ZHSS 7155 PRELIMS 2022 4E P1 QP

ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2022 SECONDARY 4 EXPRESS Candidate’s Name Class Register Number COMPUTING 7155/01 Paper 1 Written 14 September 2022 2 hours Candidates answer on the Question Paper. No additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, index number and class in the spaces at the top of this page. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue, correction fluid or correction tape. Approved calculators are allowed. Answer all questions. The number of marks is given in brackets [ ] at the end of each question or part question. You should show all your working. The total of the marks for this paper is 80. Setter: Mr. Calvin Heng Vetted by: Mr. Low Kee Ley For Examiner’s Use TOTAL This question paper consists of 16 printed pages including this cover page.

2 1 The following shows a Computer Architecture diagram. (a) Complete the table below by filling in the missing words. Some of the labels have been done for you. Note: Acronyms are not allowed! LABEL NAME A ARITHMETIC LOGIC UNIT B CONTROL UNIT C D RANDOM ACCESS MEMORY E

3 LABEL NAME F G H X Y OUTPUT [6] (b) State two functions of the device labelled B. ……………………………………………………………………………… ……………………………………………………………………………… [2] (c) Approximately how many times larger (in terms of physical address space) is a 64 bit processor compared against a 32 bit processor? (working must be clearly shown.) ……………………………………………………………………………… ……………………………………………………………………………… ……………………………………………………………………………… [2]

4 2 The Urban Redevelopment Authority (URA), Housing Development Board (HDB) and Government Technology Agency of Singapore (GovTech) collaborated to provide a public service using a mobile App for the purpose of administering vehicle parking. This App is used by motorists to pay for parking at paper coupon based public parking spaces. After the vehicle is parked, the motorist starts the mobile App and selects the name of the road and enters the estimated parking duration (in units of 30 minutes), followed by pressing the START button (the App reads in the time from the mobile phone’s clock). Prior to leaving the parking space, the motorist ends the parking session by pressing the END NOW button (the App reads in the time from the mobile phone’s clock). The App then calculates the monetary amount owed (based on the parking duration referenced against a parking rate table) and deducts the amount via a pre -arranged setting (i.e., from the motorist’s credit card). The amount will also be displayed on the screen. State the inputs, output and processes involved with this mobile App: Inputs: i. ………………………………………………………………………………… ii. ………………………………………………………………………………… iii. ………………………………………………………………………………… iv. …………………………………………………………………………………. [2] Output: v. ………………………………………………………………………………… [1] Process: vi. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. …………………………………………………………………………………. [2]

5 3 Study the following flowchart. (a) Complete the trace table with the following inputs: x = 3, y = 7 ; x = 12, y = 15 ; Y N N Y START INPUT x, y t = 0 x odd? x = 0? OUTPU T t STOP x = x – 1 y = y t = t + y x = x // 2 y = y + y t = t

6 x y t x odd? x = 0? OUTPUT 3 7 12 15 [5] (b) What does the flowchart do? …………………………………………………………………………… [1] (c) Write down two observations about this algorithm. …………………………………………………………………………… …………………………………………………………………………… [2]

7 4 There are many data types supported in the Python Programming Language. Define the String (str) data type: i. ………………………………………………………………………………… [1] William wishes to create a string variable called ‘name’ initialized with the content ‘Alison’ . Demonstrate how this would be done in Python. ii. ..……………………………………………………………………………… [1] What is Type casting? iii. ………………………………………………………………..……………… [1] What is a List? iv. …………………………………………………..…………………………… [1] A special situation arises when a List can be called an Array. Describe this special situation. v. ……………………………………………………….……………………… ……………………………………………………….……………………… [1]

8 5 Programming Languages can be classified as either compiler or interpreter types. (a) What is a compiler? ……………………………………………………………………………… ……………………………………………………………………………… [1] (b) What is an interpreter? ……………………………………………………………………………… ……………………………………………………………………………… [1] Complete the table below concerning compiled vs interpreted programming languages. Compilers Interpreters Describe two Advantages Describe two Disadvantages [8]

9 6 The following python function accepts as input a numerical grade and returns the corresponding letter grade. You are required to complete the table about Test Condition information. def numtolet(n): if type(n) != int: return 'INVALID NUMERICAL GRADE' if n > 0 and n < 10: if n == 1 or n == 2: return 'A' elif n == 3 or n == 4: return 'B' elif n == 5 or n == 6: return 'C' elif n == 7: return 'D' elif n == 8: return 'E' elif n == 9: return 'F' else: return 'INVALID NUMERICAL GRADE' Test Condition Information Table Type of Test Condition Two examples of input test data [6]

10 7 Data corruption and loss may be caused by a variety of factors. In all cases, making regular backups of data will help to prevent the loss of data in the event of data corruption. Complete the table below about causes of data loss or corruption. Describe one scenario leading to the cause of data loss or corruption and describe a relevant preventive measure that addresses the scenario you described. (note: Do not discuss making regular backups of data) Cause Scenario Preventive measure Human error Power failure [4] Complete the following passage using the helping words provided. offline divulge online weaker report stronger intersected intercepted Two-factor authentication has become increasingly important in banking as large amounts of money may be at risk as a result of authenticating a user wrongly. Most banks require two -factor authentication for their ………………………… banking services. Two -factor aut hentication is ………………………… than using only a password. It is important to keep the token in a secure location and to ………………………… a missing security token. An OTP can be ………………………… and used by an intruder during the transmission process. The secret algorithm used to generate the OTP could be weak or accidentally revealed leading to the intruder being able to generate OTPs without needing the security token. [4]