" • To the object with Id paragraph1 2