2021 SPS Computing P1

[Turn over NAME CLASS INDEX NO. ST. PATRICK'S SCHOOL PRELIMINARY EXAMINATION 2021 SUBJECT : Computing Paper 1 (7155/01) DATE : 23 August 2021 LEVEL : Secondary 4 Express DURATION : 2 hours INSTRUCTIONS TO CANDIDATES: Write your Name, Class and Index No. in the spaces at the top of this page. Write in dark blue or back pen. You may use a soft pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all the questions. The use of an approved scientific calculator is expected, where appropriate. You are reminded of the need for clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. The total number of marks for this paper is 80. INFORMATION FOR CANDIDATES: The allocated marks for each question are indicated in the brackets [ ]. For Examiner’s Use Score /80 This question paper consists of 16 printed pages, including the cover page. Candidates answer on the Question Paper.

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3 [Turn over 1 Five items of computer architecture and six descriptions are given. Draw one line from each item to its appropriate description. Item Description Data bus Transfers required memory location from processor to memory; uni-directional Address bus Stores data, instructions and the results of processing for immediate use Secondary storage Extremely fast but small data storage spaces used directly by the ALU and control unit Memory Transfers data between memory and processor; bi-directional Processor register Stores large amounts of data that will not be lost when power supply is interrupted Processes data and follows instructions; consists of an arithmetic logic unit and a control unit [5]

4 2 A software company is creating an online learning portal for adult learners. (a) The user must first register an account in the portal. The user will then receive a verification email. Upon successful verification, the user can now login to the portal. In the portal, a registered user will be able to access the profile page where he/she can edit his/her personal information, email address, password and profile picture. The user can also access the courses page where he/she can view the details of the various courses available and select the courses that he/she wishes to enroll. Upon enrolling into a course, he/she can access the course materials and the portal will automatically track his/her learning progress. During the planning stage, the problem must be decomposed into smaller, more manageable parts called modules. Identify and describe two of these modules. 1 2 [2] (b) Another team in the company is responsible in creating a detective strategy game where the player assume the role of a detective. In one part of the game, the detective can access the files of the suspects. Identify two common elements between this game and the learning portal described in part (a). 1 2 [2]

5 [Turn over 3 Consider the following algorithm. 01 Ratio_1 = 0 02 Ratio_2 = 0 03 INPUT Bigger_Num 04 INPUT Smaller_Num 05 Ratio_1 = ROUND(Bigger_Num/Smaller_Num, 3) 06 Ratio_2 = ROUND((Bigger_Num + Smaller_Num)/Bigger_Num, 3) 07 IF Ratio_1 == Ratio_2 THEN 08 OUTPUT True 09 ELSE 09 OUTPUT False 09 ENDIF (a) Complete the following trace table for the algorithm. Use the data Bigger_Num = 61.84, Smaller_Num = 38.22 as input. Bigger_Num Smaller_Num Ratio_1 Ratio_2 OUTPUT 0 0 61.84 38.22 1.618 1.618 True [3] (b) The algorithm does not include validation on the inputs. Name and describe one validation check that could be added to validate the inputs. [2]

6 (c) Decide on the data validation technique you would used in the algorithm and give a reason on your decision. [2] (d) For each of the following test case conditions, give one example of the test data that you would use to test the above algorithm. Normal Test Case [1] Error Test Case [1] Boundary Test Case [1] 4 In general, there are five stages in developing a program. For each of the following stages, describe the goal of the stage and describe one task that can be done during that stage. Gather Requirements Stage Goal Task Plan Solutions Stage Goal Task [4]

7 [Turn over 5 When we use a programming language, the source code must be translated into machine code before it can be run. Source code can be translated by a compiler or an interpreter. Describe one advantage that a compiler has over an interpreter and one advantage that an interpreter has over a compiler. Advantage of a compiler Advantage of an interpreter [2] 6 A multinational social enterprise sets up its main headquarters in Country A and establishes another office in Country B. (a) State the type of network that would be suitable to enable the office in Country B to share information with its main headquarters in Country A. [1] (b) The office in Country B uses a Local Area Network (LAN) where both wired and wireless connections are used to connect the different computers and other network devices. Describe two possible examples with reasons why the office in Country B uses both wired and wireless connections. [4]

8 (c) The social enterprise packs canned food for refugees. The flowchart below checks the weight of each canned food to determine whether it can be packed in the box. The maximum number of canned food that can be packed in a box is 6. Each canned food should only weigh between 589 and 599 grams. The number of canned food accepted and rejected is output. Accepted = Accepted + 1 START Is Accepted = LIMIT? Is Canned > 599? Yes No No Yes Is Canned < 589? Yes No Accepted = 0 Rejected = 0 LIMIT = 6 OUTPUT Accepted, Rejected END INPUT Canned Rejected = Rejected + 1

9 [Turn over Complete the trace table for the following data. 589, 590, 580, 592, 591, 599, 600, 595 Trace table Accepted Rejected Canned OUTPUT 0 0 589 1 590 2 580 1 592 3 591 4 599 5 600 2 589 6 6, 2 [4] (d) From the flowchart in (c), identify one variable and one constant. (i) Variable Constant [2]

10 (ii) State the difference between a variable and a constant. [2] (e) Study the flowchart in (c). There is a need to calculate and output the average weight of each can in a box. Describe the changes required to the algorithm, making the necessary references to the flowchart. [3] 7 Cyberattacks are intentional attempts to damage, disrupt or gain unauthorized access to one or more computer systems through the Internet. Financial institutions are very wary of phishing and pharming attacks. (a) State two tell-tale signs to identify phishing emails. 1 2 [2] (b) Explain one measure that can be taken to protect against pharming. [1]