Cambridge IGCSE Computer Studies 0420 — 2008 Oct/Nov Paper 1 · Variant 1

This document consists of 16 printed pages. IB08 11_0420_01/3RP © UCLES 2008 [Turn over *4623671366* For Examiner’s Use UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education COMPUTER STUDIES 0420/01 Paper 1 October/November 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 the end of each question paper. www.XtremePapers.com

2 © UCLES 2008 0420/01/O/N/08 For Examiner's Use 1 Explain, using examples where appropriate, the meaning of these computer terms. (a) mouse [2] (b) search engine [2] (c) buffer [2] (d) RAM [2] (e) download [2]

3 © UCLES 2008 0420/01/O/N/08 [Turn over For Examiner's Use 2 Describe two benefits of using top down design to develop computer software. 1 2 [2] 3 Write a routine using a for … to loop which inputs 100 numbers and outputs how many of the numbers were negative. [3] 4 Computer systems can be affected in various ways which could lead to data corruption. Give two ways that data might be corrupted and suggest a method of protection for each. Corruption 1 Protection method 1 Corruption 2 Protection method 2 [4]

4 © UCLES 2008 0420/01/O/N/08 For Examiner's Use 5 Describe two ways in which computers have affected how music is written and produced. 1 2 [2] 6 A supermarket uses a computer system to control and order stock. All products sold are identified with a bar code which can be read at a Point Of Sale (POS) terminal. (a) Apart from stock control, give one advantage to the supermarket of having bar codes on the products. [1] (b) Give one advantage to the customer of using POS technology. [1] (c) Describe how a computerised stock control system works. [3]

5 © UCLES 2008 0420/01/O/N/08 [Turn over For Examiner's Use 7 Many people now bank through the Internet rather than using banks located in towns. (a) Give one advantage to a bank that offers Internet banking. [1] (b) Give one disadvantage to a bank that offers Internet banking. [1] (c) Give two advantages to customers of using Internet banking. 1 2 [2] (d) Give two disadvantages to customers of using Internet banking. 1 2 [2]

6 © UCLES 2008 0420/01/O/N/08 For Examiner's Use 8 To gain access to a database, a user must first type in a user ID and then a password which needs to be verified. (a) How is a password usually verified? [1] (b) In spite of these safeguards, unauthorised access to the database is still possible. What could be done: (i) to prevent data being used by unauthorised people? [1] (ii) to prevent loss of data once the database has been illegally accessed? [1] (c) Personal data is protected to some extent by a Data Protection Act. Give two requirements of a Data Protection Act. 1 2 [2]

7 © UCLES 2008 0420/01/O/N/08 [Turn over For Examiner's Use 9 Many computer networks use the RING and STAR configurations. Compare the advantages and disadvantages of both types of networks. Include diagrams of the ring and star configurations to help in your discussion. Diagram of ring network Diagram of star network Advantages and disadvantages of star networks Advantages and disadvantages of ring networks [5]

8 © UCLES 2008 0420/01/O/N/08 For Examiner's Use 10 A large city has decided to computerise totally its traffic management system. Traffic lights and electronic road signs are now under automatic computer control. (a) Sensors are placed around the city to gather information about traffic. Describe what information would need to be gathered. [2] (b) Describe two ways the information from the sensors could be sent to the central computer which is located several miles away. 1 2 [2] (c) Give two advantages of having the traffic in the city controlled in this way. 1 2 [2]

9 © UCLES 2008 0420/01/O/N/08 [Turn over For Examiner's Use 11 Mike has decided to send information to Asif by attaching a file to an email. (a) Describe what happens after Mike writes his email, attaches the file and clicks on “send”. [2] (b) Describe two potential problems when sending attachments via emails. 1 2 [2]

10 © UCLES 2008 0420/01/O/N/08 For Examiner's Use 12 (a) A small shop selling books, CDs and DVDs uses a number of spreadsheets to keep track of its stock. One of the spreadsheets showing Sci-Fi stock is shown below. A B C D 1 Sci-Fi Stock 2 Item Code Item Cost ($) Number in stock Stock value ($) 3 15131624 25.00 15 375.00 4 18316925 16.50 10 165.00 5 18560003 30.00 10 300.00 6 12111151 12.50 20 250.00 7 00516344 11.50 20 230.00 8 15821612 17.00 15 255.00 9 10322491 23.50 20 470.00 10 Total Value 2045.00 (i) How many columns are there in the above spreadsheet? [1] (ii) What formula must be in D3 to calculate the stock value of item 15131624? [1] (iii) What formula needs to be placed in cell D10 to calculate the total value of the stock? [1] (iv) Data in B7 was found to be incorrect. The value in this cell was changed to 12.50. Which cells would automatically change when this was done? [1] (b) The owners have decided to sell the shop and all its stock. They will produce a word processed report to advertise the sale. Describe how the owners will create this report which will contain text, data from the stock spreadsheets, pictures of the shop and some of its stock. [3]

11 © UCLES 2008 0420/01/O/N/08 [Turn over For Examiner's Use 13 A large car showroom employs a systems analyst to computerise their existing manual filing systems. (a) Write down four of the stages in Systems Analysis. 1 2 3 4 [4] (b) Describe two effects on the workforce of introducing the new computer system. 1 2 [2] (c) Give two benefits to the car showroom of allowing customers to access details of cars for sale using the Internet. 1 2 [2] 14 Describe three of the stages taken to create an expert system to help in medical diagnosis. 1 2 3 [3]

12 © UCLES 2008 0420/01/O/N/08 For Examiner's Use 15 A database has been produced showing solar system statistics. Name of planet Distance from sun (x106) (km) Number of moons Number of rings Maximum surface temperature (oC) Diameter (km) Mercury 58 0 0 427 4880 Venus 108 0 0 480 12100 Earth 150 1 0 58 12756 Mars 228 2 0 17 6787 Jupiter 778 16 3 -150 143200 Saturn 1427 18 1000 -180 120000 Uranus 2871 15 11 -210 51800 Neptune 4497 8 4 -214 49528 Pluto 5914 1 0 -220 2330 (a) How many records are there in this database? [1] (b) The following search condition was typed in: (Number of moons > 0) AND (Diameter (km) < 15000) Using Name of planet, write down the results of this search: [2] (c) Write down a search condition to find out which planets have rings or have a diameter more than 50000 km. [2] (d) Name a different validation check for each of the following fields. (i) Maximum surface temperature (0C) (ii) Name of planet [2]

13 © UCLES 2008 0420/01/O/N/08 [Turn over For Examiner's Use (e) The data in the database was sorted in descending order using the Number of moons field. Using Name of planet only, write down the results of this sort. [2] 16 (a) What is meant by virtual reality? [1] (b) Describe two special devices that are used for man–machine interaction in virtual reality systems. 1 2 [2] (c) Give two examples of typical output from a virtual reality system. 1 2 [2] (d) Give one example of a use of virtual reality. [1]

14 © UCLES 2008 0420/01/O/N/08 For Examiner's Use 17 The following flowchart shows how sensors (which can be analogue or digital) and a computer are used to control the temperature of a greenhouse for plants. Complete the flowchart using the items from the list below. START STOP Read input temperature from sensor Yes Yes Yes Yes No No No No LIST OF ITEMS 1 compare input temperature with set temperature 2 is input temperature = set temperature 3 is input temperature < set temperature 4 is input temperature > set temperature 5 is input signal analogue 6 output “error” 7 read set temperature from file 8 switch on cooler 9 switch on heater 10 system fault 11 use ADC to convert signal [6]

15 © UCLES 2008 0420/01/O/N/08 [Turn over For Examiner's Use 18 A small library uses a database to monitor books being borrowed. Two of the tables in the database are linked together: • books borrowed by the customers • customer details Each customer has a library card containing a unique customer code. Each book contains a unique bar code. (a) Which data item could link the two tables together? [1] (b) Today’s date is 11 November 2008. Describe how the system would decide automatically which books were overdue and how the customers could be contacted to return the overdue books. [3]

16 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/O/N/08 For Examiner's Use 19 The manufacturing cost of producing an item depends on its complexity. A company manufactures three different types of item, with costs based on the following calculations: Item type 1: item cost = parts cost * 1.5 Item type 2: item cost = parts cost * 2.5 Item type 3: item cost = parts cost * 5.0 The company makes 1000 items per day. Write an algorithm, using pseudocode, flowchart or otherwise, which • inputs the item type and parts cost of each item • outputs the item cost for each item • calculates and outputs the average (mean) item cost per day (based on 1000 items being made). [5]

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS International General Certificate of Secondary Education MARK SCHEME for the October/November 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 October/November 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 – October/November 2008 0420 01 © UCLES 2008 1 Generally, one mark per valid point. Two examples can gain two marks. (a) mouse pointing device/controls cursor input device allows user to select options from a menu used in windows environment uses buttons/scroll wheels(s)/touch pad [2] (b) search engine used on the Internet to locate web sites/web pages/other links based on input of certain key phrases/words [2] (c) buffer temporary memory/storage area compensates for speed differences of device and CPU for data being transferred/downloaded between components of a computer system allows other functions to take place at same time examples printer keyboard [2] (d) RAM random access memory memory that can be read from and written to temporary storage/volatile/memory lost on switching off computer holds user work/programs/data [2] (e) download transfer/copy a file/data/program from a central computer/host computer/server to a smaller computer/remote station/user’s computer [2] 2 Any two from: development time is faster easier to debug easier to modify/update/understand/edit leads to a structured approach can use several programmers to work on individual modules at the same time complex/large problem/task is broken down into simpler/smaller tasks [2]

Page 3 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 3 marks: 1 mark for correct for/to loop 1 mark for BOTH input and output in the correct place 1 mark for finding out how many negative numbers input e.g. for x = 1 to 100 input n if n < 0 then neg = neg + 1 next x print neg [3] 4 Any two from: viruses hacking then changing/deleting data (NOT just hacking) surges in electricity supply loss of electricity supply/power fault in computer/storage device/storage media incorrect shutdown of computer system fault occurs during transmission of data Any two matching above named ways: antivirus software use of passwords (and ids)/firewall anti-surge power supply unit UPS back up data regularly back up data regularly retransmission [4] 5 Any two from: actual musical notes now generated by software digital sampling software can autocorrect notes/rhythm can play back a section straight after written (notes appear on screen) don’t need to understand music notation to write a score instruments play back through electronic effects machines mixers/samplers are computer controlled use of electronic/digital synthesisers electronic keyboards can now simulate any instrument music notes automatically printed out in correct format [2] 6 (a) Any one from: no need to individually price goods/can change prices easily shop assistants at tills don’t need to know prices less chance of fraud (can’t change price by simply altering price tag) fewer staff because of unmanned checkouts [1]

Page 4 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 (b) Any one from: produces an itemised bill permits unmanned checkouts/use of hand held devices whilst shopping (giving a shorter queuing time) less chance of errors in final bill [1] (c) Any three points from: bar code read/scanned/entered by POS item code identified subtracts 1 from number of that item in stock (stock file) when number in stock < minimum stock level ……. …… system automatically re-orders new stock when new stock arrives, number of item in stock is increased printouts of stock levels produced for manager [3] 7 (a) Any one from: fewer cashiers needed/less money on wages fewer branches needed/less money on rates or rent less actual cash handling/fewer chances of robbery can attract more customers (from home and abroad) can offer full banking facilities (may not be possible at smaller branches) [1] (b) Any one from: can lose customers due to lack of personal touch initial outlay on computers/software can be expensive greater risk of fraud/hacking and therefore loss of money need to set up call centres (can be expensive) [1] (c) Any two from: no time wasted travelling to the bank easier/faster to manage accounts no money spent on travelling expenses going to bank no embarrassment asking for loans face to face with a manager possible to still bank even when banks closed/can bank 24/7 don’t have to wait for post/immediate payments can be made disabled people don’t have to travel to a bank less chance of being robbed for cash [2] (d) Any two from: hackers can intercept data/risk of fraud no personal touch customers can easily mis-manage their accounts increase in phone bills without broadband, ties up the phone line increased risk of losing personal data [2]

Page 5 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 8 (a) keyed/typed in twice/compared to stored password [1] (b) (i) encrypt the data [1] (ii) Any one from: read only access back up the files regularly generations of files [1] (c) Any two 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 changes/removed if incorrect safe harbour [2] 9 ring network (1 mark) star network (1 mark) Any other three points from: star: shared resources cable failure isolates/affects only the work station where cable failed if one station/connection fails the other devices are not affected if the central hub breaks down, the whole network fails it is easier to identify faults using this type of topology it is easy to expand this type of network

Page 6 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 ring: shared resources less efficient than star because it needs to travel through all other work stations first to get to destination work station a faulty connection between two stations can cause network failure it is difficult to add a new station/device as it has to come between 2 existing stations this type works well during heavy loading it is possible to create large networks using this topology (NOTE: can get a maximum of 3 marks from advantages/disadvantages if diagrams missing or incorrect) [3] 10 (a) Any two points from: speed of the traffic information from number plates traffic violation information (e.g. jumped red light) number of vehicles on road/at junctions whether vehicles are stationary/moving/timing of vehicles [2] (b) Any two from: (fibre optic)cables connected to computer radio waves/use of transmitters use of satellite/microwave technology [2] (c) Any two from: can keep traffic moving freely….. ….. since system can control light sequences (i.e. timing) and traffic signs helps to prevent traffic build up/jams can reduce pollution levels (less stationary traffic) can re-route traffic using electronic signs if accident has occurred no need to employ/train human traffic controllers [2] 11 (a) Any two points from: local service provider receives Mike’s outbound message the destination email address is analysed service provider looks (service provider) server that handles inbound messages for destination email address email ‘bounced’ with error message if not found message is then sent to destination service provider server Asif logs onto his computer message is downloaded when he opens up his in box Asif opens the attached file [2] (b) Any two from: size of file attachment may be too large/take too long to download potential for sending viruses receiver may not have correct software to read attachment ISP could be down [2]

Page 7 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 12 (a) (i) 4 [1] (ii) = B3 * C3 [1] (iii) = SUM(D3:D9) OR = D3 + D4 + D5 + D6 + D7 + D8 + D9 [1] (iv) D7, D10 [1] (b) Any three points from: save the spreadsheets load images of stock from clipart } max of download images of stock from the internet } 2 marks scan in images/photographs of the shop/stock } for input upload images of shop and stock from a digital camera } of images load up word processor/DTP software type in the required text paste/import/insert picture into document paste/import/insert spreadsheet (data) into document insert/paste charts into document edit the images (e.g. crop, re-size, etc.) format report (e.g. fonts, layout in columns, etc.) [3] 13 (a) Any four from (order doesn’t matter): definition of the problem description of existing situation evaluation of existing solutions consideration of alternative solutions feasibility study/report fact finding/investigation technique…. …..example of technique (questionnaire, interview, document search, observation) objectives of proposed solution/requirements specification [4] (b) Any two from: re-training loss of jobs/entrenchment de-skilling health problems from over-use of computers becomes easier to search for/organise information rather than doing it manually no filing to do [2] (c) Any two from: wider audience less expensive than advertising in the press more information can be made available (e.g. pictures of cars) can do automatic calculations (e.g. monthly re-payments) can have a smaller showroom fewer sales staff needed can allow on-line test drive booking (etc.) [2]

Page 8 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 14 Any three from: gather information from experts/carry out questionnaires create knowledge base put information into the computer create knowledge base create the rules/rule base create/design the inference engine create/design the input-output interface fully test the system with known diagnostic scenarios [3] 15 (a) 9 [1] (b) Earth, Mars, Pluto (-1 for each error/addition/omission) [2] (c) (Number of rings > 0) OR (Diameter (km) > 50 000) < -------- 1 mark -------- > < ----------- 1 mark ------------- > or (Diameter (km) > 50 000) OR (Number of rings > 0) < ---------- 1 mark ---------- > < --------- 1 mark --------- > [2] (d) (i) range check character/type check (ii) character/type check length check NB check in (ii) must be different to check in (i) [2] (e) Saturn, Jupiter, Uranus, Neptune, Mars, Earth, Pluto, Mercury, Venus (any order) (any order) (1 mark for the correct data – ALL data must be correct for the mark) (1 mark for all planets in correct order) [2]

Page 9 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 16 (a) Any one point from: 3D visual world created by a computer computer simulation [1] (b) Any two from: data gloves data goggles/visors special suits fitted with sensors [2] (c) Any two from: 3D output of the surroundings sound effects smells/simulated smells movement [2] (d) Any one from: medical training general teaching investigating problems in nuclear/chemical plants 3D games design (of chemical plants, nuclear plants, bridges, buildings, etc.) virtual tours [1]

Page 10 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 17 [6]

Page 11 Mark Scheme Syllabus Paper IGCSE – October/November 2008 0420 01 © UCLES 2008 18 (a) customer code/borrower number/customer number [1] (b) Any three points from: computer reads record from book file compares date due back ……. ……. 11th November 2008/this date if date due back < November 11th …… ……. using borrower number/customer code/customer number reads corresponding record from borrower/customer file address is read from the record mail merge/email automatically sent to customer/borrower read next file until end of file [3] 19 Marking points correct loop correct inputs check for type and calculate itemcost action taken if type NOT 1, 2 or 3 calculate totalcost calculate the average totalcost both outputs in the correct place Sample algorithm: total cost = 0 for x = 1 to 1000 (1 mark) input type, partcost (1 mark) if type = 1 then itemcost = partcost * 1.5} if type = 2 then itemcost = partcost * 2.5} (1 mark) if type = 3 then itemcost = partcost * 5.0} else print error (1 mark) totalcost = totalcost + itemcost (1 mark) print itemcost next x average = totalcost/1000 (1 mark) print average (1 mark) [5]