Cambridge A Level Computer Science 9608 — 2018 May/June Paper 1 · Variant 1

This document consists of 15 printed pages and 1 blank page. DC (LEG/FC) 144487/2 © UCLES 2018 [Turn over Cambridge International Examinations Cambridge International Advanced Subsidiary and Advanced Level * 9 6 5 7 7 2 6 3 0 5 * COMPUTER SCIENCE 9608/11 Paper 1 Theory Fundamentals May/June 2018 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 9608/11/M/J/18 © UCLES 2018 Question 1 begins on the next page.

3 9608/11/M/J/18 © UCLES 2018 [Turn over 1 Four communication media and five features are shown. Draw one or more lines from each communication media to the appropriate feature(s). Communication media Feature Fibre-optic cable Radio waves Copper cable Satellite Wireless transmission Least likely to have interference Large range of wavelengths Transmits light pulses Can be twisted pair or co-axial [6]

4 9608/11/M/J/18 © UCLES 2018 2 A logo is designed as a bitmap image. (a) Describe what is meant by a bitmap image. … … … …[2] (b) A black and white bitmap image is shown. (i) Explain how a computer can store this bitmap image. … … … …[2] (ii) The image is compressed before it is attached to an email. Explain how run-length encoding (RLE) will compress the image. … … … …[2]

5 9608/11/M/J/18 © UCLES 2018 [Turn over (c) The finished logo is 500 pixels by 1000 pixels and uses 35 different colours. Estimate the file size for the logo. Give your answer in kilobytes. Show your working. Working … … … … … Answer … [4] (d) The logo is redesigned as a vector graphic. State two benefits of a vector graphic compared to a bitmap image. Give a reason for each benefit. Benefit 1 … … Reason 1 … … Benefit 2 … … Reason 2 … … [4]

6 9608/11/M/J/18 © UCLES 2018 3 An operating system (OS) is usually pre-installed on a new computer. (a) The OS performs a number of different tasks such as memory management and security management. (i) State three memory management tasks the OS performs. 1 … … 2 … … 3 … … [3] (ii) State three security management tasks the OS performs. 1 … … 2 … … 3 … … [3] (iii) State two tasks, other than memory management and security management that are carried out by an OS. 1 … … 2 … … [2]

7 9608/11/M/J/18 © UCLES 2018 [Turn over (b) Utility software is usually pre-installed on a new computer. The following table lists four programs. Put one tick (✓) in each row to indicate whether or not the program is utility software. Program True False Disk Defragmenter Word Processor Library Program Compression Software [4]

8 9608/11/M/J/18 © UCLES 2018 4 (a) An alarm system (X) is enabled and disabled using either a switch (A) or a remote control (B). There are two infra-red sensors (C, D) and one door pressure sensor (E). Parameter Description of parameter Binary value Condition A Switch 1 Switch enabled 0 Switch disabled B Remote control 1 Remote enabled 0 Remote disabled C Infra-red sensor 1 Activated 0 Not activated D Infra-red sensor 1 Activated 0 Not activated E Door pressure sensor 1 Activated 0 Not activated The alarm sounds (X = 1) if the alarm is enabled and any one or more of the sensors is activated. Draw a logic circuit to represent the alarm system. A B C X D E [3]

9 9608/11/M/J/18 © UCLES 2018 [Turn over (b) Complete the truth table for the logic expression: X = A OR (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]

10 9608/11/M/J/18 © UCLES 2018 5 A college has a client-server network. (a) The college has a file server and other servers. State the purpose of two other servers in the college network. Server 1 … Server 2 … [2] (b) The students use the network to access the Internet. One student stated, ‘The Internet and the World Wide Web are the same thing’. Tick (✓) one box to indicate whether this statement is true or false. True False Justify your choice. … … … … … … … … … …[5]

11 9608/11/M/J/18 © UCLES 2018 [Turn over (c) Students use the college’s learning resource website. Several of the web pages include PHP script. Describe the sequence of events when a student requests a web page with embedded server-side code. … … … … … … … …[4]

12 9608/11/M/J/18 © UCLES 2018 6 Parity bits can be used to verify data. (a) The following binary number is transmitted using even parity. Add the missing parity bit. Parity bit 1 0 1 1 0 1 0 [1] (b) In the following parity block, the first column contains the parity bits, and the last row contains the parity byte. A device transmits the data using even parity. (i) Circle the error in the data transmitted. Parity bit Data 1 1 0 1 0 1 1 1 1 0 0 0 1 1 1 0 0 1 0 0 1 0 1 1 1 1 1 0 1 1 1 1 Parity byte 1 1 1 1 1 0 0 1 [1] (ii) Explain how you identified the error. … … … … …[2] (c) The data received can contain errors that are not detected using parity bits. Explain how this can happen. … … … …[2]

13 9608/11/M/J/18 © UCLES 2018 [Turn over (d) Parity is not the only method to verify the data has been sent correctly. Name and describe one other method of data verification during data transfer. Name … Description … … … … … … [3]

14 9608/11/M/J/18 © UCLES 2018 7 A student plays computer games on a games console. (a) Identify two input devices and one output device used in a games console. Input device 1 … Input device 2 … Output device … [3] (b) The games console has random access memory (RAM) and read only memory (ROM). (i) State two differences between RAM and ROM. Difference 1 … … Difference 2 … … [2] (ii) Give one use for RAM in the games console. … …[1] (iii) Give one use for ROM in the games console. … …[1]

15 9608/11/M/J/18 © UCLES 2018 8 The Von Neumann model uses a series of registers. (a) Explain what is meant by the term register. … … … …[2] (b) (i) Explain the purpose of the Memory Data Register (MDR). … … … …[2] (ii) Name two registers, other than the MDR, that are used in the fetch-execute cycle. Register 1 … Register 2 … [2] (c) X is a register. The current contents of X are: 1 0 0 0 0 1 1 1 (i) The current contents of register X represent an unsigned binary integer. Convert the value in X into denary. …[1] (ii) The current contents of register X represent a Binary Coded Decimal. Convert the value in X into denary. …[1] (iii) The current contents of register X stores a two’s complement binary integer. Convert the value in X into denary. …[1]

16 9608/11/M/J/18 © UCLES 2018 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 a registered trademark. This document consists of 9 printed pages. © UCLES 2018 [Turn over Cambridge Assessment International Education Cambridge International Advanced Subsidiary and Advanced Level COMPUTER SCIENCE 9608/11 Paper 1 Written Paper May/June 2018 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 2018 series for most Cambridge IGCSE™, Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level components.

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 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.

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 3 of 9 Question Answer Marks 1 1 mark for a correct line from each communication media, max 6 6 Question Answer Marks 2(a) 1 mark per bullet, max 2 • Made up of pixels • Each pixel has one colour • Colour of each pixel stored as a binary number 2 2(b)(i) 1 mark per bullet, max 2 • Each pixel requires only one bit (as there are only two colours) • Black represented by 1 and white by 0 (or vice versa) • Bits are stored for each pixel in sequence • 11111 01010 01010 01010 01010 2 2(b)(ii) 1 mark for the explanation • Stores the colour and the number of times it occurs 1 mark for example from • An example from the bitmap given e.g. B5, W1, B1 and so on 2 2(c) 1 mark per bullet • Number of pixels 500*1000 (= 500 000) • 35 colours require 6 bits per pixel • Number of bytes (500 000 * 6) / 8 = 3 000 000 / 8 (= 375 000) • = 375 Kb 4 Copper cable Can be twisted pair or co-axial Transmits light pulses Large range of wavelengths Least likely to have interference Wireless transmission Satellite Radio waves Fibre-optic cable

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 4 of 9 Question Answer Marks 2(d) 1 mark per bullet to max 2 marks per benefit • Can resize it without pixilation • Image is redrawn/recalculated with each adjustment • Smaller file size • Storing points/equations/commands etc., not individual pixels 4 Question Answer Marks 3(a)(i) 1 mark per bullet to max 3 • Allocates / deallocates RAM to programs/tasks/processes • Keeps track of allocated and free memory locations • Swaps data to and from the hard drive • Handles virtual memory • Paging // segmentation • Memory protection, preventing a process accessing memory not allocated to it 3 3(a)(ii) 1 mark per bullet to max 3 • Sets up user accounts • Checks usernames, passwords // Authentication • Implements access rights • Automatic backup • System restore / roll back (to previous stable state) 3 3(a)(iii) 1 mark per bullet to max 2 • Device / peripheral management • File management • Process management • Input / output management • Error detection / recovery • Provides a user interface • Facilitates communication between hardware and software / hardware devices 2 3(b) 1 mark for each correct box ticked Programs True False Disk Defragmenter 9 Word Processor 9 Library program 9 Compression Software 9 4

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 5 of 9 Question Answer Marks 4(a) 1 mark per bullet: • A OR B • C OR D OR E • Final AND 3 4(b) 1 mark for each correct pair of 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 1 1 0 1 1 1 1 0 1 1 1 1 1 4

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 6 of 9 Question Answer Marks 5(a) 1 mark per server e.g. • E-mail • Print • Web 2 5(b) 1 mark for the indicating the statement is false: True False 9 1 mark per bullet for justification to max 4. • Internet is the infrastructure / global collection of networks • World Wide Web is the (multimedia web) pages / content • The World Wide Web is accessed over the Internet • Webpages are written in HTML • HTTP protocol used to transfer web pages • Internet uses IP protocol 5 5(c) 1 mark per bullet to max 4 • The browser requests the web page • The web server accesses the page • The web server processes / executes the code • The web server produces the HTML for the web page / generates the web page • The web server returns the web page to the client • The client browser displays this web page 4 Question Answer Marks 6(a) 1 mark for the correct parity Parity bit 0 0 1 0 0 0 0 0 1

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 7 of 9 Question Answer Marks 6(b)(i) 1 mark for the correct bit circled Parity bit Data 1 1 0 1 0 1 1 1 1 0 0 0 1 1 1 0 0 1 0 0 1 0 1 1 1 1 1 0 1 1 1 1 Parity byte 1 1 1 1 1 0 0 1 1 6(b)(ii) 1 mark for each bullet point • row and column has incorrect parity (odd instead of even) • the intersection identifies the error 2 6(c) 1 mark per bullet to max 2 • Errors in an even number of bits (in the same row or column) • Prevents error being identified • Could appear to be correct 2 6(d) 1 mark for the name and max 2 marks for description • Check sum • A calculation is done on a block of data • The result is transmitted with the data • Calculation repeated at receiving end • Results compared • If different an error has occurred • Hash total • Total of several fields of data • Including fields not usually used in calculations • The result is transmitted with the data • Calculation repeated at receiving end • Results compared • If different an error has occurred 3

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 8 of 9 Question Answer Marks 7(a) 1 mark for each input device to max 2 e.g. • (Handheld) remote controller • Joystick / Games pad / joypad • Accelerometer • Microphone • Suitable sensor 1 mark for output e.g. • Motor/vibrator in joystick • Speaker • Screen/monitor /TV 3 7(b)(i) 1 mark for each difference to max 2 • RAM is volatile and ROM is non-volatile • RAM can change and ROM (usually) can't be changed • ROM is read only, RAM is read/write 2 7(b)(ii) 1 mark for example e.g. • Current game • Currently running processes • Current graphics/sound 1 7(b)(iii) 1 mark for an example e.g. • Start-up instructions / boot program • Kernel of Operating System 1 Question Answer Marks 8(a) 1 mark per bullet to max 2 • Small piece / word of (fast) memory • Part of the processor • Temporary storage of data • Data is about to be / has been processed 2 8(b)(i) 1 mark per bullet to max 2 • Stores / holds data / instruction when fetched from memory • Stores / holds data which is being written to memory • The location accessed is the address held in the Memory Address Register (MAR) 2

9608/11 Cambridge International AS/A Level – Mark Scheme PUBLISHED May/June 2018 © UCLES 2018 Page 9 of 9 Question Answer Marks 8(b)(ii) 1 mark per bullet to max 2 • Current Instruction Register (CIR) • Memory Address Register (MAR) • Program Counter (PC) • Accumulator (ACC) • Index Register (IX) • Status Register • Interrupt Register 2 8(c)(i) 135 1 8(c)(ii) 87 1 8(c)(iii) –121 1