Cambridge IGCSE Computer Studies 0420 — 2008 May/June Paper 1 · Variant 1

This document consists of 17 printed pages and 3 blank pages. IB08 06_0420_01/5RP © UCLES 2008 [Turn over *5566332198* For Examiner’s Use UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMPUTER STUDIES 0420/01 Paper 1 May/June 2008 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 then end of each question paper. www.XtremePapers.com

2 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 1 Explain, using examples where appropriate, the meaning of these computer terms. (a) batch processing [2] (b) interrupt [2] (c) top down design [2] (d) laptop computer [2] (e) trackerball [2]

3 © UCLES 2008 0420/01/M/J/08 [Turn over For Examiner's Use 2 List two tasks carried out by an operating system. 1 2 [2] 3 A company has decided to set up call centres in different countries. Regular training sessions, using video conferencing, will be carried out. (a) Give one advantage of having call centres in different countries. [1] (b) Give one disadvantage of having call centres in different countries. [1] (c) Give one advantage of using video conferencing to carry out the training. [1] (d) Give one disadvantage of using video conferencing to carry out the training. [1] (e) Describe another method of training staff using modern computer technology. [1]

4 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 4 Name two types of automatic data capture and give one application for each type named. Type 1 Application 1 Type 2 Application 2 [4] 5 Computer systems can be affected by viruses. (a) What is a virus? [1] (b) Give one effect of a virus. [1] (c) How can a system be protected from viruses? [1] (d) Why would backing up data not guard against the effect of a virus? [1]

5 © UCLES 2008 0420/01/M/J/08 [Turn over For Examiner's Use 6 Students’ records are kept on a stand-alone computer (no network connections) in the principal's office. (a) It is sometimes necessary to alter students’ records. To do this efficiently, individual records need to be retrieved quickly. (i) What type of file access should be used? [1] (ii) What type of magnetic medium allows this type of access? [1] (b) Give two examples of when a student’s record would need to be altered. Example 1 Example 2 [2] (c) Students are concerned that their personal data could be misused. Name two methods that could be used to ensure personal data is kept secure. Method 1 Method 2 [2] (d) Examination results are stored in students’ records as marks out of 100. Give two different validation checks that could be performed on students’ marks. Check 1 Check 2 [2]

6 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 7 A floor turtle can use the following instructions: Instruction Meaning FORWARD n Move n mm forward BACKWARD n Move n mm backward LEFT d Turn left d degrees RIGHT d Turn right d degrees PENUP Lift the pen PENDOWN Lower the pen REPEAT n Repeat the following instructions n times ENDREPEAT Finish the REPEAT loop Start Finish 20 mm 20 mm 20 mm 70 mm 50 mm 40 mm Complete the set of instructions to draw the above shape. PENDOWN LEFT 90 FORWARD [4]

7 © UCLES 2008 0420/01/M/J/08 [Turn over For Examiner's Use 8 A student decides to use an Internet search engine at home to help her work on her Geography project. She types in: COUNTRIES EXPORTS 2007 and gets over 11 million results. (a) She wanted to know which South American countries exported coffee in 2007. How could her search be refined to reduce the number of results? [1] (b) Give one advantage of searching for information on the Internet rather than using books. [1] (c) Many people have fears about searching for information on the Internet. Give two reasons for these fears. 1 2 [2] (d) The student wishes to use files stored on her home computer when she is back in class using one of the school’s computers. How could she do this? [1]

8 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 9 The following flowchart inputs two numbers, carries out a calculation and then outputs the result. START f = (u * v)/(u + v) INPUT u, v OUTPUT f Is u + v = 0? OUTPUT “Error” Yes No (a) Complete the following table for the three sets of input data. INPUT u v OUTPUT 5 5 6 -6 12 4 [3] (b) The above algorithm has been placed in a library of routines. Give one advantage of doing this. [1]

9 © UCLES 2008 0420/01/M/J/08 [Turn over For Examiner's Use 10 A computer system comes equipped with DVD writer/reader, hard disk drive and RAM. (a) Give a different use for each of these forms of memory. DVD Hard Disk RAM [3] (b) Give another example of a memory device and give one advantage of the named device. Example Advantage [2] 11 Write down four requirements of a Data Protection Act. 1 2 3 4 [4]

10 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 12 Algorithms and programs use loops to control the number of times a particular procedure is used. Two methods are repeat … until and for … to. (a) Write a procedure using both these loop methods to input 20 numbers into a variable called x. (i) repeat … until [2] (ii) for … to [2] (b) Name another loop structure. [1]

11 © UCLES 2008 0420/01/M/J/08 [Turn over For Examiner's Use 13 A media retail company has decided to sell CDs and DVDs using an Internet only shop. (a) Describe three features you might expect to see on the shop’s website. 1 2 3 [3] (b) Give two advantages to customers of shopping using the Internet. 1 2 [2]

12 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 14 (a) Computer systems are widely used now in simulations such as crash testing new cars. Give two advantages of using simulations rather than carrying out actual testing. 1 2 [2] (b) Virtual reality is often used in simulations. Describe two man-machine interface devices which allow communication with virtual reality systems. 1 2 [2]

13 © UCLES 2008 0420/01/M/J/08 [Turn over For Examiner's Use 15 A systems analyst has designed a new computer system for a large company. (a) Name two methods of implementing this new system and describe one advantage of using each method. (Do not give the same advantage for Method 1 and Method 2.) Method 1: Advantage: Method 2: Advantage: [4] (b) Before the system is implemented, it needs to be fully tested. One of the tests will be to check that the company does not pay a worker more than $800 per week. Use examples of a worker’s pay to explain what is meant by normal test data, abnormal test data and extreme test data. Normal Abnormal Extreme [3]

14 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 16 The washroom in a hotel uses lights controlled by a computer system. If the washroom is unoccupied for 10 minutes, the lights go out automatically. As soon as someone enters, the lights come on. (a) How can the system determine if anyone is in the washroom? [2] (b) Write down a set of instructions which would enable the computer to decide when to turn out the lights. [3] (c) Give one advantage of this automatic system. [1]

15 © UCLES 2008 0420/01/M/J/08 [Turn over For Examiner's Use 17 An expert system is to be written to identify chemical compounds. (a) Describe how the expert system would be created. [3] (b) How would a user be confident that the output from this expert system was correct? [1] (c) Give one advantage of using an expert system to identify chemical compounds. [1]

16 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 18 An entertainment company keeps monthly records on a spreadsheet of all its organised rock music events. The information for May 2008 is shown below. A B C D E F G 1 Event No. of seats No. seats sold Seat price ($) Total money taken ($) Cost of event ($) Profit or Loss 2 The Bugs 4000 1700 45 76500 85000 Loss 3 Static Rocks 3000 3000 50 150000 100000 Profit 4 The Cold Apes 4000 2150 35 75250 90000 Loss 5 Monophonics 5000 4000 35 140000 125000 Profit 6 Human Senses 4000 4000 60 240000 180000 Profit 7 Ice Patrol 3000 1500 50 75000 80000 Loss 8 The Manual 2000 1650 60 99000 115000 Loss 9 (a) (i) What formula is in cell E2 to work out the total money taken for The Bugs event? [1] (ii) Complete the following statement for cell G4: =IF (E4 > , “Profit”, ) [2] (iii) Total cost of all events is to be shown in cell F9. What formula needs to be placed in F9? [1] (b) If the value in C7 was changed to 2000, which cells would be automatically updated? [2] (c) Describe how to find the break even point for any given event (i.e. when cost of event = total money taken). [2]

17 © UCLES 2008 0420/01/M/J/08 For Examiner's Use 19 Customers can withdraw cash from an Automatic Teller Machine (ATM). • withdrawal is refused if amount entered > current balance • withdrawal is refused if amount entered > daily limit • if current balance < $100, then a charge of 2% is made • if current balance $100, no charge is made Write an algorithm which inputs a request for a sum of money, decides if a withdrawal can be made and calculates any charges. Appropriate output messages should be included. [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/08 BLANK PAGE

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the May/June 2008 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 2008 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 2008 0420 01 © UCLES 2008 1 Generally, one mark per valid point. Two examples can gain two marks. (a) batch processing (processing) doesn't start until all data collected any reference to JCL no need for human interaction uses computer during "quiet" time/overnight examples payroll system, billing, cheque processing [2] (b) interrupt a signal generated by a device/program causes a break in execution of the program examples e.g. printer out of paper, keypress [2] (c) top down design break down problem/task/program into sub-problem/smaller tasks/modules stepwise refinement examples/benefits allows several programmers to work on same large task each module can easily be tested/debugged separately [2] (d) laptop computer portable computer system/can be used anywhere has integrated keyboard/screen/pointing device uses a battery/mains power not required examples can do internet/work/emails away from home/on train/on plane [2] (e) trackerball pointing device input device examples used to choose options from menus/screen icons used in selecting objects on plant control/monitoring screens [2]

Page 3 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 2 Any two from: file management input/output control memory management multitasking multiprogramming handling interrupts error reporting/handling security/checks passwords and id codes interfaces with user loads/runs programs scheduling job control/JCL/batch processing controls hardware/software [2] 3 (a) Any one from: have an alternative if staff go on strike in one country can take advantage of lower wages in some countries lower office rentals/building costs in many countries can provide 24/7 cover [1] (b) Any one from: possible language problems lack of local knowledge time differences backlash from customers in countries where jobs lost customers often don't like call centres outside their own country [1] (c) Any one from: reduced travelling costs reduced wastage of time travelling to venues set up training sessions at short notice [1] (d) Any one from: cost of equipment to set up system initially time lag if long way away often sound/picture quality is poor can be difficult to interact possible language problems different time zones [1] (e) Any one from: use of DVDs/multimedia use of Computer Based Training (CBT)/CAL use of internet [1]

Page 4 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 4 One mark for each type + 1 mark for each matching application bar code readers - used in stock taking/control - used at POS terminals to access prices sensors - any description of control/monitoring OMR/OCR - reading documents automatically - reading multi-choice questionnaires MICR - automatic reading/clearing of cheques voice recognition - text input other suitable type/device - application [4] 5 (a) program/software/code which replicates itself/copies itself [1] (b) Any one from: loss/damage to computer files/data can cause computer to crash/run inefficiently/run abnormally attach itself to other files [1] (c) Any one from: use of (up to date) anti-virus software don't use disks/CDs/DVDs/memory sticks from unknown sources only read/open emails/attachments from known sources use of firewalls (NOTE: backups, passwords, encryption, don't connect to internet, do not protect against viruses) [1] (d) Any one from: wouldn't stop actual computer being infected back up files themselves may already have virus attachments if computer infected, re-installed files would then also be infected [1] 6 (a) (i) direct/random access [1] (ii) disk/flash memory [1] (b) Any two examples from: changes to personal details e.g. phone no, address changes to academic record e.g. marks, form, subject pupil leaves the school pupil's history changes [2]

Page 5 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 (c) Any two methods from: put password on the computer put password on the file access rights any physical method to stop access e.g. lock office door when not in use encrypt the data on the file [2] (d) Any two from: range check (0 to 100 only) character/type check (must be digits only) length check (must be 1–3 characters) [2] 7 (FORWARD) 40 } RIGHT 90 } 1 mark FORWARD 70 } REPEAT 2 OR RIGHT 90 } RIGHT 90 OR FORWARD 50 } FORWARD 50 OR RIGHT 90 } 1 mark ENDREPEAT OR FORWARD 50 } LEFT 90 OR LEFT 90 } REPEAT 2 OR FORWARD 20 } 1 mark FORWARD 20 OR RIGHT 90 } RIGHT 90 OR FORWARD 20 } ENDREPEAT OR RIGHT 90 } 1 mark FORWARD 20 FORWARD 20 } PENUP [4] 8 (a) For example: SOUTH AMERICAN COUNTRIES COFFEE EXPORTS 2007 (Marks gained here for either appropriately refining the search or use of quotes to narrow down the field somewhat.) [1] (b) Any one from: much more information available can download text/diagrams/photos can have multimedia presentations can be interactive auto translation into foreign languages several people can access the same data at the same time usually up-to-date information available/continually changing much easier to X-reference information/can perform multiple query searches [1]

Page 6 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 (c) Any two reasons from: information overload reliability of information viruses could be sent 'cookies' can be downloaded risk of hackers gaining access to computer files access to some "dodgy" web sites/risk of pornographic material fears of future "junk mail" (once certain web sites accessed) [2] (d) Any one from: email the information store the data/information on disks/CD/DVD/flash/website [1] 9 (a) 2.5 Error 3 [3] (b) Any one from: would be fully tested doesn't need to be re-written each time section of program needed [1] 10 (a) One mark for each use: DVD - applications programs/software - saving data for use on other computers - saving multimedia items - backup Hard disk - stores the operating system - stores software - stores data files RAM - stores data being used by user/work area - stores currently running programs [3] (b) One mark for example and one mark for advantage: floppy disk drive - suitable for small files flash memory stick/ - non-volatile memory USB flash drive - is portable - more robust than hard drive CD-RW writer/reader - very common form of memory - large memory capacity [2]

Page 7 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 11 Any three 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 accurate data must be destroyed/deleted when no longer required/don't keep longer than necessary data user must register what data is used/stored data must be used/collected fairly and lawfully data must be held securely data must be protected from accidental damage only authorised people can have access to data fines imposed for data mis-use data should not be passed on to a 3rd party without owner's permission person can view data and have it changed/removed if incorrect safe harbour [4] 12 (a) (i) count = 0 repeat input x 1 mark 1 mark count = count + 1 until count = 20 (ii) for count = 1 to 20 input x 1 mark 1 mark next count [4] (b) while…do [1] 13 (a) Any three from: content e.g. prices, pictures of CDs, sale items, etc. hyperlinks secure payment method shopping basket feature help facility e.g. site map ability to select artist/CD/DVD title from drop down boxes ability to do artist/title searches currency conversions "customer who bought this album also bought…" facility sale confirmation by email saved customer details (for returning customers) ability to track the status of orders ability to listen to tracks/watch video clips ability to pre-order albums/DVDs returns policy [3]

Page 8 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 (b) Any two from: no time spent travelling to shop if disabled can shop from home less expensive since no travelling much wider choice of goods available can shop 24/7 [2] 14 (a) Any two from: less expensive to carry out than do real testing far safer than real thing in many cases easier to do repeat tests/vary the parameters cannot do certain tests in reality e.g. landing on Mars can get test results more quickly [2] (b) Any two from: data gloves data visor/goggles special suits fitted with sensors [2] 15 (a) One mark for each named method AND one mark for each correct advantage. Parallel running - information not lost/always copy in case of failure - allows staff to get used to new system/training Phased implementation - still have most of system if fault develops - no expense of running both systems together - easier to train staff as each module introduced Pilot implementation - still have other systems in place if fault occurs - no expense of running both systems together - can watch what happens/make decisions Direct changeover/ - time not lost/immediate use possible Big Bang - no expense of running both systems together [4] (b) normal - e.g. $0 to $800 input abnormal - e.g. < $0, > $800, letters input extreme - e.g. $0 or $800 input [3] 16 (a) One mark per point type of sensor e.g. motion sensor how sensor is used e.g. to detect movement in the washroom signals sent back to computer reference to need for ADC between sensors and computer continuous monitoring [2]

Page 9 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 (b) One mark per point repeat get signal from sensor 1 mark if signal then set timer = 10 1 mark else if timer = 0 then switch light off 1 mark else countdown timer 1 mark until system switched off 1 mark with repeat [3] (c) Any one from: more efficient on energy no need to pay somebody to go round switching off/switching on lights safety, no need to touch light switch with wet hands more hygienic [1] 17 (a) Any three points from: information from experts gathered….. …..using questionnaires/interviews/text books knowledge base is created rules (base) created inference engine created interface with users is created fully tested system with known compounds [3] (b) Any one from: fully tested/perform own tests output is given a % probability value for correctness [1] (c) Any one from: don't need expensive expert to be present can act as a second opinion can be used anywhere useful in areas/countries where the expertise doesn't exist [1] 18 (a) (i) = C2 * D2 [1] (ii) IF (E4 > 90000, "Profit", “Loss”) OR IF (E4 > F4, "Profit", "Loss") [2] (iii) = SUM(F2:F8) OR = F2+F3+F4+F5+F6+F7 [1] (b) E7, G7 (1 mark) F9 (1 mark) [2]

Page 10 Mark Scheme Syllabus Paper IGCSE – May/June 2008 0420 01 © UCLES 2008 (c) One mark per point draw a graph find break even point from the graph use formulae in spreadsheet …. …. to simulate what happens as number of seats sold changes (can use macro) Select tools then Goal seek… …. set values [2] 19 Sample algorithm: input amount if amount > balance then x = 1 (2 marks) else if amount > daily limit then x = 1 (1 mark) else x = 0 while x = 0 if balance < 100 then charge = 0.02 * amount (1 mark) else charge = 0 (1 mark) endwhile if x = 1 then print “Sorry, withdrawal refused” print charge (1 mark) Marking points 1 mark for checking if amount > balance 1 mark for checking if amount > daily limit 1 mark for some way of testing if withdrawal will be refused (value of x in above) 1 mark for checking if balance < $100… 1 mark …for calculating 2% charge 1 mark for no charge if balance >= $100 2 marks for giving correct outputs [5] break even point