Cambridge IGCSE Computer Studies 0420 — 2010 May/June Paper 1 · Variant 2

This document consists of 19 printed pages and 1 blank page. IB10 06_0420_12/6RP © UCLES 2010 [Turn over *3306820156* For Examiner's Use UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMPUTER STUDIES 0420/12 Paper 1 May/June 2010 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 2010 0420/12/M/J/10 For Examiner's Use 1 Explain, with examples where appropriate, the following five computer terms. (a) buffer [2] (b) batch processing [2] (c) e-commerce [2] (d) simulation [2] (e) email [2]

3 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use 2 A company making televisions has introduced robots to replace the human work force. (a) Describe three effects this would have on the work force. 1 2 3 [3] (b) Give two advantages to the company of introducing robots. 1 2 [2] (c) How could the robots be trained to assemble the televisions? [1] (d) A whole batch of televisions was produced with some of the parts missing. How could this error have been avoided? [1]

4 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 3 State four tasks performed at the analysis stage in systems analysis. 1 2 3 4 [4] 4 Give four features of a Data Protection Act. 1 2 3 4 [4]

5 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use 5 A bank is worried about computer crime. One of their concerns is online access to customer accounts. (a) How can a customer’s access details be discovered by criminals? [2] (b) Why would a customer using a credit card for online shopping be more of a security risk than a customer using the same card in a shop? [2] (c) Describe what measures the bank can take to safeguard customer accounts. [2]

6 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 6 An expert system is being developed to help engineers diagnose faults in aero engines. (a) Describe the steps taken to develop this new expert system. [4] (b) Another method used to identify and rectify faults is to train engineers using virtual reality systems. (i) What is virtual reality? [1] (ii) What special hardware is used to interface with virtual reality systems? [1]

7 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use 7 A screen has been developed to allow the input of data into the following fields: name, sex, address, date of birth and examination results. (a) A first attempt at designing the screen is shown below: This is not a very good input screen. Give four ways in which it could be improved. 1 2 3 4 [4] (b) (i) What is verification? (ii) Which fields should be verified? [3] Student Records Student name: ………………………………….. Sex: …………………… Student address: ……………………………………………………………… ……………………………………………………………………………………. Date of birth: ……… / ……… / ……… Exam results: Subjects and Grades Type in NEXT to go to next student or BACK to go to previous student: …………………………

8 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 8 A supermarket makes use of barcodes on all its goods as part of its automatic stock control system. (a) Describe how the price is found for each item sold. [2] (b) The following are steps in the automatic stock control system. Number the steps in the correct order. if stock level ≤ minimum stock level report printed out for the manager stock level reduced by 1 new stock value written back to file more items are ordered automatically [4] 9 A factory uses a computer system to store information about customers, spare parts and general administration. (a) Spare parts can be identified by selecting from diagrams on a computer screen. Describe what hardware would be needed to allow the parts to be selected in this way. [2]

9 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use (b) The factory needs to buy a new printer. It has decided to buy either a dot matrix printer or an inkjet printer. Discuss the advantages and disadvantages of using both types of printer in this application. Dot matrix printer: Advantages Disadvantages [3] Inkjet printer: Advantages Disadvantages [3]

10 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 10 A small company runs six cars in its fleet. They have produced a spreadsheet to compare running costs over a five month period: (a) It was decided to print out the spreadsheet formulas from D2 to E8. Using the grid below, show what formulas would be printed: D E 1 Total cost ($) Average cost per month ($) 2 3 4 5 6 7 8 [4] A B C D E 1 Car Identity Total number of km Cost per km ($) Total cost ($) Average cost per month ($) 2 10001 30 000 1.00 30 000 6 000 3 10002 20 000 4.00 80 000 16 000 4 10003 50 000 1.50 75 000 15 000 5 10004 30 000 2.00 60 000 12 000 6 10005 20 000 2.50 50 000 10 000 7 10006 30 000 1.50 45 000 9 000 8 Averages: 2.08 56 667 11 333

11 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use (b) A graph of Cost per km ($) was drawn: 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 10001 10002 10003 10004 Car identity Cost per km ($) Cost per km ($) 10005 10006 (i) Which cells were highlighted to produce this graph? [2] (ii) Describe how the average value of 2.08 would be shown on the graph. [1] (c) The data in cell C6 was changed to 3.00. Which cells would be updated automatically? [2]

12 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 11 A database has been set up showing information about cars: Car ref No of doors Engine (litres) CO2 (g/km) Fuel used (km/litre) No of cylinders A 3 1.4 145 15.3 4 B 4 2.0 193 12.3 4 C 5 2.5 231 10.9 6 D 3 2.0 190 11.2 6 E 4 1.3 120 17.5 4 F 5 1.8 180 14.6 4 G 4 3.0 240 9.5 6 H 4 1.2 115 19.7 3 (a) Using Car ref only, write down which cars would be output if the following search condition was used: (No of doors = 4) AND (Fuel used (km/litre) > 15) [2] (b) Write down a search condition to find out which cars have engines larger than 1.8 litres OR have CO2 emissions higher than 150 g/km. [2] (c) The database is sorted in ascending order on Fuel used (km/litre). Using Car ref only, write down the results of the sort. [2]

13 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use 12 (a) State two items of hardware needed to enable a standard computer system to take part in video conferencing. 1 2 [2] (b) State two additional items of software that would be needed for the video conferencing to take place. 1 2 [2] (c) Describe two potential problems when using video conferencing. 1 2 [2]

14 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 13 Study the following flowchart very carefully: START STOP PRINT N INPUT X T = X Is X = 0? N = 1 T = T/10 Is T < 10? N = N + 1 No Yes STOP PRINT “error” Yes No What output would you expect if the following data was input into the flowchart? X OUTPUT -150 540 0 [3]

15 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use 14 A safety system has been developed to stop vehicles getting too close to each other on the road. A B sensors If vehicle A gets too close to vehicle B, the brakes are automatically applied by a computer system in vehicle A. (a) What type of sensors could be used on the vehicles? [1] (b) Describe what the safety system does to constantly monitor how close the vehicle is to the vehicles in front and decide when to take action. [4] (c) Describe two potential problems with this safety system. 1 2 [2]

16 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 15 A floor turtle can use the following instructions: Instruction Meaning FORWARD d Move d cm forward BACKWARD d Move d cm backward LEFT t Turn left t degrees RIGHT t Turn right t degrees REPEAT n Repeat the next set of instructions n times ENDREPEAT End of REPEAT loop PENUP Raise the pen PENDOWN Lower the pen (In the following grid, each square is 10 cm by 10 cm.) Start End

17 © UCLES 2010 0420/12/M/J/10 [Turn over For Examiner's Use Complete the set of instructions to draw the shape (shown in bold lines) by filling in the blank lines. LEFT 90 PENDOWN FORWARD 10 RIGHT 90 [5]

18 © UCLES 2010 0420/12/M/J/10 For Examiner's Use 16 (a) Write an algorithm, using pseudocode or a flowchart, which:
inputs 50 numbers
outputs how many of the numbers were > 100 [3]

19 © UCLES 2010 0420/12/M/J/10 For Examiner's Use (b) Write an algorithm, using pseudocode or a flowchart, which:
inputs 100 numbers
finds the average of the input numbers
outputs the average [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. 0420/12/M/J/10 BLANK PAGE

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2010 question paper for the guidance of teachers 0420 COMPUTER STUDIES 0420/12 Paper 12, 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 must be read in conjunction with the question papers and the report on the examination. • CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2010 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses. www.XtremePapers.com

Page 2 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 1 (a) buffer Any two points from: – temporary … – … storage/memory – compensates for the difference in speed of peripherals and CPU – e.g. printer (buffer) [2] (b) batch processing Any two points from: – processing doesn’t start until all data is collected – JCL (any reference to Job Control Language) – no need for user interaction – processed all in one go – done at “quiet” times – e.g. billing, payroll, cheque processing [2] (c) e–commerce Any two points from: – electronic commerce – buying and selling products/services ….. – ….. using the internet/computer networks – reference to B2B (business to business) or B2C (business to consumer/customer) – e.g. on-line shopping, commodity exchanges, Internet/online banking [2] (d) simulation Any two points from: – studying the behaviour of a system – by using a model/mathematical representation – results can be predicted – e.g. flight (or other) simulator, modelling hazardous chemical processes – e.g. 10-pin bowling computer game [2] (e) email Any two points from: – electronic mail – sending messages from one device to another using computer networks/Internet – world wide form of electronic communication – can send file attachments – e.g. sending a letter without use of traditional mail service [2]

Page 3 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 2 (a) Any three points from: – loss of jobs/unemployment – deskilling – need to re-train – different jobs available/re-skilling – no longer need to do hazardous/tedious jobs [3] (b) Any two points from: – lower work force costs (no salaries to pay) – lower environmental costs (less electricity for heating/lighting) – higher throughput – more consistent product – robots don’t need breaks, holidays/work 24/7 etc. – robots don’t take industrial action [2] (c) Any one point from: – tasks repeated by skilled worker and how each task is done is memorised – tasks programmed directly into the computer/robot memory [1] (d) Any one point from: – if parts missing for a sequence, then a warning should be given and the assembly stopped – several quality control stages to spot an error early on – program in checks at each stage of assembly so robots can detect a fault immediately [1] 3 Any four points from: – understand the current system – produce data flow diagrams/system flowchart – identify user/client requirements/objectives – interpret user/client requirements/objectives – agree requirements/objectives with the user/client – collect data from the current system – fact finding (e.g. questionnaires, interviewing, etc.) – problem identification [4] 4 Any four features from: – data must be up to date – data can only be read/used for the purpose for which it was collected – data must be adequate, relevant and not excessive – data must be accurate – data must be destroyed when no longer needed/don’t keep longer than necessary – data user must register what data stored – data must be used/collected fairly and lawfully – data must be held securely – data must be protected from accidental damage – only authorised personnel can have access to the data – fines are imposed for data mis-use – data should not be passed on to a third party without permission – a person can view data and have it changed/removed if incorrect – safe harbour (countries with DPA at least as good) [4]

Page 4 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 5 (a) 1 mark each for 2 concerns OR 1 mark for concern + 1 mark for expansion: – customer goes online in a public place ….. …… and is overlooked as they enter id/password/PIN – customer receives emails taking them to a false site ….. ….. where they are asked to confirm details by entering them – customer downloads virus, spyware, ….. ….. which logs all key presses including id/password/PIN [2] (b) Any two points from: – don’t need card number for online transaction/card number already – online user is anonymous/not visible – online the customer does not need the card and signature/PIN [2] (c) Any two points from: – secure sites using encryption – use of passwords/PINs/biometrics/advice to change PIN regularly – no communications with customer requiring personal details – use of home card readers that generate codes known only to bank and customer – check with customer at each log on when they were last logged on to the website – contact customer if unusual transaction/random check – customer asked to inform bank if intending to use card in another country – customer asked to inform bank if card lost/stolen – ensure firewall is in place [2] 6 (a) Any four points from e.g.: – gather information from experts/questionnaires – create the knowledge base – type/put information into computer – create rules/rules base – create/design inference engine – create/design input–output interface – fully test the system – expert system learns [4] (b) (i) Any one point from: – 3D visual world – uses computer simulation – uses special interface devices (e.g. data gloves and goggles) [1] (ii) Any one point from: – data gloves/goggles (if not given credit in part (i)) – hardware/motors to provide movement – special suits fitted with sensors [1]

Page 5 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 7 (a) Any four improvements from: – use (text) boxes for – names – addresses – sex – date of birth – subjects – grades – separate fields into separate entry items – name into first name and last name – address into street, city etc – drop down list/combo box for – date of birth – sex – subjects – grades – calendar object for – date of birth – radio buttons for – sex – hyperlinks for – NEXT – BACK [4] (b) (i) any one point from: – check on input for errors by double entry – on screen checking – check input is same as source (ii) – name – address [3] 8 (a) Any two points from: – barcode is scanned/keyed in – barcode is validated (by check digit) – system looks up barcode in computer files/database – retrieves (and returns) price [2] (b) if stock level < minimum stock level 3 report printed out for manager 5 stock level reduced by 1 1 new stock value written back to file 2 more items are ordered automatically 4 1 mark for each correct answer up to max of 4. 4 marks for all 5 correct 3 marks for any 3 or 4 correct 2 marks for any 2 correct 1 mark for any 1 correct [4]

Page 6 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 9 (a) Any two correct input devices OR input device + correct type of screen – mouse/trackerball + CRT screen/TFT screen – touch screen + CRT screen/TFT screen – light pen + CRT screen [2] (b) Dot matrix printer: Accept a max of 2 advantages and a max of 2 disadvantages: Advantages: – suitable for dirty/dusty/damp atmospheres – cheap to maintain – cheap to run – can operate with continuous/multipart stationery Disadvantages: – poor print quality – very noisy – very limited colours [3] Inkjet printer: Accept a max of 2 advantages and a max of 2 disadvantages: Advantages: – inexpensive to purchase – high quality printouts – can use colours – supported by most operating systems – quiet Disadvantages: – run out of printing ink quickly/cartridges run out quickly – price per page/inks are expensive – not suitable for dirty/dusty/damp atmospheres [3]

Page 7 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 10 (a) Award marks as shown (each block = 1 mark): D E 1 Total cost ($) Average cost per month ($) 2 = B2 * C2 = D2 / 5 3 = B3 * C3 = D3 / 5 4 = B4 * C4 = D4 / 5 5 = B5 * C5 = D5 / 5 6 = B6 * C6 = D6 / 5 7 = B7 * C7 = D7 / 5 8 = AVERAGE (D2 : D7) Alternative answers: = SUM(D2:D7)/6 = (D2+D3+D4+D5+D6+D7)/6 = AVERAGE (E2 : E7) Alternative answers: = SUM(E2:E7)/6 = (E2+E3+E4+E5+E6+E7)/6 = D8/5 [4] (b) (i) (A1 : A7) and (C1 : C7) (1 mark) (1 mark) [2] (ii) Any one point from: – add an extra column and set all values to 2.08 – draw a line at value 2.08 on the graph – add a trend/average line using spreadsheet software [1] (c) D6, E6, C8, D8, E8 (-1 mark for each error or omission) [2] 11 (a) E, H [2] (b) (Engine (litres) > 1.8) OR (CO2 (g/km) > 150) ← (1 mark) → ← (1 mark) → Or (CO2 (g/km) > 150) OR (Engine (litres) > 1.8) ← (1 mark) → ← (1 mark) → [2] (c) G, C, D, B, F, A, E, H (1 mark for correct order (fuel used) 1 mark for ascending order) [2]

Page 8 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 12 (a) Any two items from: – webcams/digital video camera – microphones – broadband modem – networking hardware e.g. cabling/router – loud speakers/headphones [2] (b) Any two items from: – communications software – CODEC/compression software – Internet access software – driver software (for the hardware in part (a)) – echo cancellation software [2] (c) Any two problems from: – poor reception (poor sound, jerky screen images)/network failure – if more than 2 conference locations, can be difficult controlling meeting – time zones – language difficulties – power failure [2] 13 Expected output: 1 2 Error [3] 14 (a) Any one from: – infra-red – light – radar – ultrasonic / proximity [1] (b) Any four points from: – signal sent out from vehicle A – sensors pick up reflected beam – signal converted to digital by ADC – computer uses data to calculate how close vehicle B is – computer uses speed of vehicle A ….. – ….. to determine the safe distance – if the safe distance > distance between the two vehicles ….. – ….. then the driver is warned – sends signal to (actuators) apply brakes – reference to need for DAC – monitoring continues endlessly unless system deactivated * no marks for computer applies the brakes * no marks for computer senses …. * no marks for sensor taking any actions [4]

Page 9 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 (c) Any two points from: – when roads are busy, constantly braking – system may not take road conditions into consideration – over-reliance on system by the driver – only works properly if vehicle has an automatic gearbox – sensors don’t work if obstructed/dirty/malfunction [2] 15 LEFT 90 FORWARD 20 20 RIGHT 90/PENUP PENDOWN RIGHT 90 FORWARD 10 FORWARD 10 FORWARD 20 PENDOWN RIGHT 90 RIGHT 90 –––––––––––––––––––– –––––––––––––––––––– FORWARD 20 FORWARD 10 FORWARD 10 –––––––––––––––––––– RIGHT 90 PENUP LEFT 90 FORWARD FORWARD 10 FORWARD 20 PENDOWN PENUP / RIGHT 90 –––––––––––––––––––– –––––––––––––––––––– (NOTE: the second sequence of instructions could be done with a REPEAT loop i.e. REPEAT 2 FORWARD 20 RIGHT 90 ENDREPEAT FORWARD 20 It is also possible to write: REPEAT 3 FORWARD 20 RIGHT 90 ENDREPEAT followed by LEFT 180 or RIGHT 180 instead of LEFT 90) [5] 16 (a) total = 0 (1 mark) initialisation for x = 1 to 50 (1 mark) correct loop input number (1 mark) correct input and output if number > 100 then total = total + 1 (1 mark) count numbers>100 next x output total (1 mark for initialising total) (1 mark for correct loop – accept repeat loop or a while loop) (1 mark for correct input (within loop) and output (after the loop)) (1 mark for counting how many input numbers were > 100) [3]

Page 10 Mark Scheme: Teachers’ version Syllabus Paper IGCSE – May/June 2010 0420 12 © UCLES 2010 (b) total = 0 (1 mark) initialise total for x = 1 to 100 (1 mark) correct loop input number (1 mark) correct input and output total = total + number (1 mark) finding sum of numbers next x average = total/100 (1 mark) calculate average output average (1 mark for initialising total) (1 mark for correct loop – accept repeat loop or a while loop) (1 mark for correct input (inside the loop) and output (after the loop)) (1 mark for calculating total) (1 mark for calculating the average outside the loop) [3]