Cambridge A Level Computer Science 9608 — 2016 May/June Paper 1 · Variant 3

This document consists of 13 printed pages and 3 blank pages. DC (ST) 122368/2 © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 0 2 7 6 2 3 0 7 1 4 * COMPUTER SCIENCE 9608/13 Paper 1 Theory Fundamentals May/June 2016 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 on all the work you hand in. 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.

2 9608/13/M/J/16 © UCLES 2016 1 Describe two differences between a compiler and interpreter. 1 … … … … 2 … … … …[4] 2 (a) Convert the following 8-bit binary integer into denary. 01001101 …[1] (b) Convert the following denary number into Binary Coded Decimal (BCD). 82 …[1] (c) Convert the following two’s complement integer number into denary. 11001011 … … …[2] (d) Convert the following denary number into hexadecimal. Show your working. 198 …[2]

3 9608/13/M/J/16 © UCLES 2016 [Turn over 3 A company needs new software to manage its accounts. It is evaluating two different options. One option is open source software and the other is commercial software. (a) Explain what is meant by open source software. … … … …[2] (b) Explain what is meant by commercial software. … … … …[2] (c) The company has decided to purchase commercial software. Identify four benefits to the company in choosing the commercial software option. 1 … … 2 … … 3 … … 4 … …[4]

4 9608/13/M/J/16 © UCLES 2016 Question 4 begins on page 5.

5 9608/13/M/J/16 © UCLES 2016 [Turn over 4 The table shows assembly language instructions for a processor which has one general purpose register, the Accumulator (ACC) and an index register (IX). Instruction Explanation Op code Operand LDD <address> Direct addressing. Load the contents of the given address to ACC. LDX <address> Indexed addressing. Form the address from <address> + the contents of the index register. Copy the contents of this calculated address to ACC. STO <address> Store contents of ACC at the given address. ADD <address> Add the contents of the given address to ACC. INC <register> Add 1 to the contents of the register (ACC or IX). DEC <register> Subtract 1 from the contents of the register (ACC or IX). CMP <address> Compare contents of ACC with contents of <address>. JPE <address> Following a compare instruction, jump to <address> if the compare was True. JPN <address> Following a compare instruction, jump to <address> if the compare was False. JMP <address> Jump to the given address. OUT Output to screen the character whose ASCII value is stored in ACC. END Return control to the operating system. The diagram shows the contents of the index register: Index register: 1 1 0 0 1 1 0 1 (a) Show the contents of the index register after the execution of the instruction: INC IX Index register: [1]

6 9608/13/M/J/16 © UCLES 2016 (b) Complete the trace table on the opposite page for the following assembly language program. 20 LDX 90 21 DEC ACC 22 STO 90 23 INC IX 24 LDX 90 25 DEC ACC 26 CMP 90 27 JPE 29 28 JPN 31 29 ADD 90 30 OUT 31 ADD 93 32 STO 93 33 OUT 34 END : : 90 2 91 90 92 55 93 34 IX 2 Selected values from the ASCII character set: ASCII Code 65 66 67 68 69 70 71 72 Character A B C D E F G H

7 9608/13/M/J/16 © UCLES 2016 [Turn over Trace table: Instruction Working space ACC Memory address IX OUTPUT 90 91 92 93 2 90 55 34 2 20 21 22 23 24 25 26 [7]

8 9608/13/M/J/16 © UCLES 2016 5 (a) A Database Management System (DBMS) provides the following features. Draw a line to match each feature with its description. Feature Description Data dictionary Data security Data integrity A file or table containing all the details of the database design Data design features to ensure the validity of data in the database A model of what the database will look like, although it may not be stored in this way Methods of protecting the data including the uses of passwords and different access rights for different users of the database [3] A school stores a large amount of data that includes student attendance, qualification and contact details. The school is setting up a relational database to store these data. (b) The school needs to safeguard against any data loss. Describe three factors to consider when planning a backup procedure for the data. Justify your decisions. 1 … … … 2 … … … 3 … … …[6]

9 9608/13/M/J/16 © UCLES 2016 [Turn over (c) The database design has three tables to store the qualifications and grades each student has attained. The following is a sample of the data from each table. STUDENT StudentID FirstName LastName Tutor 001AT Ahmad Tan 11A 003JL Jane Li 11B 011HJ Heather Jones 10A QUALIFICATION QualCode Level Subject CS1 IGCSE Computer Science MT9 IGCSE Maths SC12 IGCSE Science STUDENT-QUALIFICATION QualCode StudentID Grade DateOfAward SC12 011HJ A 31/8/2014 SC12 003JL C 31/8/2014 CS1 003JL B 31/8/2014 (i) Draw an Entity-Relationship (E-R) diagram to show the relationships between these three tables. [2] (ii) State the type of relationship that exists between STUDENT and STUDENT-QUALIFICATION. …[1]

10 9608/13/M/J/16 © UCLES 2016 (iii) Describe how the relationship between QUALIFICATION and STUDENT-QUALIFICATION is implemented. … … … …[2] (d) (i) The database will store each student’s date of birth. Write an SQL script to add a date of birth attribute to the appropriate table. … … … …[2] (ii) Write an SQL script to display the StudentID, Grade and DateOfAward for the QualCode value of SC12. … … … … … …[3] (iii) Write an SQL script to display the FirstName and LastName and QualCode for all STUDENT-QUALIFICATIONs for which the Grade value is A. … … … … … … … …[4]

11 9608/13/M/J/16 © UCLES 2016 [Turn over 6 (a) Explain the difference between the World Wide Web (WWW) and the Internet. … … … …[2] (b) Three methods of connecting devices include fibre-optic cables, copper cables and radio waves. The table below gives descriptions relating to these connection methods. Tick (✓) one box on each row to show the method that best fits each description. Description Fibre-optic cable Copper cable Radio waves Wireless medium Twisted-pair is an example Uses light waves WiFi Fastest transmission medium [5] (c) Bit streaming is used for both real-time and on-demand services. Describe one difference between real-time and on-demand bit streaming. … … … …[2] (d) A device needs an IP address to connect to the Internet. IPv4 is the more common type of IP address. Describe, using an example, the format of an IPv4 address. … … … … … …[3]

12 9608/13/M/J/16 © UCLES 2016 (e) A computer user keys in the Uniform Resource Locator (URL) of a web page into a web browser. Describe how the browser uses the Domain Name Service (DNS) to display the web page. … … … … … … … …[4]

13 9608/13/M/J/16 © UCLES 2016 7 A bank holds personal data about its customers and their financial data. (a) Describe the difference between security and integrity of data. … … … … … … … …[4] (b) Describe three security measures that the bank could implement to protect its electronic data. Security measure 1 … Description … … … Security measure 2 … Description … … … Security measure 3 … Description … … …[6]

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16 9608/13/M/J/16 © UCLES 2016 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 International Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after the live examination series. Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge. BLANK PAGE

® IGCSE is the registered trademark of Cambridge International Examinations. This document consists of 7 printed pages. © UCLES 2016 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/13 Paper 1 Written Paper May/June 2016 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 will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2016 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.

Page 2 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9608 13 © Cambridge International Examinations 2016 1 Four from: [4] • Compiler creates an executable//an interpreter does not create an executable. • The compiled program can be independently distributed. • Compiler reports all errors at the end of compilation//an interpreter stops when it reaches an error. • Interpreter executes each statement immediately after decoding/checking it//a compiler checks the whole program for errors. • The interpreter software/source code must be present in main memory every time the program is executed//the compiled program does not require compiler/source code to be present. • Cross-compilation is possible/compile on one hardware platform to run on another. 2 (a) 77 [1] (b) 1000 0010 [1] (c) − 53 [2] One mark for ‘53’ and one mark for ‘−‘ (d) C6 [2] One mark for the answer, one mark for the method • Working e.g. 198 / 16 = 12, 198 − (12*16) = 6 3 (a) Two from: [2] • The source code comes with the software. • The user can edit the source code. • Once edited, the software is re-distributed with the changes. (b) Two from: [2] • The software is purchased. • With a licence which restricts the number of users / possible time period for use. • The program code for the software cannot be edited. (c) Four from: [4] • Support / training is readily available so help can be accessed if needed. • More robust software / fewer bugs as it has been tested more thoroughly/by more users. • Forums / user groups will exist for popular software. • Software upgrade path likely to be available (at minimal cost). • Manufacturer develops patches that can be automatically downloaded. • Compatibility is inbuilt for other commercial software.

Page 3 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9608 13 © Cambridge International Examinations 2016 4 (a) 11001110 [1] (b) [7] Instruction Working space ACC Memory address IX OUTPUT 90 91 92 93 2 90 55 34 2 20 55 21 54 22 54 23 3 24 34 25 33 26 27 28 31 67 32 67 33 'C' 34 One mark each for: • Instruction 20 • Instructions 21 and 22 • Instruction 23 • Instructions 24 and 25 • Not executing instructions 29 and 30 • Instructions 31 and 32 • Correct output

Page 4 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9608 13 © Cambridge International Examinations 2016 5 (a) One mark for each correct line. [3] (b) One mark for procedure point, one mark for justification. [6] Maximum three procedures. • How often should the data be backed up? e.g. at the end of each day • Justification e.g. student’s progress may be edited each day and should not be lost • What medium should the data be backed up to? e.g. external hard disk drive • Justification e.g. it has large enough capacity • Where should the backups be stored? e.g. off-site • Justification e.g. so if the building is damaged only the original data are lost • What is backed up? e.g. only updated files ... • Justification e.g. There are a large number of files and they are not all updated each day • When should the backup take place? e.g. overnight • Justification e.g. the system is not likely to be used then • Who is responsible for performing the backup? • Justification e.g. otherwise it may not be done • Make sure the procedure is written down and understood by staff • Justification e.g. otherwise some data may not be backed up Data Dictionary Data Integrity Data Security A file/table containing all the data about the detail of the database design Data design features to ensure the validity of data in the database Methods of protecting the data including the uses of passwords and different access rights for different users of the database A model of what the database will look like, although it may not be stored in this way

Page 5 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9608 13 © Cambridge International Examinations 2016 (c) (i) One mark for each correct relationship. [2] (ii) One-to-many [1] (iii) Two points from: [2] • The primary key in the QUALIFICATION table is QualCode. • The foreign key in the STUDENT-QUALIFICATION table is QualCode. • The primary key of QUALIFICATION is also included in QualCode. (d) (i) One mark per statement. Several statements may be on one line. [2] ALTER TABLE STUDENT ADD DateOfBirth DATE; (ii) One mark per statement. Several statements may be on one line. [3] SELECT StudentID, Grade, DateOfAward FROM STUDENT-QUALIFICATION WHERE QualCode = 'SC12'; (iii) One mark per statement. Several statements may be on one line. [4] SELECT STUDENT.FirstName, STUDENT.LastName, STUDENT- QUALIFICATION.QualCode FROM STUDENT, STUDENT-QUALIFICATION WHERE STUDENT-QUALIFICATION.Grade = 'A' AND STUDENT.StudentID = STUDENT-QUALIFICATION.StudentID; Alternative answer: SELECT FirstName, LastName, STUDENT-QUALIFICATION.QualCode FROM STUDENT, INNER JOIN STUDENT-QUALIFICATION ON STUDENT.StudentID = STUDENT-QUALIFICATION.StudentID WHERE Grade = 'A'; STUDENT STUDENT- QUALIFICATION QUALIFICATION

Page 6 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9608 13 © Cambridge International Examinations 2016 6 (a) Two from: [2] • WWW is a collection of interlinked, hypertext documents/webpages/multimedia resources (accessed via the Internet) //WWW is content from web servers organised as web pages • Internet is the global connection of interconnected computer networks • The Internet uses TCP/IP protocol / WWW uses http protocols to transmit data (b) [5] Description Fibre-Optic cables Copper cables Radio waves ‘Wireless’ media
Twisted-pair is an example
Uses light waves
WiFi
Fastest transmission media
(c) One pair from: [2] • Real-time - a live stream of an event that is currently taking place • On-demand - streaming of an event/programme that has taken place in the past • Real time – the event is captured live with a video camera connected to a computer • On-demand – Existing media are encoded to bit streaming format and uploaded to a server • Real-time – cannot be paused / rewound etc • On-demand – can be paused / re-wound / fast forwarded etc (d) Two marks for description, one mark for correct example. [3] • Four numbers separated with ‘.’ • Each number is between 0 and 255 / 00 and FF in Hex / stored in one byte. • 32 bits long • Correct example

Page 7 Mark Scheme Syllabus Paper Cambridge International AS/A Level – May/June 2016 9608 13 © Cambridge International Examinations 2016 (e) Four from: [4] • URL is a reference address to a resource on the Internet. • The URL is passed to the nearest Domain Name Server (by browser software). • DNS server stores a database / list of URLs and matching IP addresses. • DNS (Name Resolver) looks for the URL in its database. • Finds the matching IP address and returns it to the originator. • Or if it cannot find it, it forwards to another Domain Name Server at a higher level. • (Original) DNS server adds the returned IP address to its cache. • (Original) DNS server returns the IP address to the browser. 7 (a) Four from: [4] • Security is keeping the data safe. • Integrity is making sure that the data is correct / valid. • Security is the prevention of data loss. • Integrity ensures that the data received is the same as the data sent / data copied is the same as the original. • Example of ensuring security, e.g. usernames and passwords, firewalls etc... • Example of ensuring integrity, e.g. parity checks, double entry etc... (b) Three pairs from: [6] • Installing a firewall and ensuring it is switched on. • To stop unauthorised access / hackers gaining access to the bank’s computer network. • Use authentication methods such as passwords and usernames. • Passwords should be strong / biometrics. • Encrypt the data. • So that if data is accessed it will be meaningless / only accessed by those with decryption key. • Set up access rights... • To stop users reading/editing data they are not permitted to access. • Installing and running an up to date anti-malware program (anti-virus/anti-spyware etc.). • To detect / remove / quarantine viruses / key-loggers etc. • Make regular backups of the data. • To separate device or off site to enable recovery if necessary. • Employ measures for physical security. • Example of a measure for physical security.