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

This document consists of 14 printed pages and 2 blank pages. DC (LEG/CB) 171630/4 © UCLES 2019 [Turn over * 4 6 2 6 0 5 7 6 4 3 * COMPUTER SCIENCE 9608/11 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 9608/11/O/N/19 © UCLES 2019 1 Von Neumann is an example of a computer architecture. (a) The diagram has registers used in Von Neumann architecture on the left and descriptions on the right. Draw one line to match each register with its correct description. Register Description Current Instruction Register Memory Address Register Program Counter Memory Data Register Stores the address of the memory location about to be written to or read from Stores the address of the next instruction to be read Stores the address of the input device from which the processor accesses the instruction Stores the instruction that is being decoded and executed Stores the data that has just been read from memory, or is about to be written to memory [4]

3 9608/11/O/N/19 © UCLES 2019 [Turn over (b) Many components of the computer system transfer data between them using buses. One example of a bus is an address bus. (i) Name two other buses that exist within a computer and give the purpose of each. Bus 1 … Purpose … … … Bus 2 … Purpose … … … [4] (ii) State the benefit of increasing the address bus width from 16 bits to 32 bits. … … [1] (c) The following statements describe features of a low-level language. Complete the statements by writing the appropriate terms in the spaces. A … is a sequence of instructions that are given an identifier. These instructions may need to be executed several times. A … is an instruction that tells the assembler to do something. It is not a program instruction. The processor’s instruction set can be put into several groups. One of these groups is … . [3]

4 9608/11/O/N/19 © UCLES 2019 2 Aaron uses a desktop computer to do school work. (a) Aaron has a mouse and keyboard that he can use as input devices and a monitor as an output device. (i) Identify two additional input devices Aaron could use with his desktop computer. 1 … 2 … [2] (ii) Identify two additional output devices Aaron could use with his desktop computer. 1 … 2 … [2] (iii) Aaron needs to store a large number of applications and data on his computer. He needs at least 50GB of secondary storage space. Identify one internal secondary storage device for Aaron’s computer. … … [1] (iv) Describe the internal operation of a trackerball mouse. … … … … … … [3]

5 9608/11/O/N/19 © UCLES 2019 [Turn over (b) Aaron’s computer has an operating system (OS). The OS manages the running processes and provides a user interface. Describe these OS management tasks. Process management … … … … … … Provision of a user interface … … … … … … [6] (c) Aaron’s computer has a virus checker and backup software. Describe these utility programs. Virus checker … … … … Backup software … … … … [4]

6 9608/11/O/N/19 © UCLES 2019 (d) Aaron creates a web page using JavaScript code and HTML tags. Describe how the JavaScript code is translated using an interpreter. … … … … [2]

7 9608/11/O/N/19 © UCLES 2019 [Turn over 3 (a) A bank approves a customer for an account based on the criteria in the following table. Parameter Description of parameter Binary value Condition A Employed 1 True 0 False B Self-employed 1 True 0 False C Over 21 1 True 0 False D Earn more than 30 000 1 True 0 False E Another account 1 True 0 False A customer is approved (X = 1) if the person: • is over 21 and employed or • is over 21 and self-employed and • either earns more than 30 000 or • has another account. Draw a logic circuit to represent the model. A B X D E C [5]

8 9608/11/O/N/19 © UCLES 2019 (b) Complete the truth table for the logic expression: X = (A AND C) OR (NOT 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]

9 9608/11/O/N/19 © UCLES 2019 [Turn over 4 Customers of a bank can access their account information by logging in on the bank’s website. (a) The bank has a client-server model of networked computers. (i) Describe, using the bank as an example, the key features of a client-server model. … … … … … … [3] (ii) Give two other examples of applications that can use the client-server model. 1 … … 2 … … [2] (b) The bank’s customers log in to the website using a web application. Explain why the web application uses server-side scripting. … … … … … … [3]

10 9608/11/O/N/19 © UCLES 2019 (c) The bank is upgrading its local area network (LAN) copper cables to fibre-optic cables. (i) State two benefits to the bank of upgrading to fibre-optic cable from copper cable. 1 … … 2 … … [2] (ii) State two drawbacks of upgrading to fibre-optic cables. 1 … … 2 … … [2]

11 9608/11/O/N/19 © UCLES 2019 [Turn over (d) The bank uses a relational database, ACCOUNTS, to store the information about customers and their accounts. The database stores the customer’s first name, last name and date of birth. The bank has several different types of account. Each account type has a unique ID number, name (for example, regular or saving) and bonus (for example, $5.00, $10.00 or $15.00). A customer can have more than one account. Each customer’s account has its own ID number and stores the amount of money the customer has in that account. The bank creates a normalised, relational database to store the required information. There are three tables: • CUSTOMER • ACCOUNT_TYPE • CUSTOMER_ACCOUNT (i) Write the attributes for each table to complete the database design for the bank. CUSTOMER( … … …) ACCOUNT_TYPE( … … …) CUSTOMER_ACCOUNT( … … …) [3] (ii) Identify the primary key for each table that you designed in part (d)(i). CUSTOMER … ACCOUNT_TYPE … CUSTOMER_ACCOUNT … [2] (iii) Identify one foreign key in one of the tables that you designed in part (d)(i). Table name … Foreign key … [1]

12 9608/11/O/N/19 © UCLES 2019 (iv) The following table has definitions of database terms. Write the correct database term in the table for each definition. Definition Term All the data about one entity The data in one row of a table A column or field in a table [3]

13 9608/11/O/N/19 © UCLES 2019 [Turn over 5 (a) The bit depth of an image dictates how many different colours can be represented by each pixel. (i) State the number of different colours that can be represented by a bit depth of 8 bits. … [1] (ii) One binary colour is represented by 0100 1110 Convert the unsigned binary number 0100 1110 into denary. … [1] (b) Convert the denary number −194 into 12-bit two’s complement. … [1] (c) (i) Convert the Binary Coded Decimal (BCD) value 0110 1001 into denary. … [1] (ii) Identify one practical application where BCD is used. … … [1] (d) One example of a character set used by computers is ASCII. Describe how one character is represented in a character set. … … … … [2]

14 9608/11/O/N/19 © UCLES 2019 (e) Data can be compressed using either lossy or lossless compression. Tick (✓) one box in each scenario to identify whether lossy or lossless compression should be used. Justify your choice. (i) A program written in a high-level language. Lossy Lossless Justification … … … … [2] (ii) A photograph that needs to be emailed to a friend. Lossy Lossless Justification … … … … [2] (iii) You need to upload a video that you have created to a website. Lossy Lossless Justification … … … … [2]

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16 9608/11/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 8 printed pages. © UCLES 2019 [Turn over Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/11 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.

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 2 of 8 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 October/November 2019 © UCLES 2019 Page 3 of 8 Question Answer Marks 1(a) 1 mark for each correct line 4 1(b)(i) 1 mark for naming, 1 mark for purpose for each bus • Data bus • Carries data between the processor and memory / carries data that is currently being processed. • Control bus • Transmits signals between the control unit and the other components 4 1(b)(ii) Significant increase in the number of directly addressed memory locations // increases the number of directly addressable memory locations from 216 to232 1 1(c) 1 mark for each correctly inserted term A macro is a sequence of instructions that are given an identifier. These instructions may need to be executed several times. A directive is an instruction that tells the assembler to do something. It is not a program instruction. The processor’s instruction set can be put into several groups. One of these groups is data movement // input and output // arithmetic operations // jump instructions // compare instructions // modes of addressing. 3 Register Description Current Instruction Register Memory Address Register Program Counter Memory Data Register Stores the instruction that is being decoded and executed Stores the address of the input device from which the processor accesses the instruction Stores the data that has just been read from memory, or is about to be written to memory Stores the address of the next instruction to be read Stores the address of the memory location about to be written to or read from

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 4 of 8 Question Answer Marks 2(a)(i) 1 mark per device to max 2 e.g. • Trackpad/touchpad • microphone • touchscreen • scanner 2 2(a)(ii) 1 mark per device to max 2 e.g. • printer • speakers • touchscreen 2 2(a)(iii) Magnetic hard disk drive // solid state drive 1 2(a)(iv) 1 mark per bullet point to max 3 • The ball touches horizontal and vertical rollers • When the ball rotates / moves • « one or both of the rollers rotate as well • Each roller connects to a shaft which spins a disk with holes • Infrared beams shine through the holes in the disks • As the ball moves the roller the beam is broken by the space between the holes • ... creating pulses of light • The distance and/or speed of the mouse is determined from the rate of the pulses • « by an on-board processor chip // by driver software in the computer 3 2(b) 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 the resources the processes need • Enables processes to share information • Prevents interference between processes// resolution of conflicts Provision of a user interface: • Allows a user to communicate with the hardware // vice-versa • « by making navigation around the system easier • Provides facility for user inputting data • Provides facility for outputting to the user • By example e.g. command line / GUI / menu-driven 6

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 5 of 8 Question Answer Marks 2(c) 1 mark per bullet point to max 3 for each utility program, max 4 in total Virus checker: • Scans files stored on a computer system for malicious code • Scans files when they enter the system / memory stick inserted / download etc. • Sets up a schedule for virus-checking • Isolates / quarantines / deletes viruses • Regularly updates the virus definitions Backup software: • Creates a copy of the contents of a disk / partition. Can be set up to automatically backup // schedules backups • Allows the user to decide what is backed up, e.g. all data // all files that have changed since the last backup • Allows the user to set up an off-site backup • May encrypt the backup files • Restores the data if necessary 4 2(d) 1 mark per bullet point to max 2 • The code is translated one line at a time • ... and executed immediately • The interpreter stops as soon as it finds an error 2 Question Answer Marks 3(a) 1 mark for each gate • A AND C • B AND C • D OR E • (B AND C) AND (D OR E) • Final OR 5

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 6 of 8 Question Answer Marks 3(b) 1 mark for each pair of correct rows 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 0 1 0 1 1 1 1 0 0 1 1 1 1 4 Question Answer Marks 4(a)(i) 1 mark per bullet point to max 3. If no application to the bank max 2 • The bank's server holds the customer account data / website • ... and performs the requested tasks / processes. The computers used by the customers are the clients « • « that send requests to the server • « which returns the results of the request • « E.g. a customer asks for a list of recent transactions on their account. 3 4(a)(ii) 1 mark per example to max 2 e.g. • Sending and receiving email • A company or school centrally storing files • Using a print server • Using a file server 2 4(b) 1 mark per bullet point to max 3 • All data is held on the server // All processing is performed on the server • The server only sends the results of the query to the client • The client does not have access to all the data • ... which keeps the data more secure / consistent • Customers can be identified when they log in • «from a database of usernames and passwords 3

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 7 of 8 Question Answer Marks 4(c)(i) 1 mark per bullet point to max 2 • Less interference in the signal • The signal does not degrade as quickly // Needs less signal boosting • More secure // more difficult to hack • Greater bandwidth // Faster transmission speeds possible 2 4(c)(ii) 1 mark per bullet point to max 2 • Initial installation cost is higher // Cable / hardware is more expensive to buy per metre • Specialists / trained personnel are needed to install / maintain • Difficult to terminate // The electronics at both ends are more complex • Fibres can break when bent • Only transmits data in one direction // Cannot transmit power, only data 2 4(d)(i) 1 mark per table • Table CUSTOMER with fields FirstName, LastName, DateOfBirth, CustomerID • Table ACCOUNT_TYPE with fields AccountID, Name, Bonus • Table CUSTOMER_ACCOUNT with fields ID, CustomerID, AccountID, Amount CUSTOMER (CustomerID, FirstName, LastName, DateOfBirth) ACCOUNT_TYPE (AccountID, Name, Bonus) CUSTOMER_ACCOUNT (ID, CustomerID, AccountID, Amount) 3 4(d)(ii) 1 mark for 1 or 2 correct Primary Keys, 2 marks for 3 correct Primary Keys CUSTOMER: CustomerID ACCOUNT_TYPE: AccountID CUSTOMER_ACCOUNT: ID 2 4(d)(iii) 1 mark for both table name and Foreign Key Table: CUSTOMER_ACCOUNT Foreign Key: CustomerID / AccountID 1 4(d)(iv) 1 mark for each correct term Definition Term All the data about one entity Table / Relation The data in one row of a table Tuple / Record A column or field in a table Attribute 3

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED October/November 2019 © UCLES 2019 Page 8 of 8 Question Answer Marks 5(a)(i) 256 1 5(a)(ii) 78 1 5(b) 1111 0011 1110 1 5(c)(i) 69 1 5(c)(ii) Any scenario where a single digit needs to be transmitted / displayed e.g. calculator / digital clock 1 5(d) 1 mark per bullet to max 2 • Each character is represented by a unique • « denary / hexadecimal / binary number 2 5(e)(i) 1 mark per bullet to max 2 Lossless: • All the data is needed // the original file is fully restored • If any data is lost, the program will not run • Probably does not require significant reduction in file size // a program written in a high-level language is just text, so does not need much reduction in size 2 5(e)(ii) 1 mark per bullet to max 2 Lossy: • All the data is not required • The number of colours / resolution can be reduced without the user noticing • Email requires a significantly smaller file size // takes less time to transmit Lossless: • A high quality image may be needed • All of the data is needed // cannot afford to lose any data // the original file is fully restored 2 5(e)(iii) 1 mark per bullet to max 2 Lossy: • Some loss of quality will not be noticed // high quality video not needed on the website • A more significant reduction may be needed • Takes a shorter time to upload / download // requires less bandwidth Lossless: • A high quality video may be needed • Might only be a short video clip • All of the data is needed // cannot afford to lose any data // the original file is fully restored 2