TIME: 2 HOURS 30 MINUTES

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1 NATIONAL QUALIFICATIONS 2010 Estimate Examination Paper TIME: 2 HOURS 30 MINUTES COMPUTING HIGHER Attempt all questions in Section I. Attempt all questions in Section II. Attempt one sub-section in Section III Part A Artificial Intelligence Page 9 Questions Part B Computer Networking Page 12 Questions Part C Multimedia Technology Page 16 Questions For the sub-section chosen, attempt all questions. Read all questions carefully. Do not write on the question paper. Write as neatly as possible. The security of this examination paper requires that it is withdrawn from candidates after the examination and also after any discussion of the candidates results. This will ensure that the paper continues to be secure for your centre and others during presentation year 2009/2010. Any appeals made based on this paper will assume that these security precautions are in place Perfect Papers All rights reserved. Page one

2 SECTION I Attempt all questions in this section. 1. A company logo has been created using a painting package. The graphic is stored in a bitmapped graphics format. (a) Explain how bit-mapped graphics are stored. 1 One factor which can affect the quality of the above graphic is the bit depth. Explain what is meant by this term What is the 8 bit two s complement representation of the number A computer has a 24-bit data bus, 32 bit address bus and 16 control lines. (a) The read and write lines are two control lines. Describe the function of one other control line. 1 Calculate the maximum amount of memory that can be addressed by this computer. Show all your working and express your answer in appropriate units Describe how spooling operates as part of the printing process (a) Describe the effect that the use of cache memory would have on system performance. 2 Explain why applications based tests could be described as the best measure of system performance A school intranet allows pupils to have access to the internet through a web server on the intranet. Apart from allowing shared Internet access, state two functions that the web server is likely to provide Name one different type of utility software The software development process can be described as iterative. State what is meant by this term At the end of a swim event, all competitor data is entered into a file. Name a standard algorithm that would be used to find the slowest swimmer in the event Program design should aim to produce software that is reliable and robust. State what is meant by each of these terms. 2 Page two

3 SECTION I (continued) 11. The first stage of the software development process is analysis. Describe two techniques used by software development staff at the analysis stage Programmers can make use of a module library. Each module should be clearly documented describing the parameters required. (a) Describe two reasons why a programmer may use a module library. 2 The parameters may be passed by reference or by value. Describe one difference between passing parameters by reference and by value. 2 Indentation and white space are two factors which make a programs code maintainable. Describe one other factor which increases the maintainability of a program Numeric data can be stored as integer or real numbers. If there is a limited amount of memory available, which data type would be more easily stored? Explain your answer Suggest a suitable set of test data for a program that will be used to convert the number of a month into the name of that month. For example, if 6 was entered the word June would be output. 2 [END OF SECTION 1] (30) Page three

4 SECTION II Attempt all questions in this section. 15. A group of music students have been given the task of creating the programme for the school concert to be held in June. They have been given a digital camera, with a 1GB memory card, to take photographs of the main performers. The camera is set to a bit depth of 24 with resolution of 3500 x 2500 pixels. (a) Calculate the file size of a single image. Your answer should show all working and be expressed in appropriate units. 3 What is the maximum number of images of this size that can be stored on the memory card? 2 State two reasons why digital images are stored as JPEGs. 2 The camera is connected to the computer. Two functions of the operating system that are involved when transferring files are file management and input/output functions. Describe a task that each of these functions would perform in this situation. 2 The music department have recently purchased new photo editing software to allow the pupils to alter the digital images before importing into a desktop publishing program. Before purchasing the software, the department had to ensure that it was compatible with the computer system they had. State two compatibility issues that would have been considered before purchasing new software. 2 (f) The students have decided to backup all their photographs from the hard disk of the computer. A solid-state storage device or rewritable DVD could be used. Recommend one of these devices and give a reason to justify your choice. 1 Page four

5 SECTION II (continued) 16. A family have four standalone desktop computers in their home which they want to connect to form a small local area network. (a) The network could be set up as a peer-to-peer or client-server network. Describe two main differences between these networks. 2 What specific hardware and software will need to be present in the desktop computers in order for them to be connected to the network? 2 The children in the family want to play computer games across the network but they feel that the system performance could be better. Suggest, with reasons, two hardware improvements that could be made to increase performance. 2 A computer connected to the network may be more liable to virus infections than others. Name and describe one class of virus that an anti-virus utility might detect when installed. 2 The family have an ink jet printer that can be connected to a computer using a parallel interface. The printer was inexpensive and has a very small buffer. (i) State one function of an interface. 1 Explain how a larger printer buffer might be an advantage in this scenario The fetch-execute cycle contains a number of stages which result in the execution of an instruction by the processor. (a) Complete the missing steps of the fetch-execute cycle activate the Read line on the Control Bus Decode and execute instruction 3 Clock speed is a measure of computer performance. Explain why clock speed is a potentially unreliable measure of computer performance when comparing different processors. 2 Describe one reason why FLOPS is a more reliable measure of computer performance than clock speed. 1 [Turn over Page five

6 SECTION II (continued) 18. An on-line clothing company requires a piece of software to be developed to store and process customer details and orders efficiently and to record and reorder stock when required. The software development team decide to use a high level language to create the package required. (a) A procedural or event-driven language could be used. Compare the suitability of each type of language for the clothing company s purpose. 4 The programmers use both a compiler and interpreter when developing a software product. (i) Why would an interpreter be used when developing software? 2 Explain in terms of efficiency the difference between using a compiler compared to an interpreter when translating the pseudocode below. 1. loop 100 times 2. ask for customer ID 3. store ID in array 4. end loop Your answer should mention both memory usage and processor time for each type of translator. 2 Customers are given a unique ID number when the register with the clothing company. Customer ID s are created using the first 3 letters of the customers surname and the last 3 letters of their postcode. This ID is stored in a 1-D array. For example: Mr J Brown with a postcode of EH15 6NW has a customer ID of BRO6NW (i) What is meant by a 1-D array? 2 (iii) Using code from a programming environment with which you are familiar, show how to create this ID. 3 Using a design notation with which you are familiar, write an algorithm that would find a particular customer ID from the array. 4 Explain why a programmer might want to limit the scope of a variable. 2 A section of code from the system is shown below: Reorder = calculate_reorder(stock_number, reorder_level) Which feature of a high level has been implemented as calculate_reorder? 1 Page six

7 SECTION II (continued) 19. A software house has been approached by a client and asked to create a program which will construct detailed reports for its customers. (a) The software house appoints a project manager. Describe two aspects of the role of the project manager. 2 Name and describe a document that the systems analyst will produce as a result of the analysis stage of the project. 2 The testing stage involves both the software house and the client. Explain why both parties are required at this stage. 2 The software is tested using a comprehensive set of test data. State two other methods of testing comprehensively. 2 After the reporting software has been in place for a couple of weeks the client asks the software house to carry out adaptive maintenance. (i) Describe one situation where the program may require adaptive maintenance. 1 Who is most likely to meet the cost of the adaptive maintenance? Justify your answer. 2 (60) [END OF SECTION II] [Turn over Page seven

8 SECTION III Attempt ONE sub-section of Section III Part A Artificial Intelligence Page 9 Questions Part B Computer Networking Page 12 Questions Part C Multimedia Technology Page 16 Questions For the sub-section chosen, attempt all questions. Page eight

9 SECTION III Part A Artificial Intelligence Attempt all questions. 20. An ornithology group want to create an expert system about birds to help quick identification. Here is some information that they would like included in the knowledge base. Birds are warm-blooded vertebrate animals that lay eggs. Birds can be grouped into those that fly and those that cannot. Examples of birds that cannot fly are the Cassowary, Emu and Penguin. Flying birds include the House Wren and Kingfisher. The House Wren is approximately 12cm in size and a dark brown colour who prefer to be located near human houses. The Kingfisher has a bright blue back and tail and is around 17cm in length. They are often located near water. (a) Create a semantic net to display the information given above. 6 Describe two advantages of using an expert system to identify birds. 2 Knowledge bases can be searched using either a depth-first or breadth-first search algorithm. (i) Describe what is meant by each of these search methods. You may use a diagram to illustrate your answer. 2 Explain why depth first would be more efficient than breadth first in the searching of large trees. 2 The developed bird identification expert system includes justification of reasoning. (i) Explain what justification facilities do. 2 Explain why these facilities are useful for users of the system. 2 (iii) Explain how heuristics could be used in this system. 2 The birds system could be implemented using a functional programming language. Name a functional language. 1 [Turn over Page nine

10 SECTION III Part A Artificial Intelligence (Continued) 21. GardenGlory are a company that produce garden ornaments made out of metal. The company are investigating the use of an intelligent robot to examine ornaments that have been identified as imperfect on the production line. Slight damage could be fixed while badly damaged ornaments would have to be scraped. Two areas of artificial intelligence are computer vision and pattern recognition. (a) How would pattern matching be used to identify a slightly damaged ornament? 2 Describe one problem that could occur when computer vision is used to select ornaments to fix. 2 Hardware developments have allowed these areas of AI research to become more successful over the last 20 years. Describe one such hardware development and explain how it has contributed to the success of vision systems Some of the earliest research into the field of artificial intelligence relates to rule-based systems for playing strategic games. Early computers were programmed to play games such as noughts and crosses. (a) Describe two difficulties in developing a rule-based system for playing chess. 2 Give one reason why a human player may not be able to decide whether they were playing against a computer opponent or another human. 2 Simple rule-based systems are not really classed as being intelligent. Describe a feature of such a system that, if included, would justify it being considered intelligent. 2 A rule-based system could be implemented using a procedural language or a declarative language. Describe one advantage and one disadvantage of choosing a declarative language as a development environment. 2 It would be an advantage if a computer game could recognise and respond to various commands spoken by the player. In speech recognition software, there are four main stages of natural language processing. (i) Speech recognition is the first stage of NLP. State the next two stages of NLP. 2 Describe two difficulties, related to voice recognition, which would need to be overcome in a successful implementation of NLP in a game playing environment. 2 Page ten

11 SECTION III - Part A Artificial Intelligence (continued) 23. The Kennel Club have created a knowledge base to describe breeds of dog. An extract from this knowledge base is shown below. 1 type(pointer, gundog). A pointer is a type of gundog. 2 type(flushing, gundog). 3 type(retriever, gundog). 4 is_a(labrador,retriever). A labrador is an example of a retrieving dog. 5 is_a(newfoundland,retriever). 6 is_a(cocker_spaniel,flushing). 7 is_a(springer_spaniel,flushing ). 8 is_a(king_charles,flushing). 9 is_a(english_setter,pointer). 9 is_a(irish_setter,pointer). 10 fav_game(pointer,grouse). The favourite game bird of a pointing dog is grouse. 11 fav_game(flushing,pheasant). 12 fav_game(retriever,waterfowl). 13 type(x,y):- is_a(x,z), X is type Y if type(z,y). X is classed as Z and Z is type Y. (a) What would be the output from the following query??fav_game(pointer,x). 1 (i) What would be the solution(s) to the following query? 1? is_a(x,flushing). Assuming that a depth-first search is used, trace the first solution to the query:? type(springer_spaniel,x). You must include the correct use of each of the following words in your trace. sub-goal and instantiation (or instantiated). 4 (i) What is the solution to the query?? NOT(is_a(labrador, pointer). 1 Explain how the program arrived at this solution. 1 (i) Line 13 makes use of inheritance. Describe what inheritance means in this context. 2 Create a new inheritance rule to allow the following question to be answered. What is the favourite game bird of an Irish Setter? 2 (50) Page eleven

12 SECTION III Part B Computer Networking Attempt all questions. 24. The ScotBank has three offices each office is connected to the company network as detailed in this diagram. (a) (i) State the class of the ScotBank network. Justify your answer. 2 Certain IP addresses are reserved. Give one example of a reserved IP address and state its purpose. 2 (iii) What is the maximum number of nodes which can be added to this network? Justify your answer. 3 Channel A connects the Glasgow office to the Aberdeen office. Which type of connection would provide a suitable secure high speed link between the two offices? 1 Page twelve

13 24. (continued) SECTION III - Part B Computer Networking (Continued) Bank records are regularly uploaded from the Inverness office to the Glasgow office. (i) Name the protocol that would be used to upload files to the Glasgow office. 1 Paul is working from home and tries to upload some data to the Glasgow office from his home computer but the upload is blocked by the firewall. Explain how the firewall may have blocked this upload. 2 When Paul gets to the Inverness office he uploads some data to the Glasgow office but the message Error: Bad CRC... resend data appears on his computer screen. (i) Explain, in detail, why this message has been displayed. 3 Describe one possible cause of this error. 1 TCP/IP is used for communication between offices and stations on the network. (i) Describe two operations carried out by TCP. 2 Describe one operation carried out by IP. 1 (f) The offices are connected by switches. Explain why a switch would be considered more secure than a hub? 2 (g) Hackers have somehow gained unauthorised access to the computer systems in the Glasgow office. Give one reason why the staff are concerned about data integrity as a result of this unauthorised access? 1 [Turn over Page thirteen

14 SECTION III - Part B Computer Networking (Continued) 25. Webster online is a web site which sells CDs, DVDs and other entertainment related goods. (a) Every page of the website includes the following HTML code: <meta name= description content= Webster specialise in CDs, DVDs, Games and other entertainment media at bargain prices. Always a good deal at Webster. > What is the purpose of this code? 1 The webmaster for Webster looks at the log of visits to the site and finds that on IP address visits many times each day. A sample from the web site visitors log for this IP address is show below: Time of visit IP Browser Message 04:36: YouSearchBot 200 OK (i) What kind of program is generating these log entries? 1 Describe how this program uses the line of code in part (a) above? 2 An is received from a customer who claims that the Webster site is blocked by her ISP. (i) Describe two reasons why a site which was not intended to be blocked may be blocked by Internet filtering software. 2 The ISP uses a walled garden system. What would have to be done to allow access to the Webster site? 1 Meta Search Engines always provide better search results Do you agree with this statement? Justify your answer. 2 Webster use both disaster avoidance and disaster recover strategies to protect their server. (i) Describe two disaster avoidance techniques with which you are familiar. 2 Regular backups of the server are part of the disaster recovery strategy. Describe how mirror disks can be used to back up the Webster server. 2 Page fourteen

15 SECTION III - Part B Computer Networking (Continued) 26. ParentHelper is a child tracking and locating system which parents can use. It consists of a GPS receiver which links to a mobile transmitter. (a) The GPS receiver is connected to the transmitter using wireless technology to form a wireless personal area network (WPAN). (i) The manufacturer of ParentHelper would like to add additional functions to the system by allowing other devices to connect to the WPAN. Suggest two additional devices which could make use of the WPAN. 2 For each of your chosen devices, describe how it could be used as part of the WPAN? 2 Each device on the WPAN has a MAC Address. (i) What does MAC stand for? 1 Explain why it is necessary for a device on the network to have a MAC address? 1 Parents can receive updates on their child s location via WAP, via HTTP or sent in an encrypted . (i) (iii) Give two advantages of using WAP rather than HTTP for viewing information on a mobile device? 2 Describe two differences between web pages created using WML tags and web pages created using HTML tags. 2 State the law which makes it a legal requirement to make an encrypted readable if instructed to by the police. 1 A VoIP (Voice over IP) service is added to the ParentHelper transmitter. This allows parents to listen to their child. VoIP data is sent over a packet-switched network. (i) (iii) Some parents complain that the audio they receive stutters or has sections missing. Describe why the packet switched network may be causing this problem. 2 Describe one advantage of a circuit-switched network over a packet-switched network. 1 Which type of maintenance would be required to fix the problem with the VoIP service described above? 1 The ParentHelper transmitter saves data to a solid state storage device when no connection available to transmit. Identify one reason why a solid state device is used rather than any other storage device. 1 [END OF SECTION III PART B] (50) Page fifteen

16 SECTION III Part C Multimedia Technology Attempt all questions. 27. David is developing a website for his local church. He must decide whether to use a WYSIWYG editor or a text editor. (a) Recommend the type of software that he should use, giving two clear reasons for your choice. 2 David creates the logo shown using vector graphics software and saves it using the SVG file format. Describe two advantages of using SVG rather than GIF to store this logo. 2 The Youth section of the website contains video footage of a recent camping trip. (i) The clip lasts for 30 seconds and was captured using the following settings: 25 frames per second 160 x 120 pixels true colour Calculate the uncompressed file size of the video clip. Show all working and express your answer in appropriate units. 3 Describe the term bit-rate as it refers to video data. 1 (iii) Explain the role of DSP during playback of video data. 1 The website contains the following images: Image 1 Image 2 Image 1 above is stored as an interlaced GIF. (i) Explain how Image 1 would be displayed by browser software. 2 Give one advantage of interlacing images in this way. 1 Image 2 above is compressed using RLE. Describe how RLE compression reduces the file size of Image 2. 2 (f) Background music for the website is saved as MIDI data. (i) Describe the purpose of the pitch and tempo attributes of MIDI data. 2 Give one disadvantage of using MIDI data to store the background music. 1 (g) Before the website is made live, systematic testing must be carried out. State two ways in which the website should be tested. 2 Page sixteen

17 SECTION III - Part C Multimedia Technology (Continued) 28. Laura is creating a multimedia application to teach primary pupils about animals and their habitats. (a) The application will include a number of 2D graphical images. Describe one task carried out by the GPU when displaying 2D images. 1 Laura decides to embed the images within the application rather than create links to the images. (i) Explain what is meant by the term 'embed'. 1 Describe one benefit of this decision. 1 An image of a parrot is used in the application. The image is stored using indexed colour. The image and its matching colour palette are shown below: (i) Name one file format that makes use of indexed colour. 1 Explain how the use of indexed colour is a more efficient way of storing colour information than RGB. 2 (iii) Explain the need for dithering with indexed colour images. 2 The application includes several voice recordings. The recordings are captured in stereo at 44.1 KHz using 16-bit sound. (i) Calculate the uncompressed file size of a recording that lasts for 45 seconds. Show all working and express your answer in appropriate units. 3 The voice recordings are stored as RIFF files. RIFF is an example of a container file. Explain what is meant by the term 'container file'. 1 (iii) After capturing, Laura used sound editing software to adjust the voice recordings. Original recording After adjustment Name the feature of the sound editing software used to make this adjustment and explain how this feature improves playback of the recordings. 2 [Turn over Page seventeen

18 SECTION III - Part C Multimedia Technology (Continued) 29. Pranav is developing a VR simulation that will be used to train helicopter pilots. (a) VRML is used to produce the 3D graphics that form part of the simulation. Describe two features of VRML that make it an appropriate choice of file format for a training simulation. 2 The following VRML code is used to create a 3D object that is part of the simulation: #VRML V1.0 ascii Texture2 { filename "metallic.jpg"} Cube { width 1 height 2 depth 0.15 } Translation { translation } Rotation { rotation } Identify three attributes of the 3D object that are described by this code. 1 The simulation makes use of surround sound. (i) Explain what is meant by the term surround sound. 1 Explain one benefit of using surround sound in this situation. 1 Page eighteen

19 SECTION III - Part C Multimedia Technology (Continued) 30. Graeme uses his mobile phone to capture a video clip at a Give This concert. He later uses the video editing software on his mobile phone to arrange multiple clips on the timeline. mmm/.jm ;ol (a) Describe the use made of the timeline feature of video editing software. 1 Graeme decides to improve how the individual clips are linked together. Name one feature of video editing software that could be used for this purpose. 1 The video sequence is saved using the MPEG codec. (i) Explain the need to use a codec in this situation. 1 Describe one feature of the MPEG codec. 1 Graeme can transfer the video sequence to his laptop using either WiFi or Bluetooth connectivity. (i) Give one advantage of using WiFi over Bluetooth for this purpose. 1 Give one advantage of using Bluetooth over WiFi for this purpose. 1 Graeme can use his mobile phone to watch live TV and listen to Internet radio. Each of these will be played using streaming. (i) Explain what is meant by the term 'streaming'. 2 The ability of the mobile phone to cope with the demands of streaming will depend on the technological features of the device. (1) Explain how the development of storage technologies will benefit the performance of the mobile phone when streaming data. 2 (2) Name one development in the area of communications and explain how it benefits the performance of the mobile phone when streaming data. 2 (50) [END OF SECTION III PART C] [END OF QUESTION PAPER] Page nineteen

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