UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level

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1 UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level * * COMPUTING 9691/21 Paper 2 October/November hours 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 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 This document consists of 14 printed pages and 2 blank pages IB13 11_9691_21/3RP UCLES 2013 [Turn over

2 2 BLANK PAGE UCLES /21/O/N/13

3 3 1 The Computing Department has a problem keeping track of its teaching resources Juan, a student, has been asked to design and program a solution as his computing project It will be the first large problem he has worked on He intends to write one large program that follows the process right through His teacher tells him to break the problem into smaller parts (a) State and justify three of the reasons his teacher could give him for breaking the problem into smaller parts Reason 1 Reason 2 Reason 3 [6] UCLES /21/O/N/13 [Turn over

4 4 Juan decides that the design will include the following modules: update the resource file when a new teaching resource is purchased o input all the data about the resource o generate a resource ID for the resource o store in the resource file update the resource file when a current resource is discarded (b) (i) Describe one diagrammatic method for showing how these modules are related [2] (ii) your method with the modules above [2] UCLES /21/O/N/13

5 5 (c) Name two features of a high-level programming language that help with this modular approach 1 2 [2] (d) Juan realises that he will have to pass data from one module to another Explain how this is done [2] UCLES /21/O/N/13 [Turn over

6 6 (e) Juan will need the program to hold large amounts of data His design will include reading the data from the sequentially-organised resource file into several arrays Describe three differences between the features of an array and a sequential file [6] (f) Juan wants to use an array, NumberOfCopies to store whole numbers In a high-level programming language: declare the array of size 5000 initialise the array to 0 Programming language Code [4] UCLES /21/O/N/13

7 7 2 (a) Juan has little programming experience, but has to write code for this program He has written the following pseudocode statements each statement describe what is wrong and write a correct version (i) IF Index > 5000 OR < 0 THEN OUTPUT "Error" Description Correct statement [2] (ii) NumberOfCopies[Index] + 1 NumberOfCopies[Index] Description Correct statement [2] (iii) NumberOfCopies[Index] "three" Description Correct statement [2] UCLES /21/O/N/13 [Turn over

8 8 (b) Juan needs to design the code for a part of the program that determines where resources are kept If the resource has: an ID less than 1001 it will be kept in Cabinet 1 an ID between 1001 and 3000 it will be kept in Cabinet 2 o even numbered IDs in Drawer 1 o odd numbered IDs in Drawer 2 an ID between 3001 and 5000 it will be kept in Cabinet 3 Write pseudocode that processes the variable ResourceID and outputs where the resource is kept nested IF statements [6] UCLES /21/O/N/13

9 9 (c) In a high-level programming language write code that processes the variable ResourceID and outputs where the resource is kept a CASE/SELECT statement Programming language Code UCLES /21/O/N/13 [Turn over [6]

10 10 3 (a) An interface is to be designed to add a new resource The user must: enter the name of the resource choose the type of the resource select the purchase date The program generates and displays: a new resource ID where the resource is kept The user must be able to save the data, clear/cancel the input, and move on to entering another resource Design a graphical user interface (GUI) Pay particular attention to layout and effective use of the controls you would expect to find in a GUI Add new resource(s) [6] UCLES /21/O/N/13

11 11 (b) A report will show all the items that have been entered on a particular day It will show each resource ID and where the resource is kept The resources will be grouped by type Design the report layout [5] UCLES /21/O/N/13 [Turn over

12 12 An array, MyResource, size 5000, data type INTEGER, is used to store the resource IDs An array, KeptIn, size 5000, data type STRING, is used to store where a resource is kept A resource with resource ID MyResource[X] is kept at KeptIn[X], where X is an integer variable 1 2 X MyResource KeptIn X Cabinet2 Drawer Juan writes the pseudocode that searches MyResource for a given resource ID and outputs where the resource is kept flag 0 INPUT P FOR X 1 TO 5000 IF myresource[x] = P THEN OUTPUT keptin[x] flag 1 ENDIF NEXT IF flag = 0 THEN OUTPUT "Not Found" ENDIF UCLES /21/O/N/13

13 13 (c) Give four techniques that should have been applied to the pseudocode to make it easier to understand [4] (d) Re-write the pseudocode using a REPEAT UNTIL loop Make use of the techniques you gave in (c) to produce self-documented code [6] UCLES /21/O/N/13 [Turn over

14 14 (e) (i) If Juan were to perform a dry run on the pseudocode using a trace table, state one type of error he might find Give an example Type 1 Example State another type of error he might find later Give an example Type 2 Example [4] (ii) Juan has written his program and one module appears not to work Explain how Juan can use a break point and stepping to debug his program [3] UCLES /21/O/N/13

15 15 4 Juan is also learning about recursion He writes the pseudocode for a recursive function 1 FUNCTION Add(N) 2 DECLARE R 3 IF N <= 0 4 THEN 5 R 0 6 ELSE 7 R N + Add(N 1) 8 ENDIF 9 RETURN R 10 ENDFUNCTION (a) What is the scope of the variable R? [1] (b) State the line number which shows that this function is recursive [1] (c) List the function calls that are generated by an initial call of Add(3) [3] UCLES /21/O/N/13

16 16 BLANK PAGE 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 UCLES /21/O/N/13

17 UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level * * COMPUTING 9691/22 Paper 2 October/November hours 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 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 This document consists of 14 printed pages and 2 blank pages IB13 11_9691_22/3RP UCLES 2013 [Turn over

18 2 1 Jemma is designing a program that will work out the end of year bonuses for her employees The main steps are: input employee's data calculate the bonus calculate deductions o tax o optional contribution to charity print out the bonus (a) Draw a structure diagram to show the modules that will be needed [3] UCLES /22/O/N/13

19 3 (b) Each module is programmed by Jemma Describe three program coding techniques she should use to help Freddie who will maintain the code Technique 1 Technique 2 Technique 3 [6] UCLES /22/O/N/13 [Turn over

20 4 (c) (i) Jemma is using the variable Percentage in one module and a different variable called Percentage in another module Explain the feature of a high-level programming language that avoids any possible conflict [2] (ii) Some modules require data values that originate from another module Explain the feature of a high-level programming language that enables this [2] UCLES /22/O/N/13

21 5 (d) Jemma is designing a range validation check for the input of an employee s pay The pay range depends on the employee s job type, which may be P(part-time), F(full-time) or C(commission only) A part-time employee will earn between $100 and $ a year A full-time employee will earn between $5 000 and $ a year A commission only employee will earn between $0 and $ a year Complete the table showing five more rows of test data Give a different reason for each, describing what is being tested Job type Pay Reason F Normal data within pay range for full-time [5] UCLES /22/O/N/13 [Turn over

22 6 2 James plans to store the titles and authors of his favourite ebooks in an array He has 56 ebooks at the moment and expects to reach 150 A two-dimensional array MyEbooks is to be used (a) In a high-level programming language, write the array declaration statement Programming language Declaration [3] (b) (i) Why is it good programming practice to initialise the array MyEbooks? [1] (ii) Write program code to initialise the array MyEbooks Programming language Code [3] (c) At present when the program terminates all the ebook data are lost How can these data be stored and made available every time the program is run? [3] UCLES /22/O/N/13

23 7 (d) James friend, Jatinder, uses his idea, but decides to store more information about each of her ebooks Complete the following table a single numerical value for Field size Identifier Description Data type Field size (Bytes) EbookID a unique ebook ID, a whole number between 1 and 500 BookTitle the title of the ebook STRING Author DateBought Cost Fiction the author of the ebook date bought price paid fiction or non-fiction [8] UCLES /22/O/N/13 [Turn over

24 8 3 Aisha wants to write a program that checks the password to her personal computer The program should check each attempt to enter the password correctly and should terminate after three wrong attempts She wants the log-in screen to display: a prompt to enter the password space to enter the password how many attempts have been made if the log-in has been successful or not a means of cancelling the log-in process (a) Draw a suitable layout for the screen Aisha s log-in screen [5] Aisha writes her first try at designing the code in pseudocode She wants the password to be "Aisha", her name 1 Attempt 0 2 REPEAT 3 INPUT Password 4 Attempt Attempt UNTIL (Password = "Aisha") OR (Attempt > 3) 6 IF Password = "Aisha" 7 THEN 8 OUTPUT "Password correct" 9 ELSE 10 OUTPUT "No valid password entered" 11 ENDIF UCLES /22/O/N/13

25 9 (b) (i) Complete the trace table using "Aisha" as input Attempt 0 Password Aisha Password = "Aisha" Attempt > 3 Password = "Aisha" OR Attempt > 3 Output [3] (ii) Complete the trace table using the following sequence of inputs: "aisha", "Asha", "AISHA" Attempt Password Password = "Aisha" Attempt > 3 Password = "Aisha" OR Attempt > 3 Output 0 UCLES /22/O/N/13 [Turn over [5]

26 10 (c) This piece of code does not do what Aisha intended There is an error (i) State the type of error [1] (ii) There are several ways to correct this One is to change line 5 Rewrite line 5 [1] (d) State why someone s name is not a good password [1] (e) Describe how to choose a more secure password [2] UCLES /22/O/N/13

27 11 BLANK PAGE Question 3 continues on page 12 UCLES /22/O/N/13 [Turn over

28 12 (f) Having entered a correct password, Aisha wants to present a menu screen The user is to enter a number between 1 and 4 to make a choice Option 1 - Option 2 - social network Option 3 - schoolwork Option 4 - favourite websites The number entered is to be stored in a variable, Choice Each option calls an appropriate procedure (i) Write program code which inputs the user s choice, validates this choice, uses nested IF statements to call the appropriate procedure Programming language Code [6] UCLES /22/O/N/13

29 13 (ii) Rewrite your IF statements using a CASE/SELECT statement to implement the menu options [4] UCLES /22/O/N/13 [Turn over

30 14 4 Aisha writes the following pseudocode for a recursive function that works out the greatest common divisor of two positive integers: 0 FUNCTION Divisor(x, y) 1 IF y = 0 2 THEN 3 RETURN x 4 ELSE 5 x x MOD y 6 RETURN Divisor(y, x) 7 ENDIF 8 ENDFUNCTION (a) (i) Trace the call Divisor(8, 2) Line number x y RETURN [2] (ii) Trace the call Divisor(38, 7) Line number x y RETURN [4] UCLES /22/O/N/13

31 15 (b) (i) State the purpose of line 1 [1] (ii) State what would happen if line 1 were not present [1] (c) What happens if x is less than y? [3] UCLES /22/O/N/13

32 16 BLANK PAGE 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 UCLES /22/O/N/13

33 UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level * * COMPUTING 9691/23 Paper 2 October/November hours 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 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 This document consists of 16 printed pages and 4 blank pages IB13 11_9691_23/4RP UCLES 2013 [Turn over

34 2 1 The Science Department has a problem keeping track of its equipment Ashvin has been asked to design and program a solution as his Computing Project (a) Ashvin has little programming experience, but has to write code for this program He starts by writing some pseudocode each statement, describe what is wrong and write a correct version (i) NoOfBalances + 1 NoOfBalances Description Correct statement [2] (ii) IF NoOfPipettes > NoOfBeakers OR < NoOfBottles THEN OUTPUT Check the numbers Description Correct statement (iii) Explain why it is considered bad practice to start a project by writing program code [2] [1] UCLES /23/O/N/13

35 3 (b) This project was the largest computing problem Ashvin had worked on His friends wrongly advised him to program a solution as a whole He decided to break the problem into smaller parts State and justify three of the reasons Ashvin gave his friends for breaking the problem into smaller parts Reason 1 Reason 2 Reason 3 [6] UCLES /23/O/N/13 [Turn over

36 4 Ashvin decides the design will include the following modules: Update the equipment file when new equipment is bought o Generate an equipment ID for an item of science equipment o Input all the data about the piece of equipment Update the equipment file when old equipment is discarded (c) (i) Describe how a structure diagram will help Ashvin [2] (ii) Draw a structure diagram for the above modules [2] UCLES /23/O/N/13

37 5 (d) Ashvin splits the first alternative module (Generate an equipment ID for an item of science equipment) into two smaller modules: Generate an equipment ID for an item of science equipment Store the item record in the resource file Re-draw your diagram adding the two new modules [2] (e) The module that stores all the equipment data needs to receive a data value produced in another module (i) What data value is this? (ii) Explain how this is done [1] UCLES /23/O/N/13 [Turn over [2]

38 6 2 (a) (i) Explain how individual letters are represented inside a computer system (ii) How does the computer system use this representation to put lower case letters into alphabetical order? [2] [1] UCLES /23/O/N/13

39 7 (b) Part of Ashvin s program will involve comparing equipment names, such as cable and capacitor The flowchart outputs the two words in alphabetical order Complete the flowchart using the statements in the box below START INPUT Word1, Word2 1 OUTPUT Word1, Word2 2 OUTPUT Word2, Word1 3 Index Index Index 1 5 Word1[Index] < Word2[Index]? 6 Length(Word1) < Index? Word1[Index] = Word2[Index]? No No Yes Yes Yes No Length(Word2) < Index? Yes OUTPUT Word2, Word1 No STOP [6] UCLES /23/O/N/13 [Turn over

40 8 (c) Ashvin will use an array Equipment to hold equipment names In a high-level programming language: declare the array of size 500 initialise the array Programming language Code [4] UCLES /23/O/N/13

41 9 (d) Ashvin needs to design the code for a part of the program that decides where equipment is kept If the item has an ID less than 2000 it will be kept in the Physics Laboratory If the item has an ID between 2001 and 4000 it will be kept in the Biology Laboratory If the item has an ID between 4001 and 8000 it will be kept in the Chemistry Laboratory o If the item has an ID ending in a zero it will have to be kept in a locked cabinet Write pseudocode that processes the variable EquipID and outputs where the equipment is kept, using nested IF statements [6] UCLES /23/O/N/13 [Turn over

42 10 (e) In a high-level programming language write code that carries out the selections using a CASE/SELECT statement Programming language Code [5] UCLES /23/O/N/13

43 11 BLANK PAGE Question 3 begins on page 12 UCLES /23/O/N/13 [Turn over

44 12 3 (a) An interface is to be designed to add a new piece of equipment The user will: enter the name of the equipment choose the science subject it will be used in if Chemistry, indicate if secure storage is necessary select the purchase date The program generates and displays: a new equipment ID where the equipment is to be kept The user must be able to save the data, clear/cancel the input, and move on to entering another piece of equipment Design a graphical user interface (GUI) Pay particular attention to layout and effective use of the controls you would expect to find in a GUI Add new equipment [6] UCLES /23/O/N/13

45 13 (b) A report will show all the items that have been entered on a particular day It will show each equipment ID and where the equipment is kept Equipment for the same science subject will be grouped together Design the report layout [5] UCLES /23/O/N/13 [Turn over

46 14 An array, Catalog, size 8 000, data type INTEGER, is used to store the equipment IDs An array, KeptIn, size 8 000, data type STRING, is used to store where a piece of equipment is kept A piece of equipment with equipment ID Catalog[X] is kept at KeptIn[X] where X is an integer variable 1 2 X Catalog KeptIn X Chem Lab - Locked Ashvin writes the pseudocode that searches Catalog for a given equipment ID The output is to be where the piece of equipment is kept flag 0 INPUT P FOR X 1 TO IF catalog[x] = P THEN OUTPUT keptin[x] flag 1 ENDIF NEXT IF flag = 0 THEN OUTPUT Not Found ENDIF UCLES /23/O/N/13

47 15 (c) Give four techniques that should have been applied to the pseudocode to make it easier to understand [4] (d) Re-write the pseudocode using a REPEAT UNTIL loop Make use of the techniques you used in your answer to part (c) [6] UCLES /23/O/N/13 [Turn over

48 16 (e) Ashvin will perform dry runs on the pseudocode using a trace table and a variety of test data He hopes to find any logic errors and avoid run-time errors occurring later (i) State what is meant by a logic error and give an example Logic error Example [2] (ii) State what is meant by a run-time error and give an example Run-time error Example [2] UCLES /23/O/N/13

49 17 4 Ashvin is also learning about recursion He writes the pseudocode for a recursive function 1 FUNCTION Calc(X) 2 DECLARE Temp 3 IF X > 0 4 THEN 5 Temp X + Calc(X 2) 6 ELSE 7 Temp 0 8 ENDIF 9 RETURN Temp 10 ENDFUNCTION (a) What is the scope of the variable Temp? [1] (b) State the line number which shows that this function is recursive [1] (c) List the function calls that are generated by an initial call Calc(5) [3] (d) What will be returned by the call Calc(6)? [1] UCLES /23/O/N/13

50 18 BLANK PAGE UCLES /23/O/N/13

51 19 BLANK PAGE UCLES /23/O/N/13

52 20 BLANK PAGE 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 UCLES /23/O/N/13

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level

*1718852929* UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education Advanced Subsidiary Level and Advanced Level COMPUTING 9691/22 Paper 2 October/November 2013 2 hours Candidates