Cambridge A Level Computer Science 9608 — 2019 Oct/Nov Paper 1 · Variant 3

This document consists of 14 printed pages and 2 blank pages. DC (SC/TP) 171632/4 © UCLES 2019 [Turn over * 1 9 3 6 5 5 4 5 5 9 * COMPUTER SCIENCE 9608/13 Paper 1 Theory Fundamentals October/November 2019 1 hour 30 minutes Candidates answer on the Question Paper. No Additional Materials are required. No calculators allowed. READ THESE INSTRUCTIONS FIRST Write your centre number, candidate number and name in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. Answer all questions. No marks will be awarded for using brand names of software packages or hardware. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. The maximum number of marks is 75. Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level

2 9608/13/O/N/19 © UCLES 2019 1 In a supermarket, a self-checkout machine allows customers to scan the barcodes of products and then pay for their shopping. These are an alternative to the traditional cashier-staffed checkout. (a) The self-checkout machine has a touchscreen. (i) Identify two other input devices that self-checkout machines have. 1 … 2 … [2] (ii) Identify two other output devices that self-checkout machines have. 1 … 2 … [2]

3 9608/13/O/N/19 © UCLES 2019 [Turn over (iii) The touchscreen uses capacitive technology. The sequence of steps 1 to 6 describes the internal operation of the touchscreen. The statements A, B, C and D are used to complete the sequence. A Charge is drawn to the point of contact. B The screen has a layer that stores an electrical charge. C There is a change in the electrostatic field. D The coordinates are sent to the touchscreen driver. Write one of the letters A to D in each appropriate row to complete the sequence. 1 … 2 When the user touches the screen 3 … 4 … 5 The coordinates of the point of contact can be calculated. 6 … [2] (b) The self-checkout machines have primary storage. (i) Give two reasons why the self-checkout machine needs primary storage. 1 … … 2 … … [2] (ii) The self-checkout machines use Static RAM (SRAM) for their cache. The following table has statements about SRAM or Dynamic RAM (DRAM). Tick (✓) one box in each row to identify whether the statement is about SRAM or DRAM. Statement SRAM DRAM More expensive to make Requires refreshing (recharging) Made from flip-flops [2]

4 9608/13/O/N/19 © UCLES 2019 (c) The self-checkout machines connect to a server that stores all the data for the supermarket. This is a client-server network. (i) Describe, using an example for the supermarket, the client-server network model. … … … … … … … … [4] (ii) The supermarket is concerned about the security and integrity of the data on the server. Identify two methods that can be used to minimise the security risk to the data, and one method to protect the integrity of the data. Security 1 … … Security 2 … … Integrity … … [3]

5 9608/13/O/N/19 © UCLES 2019 [Turn over 2 Leonardo’s mobile phone has an operating system (OS). (a) Describe the following key management tasks that the mobile phone operating system carries out. Process management … … … … … … Memory management … … … … … … [6] (b) Leonardo uses the mobile phone to record his voice. (i) Describe how sound sampling is used by the mobile phone to encode the sound. … … … … [2]

6 9608/13/O/N/19 © UCLES 2019 (ii) Leonardo records his voice twice. Each recording is the same length and has the same sampling resolution. The first recording has a sampling rate of 44 100 Hz. The second recording has a sampling rate of 21 000 Hz. Describe how the different sampling rates will affect the recording and the sound file. … … … … [2] (iii) Leonardo transfers the recordings to his laptop computer. He uses sound editing software to delete some sections of the recordings, and copy and paste to replicate other sections. Describe two other features of sound editing software Leonardo can use to edit the recordings. 1 … … … … 2 … … … … [4]

7 9608/13/O/N/19 © UCLES 2019 [Turn over 3 A hotel needs to record information about customers and their bookings. (a) The hotel has two types of room: double and family. Each room has a unique room number. The hotel stores information about the customers including their name, address and contact details. When a customer books a room, they give the start date and the number of nights they want to stay. If a customer wants more than one room, each room must have a separate booking. Each booking has an ID number. The hotel creates a normalised, relational database to store the required information. There are three tables: • CUSTOMER • ROOM • BOOKING (i) Complete the database design for the hotel by writing the attributes for each table. CUSTOMER( … … … ) ROOM( … … … ) BOOKING( … … … ) [3] (ii) Identify the primary key for each table that you designed in part (a)(i). CUSTOMER … ROOM … BOOKING … [2]

8 9608/13/O/N/19 © UCLES 2019 (iii) Identify one foreign key in the tables that you designed in part (a)(i). Table name … Foreign key … [1] (b) The hotel wants to use a Database Management System (DBMS) to set up and manage the database. Describe, using examples, how the hotel can use the following DBMS tools: Developer interface … … … … … Query processor … … … … … [5] (c) The following table has four SQL scripts. Tick (✓) one box in each row to identify whether the script is an example of a Data Definition Language (DDL) statement or a Data Manipulation Language (DML) statement. Script DDL DML CREATE TABLE FILMS SELECT FilmID FROM FILMS ALTER TABLE FILMS ADD PRIMARY KEY (FilmID) CREATE DATABASE MYDATA [2]

9 9608/13/O/N/19 © UCLES 2019 [Turn over 4 (a) Convert the unsigned binary number 0101 1111 1100 into denary. … [1] (b) Convert the denary number −239 into 12-bit two’s complement. … [1] (c) Convert the two’s complement number 0110 0101 into denary. … [1] (d) Convert the Binary Coded Decimal (BCD) value 0110 0101 into denary. … [1] (e) Convert the denary number 222 into hexadecimal. … [1]

10 9608/13/O/N/19 © UCLES 2019 5 (a) Draw a logic circuit to represent the logic expression: X = NOT (A OR C) OR (A AND NOT B) A B C X [5] (b) Complete the truth table for the logic expression: X = NOT (A OR C) OR (A AND NOT B) 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]

11 9608/13/O/N/19 © UCLES 2019 [Turn over Question 6 begins on the next page.

12 9608/13/O/N/19 © UCLES 2019 6 Willow is creating a website. One of the web pages includes the following JavaScript code and HTML tags. 01 <html> 02 <body> 03 <form> 04 <p id="displayQuestion"></p> 05 <input type="text" id="answer"> 06 <button id="submit" onclick="checkAnswer()"> Submit </button> 07 </form> 08 </body> 09 <script> 10 val1 = Math.floor((Math.random() * 10) + 1); 11 val2 = Math.floor((Math.random() * 10) + 1); 12 document.getElementById("displayQuestion").innerHTML = "What is" + val1.toString() + "*" + val2.toString() + "?"; 13 function checkAnswer(){ 14 userAnswer = document.getElementById("answer").value; 15 answer = val1 * val2 16 if (userAnswer == answer.toString()){ 17 alert("Correct, well done"); 18 }else{ 19 alert("Sorry that's incorrect"); 20 } 21 } 22 </script> 23 </html> (a) (i) Name three functions in the JavaScript code. 1 … 2 … 3 … [3] (ii) Identify every line number of the JavaScript code that generates an output. … … [2] (iii) Identify the line number of the JavaScript code that takes data the user has input and stores it in a variable. … [1]

13 9608/13/O/N/19 © UCLES 2019 [Turn over (iv) Describe the purpose of the code on line 16. … … … … [2] (b) Willow used functions from a JavaScript program library in the web page. Describe the benefits to Willow of using program libraries to create the web page. … … … … … … … … [4]

14 9608/13/O/N/19 © UCLES 2019 7 The following table has descriptions of modes of addressing. Complete the table by writing the name of the addressing mode for each description. Addressing mode Description Form the address by adding the given number to a base address. Load the contents of the calculated address to the Accumulator (ACC). Load the contents of the address held at the given address to ACC. Load the contents of the given address to ACC. Form the address from the given address + the contents of the Index Register. Load the contents of the calculated address to ACC. Load the given value directly to ACC. [5]

15 9608/13/O/N/19 © UCLES 2019 BLANK PAGE

16 9608/13/O/N/19 © UCLES 2019 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 2019 [Turn over Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/13 Paper 1 Written Paper October/November 2019 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 2019 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 October/November 2019 © UCLES 2019 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 October/November 2019 © UCLES 2019 Page 3 of 9 Question Answer Marks 1(a)(i) 1 mark per input device to max 2 e.g. • Barcode scanner / Infra-red scanner • Pressure sensor • RFID / chip reader • Bank note scanner • Pin / key pad • Magnetic strip reader 2 1(a)(ii) 1 mark per output device to max 2 e.g. • Speaker • Printer • LCD screen 2 1(a)(iii) 1 mark for at least two statements in the correct position, 2 marks for all four statements in correct position. 1 B «. «.. (The screen has a layer that stores an electrical charge) 2 When the user touches the screen 3 A ««« (Charge is drawn to the point of contact) 4 C ««« (There is a change in the electrostatic field) 5 The coordinates of the point of contact can be calculated 6 D «««. (These coordinates are sent to the touchscreen driver) 2 1(b)(i) 1 mark per bullet point to max 2 • To store the files needed to boot the system • To store parts of the self- checkout machine operating system • To store the self-checkout machine software • To store the intermediate data / running total for items purchased 2 1(b)(ii) 1 mark for at least one correct row, 2 marks for all three correct rows Statement SRAM DRAM More expensive to make 9 Requires refreshing (recharging) 9 Made from flip-flops 9 2

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 4 of 9 Question Answer Marks 1(c)(i) 1 mark per bullet point to max 3 plus 1 mark for suitable example • When a barcode on an item is scanned • « the server performs any requested tasks // the server looks up the details of the product • The self-checkout machine is a client • « that send requests to the server // the self-checkout machine asks for, e.g. the price of the item • The server returns the results of the request // the server returns e.g. the item price • Self-checkout machine displays e.g. price to the user 4 1(c)(ii) 1 mark for each security method to max 2, 1 mark for integrity Security • encryption • access rights • username and password // biometrics // user accounts • backup // disk mirroring • firewall • Physical methods (e.g. CCTV, locked rooms etc.) Integrity • checksum • parity • validation on input 3 Question Answer Marks 2(a) 1 mark per bullet point to max 4 for each management task, max 6 in total Process Management • Manages the scheduling of processes • « allows multi-tasking / multi-processing • « ensures fair access • « handles priorities • Manages which resources the processes require • Enables processes to share information • Prevents interference between processes // resolution of conflicts Memory Management • Allocates memory to processes • Ensures fair usage of memory • Organises memory / by example • Makes use of virtual memory • Keep processes separate • To release memory when a process stops 6

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 5 of 9 Question Answer Marks 2(b)(i) 1 mark per bullet point to max 2 • The amplitude of the wave is measured • « at set, regular time intervals • The value is stored as a binary number 2 2(b)(ii) 1 mark per bullet point • Sampling resolution of 44100 Hz takes more samples per second, so the file size will be larger // Sampling resolution of 21000 Hz takes fewer samples per second, so the file size will be smaller • At a resolution of 44100 Hz, the sound recording is a closer / more accurate representation of Leonardo's voice // At a resolution of 21000 Hz, the sound recording is a less accurate representation of Leonardo's voice 2 2(b)(iii) 1 mark for naming a feature, 1 mark for description, max 2 marks for each feature e.g. • Amplify • ... Increase the volume of a section of sound • Change pitch • ... Increase/decrease frequency of section(s) • Change sampling resolution • « to change the accuracy of the sound / file size 4 Question Answer Marks 3(a)(i) 1 mark per table • CUSTOMER table has at least customer ID, customer name, address and contact details • ROOM has at least room number, room type, • BOOKING has at least booking ID, room number, customer ID, start date, number of nights CUSTOMER (CustomerID, Name, Address, ContactDetails) ROOM (RoomNumber, RoomType) BOOKING (BookingID, RoomNumber, CustomerID, StartDate, NumberNights) 3

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 6 of 9 Question Answer Marks 3(a)(ii) 1 mark for 1 or 2 correct Primary Keys, 2 marks for 3 correct Primary Keys CUSTOMER: CustomerID ROOM: RoomNumber BOOKING: BookingID 2 3(a)(iii) 1 mark for both table name and Foreign Key Table: BOOKING Foreign Key: CustomerID / RoomNumber 1 3(b) 1 mark per bullet point to max 2 plus 1 mark for suitable example for each DBMS tool Developer Interface • To create user friendly features e.g. forms to enter new bookings • To create outputs e.g. report of bookings on a given date • To create interactive features e.g. buttons and menus Query processor • To create SQL/QBE queries • To search for data that meets set criteria, e.g. all bookings for next week • To perform calculations on extracted data, e.g. number of empty rooms tomorrow 5 3c 1 mark for at least two correct rows, 2 marks for all four correct rows Script DDL DML CREATE TABLE FILMS 9 SELECT FilmID FROM FILMS 9 ALTER TABLE FILMS ADD PRIMARY KEY (FilmID) 9 CREATE DATABASE MYDATA 9 2 Question Answer Marks 4(a) 1532 1 4(b) 1111 0001 0001 1 4(c) 101 1 4(d) 65 1 4(e) DE 1

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 7 of 9 Question Answer Marks 5(a) 1 mark for each correct gate • A OR C • NOT(A OR C) • NOT B • A AND NOT B • Final OR 5 5(b) 1 mark for each pair of rows A B C Working space X 0 0 0 1 0 0 1 0 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

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 8 of 9 Question Answer Marks 6(a)(i) 1 mark per bullet point to max 3 • checkAnswer • Math.floor // floor • Math.random // random • getElementById • toString • alert 3 6(a)(ii) 1 mark per bullet point • 12 • 17 and 19 2 6(a)(iii) 14 1 6(a)(iv) 1 mark per bullet point to max 2 • Converts the number in the variable answer to a string • Compares the value in userAnswer with the string value of answer • The if determines which line is executed next 2 6(b) 1 mark per bullet point to max 4 • Using program libraries saves time • « as she does not have to write some routines • Program library routines should already be thoroughly tested • « so, Willow can use them without having to spend time checking they work / correcting errors • Program library routines may perform complex tasks • ... so, Willow won’t have to work out how to code them 4

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 9 of 9 Question Answer Marks 7 1 mark for each correct addressing mode Addressing mode Description Relative Form the address by adding the given number to a base address. Load the contents of the calculated address to the Accumulator (ACC). Indirect Load the contents of the address held at the given address to ACC. Direct Load the contents of the given address to ACC. Indexed Form the address from the given address + the contents of the Index Register. Load the contents of the calculated address to ACC. Immediate Load the given value directly to ACC. 5