MOCK GCE EXAMINATION

Transcription

1 Ministry of Secondary Education Progressive Comprehensive High School PCHS Mankon Bamenda Department of Computer Studies Republic of Cameroon Peace Work Fatherland School Year 2013/2014 MOCK GCE EXAMINATION April 2014 Subject Title Computer Science Paper N Paper 3 Practical Subject Code N 795 ADVANCED LEVEL Examiner: DZEUGANG Placide Time allowed: Three hours Carry out ALL the tasks given. For your guidance, the approximate mark for each part of a task is indicated in brackets. Great importance is attached to the accuracy, layout and labelling of diagram and computer-generated outputs. You are reminded of the necessity for good English and orderly presentation of your answers. Record in the booklet provided any information requested or that you believe would make it easier to understand how you carried out task and answered questions Where an imperative programming language is required to write program code, Only C programming language should be used. If need be, supervisors will assist you in recording details of intermediate work carried out on the computer More questions and Lesson notes in Computer Science on Page 1 of 6

2 INSTRUCTIONS A candidate folder is available for you on the desktop with the name MockApril2014CandidateFolder You should rename it with your name. It contains one file: allocation.c useful for TaskB. All of your files should be saved in your folder. Only the extension.c is accepted for any c program file,.docx for any word processor document and.xlsx for any spreadsheet file. Exercise 1: (Programming Applied to Memory Management) Instructions for exercise: Analyze the problem in your booklet. Also record inside any other information requested, or that you believe would make it easier to understand the exercise you have carried out. Save all your work carried out on the computer in your candidate folder. Carry out the instructions/tasks below in order to write and/or modify a program that allocates memory partitions to processes using the algorithms described below. The real challenge of efficiently managing memory is seen in the case of a system which has multiple processes running at the same time. Since primary memory can be space-multiplexed, the memory manager can allocate a portion of primary memory to each process for its own use. However, the memory manager must keep track of which processes are running in which memory locations, and it must also determine how to allocate and deallocate available memory when new processes are created and when old processes complete execution. While various different strategies are used to allocate space to processes competing for memory, three of the most popular are Best fit, Worst fit, and First fit. Each of these strategies are described below Best fit: The allocator places a process in the smallest block of unallocated memory in which it will fit. Worst fit: The memory manager places a process in the largest block of unallocated memory available. First fit: The operating system, begins at the start of primary memory and allocates memory from the first hole it encounters large enough to satisfy the request. More questions and Lesson notes in Computer Science on Page 2 of 6

3 TASK A [10 marks] In order to develop the program, we consider the main memory as divided into fixe partitions of different lengths. 1. Given memory partitions of 100K, 500K, 200K, 300K, and 600K (in order), how would each of the First-fit, Best-fit, and Worst-fit algorithms place processes of 212K, 417K, 112K, and 426K (in order)? Draw a chart in each case. (6 mks) 2. Which algorithm makes the most efficient use of memory? (2 mks) TASK B: [40 marks] 1- The code in your candidate folder implements one of the above algorithms for one process. Open it, make sure that the code is similar as the one in appendix 5, run it using the following input in order: 5, 50, 200, 70, 115, 15 and 60. Print a copy of your output (4 mks) 2- Which among the three algorithms stated is implemented by the code in the program?(2 mks) 3- The three above mentioned algorithms are represented in appendix 1 in pseudocode and the following variables and/or data structures where used: n: integer number of partitions blocksize: integer size of each partition in Kb blocknb: integer index of the chosen partition size[max]: array of available partitions rem[max]: array of remaining partition sizes after subtracting the size of the arriving block a) Convert each algorithm into a C function to be saved in a header file named header.h. (9 mks) b) Write a main program named TaskB1 that makes use of the header file in question 3.a) to implement the three algorithms. An appropriate menu should enable the user to choose which algorithm to use during the execution. (10 mks) c) Run your program using the inputs in question 1) and print out a copy of the output (3mks) 4- Modify the above program once more so that it can be used to allocate space to more than one algorithm as it is the case in TaskA. Save the program as TaskB2. Run it using the input given in TaskA and print a copy of the output. (12 mks) Exercise 2: (Data analysis using Spreadsheet and programming) TASK C: [20 marks] 1. Prepare your worksheet as shown in appendix 2: (3 mks) 2. Adjust the column widths when necessary. Perform the following: a. Use the flowchart in appendix 3 to calculate the commission in cell D4. The commission is based upon the salesperson's sales. (2 mks) b. Using the formula below, calculate the Total Salary in column D. Total Salary = Salary + Commission. (1mk) More questions and Lesson notes in Computer Science on Page 3 of 6

4 c. Use Vlookup function or the flowchart in appendix 4 to fill in evaluation criteria in Evaluation column according to evaluation table. (4mks) d. Use the appropriate function to calculate the following: (5mks) i. Average Salary in cell E14 ii. Highest Total Salary in cell E15 iii. Lowest Total Salary in cell E16 iv. Number of Salesperson in cell E17 v. Number of person whose Total Salary is more than $100,000 in cell E18. e. Format all numeric values to currency Fcfa with 0 decimal places. (E.g formatted as 12 Fcfa). (2mks) f. Insert a row between row 9 and 10. Type in your name as the salesperson in this new row. Enter for the total sales and for base salary. Copy the appropriate formulas into Commission, Total Salary and Salesperson's Evaluation. (2mks) g. Save your file and close the program. (1 mk) TASK D: [30 marks] The following exercise consists of solving the same problem as in TaskC using C programming. We consider the following data structures: salesperson = record name: string(20) sales: number salary: number endrecord; ABC = array of 100 salesperson FABC = file of salesperson 1- Write in your booklet the declaration of the above data structures successively using appropriate data type. (5 mks). 2- Write a C function called readsale() that read the name, the sales and the salary of a sales person and return it one record (or structure). The code of the function should be copied in the answer booklet. (5 mks) 3- Write a main program that use the function readsale() and calculate the commission, the total salary and determine the evaluation of a salesperson using the formula and flowcharts given in TaskC; then display them. Save it as TaskD1. (10 mks) 4- Using a file of structure or an array of structure, modify the program TaskD1 to display the information on many salespersons and their commission, total salary and evaluation and save it as TaskD2. (10 mks) More questions and Lesson notes in Computer Science on Page 4 of 6

5 Function firstfit(blocksize) for(i from 1 to n) do if(size[i]>=blocksize) return i; endif ; return -1; endfunct APPENDIX 1: Pseudocodes of memory allocation algorithms function bestfit(blocksize) for(i from 1 to n) do rem[i] size[i]-blocksize; index -1; small 10000; for (i from 1 to n) do if(rem[i]>=0&&rem[i]<small) small rem[i]; index i; endif return index; endfunct function worstfit(blocksize) for(i from 1 to n) do rem[i]=size[i]-blocksize; enffor index -1; big -1; for(i from i to n) do if(rem[i]>big) big rem[i]; index i; endif return index; endfunct APPENDIX 2: ABC salespersons Salaries APPENDIX 3: Flowchart to calculate commission More questions and Lesson notes in Computer Science on Page 5 of 6

6 APPENDIX 4 : Flowchart to calculate total salaries of salespersons APPENDIX 5 : Source code of the allocation program #include<stdio.h> #define max 10 int main() int i,j,n,blocksize; int size[max]; printf("enter the number of blocks:"); scanf("%d",&n); for(i=1;i<=n;i++) printf("enter the size of block %d: ",i); scanf("%d",&size[i]); printf("\nenter the size of Arriving block:"); scanf("%d",&blocksize); for(i=1;i<=n;i++) if(size[i]>=blocksize) printf("arriving block is allocated to block %d ",i); break; if(i==n) printf("no sufficient block for %d K",blocksize); return 0; More questions and Lesson notes in Computer Science on Page 6 of 6