Cambridge IGCSE Computer Studies 0420 — 2012 Oct/Nov Paper 1 · Variant 3

This document consists of 20 printed pages. IB12 11_0420_13/3RP © UCLES 2012 [Turn over *2083839975* For Examiner's Use UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMPUTER STUDIES 0420/13 Paper 1 October/November 2012 2 hours 30 minutes Candidates answer on the Question Paper. No Additional Materials are required. 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 a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, 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. www.XtremePapers.com

2 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 1 For advertising at a trade fair, a company has a choice of computer facilities. One option is a stand-alone computer with multimedia facilities. The other option is a computer with Internet access to the company’s website. Discuss the benefits and drawbacks of each method. Stand-alone computer with multimedia Benefit Drawback Internet website Benefit Drawback [4] 2 New software is often developed using top-down (modular) design. Give three benefits of using this method of development. 1 2 3 [3]

3 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use 3 Five descriptions are given on the left of the diagram below. Five computer applications are shown on the right of the diagram. Using arrows, link each description to the correct application. use of synthesisers to combine simple waveforms to produce more complex sounds animation audio-visual communication using compression and echo cancellation software MP3 use of avatars in the sequence of images one after the other to produce special effects music generation audio compression technology to compress large files into smaller files often used in media simulation imitation of a real event using a mathematical model of a set of formulas video-conferencing [5]

4 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 4 (a) Describe four different communication methods that use the Internet. 1 2 3 4 [4] (b) Give two drawbacks of using the Internet for communications. 1 2 [2] (c) Mobile phones are a common method of communication. Describe four types of application, other than the Internet, that may be available on a mobile phone. 1 2 3 4 [4]

5 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use 5 A program requires the user to type in a user ID which must be in the form: XX999999 where X stands for any letter, and 9 stands for any digit. (a) Name two possible validation checks that could be applied to this user ID. 1 2 [2] (b) Name a validation check that could not be used on this occasion. Give a reason for your choice. Name Reason [2] 6 The following is a list of stages when an email is sent and received. Write the numbers from 1 to 8 in the right-hand column to put each stage of the process in the correct order. The first one has been done for you. Description of stage Order of stage The message travels over the Internet and arrives at recipient’s ISP mail server Message sent to sender’s ISP mail server Recipient logs on to read his messages The sender composes his message and activates the send command 1 Message held in recipient’s electronic mail box ISP mail server examines address associated with message Message retrieved and sent to recipient’s computer to be opened and read Sender’s ISP mail server decides how to route the message [7]

6 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 7 Credit card fraud in many countries is now reducing. (a) What changes to credit card technology have helped this reduction? [1] However, there has been a large increase in online fraud. This has resulted in fraudulent use of bank accounts. (b) Name and describe three ways bank account information (such as passwords) can be accessed illegally. 1 Description 2 Description 3 Description [6]

7 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use 8 Word processors often use language translators and spell checkers to help users when composing documents. (a) A user selects the spell checker to check a document, but two errors in the document are not identified. Give two possible reasons for this. 1 2 [2] (b) The user also types in the following statement: This is an example of a translation using a word processor and selects the language translator English-Russian and the following text is produced: Это пример перевода на текстовом редакторе Such translations are often not very good. Give one reason for this. [1] (c) Describe two other features you might expect to find in a typical word processor. 1 2 [2]

8 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 9 Study this flowchart very carefully. START STOP C = 1 H = 0 T1 = 0 T2 = 0 T3 = 0 is number > 999 ? T3 = T3 + 1 T2 = T2 + 1 T1 = T1 + 1 C = C + 1 is number > 99 ? is number > H ? is C <= 10 ? No No No INPUT number OUTPUT T1, T2, T3, H Yes Yes H = number Yes Yes No

9 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use Complete the trace table for the following data: 1500, 1000, 100, 10, 999, 99, 2000, 5, -3, 0 C H T1 T2 T3 number OUTPUT [6]

10 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 10 You have just been appointed as the IT representative of a small engineering company. The company need to buy: • external backing storage • printers • input devices Choose a suitable example for each and give a reason for your choice. External storage device Reason for choice Printer type Reason for choice Input device Reason for choice [6]

11 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use 11 A database was set up showing the largest ocean-going liners. Part of the database is shown below. Liner ID Year built Gross Tonnage Country of Registration Country of Construction OA 2009 225 282 Norway Finland IN 2008 154 407 Norway Finland QM 2004 148 528 UK France EX 2000 137 308 Norway Finland VO 1999 137 276 Norway Finland GP 1997 108 865 UK Italy DE 1996 101 509 USA Italy SP 1995 77 499 UK Italy SO 1988 73 192 Norway France FR 1972 66 343 France France QE 1940 86 673 UK UK NO 1935 79 280 France France MJ 1922 56 561 UK Germany TI 1912 46 329 UK UK MA 1907 31 938 UK UK (a) How many records are shown in the above part? [1] (b) Using Liner ID only, what would be output if the following search condition was typed in: (Year built < 2000) AND (Country of Registration = Country of Construction)? [2] (c) Write the search condition to find out which liners have a gross tonnage larger than 80 000 or are registered in the UK. [2]

12 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 12 (a) A spreadsheet was set up to determine if a triangle is right-angled. Part of the spreadsheet is shown below. A B C D E 1 a b c a2 + b2 - c2 is triangle right-angled? 2 2 5 6 -7 No 3 3 4 5 0 Yes 4 3 6 8 -19 No 5 5 12 13 0 Yes 6 7 24 25 0 Yes 7 8 15 17 0 Yes (i) What formula must be in D3? [1] (ii) Complete the formula that must be in column E to generate the output Yes or No. Use cell E3 as your example. = IF (D3 = 0, , ) [1] (iii) How could the spreadsheet be used if a and b values were known and it was required to predict the value of c to get a right-angled triangle? [2]

13 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use (b) Apart from the use of formulas and functions, give three features of spreadsheet software. 1 2 3 [3]

14 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 13 A large hotel uses eight lifts (elevators) to carry passengers between its sixty floors. A computer is used to control and monitor the lifts. Each lift has three registers to represent its state. 32 16 8 4 1 Thus 2 lift presently on 27th floor lift going up lift ID number 4 1 4 2 1 0 1 1 1 1 0 0 0 1 1 refers to: 32 16 8 4 2 1 1 Floor number 0 to 60 Lift ID number 0 to 7 UP/DOWN 1 = lift going up and 0 = lift going down Register 3 Register 1 Register 2 4 2 1 (a) If the three registers contain the following data: 32 16 8 4 1 2 1 4 2 1 1 1 1 1 0 1 1 0 0 0 what information about the lift is shown? [2] (b) How would the following information be shown in the three registers: lift 6 presently on the 45th floor and going down 32 16 8 4 1 2 1 4 2 1 [2]

15 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use (c) (i) A customer is on the 14th floor and wants to go to the 50th floor. She presses the button to call the lift. What two pieces of information would the computer check to identify which of the eight lifts should be made available? 1 2 [2] (ii) Using your answers to part (i), which of the following lifts would be made available to the customer? 1 0 0 0 1 0 0 1 0 0 A 0 0 1 0 0 0 1 1 1 1 B 1 1 0 0 1 1 0 0 1 0 C 0 0 1 0 1 1 1 0 1 0 D [1] (d) An engineer wishes to test that this computer system detects incorrect data. Describe what input the engineer might use to check that the computer can correctly identify a fault condition. [2]

16 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 14 The following flowchart shows how a computer and sensors are used to control the environment in a greenhouse. Temperatures must be between 25°C and 35°C. Light must be between 50 and 80 light units. (a) Complete the flowchart, using item number only, from the list of items given below. START INPUT reading from temperature sensor Yes Yes No No No No Item Number Item Description 1 convert temperature sensor reading using ADC 2 convert light sensor reading using ADC 3 input reading from light sensor 4 is light sensor reading < 50 light units? 5 is light sensor reading > 80 light units? 6 is temperature reading < 25 °C? 7 is temperature reading > 35 °C? 8 send signal to activate switch to turn on lights 9 send signal to motor to close blinds 10 send signal to motor to open windows 11 send signal to activate switch to turn on heater [5]

17 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use (b) The computer also checks on humidity levels (using humidity sensors) which must be between the values of 40 and 90. If humidity is too low, water is sprayed into the air. If humidity is too high, fresh air is allowed to enter. Write the necessary commands in the following flowchart section to show how the humidity levels are controlled: Yes Yes No No [4]

18 © UCLES 2012 0420/13/O/N/12 For Examiner's Use 15 (a) Complete the truth table for the following logic circuit: A B X C AND AND AND NOT OR A B C 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]

19 © UCLES 2012 0420/13/O/N/12 [Turn over For Examiner's Use (b) The above logic circuit uses AND, OR and NOT gates. Name another logic gate and complete its truth table. Name of gate A B X 0 0 0 1 1 0 1 1 [3]

20 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. University of 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. © UCLES 2012 0420/13/O/N/12 For Examiner's Use 16 A small café sells five types of item: bun 0.50 dollars coffee 1.20 dollars cake 1.50 dollars sandwich 2.10 dollars dessert 4.00 dollars Write an algorithm, using pseudocode or a program flowchart only, which • inputs every item sold during the day, • uses an item called “end” to finish the day’s input, • adds up the daily amount taken for each type of item, • outputs the total takings (for all items added together) at the end of the day, • outputs the type of item that had the highest takings at the end of the day. [6]

CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the October/November 2012 series 0420 COMPUTER STUDIES 0420/13 Paper 1, maximum raw mark 100 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 October/November 2012 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components. www.XtremePapers.com

Page 2 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 1 1 mark for each benefit and 1 mark for each drawback Stand alone computer: benefits: – sound – animation/graphics – no need for Internet access – more secure (less likely to be hacked) drawbacks: – not up-to-date – expensive multimedia equipment – need to take multimedia presentation file(s) and back-up(s) Internet website: benefits: – use of pop ups/pop-unders (to advertise on other websites) – ability to use hyperlinks – available world wide both ways drawbacks: – expensive to maintain a website – Internet security issues (hacking into (company) website; phishing; pharming) – poor Internet access can make video/sound unacceptable [4] 2 Any three benefits from: – several programmers can work on same software package – it is easier to debug modules than a whole program – it is easier to test modules than test the whole program – can use modules from a bank of routines (saving time and money) – enable large tasks to be broken down into more manageable smaller tasks [3]

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 3 1 mark per correct arrow connecting left with right [5] 4 (a) Any four from: – use of video-conferencing/webcams – use of emails (and attachments) – use of VoIP systems – instant messaging – chat rooms – social networking sites – bulletin boards – blogs – (on-line) gaming with others [4] use of synthesisers to combine simple wave forms to produce more complex sounds use of compression software and echo cancellation software to allow effective communications use of avatars in the sequence of images one after the other to produce special effects audio compression technology to compress large files into smaller files which can be played back without loss of quality imitation of a real event using a set of mathematical formulas to create a model animation MP3 music generation simulation video-conferencing

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 (b) Any two from: – easier access to inappropriate material – poor internet connection can cause delays/lag/drop outs – more open to people who may wish to harm you – security issues/viruses – too much time spent on the computer/health and safety issues [2] (c) Any four from (for example): – GPS – MP3/music files – game playing – camera/video – calendar function – calculator/utility functions – Bluetooth – SMS/MMS/text messaging [4] 5 (a) – format check – length check [2] (b) name: reason: – range check – mixture of letters & digits – character/type check – mixture of letters & digits – check digit – it contains letters – existency check – does not check format/length – cross field check – only 1 field present [2] 6 1 mark per correct stage Description of stage Order of stage The message travels over the Internet and arrives at recipient’s ISP mail server 5 Message sent to sender’s ISP mail server 2 Recipient logs on to read his messages 7 The sender composes his message and activates the send command 1 Message held in recipient’s electronic mail box 6 ISP mail server examines address associated with message 3 Message retrieved and sent to recipient’s computer to be opened and read 8 Sender’s ISP mail server decides how to route the message 4 [7]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 7 (a) use of chip and PIN technology – introduction of EMV (international standard for smart card payments) – tighter checks on usage (automated phone checks/card readers/the use of ‘verisafe’ concept) [1] (b) 1 mark for name and 1 mark for corresponding description phishing: – fraudster sends out email – user thinks email is legitimate – clicks on link and is taken to bogus website pharming: – malicious code installed on user’s computer or server – code mis-directs user to fraudulent website without their knowledge keylogging/spyware: – program installed on a computer tp monitor all key presses and sends data back to writer of spyware or spyware: – scan files on hard drive – ‘snoop’ applications hacking: – unauthorised access to computer system – often to do malicious harm (e.g delete files) shoulder surfing: – the act of watching a person key in secure data (e.g. PIN, password, etc) – stealing security data by using binoculars, CCTV near ATMs etc. to watch key presses etc. war driving – locating a wireless network by touring around an area – requires a laptop [6] 8 (a) Any two from: – can’t pick up semantics (e.g. incorrect use of the words weather/whether) – could be set to wrong version (e.g. US/UK/other English etc.) [2] (b) Any one from: - simple translators do literal translations/use incorrect syntax - can’t pick up the nuances/colloquial words in a language - problems with grammar - no equivalent words in other language [1]

Page 6 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 (c) Any two from: e.g. - change font size/type - change font colour/type - use of columns - search and replace words [2] 9 C H T1 T2 T3 number OUTPUT 1 0 0 0 0 1500 2 1500 1 1000 3 2 100 4 1 10 5 1 999 6 2 99 7 2 2000 8 2000 3 5 9 3 -3 10 4 0 11 5 5, 2, 3, 2000 1 mark 1 mark 1 mark 1 mark 1 mark < - - - - - 1 mark - - - - - > [6] 10 1 mark for device + 1 mark for reason backing memory device: – memory stick/flash memory – portable, very small device/large memory – CD/DVD-RW drive – common media/large memory/portable – (external) hard disk drive – very large memory/portable – solid state memory – no moving parts/lightweight/portable – floppy disc drive – portable printer type: – dot matrix printer – can operate on dirty/damp atmospheres – 3D printer – can produce working prototypes – laser printer – high quality, fast output for multiple copies – inkjet printer – high quality, low volume output – (graph) plotter – producing very large, accurate drawings

Page 7 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 input device (for e.g.): – keyboard – for keying in data into W/P, S/sheet, etc. – light pen – used with CAD packages – mouse/trackerball – pointing device for selecting options – touch screen – easy to use, suitable when limiting options – joystick – easier to control pointer – specialist CAD devices – specific to engineering company – microphone – easier for disabled people to enter data – webcam – video conferencing [6] 11 (a) 15 records [1] (b) FR, QE, NO, TI, MA (-1 mark for each error or omission) [2] (c) (Gross Tonnage > 80 000) OR (Country of Registration = “UK”) < - - - - - - - 1mark - - - - - - > < - - - - - - - - - - - 1 mark - - - - - - - - - - > or (Country of Registration = “UK”) OR (Gross Tonnage > 80 000) < - - - - - - - - - 1mark - - - - - - - - > < - - - - - - - - - 1 mark - - - - - - - -> [2] 12 (a) (i) (=) (A3 * A3 + B3 * B3) – (C3 * C3) OR (=) (A3 ^ 2 + B3 ^ 2) – (C3 ^ 2) [1] (ii) = IF (D3 = 0, “Yes”, “No”) Quotes essential [1] (iii) Any two from: – draw graphs (e.g. line graph) – make use of graph to find c – insert formula to calculate c values/
( a2 + b2 ) gives c values – add another column [2] (b) Any three from (for e.g.): – can draw graphs (e.g. line graph) – cell merging – cell formatting (e.g. date, numerical, text, string, etc.) – cell locking – cut/copy/paste/replicate formulae – automatic recalculation – goal seek [3]

Page 8 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 13 (a) - lift 7 - presently on 56th floor - going down [2] (b) 0 1 1 0 1 0 1 1 0 1 < - - - - - - - 1 mark - - - - - - > < - - - - - - - - - - 1 mark - - - - - - - - > [2] (c) (i) Any two from: – is lift in service? – is a lift already on the 14th floor? – is the ultimate destination of a lift in motion the 14th floor? – which lift is nearest 14th floor? – which lifts are going up? – which floor is the lift on? – which lifts are below 14th floor? [2] (ii) D [1] (d) Any pair of points from: – lift is on floor 000 } 1 mark – going down } 1 mark – lift is on floor 60 } 1 mark – going up } 1 mark – floor number > 60 } 1 mark – going up/down } 1 mark – lift out of commission } 1 mark – going up/down } 1 mark [2]

Page 9 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 14 (a) [5] START INPUT reading from temperature sensor 1 6/7 7/6 11/10 10/11 3 2 4/5 5/4 8/9 9/8 Yes No Yes No Yes No Yes No (1 mark) (1 mark) (1 mark) (1 mark) (1 mark) pairs MUST match up: 6 with 11 and 7 with 10 pairs MUST match up: 4 with 8 and 5 with 9

Page 10 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 (b) [4] input readings from the humidity sensors convert humidity sensor readings into digital signals using an ADC is humidity reading < 40? is humidity reading > 90? send signal (to motor) to open the windows No No 1 mark 1 mark for both correct 1 mark for both correct 1 mark send signal to (open valve and) spray water into the air Yes Yes

Page 11 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 15 (a) A B C X 0 0 0 1 0 0 1 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 1 0 1 1 0 1 1 1 1 1 [4] (b) 1 mark for gate name + 1 mark for each pair of outputs in truth table. NAND gate NOR gate A B X A B X 0 0 1 0 0 1 0 1 1 0 1 0 1 0 1 1 0 0 1 1 0 1 1 0 [3] 1 mark 1 mark 1 mark 1 mark

Page 12 Mark Scheme Syllabus Paper IGCSE – October/November 2012 0420 13 © Cambridge International Examinations 2012 16 sample program: x = 0: tbun = 0: tcoffee = 0: tcake = 0: tsand = 0: tdessert =0 1 mark repeat 1 mark input item 1 mark if item = “bun” then tbun = tbun + 0.5 else if item = “coffee” then tcoffee = tcoffee + 1.20 else if item = “cake” then tcake = tcake + 1.50 2 marks else if item = “sandwich” then tsand = tsand + 2.10 else if item = “dessert” then tdessert = tdessert + 4.00 else print “error” until item = “end” if tbun > x then x = tbun if tcoffee > x then x = tcoffee if tcake > x then x = tcake 2 marks if tsand > x then x = tsand if tdessert > x then x = tdessert total = tbun + tcoffee + tcake + tsand + tdessert 1 mark print total, x 1 mark marking points: – complete initialization – correct loop structure (could be while – end while or do – until loop.) – input item INSIDE the loop – check on which item has been input – *summation of value of each item input – check if each item total is the largest value – variable (e.g. x) takes on the highest total value – total value of ALL five totals – correct output OUTSIDE the loop [6]