Cambridge A Level Computer Science 9608 — 2019 May/June Paper 1 · Variant 3

This document consists of 14 printed pages and 2 blank pages. DC (SC) 163550/3 © UCLES 2019 [Turn over Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level * 1 3 8 9 7 7 8 0 4 2 * COMPUTER SCIENCE 9608/13 Paper 1 Theory Fundamentals May/June 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.

2 9608/13/M/J/19 © UCLES 2019 1 A computer has an operating system (OS) and utility software. (a) The following table lists key management tasks performed by an operating system and their descriptions. Complete the table by writing the missing management task names and descriptions. Management task Description Memory management Provides user accounts and passwords Handles the signals sent when the attention of the processor is required elsewhere Provision of a software platform [4] (b) A hard disk formatter and a hard disk defragmenter are two examples of utility software. (i) Describe the actions performed by a hard disk formatter and a hard disk defragmenter. Hard disk formatter … … … … Hard disk defragmenter … … … … [4]

3 9608/13/M/J/19 © UCLES 2019 [Turn over (ii) Identify three other examples of utility software that can be installed on the computer. 1 … … 2 … … 3 … … [3]

4 9608/13/M/J/19 © UCLES 2019 2 Frankie is a software developer. He is developing a program to manage customer records for a client with an online retail business. He must ensure that data stored about each customer are both secure and private. (a) State the difference between security and privacy. … … … … [2] (b) Computer systems can be protected by physical methods such as locks. Describe two non-physical methods used to improve the security of computer systems. 1 … … … … … … 2 … … … … … … [6]

5 9608/13/M/J/19 © UCLES 2019 [Turn over (c) A computer uses parity blocks to check the data that has been received is the same as the data that has been transmitted. The following is an example of a parity block. Parity bit Data 1 1 1 1 0 0 0 1 0 0 0 0 1 1 1 0 1 1 0 1 1 0 0 1 Parity byte 1 1 0 1 1 0 0 1 (i) Describe how a parity block check can identify a bit that has been corrupted during transmission. … … … … … … … … [4] (ii) Give a situation where a parity block check cannot identify corrupted bits. … … [1]

6 9608/13/M/J/19 © UCLES 2019 (d) One principle of the ACM/IEEE Software Engineering Code of Ethics is to always act in the best interest of the client. Explain how Frankie can ensure that he is acting in the best interest of his client. … … … … … … … … [3] (e) When the program is complete, Frankie uses a compiler to prepare the program for the client. Explain why Frankie uses a compiler instead of an interpreter. … … … … … … … … [3]

7 9608/13/M/J/19 © UCLES 2019 [Turn over 3 A company uses a relational database, EMPLOYEES, to store data about its employees and departments. (a) The company uses a Database Management System (DBMS). (i) The DBMS has a data dictionary. Describe what the data dictionary stores. … … … … [2] (ii) The DBMS has a query processor. Describe the purpose of a query processor. … … … … [2] (b) Relationships are created between tables using primary and foreign keys. Describe the role of a primary and a foreign key in database relationships. … … … … [2]

8 9608/13/M/J/19 © UCLES 2019 (c) In the company: • An employee can be a manager. • A department can have several managers and several employees. • An employee can only belong to one department. The EMPLOYEES database has three tables: EMPLOYEE_DATA( EmployeeID, FirstName, LastName, DateOfBirth, Gender, DepartmentNumber) DEPARTMENT(DepartmentNumber, DepartmentName) DEPARTMENT_MANAGER(DepartmentNumber, EmployeeID, role) Complete the entity-relationship (E-R) diagram for the EMPLOYEES database. EMPLOYEE_DATA DEPARTMENT DEPARTMENT_MANAGER [3] (d) Give three reasons why the EMPLOYEES database is fully normalised. 1 … … 2 … … 3 … … [3]

9 9608/13/M/J/19 © UCLES 2019 [Turn over (e) Part of the EMPLOYEE_DATA table is shown. EmployeeID FirstName LastName DateOfBirth Gender DepartmentNumber 156FJEK Harvey Kim 12/05/1984 Male S1 558RRKL Catriona Moore 03/03/1978 Female F2 388LMDV Oscar Ciao 01/01/1987 Male F2 (i) Write a Data Definition Language (DDL) statement to create the EMPLOYEES database. … … [1] (ii) Write a DDL statement to define the table EMPLOYEE_DATA, and declare EmployeeID as the primary key. … … … … … … … … … … [5]

10 9608/13/M/J/19 © UCLES 2019 (iii) Write a Data Manipulation Language (DML) statement to return the first name and last name of all female employees in the department named Finance. … … … … … … … … … … [5]

11 9608/13/M/J/19 © UCLES 2019 [Turn over 4 A program is written in assembly language. (a) The op codes LDM and LDD are used to load a register. The op code LDM uses immediate addressing, and the op code LDD uses direct addressing. Describe what happens when the following instructions are run. LDM #300 … … LDD 300 … … [2] (b) Assembly language instructions can be grouped by their purpose. The following table shows four assembly language instructions. Tick (✓) one box in each row to indicate the group each instruction belongs to. Instruction Description Jump instruction Arithmetic operation Data movement LDR #3 Load the number 3 to the Index Register ADD #2 Add 2 to the Accumulator JPN 22 Move to the instruction at address 22 DEC ACC Subtract 1 from the Accumulator [3]

12 9608/13/M/J/19 © UCLES 2019 (c) The processor handles interrupts within the fetch-execute cycle. (i) Give one example of a hardware interrupt and one example of a software interrupt. Hardware … … Software … … [2] (ii) Explain how the processor handles an interrupt. … … … … … … … … … … [5]

13 9608/13/M/J/19 © UCLES 2019 [Turn over 5 Xander creates a presentation that includes images, video and sound. (a) The images are bitmap images. A bitmap image can be made up of any number of colours. Each colour is represented by a unique binary number. Draw one line from each box on the left, to the correct box on the right to identify the minimum number of bits needed to store each maximum number of colours. Maximum number of colours Minimum number of bits 68 256 127 2 249 1 2 3 7 8 9 [3]

14 9608/13/M/J/19 © UCLES 2019 (b) One of the videos has a frame rate of 40 fps (frames per second). (i) State what is meant by 40 fps. … … [1] (ii) One video uses interlaced encoding, and a second video uses progressive encoding. Describe two differences between interlaced and progressive encoding. 1 … … … … 2 … … … … [4] (c) The sound track has a sampling rate of 88.2 kHz and a sampling resolution of 32 bits. State what is meant by a sampling rate of 88.2 kHz and a sampling resolution of 32 bits. Sampling rate of 88.2 kHz … … … Sampling resolution of 32 bits … … … [2]

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16 9608/13/M/J/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 10 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 May/June 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 May/June 2019 series for most Cambridge IGCSE™, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 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.

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 3 of 10 Question Answer Marks 1(a) 1 mark for each correct entry Management task Description Memory management Handles the allocation of memory to processes // Ensures two programs do not attempt to use the same memory locations // Keeps track of allocated and free memory locations Security management Provides user accounts and passwords Interrupt processing Handles the signals sent when the attention of the processor is required elsewhere Provision of a software platform Provides an environment within which programs can be run 4 1(b)(i) 1 mark per bullet point to max 2 for formatter, max 2 for defragmenter hard disk formatter • Makes existing data inaccessible • Partitions the disk into logical drives • Sets up the (specified) file system • Prepares the disk for initial use • May check for errors on the disk hard disk defragmenter • Re-organises the disk contents • Moves split files so they are contiguous • Creates a larger area of (contiguous) free space 4 1(b)(ii) 1 mark per bullet point For example: • Backup software • File compression • Virus checker • Disk contents analysis / repair 3

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 4 of 10 Question Answer Marks 2(a) 1 mark per bullet point • Security: keep data safe from accidental/malicious damage/loss • Privacy: keep data confidential // only seen by authorised personnel 2 2(b) 1 mark for identifying method 2 marks for description to max 2 × 3 For example: • User accounts • User has a username and password Access to resources can be limited to specific accounts • Cannot access system without valid username and password // prevents unauthorised access to the system • Firewall • All incoming and outgoing network traffic goes through firewall • Blocks signals that do not meet requirements • Keeps a log of signals • Applications can have network access restricted • Anti-malware • Scans for malicious software • Quarantines or deletes any malicious software found • Scans can be scheduled at regular intervals • Should be kept up to date • Auditing • Logging all actions/changes to the system • In order to identify any unauthorised use • Application Security (accept equivalent) • Applying regular updates / patches • Finding, fixing and preventing security vulnerabilities in any (installed) application 6 2(c)(i) 1 mark per bullet to max 4 • Each byte has a parity bit // horizontal parity • An additional parity byte is sent with vertical (and horizontal) parity • Each row and column must have an even/odd number of 1s • Identify the incorrect row and column • The intersection is the error 4 2(c)(ii) 1 mark for correct answer • Errors in an even number of bits (could cancel each other out) 1

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 5 of 10 Question Answer Marks 2(d) 1 mark per bullet point to max 3 For example: He should ... • ...Keep the client’s personal data private • ...Involve the client in the development // «Communicate with the client • «Provide the solution that the client asked for • ...Keep the project running on time // budget • ...Keep the client informed of any problems/delays 3 2(e) 1 mark per bullet point to max 3 • He uses a compiler because it creates a separate executable file • The executable means the client cannot access the source code // edit the program • The executable means the client does not need the IDE / compiler • It will (probably) be faster to run the executable than to interpret the source code every time the program is run 3 Question Answer Marks 3(a)(i) 1 mark per bullet point • Stores all the information about the database // data about the data // metadata about the data • For example, fields, data types, validation, keys 2 3(a)(ii) 1 mark per bullet point to max 2 • Allows the user to enter criteria • Searches for data which meets the entered criteria • Organises the results to be displayed to the user 2 3(b) 1 mark per bullet point to max 2 • Primary key uniquely identifies each tuple // Each tuple in the table is unique • Primary key can be used as a foreign key in another table • «.. to form a link/relationship between the tables By example: • Identification of a primary key in a table • Describing that primary key in another table as a foreign key 2

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 6 of 10 Question Answer Marks 3(c) 1 mark for each correct link 3 3(d) 1 mark per bullet point to max 3 • There are no repeating groups (1NF) • There are no partial dependencies (2NF) • There are no non-key dependencies // There are no transitive dependencies (3NF) 3 3(e)(i) 1 mark for correct answer CREATE DATABASE EMPLOYEES; 1 3(e)(ii) 1 mark per bullet • Create table EMPLOYEE_DATA with open and close brackets • EmployeeID as VarChar restricted to max 7, Gender as a VarChar restricted to max 6, DepartmentNumber as a VarChar restricted to max 2 • FirstName and LastName as VarChar (any max lengths must be reasonable) • Date of birth as Date • Declaring EmployeeID as PK CREATE TABLE EMPLOYEE_DATA ( EmployeeID VarChar(7), FirstName VarChar, LastName VarChar, DateOfBirth Date, Gender VarChar(6), DepartmentNumber VarChar(2), PRIMARY KEY (EmployeeID) ); 5

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 7 of 10 Question Answer Marks 3(e)(iii) 1 mark per bullet • Select FirstName and LastName only • From both tables • Where DepartmentName = “Finance” • AND Gender = “Female” • Joining tables (either AND, or inner join) SELECT FirstName, LastName FROM EMPLOYEE_DATA, DEPARTMENT WHERE DepartmentName = "Finance" AND Gender = "Female" AND DEPARTMENT.DepartmentNumber = EMPLOYEE_DATA.DepartmentNumber; 5 Question Answer Marks 4(a) 1 mark per bullet • LDM #300 The (denary) number 300 is loaded (into the register) • LDD 300 The contents of address 300 are loaded (into the register) 2 4(b) 1 mark for JPN correct 1 mark for both of ADD and DEC correct 1 mark for LDR correct Description Jump instruction Arithmetic operation Data movement LDR #3 Load the number 3 to the Index Register 9 ADD #2 Add 2 to the Accumulator 9 JPN 22 Move to the instruction at address 22 9 DEC ACC Subtract 1 from the Accumulator 9 3

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 8 of 10 Question Answer Marks 4(c)(i) 1 mark for hardware interrupt 1 mark for software interrupt For example: Hardware interrupt • Printer out of paper • No CD in drive Software interrupt • A running program needs input • Runtime error, e.g. division by zero 2 4(c)(ii) 1 mark per bullet to max 5 • At the start / end of each fetch-execute cycle the processor checks for interrupt(s) • Check if an interrupt flag is set // Check if bit set in interrupt register • Processor identifies source of interrupt • Processor checks priority of interrupt • If interrupt priority is high enough // Lower priority interrupts are disabled • Processor saves current contents of registers // saves current job on stack • Processor calls interrupt handler / Interrupt Service Routine (ISR) • Address of ISR is loaded into Program Counter (PC) • When servicing of interrupt complete, processor restores registers // job from stack is restored • Lower priority interrupts are re-enabled • Processor continues with next F–E cycle 5

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 9 of 10 Question Answer Marks 5(a) 1 mark for each correctly linked box on the right 3 5(b)(i) 1 mark for correct answer 40 images or frames are displayed/recorded each second 1 5(b)(ii) 1 mark per bullet to max 4 • Progressive – each frame contains (all the lines for) the complete image • Interlaced – each frame contains half the (number of lines) of the complete image • Progressive – frames are not divided into fields • Interlaced – each frame divided into two fields // One field contains the data for the even numbered rows / lines and the other has the data for the odd numbered rows / lines. • Progressive – complete frames are displayed in sequence • Interlaced – data from two frames is displayed simultaneously • Progressive – the number of images stored is the same as the frame rate // the rate of picture display is the same as the frame rate. • Interlaced – the rate of picture display (the field rate) is twice the rate of image frame display (the frame rate). • Progressive means the entire frame is refreshed each time • Interlaced means only half the frame is refreshed • Progressive has high bandwidth requirements • Interlaced halves the transmission bandwidth requirements. 4 Maximum number of colurs Minimum number of bits 1 68 2 256 3 127 7 2 8 249 9

9608/13 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2019 © UCLES 2019 Page 10 of 10 Question Answer Marks 5(c) 1 mark per bullet 88.2 kHz • The sound wave is sampled 88200 times per second 32 bits • Each sample is stored as a 32-bit binary number 2