SRSS 2020 P1

This question paper consists of 14 printed pages including the cover page. [Turn over SERANGOON SECONDARY SCHOOL PRELIMINARY EXAMINATION SECONDARY 4 EXPRESS CANDIDATE NAME ( ) CLASS CENTRE NUMBER S INDEX NUMBER COMPUTING 7155/01 Paper 1 25 August 2020 2 hours Setter(s): Mr Adrial Tan READ THESE INSTRUCTIONS FIRST Write you Centre number, index number and name 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 or correction fluid. 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 number of marks for this paper is 80. For Examiner’s Use 80

2 1 (a) The diagram below shows four logic gates on the left and three sets of Boolean values on the right. The Boolean values have been extracted from the truth tables of logic gates. Draw one line from each logic gate to the correct set of Boolean values. Each set of Boolean values may have more than one logic gate matched to it. Logic gates Boolean Values [4] A B X 0 0 1 0 1 1 A B X 0 0 0 1 1 1 A B X 0 1 0 1 1 0 A A A A B B B B X X X X

3 (b) Draw a logic circuit to represent the following Boolean statement. Do not simplify the statement. X = (A OR (NOT B NAND C)) AND (A NOR B) [5] (c) Complete the truth table for the Boolean statement: X = (A OR (NOT B NAND C)) AND (A NOR B) A B C Working Space X 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 [4] A B C X

4 2 Insert five of the following word(s) about network devices and terms used in the correct place in the text below. DHCP server firewall LAN cable modem network hub network interface card network switch router (a) The ……………………………………..… is the hardware interface that enables the transfer of data between a device and a network. (b) The ……………………………………..… is a device that constructs a single network by connecting two similar networks together. (c) The ……………………………………..… is a device responsible for modulating and demodulating digital data when data is transmitted over long distances. (d) The ……………………………………..… is a device that forwards packets between separate networks. (e) The ……………………………………..… is a device that transmits received packets to all connected devices. [5] 3 During the outbreak of COVID-19 pandemic, countries all over the world went into lockdowns. Technology was extensively used to minimise the impact on the everyday lives of people. (a) Give two social and two economic benefits that technology has brought about on the everyday lives of people during the lockdowns. Social benefit 1 …………………………………………………………………………. ……………………………………………………………………………………………. Social benefit 2 …………………………………………………………………………. ……………………………………………………………………………………………. Economic benefit 1 …………………………………………………………………….. ……………………………………………………………………………………………. Economic benefit 2 …………………………………………………………………….. ………………………………………………………………………………………… [4]

5 (b) Give two negative impacts that technology may have brought about on the everyday lives of people during the lockdowns. 1 …………………………………………………………………………………………................................................................................................................................ 2 …………………………………………………………………………………………………………………………………………………………………………………… [2] 4 (a) Convert the binary number 1001 0110 into a positive whole denary number. Show your workings. ……………………………………………………………………………………............…………………………………………………………………………………………….…………………………………………………………………………………………….………………………………………………………………………………………… [2] (b) Convert the positive whole denary number 459 into a hexadecimal number. Show your workings. ……………………………………………………………………………………............…………………………………………………………………………………………….…………………………………………………………………………………………….………………………………………………………………………………………… [2] (c) RGB colour codes are used to describe colours which can be displayed on computer systems. Describe how number systems are used in the RGB colour code system. ……………………………………………………………………………………............…………………………………………………………………………………………….…………………………………………………………………………………………….…………………………………………………………………………………………….…………………………………………………………………………………………….…………………………………………………………………………………………….………………………………………………………………………………………… [3]

6 5 The following spreadsheet shows the profit or loss on sales at Hougang 88 Drink Stall during a five week period. A B C D E F 1 Hougang 88 Drink Stall 2 Cost Price Selling Price Weekly Expenses $ 1250.00 3 Soya Bean Milk $ 0.35 $ 1.30 4 Grass Jelly $ 0.45 $ 1.50 5 6 Soya Bean Milk Sales Grass Jelly Sales Sales ($) Expenses ($) Profit/Loss 7 Week 1 850 750 $2,230.00 $1,885.00 Profit 8 Week 2 550 650 $1,690.00 $1,735.00 Loss 9 Week 3 750 200 $1,275.00 $1,602.50 Loss 10 Week 4 800 300 $1,490.00 $1,665.00 Loss 11 Week 5 700 850 $2,185.00 $1,877.50 Profit 12 (a) What is the data type in cell B7? ………………………………………………………………………………………… [1] (b) Write down a formula that could be in cell D7 to calculate the amount of sales for week 1. ………………………………………………………………………………………… [2] (c) Describe how the formula in D7 can be copied into the cells D8, D9, D10 and D11. ………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………… [2] (d) Write down a formula that could be in cell F7 to determine if the stall was making a profit or a loss for week 1. ………………………………………………………………………………………... [2]

7 6 The following flowchart shows how barcodes are used at the point of sale in an automatic stock control system. Select statements from the list below, using numbers only, to complete the flowchart. [5]

8 7 To enhance contact tracing in public places during the COVID-19 pandemic, the government has tasked SingStar to create a kiosk with an automated gantry system that can be installed at all public spaces such as retail malls, public libraries and sports facilities. The information of people visiting such public spaces are stored in a central database where other information from other agencies reside, such as the information of people on quarantine or who are infected by the COVID-19 virus. • The contact tracing kiosk will require visitors to scan their NRIC and enter their contact number. • A thermal scanner will scan the temperature of the visitor and log it into the visitor’s visit record together with the visitor’s NRIC number and contact number. • The system will search through the central database to determine if the visitor is currently on home quarantine, or is an undischarged patient tested positive for the COVID-19 virus. • The system will search through the central database against the visitor’s home address, to determine if anybody residing at the address is currently on home quarantine, or who are currently infected by the COVID-19 virus. • The system will search through the central database to determine if the visitor has recently been to any public spaces and came into close contact with someone who was infected with COVID-19 virus. • The gantry will automatically open to allow the visitor to enter the premise and display a “Welcome” message on a LCD panel if all checks are clear, or display an “Entry Denied” message on the LCD panel if the visitor fails any of the checks. (a) Name two input devices that may be used in the automated gantry system. 1 ………………………………………………………………………………………… 2 ……………………………………………………………………………………… [2] (b) When developing the system, SingStar system developers used modular decomposition to break down the system into smaller, more manageable modules to develop. One such module is the thermal scanning system. Name four other possible modules that can be decomposed from the problem. M