Cambridge IGCSE Computer Studies 0420 — 2007 May/June Paper 1 · Variant 1

This document consists of 19 printed pages and 1 blank page. IB07 06_0420_01/6RP © UCLES 2007 [Turn over *7053608159* For Examiner's Use UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMPUTER STUDIES 0420/01 Paper 1 May/June 2007 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 2007 0420/01/M/J/07 For Examiner's Use 1 Explain, with examples, the following five computer terms: (a) virus [2] (b) verification [2] (c) interrupt [2] (d) simulation [2] (e) electronic scabbing. [2]

3 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use 2 Describe, with examples, two types of test data which could be used to test a system. 1 2 [4] 3 Describe the difference between speech recognition and speech synthesis. [2] 4 State three tasks done by the operating system. 1 2 3 [3]

4 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 5 Use of computing and communication technologies has meant that many workers can now work from home, rather than having to travel to the office. State one advantage and one disadvantage of working from home from the point of view of: (i) the worker Advantage Disadvantage (ii) the company. Advantage Disadvantage [4] 6 Describe one type of diagram that can be used by a systems analyst when producing system documentation. Type of diagram Description [2]

5 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use 7 A hospital has decided to computerise its administration system. (a) Give three ways this could affect the hospital workers. 1 2 3 [3] The hospital will be using a database which holds confidential personal data. (b) State two precautions that the hospital should take to prevent unauthorised access to the data. 1 2 [2] (c) Describe how the database could be recovered if it became corrupted. [1] (d) Give one example, in each case, of when it would be necessary to amend data, delete data and insert data into the patient database. Amend Delete Insert [3]

6 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 8 Digital cameras do not use film. Therefore, there is no need to pay to develop the film and produce prints. (a) Give two other advantages of using digital cameras rather than traditional cameras. 1 2 [2] (b) On what does the quality of the pictures taken by the digital camera mainly depend? [1]

7 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use 9 A 7-segment display is used to indicate which floor a lift is on. Each segment is numbered as shown: 1 7 4 2 3 6 5 A byte is used to hold the data needed to light the correct segments. Bit 0 is always zero. For example, 3 is represented by 1 1 7 4 2 3 and by 0 0 1 1 1 1 0 7 6 5 4 3 2 1 0 Bit Number (a) If the lift is to stop at more than one floor, the data is held in successive bytes. For example: 0 0 0 0 1 1 1 0 1 FIRST BYTE: SECOND BYTE: 1 0 1 1 0 1 0 Which floor numbers are stored in each byte? First byte floor number Second byte floor number [2] (b) What bit pattern is used to indicate Floor 2? [1] (c) The lift is travelling down to stop at Floors 5, 3 and 1. When it stops at Floor 5, a passenger gets in and presses the button for Floor 2. How does the system ensure that the lift stops at Floors 3, 2 and 1 in that order? [3]

8 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 10 The following spreadsheet shows the number of mice, keyboards and trackerballs ordered by five customers. The value of each item is: Mouse $ 5 Keyboard $10 Trackerball $20 A B C D E F 1 Customer Number Number of Mice Number of Keyboards Number of Trackerballs Value of Order($) Free Delivery 2 1234 10 15 11 420 3 5678 9 20 15 545 4 9012 8 11 7 290 5 3456 6 20 15 530 6 7890 5 4 15 365 7 Total Order Value ($): (a) (i) Name a cell which contains a numerical value. (ii) Name a cell which contains text only. [2] (b) What formula must be placed in cell E2 to calculate the value of the order for customer 1234? [2] (c) How could the formula in Question 10 (b) be replicated in cells E3 to E6? [2]

9 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use (d) What formula should be placed in cell E7 to add up the totals in column E? [1] (e) If the formula IF (E4>400 THEN “Y” ELSE “N”) was placed in cell F4, what output would be produced in that cell? [1]

10 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 11 Study the following flowchart very carefully. START STOP S = 1 S = S + 1 INPUT X X = X/10 Is X < 1 OUTPUT S Yes No

11 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use (a) Complete the following table showing the expected output from the flowchart for the three sets of input data: INPUT X OUTPUT S 48 9170 - 800 [3] (b) Input data needs to go through a validation process. (i) Explain the term validation. (ii) Describe one type of validation check. [2]

12 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 12 Describe three ways you could modify a typical input/output environment to enable people with disabilities to use the computer system. 1 2 3 [3] 13 Items sold in supermarkets are all marked with bar codes. (a) Customers are given an itemised bill at the checkout. Give two advantages to the customer. 1 2 [2] (b) Give two ways the information on the bar code can be input at the checkout. 1 2 [2] (c) Describe how bar codes are used in automatic stock control. [3]

13 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use 14 A database has been set up by a car dealer to maintain information on cars currently available for sale. A section of the database is shown below. Ref No Manufacturer Model Doors 0-100 kph time (sec) Top Speed (kph) Price ($) 1015 Bentley Arnage 4 6.0 250 300 000 1023 Porsche Boxster 2 5.5 266 55 000 1158 Fiat Stilo 5 12.4 170 14 000 1911 Maserati GT 2 4.8 288 105 000 2051 Lexus GS 4 6.3 250 95 000 2081 Renault Laguna 5 8.4 220 25 000 2516 Porsche Cayenne 5 5.6 260 130 000 3331 VW Golf 3 9.3 200 27 500 3456 Lotus Elise 2 5.7 205 42 500 (a) How many records are shown in the section of the database above? [1] (b) If the following query was input (Top Speed (kph) > 250) OR (Doors = 2) using Ref No only, which items would be output? [2] (c) Write down a query which outputs cars which cost more than $60 000 and have a 0-100 kph time (sec) of less than 7.0. [2] (d) The car dealership has decided to produce a website which allows potential customers to search its database of cars on-line. Give two advantages to the car dealership of doing this. 1 2 [2]

14 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 15 An Expert System is to be created to help diagnose faults in electronic components. The diagram in Fig. 1 summarises how the knowledge base was created and how it is used to help technicians. Some parts of the diagram have been left blank. Knowledge base and rule base Input answers to a series of questions Fig.1

15 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use (a) Complete the diagram in Fig. 1 by putting the following statements in the correct boxes: 1 Inference engine queries the knowledge base 2 Display results 3 Collect data from experts 4 Create knowledge base and rule base. [3] (b) Describe a typical input interface you would find on a diagnostic Expert System. [1] (c) Describe the output you would expect to see from this system. [1] (d) Give another example of an Expert System. [1]

16 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 16 Modern car engines use fuel injection systems which are controlled by microprocessors called Engine Control Units (ECUs). The fuel injection system controls the amount of fuel that goes into the engine. Sensors monitor engine conditions and feed the data back to the ECUs. Fuel Injection System ECU Engine fuel data from the sensors control signals (a) Name two types of sensors used to monitor engine conditions. 1 2 [2] (b) Describe how information from the sensors is used to control the fuel injection system. [3] (c) Give an advantage of using automatic fuel injection systems rather than simpler mechanical fuel devices. [1] (d) The fuel injection system operates in real time. Why would batch processing not be appropriate in this application? [1]

17 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use 17 Geography students have access to course materials on their college website. A web browser is used to access these materials. Describe three features of a web browser which would be suitable for this application. 1 2 3 [3]

18 © UCLES 2007 0420/01/M/J/07 For Examiner's Use 18 A company has bought laptop computers for training purposes and for information retrieval. These computers will use the Internet and have multimedia capabilities. (a) State two advantages and one disadvantage of using the Internet to search for information when compared to using CD-ROMs or paper-based systems. Advantage 1 Advantage 2 Disadvantage [3] (b) The company has chosen to use broadband for Internet connections. Why was broadband chosen rather than dial-up modem connections? [1] (c) The laptops are linked to the network using wireless connections. Give one advantage and one disadvantage of using wireless connections. Advantage Disadvantage [2]

19 © UCLES 2007 0420/01/M/J/07 [Turn over For Examiner's Use 19 A company has 5000 CDs, DVDs, videos and books in stock. Each item has a unique 5-digit code with the first digit identifying the type of item, i.e. 1 = CD 2 = DVD 3 = video 4 = book For example, for the code 15642 the 1 identifies that it is a CD, and for the code 30055 the 3 identifies that it is a video. Write an algorithm, using pseudocode or otherwise, that • Inputs the codes for all 5000 items • Validates the input code • Calculates how many CDs, DVDs, videos and books are in stock • Outputs the four totals. [5]

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. 0420/01/M/J/07 BLANK PAGE

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2007 question paper 0420 COMPUTER STUDIES 0420/01 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. All Examiners are instructed that alternative correct answers and unexpected approaches in candidates’ scripts must be given marks that fairly reflect the relevant knowledge and skills demonstrated. 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 2007 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 Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 1 (a) virus any two points from: program/software worm = 0 which replicates/copies itself trojan horse = 0 alters/damages files/alters files or data name of virus = 0 e.g. examples of the effect of a virus bomb = 0 [2] (b) verification any two points from: check on input for errors/checking before & after transfer by double entry proof reading = 0 on screen checking comparing input/use of second operator e.g. password typed in twice [2] (c) interrupt any two points from: a signal/request generated by a device/program power cut = 0 causes a break in execution of a program/stops program e.g. printer out of paper [2] (d) simulation any two points from: studying behaviour of a system games = 0 by using a model/represents real life/mathematical representation results can be predicted e.g. flight/other simulator, modelling hazardous chemical reaction [2] (e) electronic scabbing any two points from: allows managers to switch … word processing/computer processing duties … from striking clerks in one country to non-striking clerks in another [2]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 2 Any two types from: (1 mark for naming type of test data. 1 mark for description or suitable example) Normal - acceptable/valid data - data has expected outcomes - example (e.g. day of month 1 to 31) needs context, range OK Abnormal - data outside limits of acceptability/validity Erroneous - example (e.g. day of month –1, 50, etc.) Extreme - data at limits of acceptability/validity Boundary - example (e.g. day of month 1, 31, etc.) [4] 3 Two points one from each group: speech recognition is a form of input; speech recognition requires a microphone; speech recognition is an example of an expert system speech synthesis is a form of output speech synthesis requires speakers in speech synthesis words are chosen from a database [2] 4 Any three points from: file management resource management = 0 input/output control/peripheral management spooling memory management multitasking/JCL/batch processing multiprogramming handling interrupts error reporting/handling security interfaces with users/WIMP type interfaces loads/runs programs processor management manages user accounts copy/save/format/DOS utilities [3]

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 5 (i) Any one advantage and any one disadvantage from: advantages disadvantages no travel (∴ saves money) too many distractions no time wasted in travelling less social interaction with others more time for family life less visible status for senior employees more flexible working hours equal opportunities for all more motivated (**) (ii) Any one advantage and any one disadvantage from: advantages disadvantages lower overheads (no offices) less control over work force more flexible/contented (**) could be doing work for more than one company work force easier to employ disabled people difficult to get company loyalty workers can be anywhere in more difficult to react quickly to changing situations the world can tap into world wide expertise (** - only allow in (i) OR (ii) not both) [4] 6 One mark for name and one mark for description Data flow diagrams - describes data input/output into the system - shows what happens to data within the system (during processing and storage) Modules/Structure - shows logic behind program structure Diagrams/ - allows task to be split into individual parts - shows links in modules (Systems) flowcharts/ - shows hardware diagrams - shows how hardware links - shows how processes are carried out Gantt/Pert charts - shows each stage with deadlines/milestones (critical path analysis) [2]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 7 (a) Any three points from: deskilling retraining needed loss of jobs frees staff from admin jobs less time wasted looking for lost paperwork [3] (b) Any two from: passwords (changed regularly) encryption = 0 use of ids/log on ids/user names removal of external memory = 0 firewalls physical measures (e.g. locked rooms) logging off after use [2] (c) Any one point from: use of back up files generations of files (GFS) [1] (d) amend - change name/address/doctor etc. change of age = 0 - new illness - re-admission delete - patient leaves area/country leaves hospital = 0 - patient dies insert - new patient arrives - new baby born [3] 8 (a) Any two from: transfer images directly to computer (no need to scan in) can easily wipe photos from memory video possible = 0 view pictures immediately adjust pictures immediately store more pictures in less space [2] (b) Any one point from: number of pixels/memory size the sensor (determines number of pixels) [1]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 9 (a) 7 5 [2] (b) 10110110 [1] (c) Any three points from: Notes lift is going down Notes required floor is less than present floor Sorts remaining numbers into descending order of floors [3] 10 (a) (i) Any cell in the range A2:D6 (ii) Any cell in the range A1:F1, C7, D7 [2] (b) (B2*5) + (C2*10) + (D2*20) (-1 for each error) NB Brackets not needed [2] (c) Any two points from: Highlight/select E2/copy E2 paste into cells E3 to E6 (or equivalent (select + sign) using drag and drop, for example) [2] (d) SUM(E2:E6) E2 + E3 + E4 + E5 + E6 [1] (e) N [1]

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 11 (a) 2 4 1 [3] (b) (i) Any one point from: computer check on input data check data is wrong/correct = 0 detects any data which is incomplete or not reasonable (ii) Any one point from: length check – e.g. only 30 characters in name field character check – e.g. name doesn’t contain numeric chars range check – e.g. day of month in date is between 1 and 31 format check – e.g. date in the form xx/yy/zz check digit – e.g. end digit on bar code to check if it is valid type check – e.g. integer, real (presence check = 0) [2] 12 Any three points from: (NB if disability mentioned, shouldn’t conflict with method/device) large/concept keyboards/switches braille keyboards (for partially sighted/blind) tracker ball to move pointer if keyboard/mouse can’t be used touch screens (using head wands) software to predict words (e.g. for dyslexic people) speech recognition foot activated control (if no arm movement) large icons/fonts on screens ( – if partially sighted) braille printers speech synthesis speakers = 0 large screen choice of colours [3]

Page 8 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 13 (a) Any two advantages from: know prices of each item/check errors proof of purchase can check totals themselves can check items [2] (b) Any two ways from: using bar code reader/scanner/wand/gun to read bar code key in/type in/enter manually the number under the bar code laser = 0 light pen = 0 [2] (c) Any three points from: bar code read item identified on the file number of items reduced by 1 each time item is sold when new item come in/returned stock level increased by 1 minimum stock level stored on file if stock level less than minimum/reorder level … … automatic re-ordering done alert that stock low = 0 [3] 14 (a) 9 [1] (b) 1023, 1911, 3456, 2516 (-1 for each ref number missing or for each incorrect ref number) [2] (c) Ignore case, comma 7 (Price($) > 60000) AND (0-100 kph time (sec) < 7.0) <------ 1 mark ----> <----------------- 1 mark ----------------> (0-100 kph time (sec) < 7.0) AND (Price($) > 60000) <------------ 1 mark ------------> <----------- 1 mark --------> [2] (d) Any two points from: bigger audience/world wide audience no need to advertise in the press (∴ cheaper) no showroom = 0 can have automatic replies to customers open 24/7 [2]

Page 9 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 15 (a) 1 for each correct box max 3 [3] (b) Any one point from: multiple choice questions yes/no answers takes user through the possible options touch screen with options [1] (c) Any one point from: possible faults % probability of the fault [1]

Page 10 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 (d) Any one from: e.g. chess oil/mineral prospecting tax/financial calculations medical diagnostics speech recognition rock identification [1] 16 (a) Any two sensors from: airflow (mass of air) fuel level = 0 oxygen/gas sensor heat sensor = 0 throttle/accelerator position/potentiometer thermometer = 0 temperature voltage (manifold) pressure (engine) speed [2] (b) Any three points from: data from sensors fed to ADC data is fed continuously (loop) ADC converts data to digital form and sends information to ECU ECU has been programmed/stored with key values/data information from sensors compared with stored data signals sent to injectors to alter their operation as required reference to need for DAC reference to need for actuators [3] (c) Any one point from: environment (exhaust gases controlled) (better) fuel economy/more efficient fewer moving parts doesn’t go “out of tune” improved engine life = 0 fuel injection more accurate [1] (d) Any one point from: requires an immediate response needs to be on-line [1]

Page 11 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 17 Any three features from: links to associated resources possible within text (hyperlinks) hot spots – in pictures/maps forward/back buttons – allows review of resources favourites – maintains links to resources between sessions history – previous searches for example refresh – updates pages for example filters – takes out unwanted information for example [3] 18 (a) Any two advantages from: huge amount of information information is constantly updated immediate access to information from research papers use of search engines e-mail facilities give access to world experts Any one disadvantage from: need to know how to do searches properly bad searches can give wrong or irrelevant information unknown reliability likely to download virus phone lines engaged if not using broadband (OK if not given in (b)) (open to) fraud/hacking while on line [3] (b) Any one point from: very fast transfer (ideal for video clips) speed of internet connection = 0 always “on” (no need for dial up) not metered telephone lines not tied up/don’t need extra lines (if not given in (a)) [1] (c) Any one benefit from: (NOT advantages of laptop computers) no trailing wires can sit anywhere within the room Any one disadvantage from: slower transmission speed range is limited security problems health problems [2]

Page 12 Mark Scheme Syllabus Paper IGCSE – May/June 2007 0420 01 © UCLES 2007 19 General marking points: loop – 1 mark input in correct place – 1 mark checks on code – 1 mark correct use of if/then/else or case statements – 1 mark increment all totals – 1 mark error recognition/validation – 1 mark correct output in correct place – 1 mark [5] Sample program 1: set c, d, v, b = 0: set count = 0 repeat 1 mark input code 1 mark x = code/10000 } y = INT(x) } 1 mark if y = 1 then c = c + 1 } else if y = 2 then d = d + 1 } else if y = 3 then v = v + 1 } 2 marks else if y = 4 then b = b + 1 } else print “error” 1 mark count = count + 1 until count = 5000 print c, d, v, b 1 mark Sample program 2: set c, d, v, b = 0: set count = 0 repeat 1 mark input code 1 mark if code >= 1000 and code < 2000 then c = c + 1 } else if code >= 2000 and code < 3000 then d = d + 1 } else if code >= 3000 and code < 4000 then y = y + 1 } 3 marks else if code >= 4000 and code < 5000 then b = b + 1 } else print “error” 1 mark count = count + 1 until count = 5000 print c, d, v, b 1 mark (NOTE – OK to use statements such as if code begins with a 1 as code checks)