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

Cambridge International AS & A Level This document has 16 pages. Blank pages are indicated. DC (LEG/FC) 183147/3 © UCLES 2020 [Turn over * 0 6 4 4 5 5 6 7 9 2 * COMPUTER SCIENCE 9608/11 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 9608/11/M/J/20 © UCLES 2020 1 A computer program makes use of data validation routines and verification of data input. (a) Complete these two sentences about data validation and verification. 1. … checks that the data entered is reasonable. One example is … . 2. … checks that the data entered is the same as the original. One example is … . [4] (b) The program is installed on a computer system that has security measures in place to protect its data. Complete the following table. Security measure Description … … Data are written on two or more disks simultaneously. Encryption … … … … … … A copy of the data is taken and stored in another location. [3]

3 9608/11/M/J/20 © UCLES 2020 [Turn over 2 Kal teaches Computer Science and uses different devices when teaching his students. (a) Tick (✓) one or more boxes on each row to indicate whether each device is an input device, an output device, or both. Device Input Output LCD monitor Microphone Keyboard Touchscreen [2] (b) Kal has built a 3D printer to show students how it works. (i) The steps 1 to 9 describe the basic internal operation of a 3D printer. The following five statements are used to complete the sequence of steps. A A stepper motor moves the nozzle into position B A fan cools the layer C The software splits the object into slices D The nozzle extrudes the molten plastic E The data about the slices is sent to the printer Write one of the letters A, B, C, D or E in the appropriate step to complete the sequence. 1. The object is designed using Computer Aided Design (CAD) software 2. … 3. … 4. The solid plastic is melted and transferred to the nozzle 5. … 6. … 7. The steps 5 to 6 are repeated until the layer is complete 8. … 9. The steps 4 to 8 are repeated for each subsequent layer [4]

4 9608/11/M/J/20 © UCLES 2020 (ii) The 3D printer has both RAM and ROM. Describe the purpose of RAM and ROM in a 3D printer. RAM … … … … ROM … … … … [4]

5 9608/11/M/J/20 © UCLES 2020 [Turn over 3 Lana creates a website. The web pages of the website contain JavaScript and PHP code. (a) Describe the purpose of the following JavaScript statement. document.getElementById("text 2").innerHTML = 10 + 2; … … … … [2] (b) Describe the purpose of the following JavaScript code. function calculateValue(value1, value2){} … … … … [2] (c) Describe the purpose of the following PHP code. $number1 = 2; echo $number1 ** 3; … … … … [2]

6 9608/11/M/J/20 © UCLES 2020 4 A digital camera takes a bitmap image. The image is 2000 pixels wide by 1000 pixels high with a colour depth of 24-bits. (a) Calculate an estimate of the file size for the image. Give your answer in megabytes. Show your working. Working … … … … … Answer … MB [3] (b) A second image is taken, this time in black and white. It has the same number of pixels, but the file size is smaller. Explain why the file size is smaller. … … … … [2] (c) The digital camera allows a user to add text to an image. The text is encoded as ASCII values. The table shows the ASCII denary values for five characters. Character ASCII denary value a 97 b 98 c 99 d 100 e 101 (i) Give the 8-bit binary value for the ASCII character ‘b’. … … [1]

7 9608/11/M/J/20 © UCLES 2020 [Turn over (ii) Complete the table by writing the ASCII denary value for the character ‘t’ and its hexadecimal equivalent. Character t ASCII denary value Hexadecimal value [2]

8 9608/11/M/J/20 © UCLES 2020 5 (a) A logic circuit is given: X A B C Complete the following truth table for the logic circuit. 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]

9 9608/11/M/J/20 © UCLES 2020 [Turn over (b) Identify one logic gate not used in the logic circuit in part (a). Draw the symbol for this logic gate and complete its truth table. Logic gate: … Symbol: Truth table: Input Output A B 0 0 0 1 1 0 1 1 [3]

10 9608/11/M/J/20 © UCLES 2020 6 A processor has one general purpose register, the Accumulator (ACC), and an Index Register (IX). (a) The table gives three assembly language instructions for loading data into the ACC. It also identifies the addressing mode used for each instruction. Instruction Addressing mode A LDM #193 Immediate B LDD 193 Direct C LDX 193 Indexed (i) State the contents of the Accumulator after each of the instructions A, B and C are run. A … … B … … C … … [3] (ii) Name two other addressing modes. 1 … 2 … [2] (b) The ACC is a general purpose register. The IX is a special purpose register. Identify two other special purpose registers used in the fetch-execute cycle and describe their role in the cycle. Register 1 … Role … … … Register 2 … Role … … … [4]

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12 9608/11/M/J/20 © UCLES 2020 7 A driving school teaches people how to drive cars. The school has a relational database, DRIVING_SCHOOL, to store information about instructors, students, lessons and the cars used by instructors. INSTRUCTOR(InstructorID, FirstName, LastName, DateOfBirth, Level) CAR(Registration, Make, Model, EngineSize) INSTRUCTOR_CAR(InstructorID, Registration) STUDENT(StudentID, FirstName, LastName, DateOfBirth, Address1) LESSON(LessonID, StudentID, InstructorID, LessonDate, LessonTime) (a) Give two benefits to the driving school of using a relational database instead of a flat file. 1 … … 2 … … [2] (b) Complete the entity-relationship diagram for the database DRIVING_SCHOOL. INSTRUCTOR INSTRUCTOR_CAR LESSON CAR STUDENT [4]

13 9608/11/M/J/20 © UCLES 2020 [Turn over (c) The table shows some sample data for the table INSTRUCTOR. InstructorID FirstName LastName DateOfBirth Level Ins01 Jayden Han 05/06/1974 1 Ins02 Freda Choi 06/02/1978 2 Ins03 Kelly Kim 01/12/1966 1 Ins04 Santana Thompson 09/09/1985 3 Complete the Data Definition Language (DDL) statement to create the table INSTRUCTOR. ………………………………………………………………………… TABLE INSTRUCTOR( InstructorID VARCHAR(5), FirstName VARCHAR(15), LastName VARCHAR(15), DateOfBirth DATE, Level ………………………………………………………………………… , ………………………………………………………………………… (InstructorID) ); [3] (d) The table STUDENT needs an additional field to store the student’s telephone number, for example 012-3456. Write a Data Definition Language (DDL) statement to add the new field to the table STUDENT. … … … … [2] (e) Write a Data Manipulation Language (DML) statement to return the date and time of all future lessons booked with the instructor whose InstructorID is Ins01. … … … … … … … [4]

14 9608/11/M/J/20 © UCLES 2020 8 Bart plays computer games on his stand-alone games console. The games console has an operating system. (a) Describe the tasks performed by the operating system to manage the main memory in the games console. … … … … … … … … [4] (b) The computer games are written in a high-level language. Bart does not need a compiler or an interpreter to run the games he buys for his console. Explain why the games run without the need for a compiler or an interpreter. … … … … [2] (c) When Bart is at work, he connects his work laptop to his employer’s Local Area Network (LAN). The LAN has both a router and a gateway. Give two similarities and one difference between a router and a gateway. Similarity 1 … … Similarity 2 … … Difference … … … [3]

15 9608/11/M/J/20 © UCLES 2020 9 Utility programs are examples of system software. (a) Complete the table by writing the name of the utility program for each description. Description Utility program Reorganises files on a disk to improve efficiency Scans a hard disk to identify bad sectors Prepares a hard disk for first use [3] (b) File compression is one example of a utility program. Tick (✓) one box on each row to indicate whether the action is an example of lossy compression or lossless compression. Action Lossy Lossless Reducing the resolution of an image Using run-length encoding on a text file Reducing the sampling rate of a sound file [1]

16 9608/11/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 10 printed pages. © UCLES 2020 [Turn over Cambridge International AS & A Level COMPUTER SCIENCE 9608/11 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.

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 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.

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 3 of 10 Question Answer Marks 1(a) 1 mark for each correctly completed term. Validation checks that the data entered is reasonable. One example is a presence check. Verification checks that the data entered is the same as the original. One example is double entry. 4 1(b) 1 mark for each correct entry Security measure Description Disk mirroring Data are written on two or more disks simultaneously. Encryption Contents are scrambled so they cannot be understood without a decryption key Backup A copy of the data is taken and stored in another location 3 Question Answer Marks 2(a) 1 mark for first three rows, 1 mark for the touchscreen being both. Device Input Output LCD Monitor  Microphone  Keyboard  Touchscreen   2

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 4 of 10 Question Answer Marks 2(b)(i) 1 mark for 1 correct entry 2 marks for 2 correct entries 3 marks for 3 correct entries 4 marks for 5 correct entries 1 The object is designed using Computer Aided Design (CAD) software 2 C (The software splits the object into slices) 3 E (The data about the slices is sent to the printer) 4 The solid plastic is melted and transferred to the nozzle 5 A (A stepper motor moves the nozzle into position) 6 D (The nozzle extrudes the molten plastic) 7 The steps 5 to 6 repeat until the layer is complete 8 B (A fan cools the layer) 9 The steps 4 to 8 are repeated for each subsequent layer 4 2(b)(ii) 1 mark per bullet point. Max 3 for RAM, max 2 for ROM RAM • Stores currently running parts of the 3D printer software • Stores the data about the layers being printed // contents of buffer • Stores current progress of printing • Stores the data about the printer, e.g. Plastic levels, nozzle position ROM • Stores the operating software for the 3D printer // OS for the 3D printer • Stores the boot-up/start-up instructions for the 3D printer 4 Question Answer Marks 3(a) 1 mark per bullet point • Outputs 12 // the result of 10 + 2 • In the object with the name "text 2" 2 3(b) 1 mark per bullet point • Declares a function called calculateValue • ... which takes two values as parameters 2

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 5 of 10 Question Answer Marks 3(c) 1 mark per bullet point to max 2 • Assigns the value 2 to the variable $number1 • Outputs to the screen • the result of $number1 to the power of 3 2 Question Answer Marks 4(a) 1 mark per bullet point • 2000 * 1000 * 24 = 48 000 000 bits • 48 000 000 / 8 / 1024 / 1024 • = 6 MB or 5.7 MB 3 4(b) 1 mark per bullet point to max 2 • Only 1 bit needed to store the colour of each pixel ... • ... so number of pixels * bit depth is 2000 * 1000 * 1 (rather than 2000 * 1000 * 24) • ... so the calculation (in part 4(a)) results in smaller figure for file size 2 4(c)(i) 0110 0010 1 4(c)(ii) 1 mark for each correct line Character t ASCII denary value 116 Hexadecimal value 74 2

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 6 of 10 Question Answer Marks 5(a) 1 mark for each pair of correct answers (shaded) A B C Working space X 0 0 0 0 0 0 1 1 0 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 1 0 0 1 1 1 0 4

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 7 of 10 Question Answer Marks 5(b) 1 mark for name, 1 mark for symbol, 1 mark for truth table • NAND Input Output A B 0 0 1 0 1 1 1 0 1 1 1 0 • NOR Input Output A B 0 0 1 0 1 0 1 0 0 1 1 0 3 Question Answer Marks 6(a)(i) 1 mark for each correct answer A: The number 193 B: The data in memory location 193 C: The data in the memory location found by adding the contents of the IX to 193 3 6(a)(ii) 1 mark each correct answer • Indirect • Relative 2

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 8 of 10 Question Answer Marks 6(b) 1 mark for correctly naming register, 1 mark for appropriate role • Program counter // PC • Stores the address of the next instruction to be fetched • Memory address register // MAR • Stores the address where data/instruction is to be read from or saved to • Memory data register // MDR • Stores data that is about to be written to memory // Stores data that has just been read from memory • Current instruction register // CIR • Stores the instruction that is currently being decoded/executed 4 Question Answer Marks 7(a) 1 mark per bullet point to max 2 • Reduced data redundancy • Reduced data dependency • Improved data integrity • Improved data privacy • Program-data independence • Ability to create ad hoc queries 2 7(b) 1 mark for each correct link 4 INSTRUCTOR LESSON INSTRUCTOR_CAR CAR STUDENT

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 9 of 10 Question Answer Marks 7(c) 1 mark for each correctly completed statement • CREATE (line 1) • INTEGER (line 6) • PRIMARY KEY (line 7) CREATE TABLE INSTRUCTOR( InstructorID VARCHAR(5), FirstName VARCHAR(15), LastName VARCHAR(15), DateOfBirth DATE, Level INTEGER, PRIMARY KEY (InstructorID) ); 3 7(d) 1 mark per bullet point • Alter table student • Add an appropriate identifier with suitable data type ALTER TABLE STUDENT ADD TelNum VARCHAR; 2 7(e) 1 mark per bullet point • Select lesson date and lesson time • From table LESSON • Where InstructorID = “Ins01” • And lesson date is greater than today’s date SELECT LessonDate, LessonTime FROM LESSON WHERE InstructorID = "Ins01" AND LessonDate > #######; 4 Question Answer Marks 8(a) 1 mark per bullet point to max 4 • Reads/writes data to/from RAM • … e.g. current data/instructions from a game so the CPU can access it • Allocates virtual memory • … when there is insufficient RAM to run a program/game • Allocates RAM to optimise performance • Paging • Segmentation 4

9608/11 Cambridge International AS & A Level – Mark Scheme PUBLISHED May/June 2020 © UCLES 2020 Page 10 of 10 Question Answer Marks 8(b) 1 mark per bullet point to max 2 • Software will have been built using a compiler // the software is pre- compiled • Software is an executable file // the game is already in machine code // the game is already set-up to run on the console • Source code is not provided so does not need compiling/interpreting 2 8(c) 1 mark for each similarity, max 2 • Both devices regulate network traffic between two networks // connect two networks • Both receive packets from a network and both forward packets onto a network 1 mark for a difference • A Router connects two networks using the same protocol, a Gateway can connect two networks using different protocols 3 Question Answer Marks 9(a) 1 mark for each correctly identified utility program Description Utility program Reorganises files on a disk to improve efficiency Defragmentation software Scans a hard disk to identify bad sectors Disk contents analysis / repair software Prepares a hard disk for first use Disk formatter 3 9(b) 1 mark for 3 correct answers Action Lossy Lossless Reducing the resolution of an image  Using run-length encoding on a text file  Reducing the sampling rate of a sound file  1