JYSS 2020 Computing P1

JUNYUAN SECONDARY SCHOOL PRELIMINARY EXAMINATION 2020 SECONDARY FOUR EXPRESS CANDIDATE NAME CLASS INDEX NUMBER COMPUTING 7155/01 Paper 1 Written 31 Aug 2020 Candidates answer on the Question Paper. 2 hours No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number 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 or graphs. 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. This document consists of 13 printed pages and 1 blank page. [Turn over For Examiner’s use 80

2 1 The following list shows five types of storage mediums: flash memory card internal hard disk CD-ROM DVD external hard disk (a) The table below shows five applications. For each application, choose the most appropriate storage medium from the list above. Application Storage Medium Storage of a text book in electronic form Storage of photographs in a mobile phone A offline backup of a complete PC file system Storage of an operating system and applications software Playback of video files [5] (b) (i) From the list above, name the storage medium which is an example of a solid state memory. [1] (ii) Give two advantages of using solid state memory. 1 2 [2]

3 4E Computing P1 2020 Prelim [Turn over 2 The following diagram shows six network terms and six descriptions. Draw a line from each network term to its best description. Network term Description Wired network A component that receives and forwards data packets using IP addressing Wireless network A combination of computers and components that are only connected using cables Bridge An internal component that allows a computer to connect to a network Router A combination of computers and components that are only connected using radio waves Network Interface Card (NIC) A combination of computing devices covering a large-scale geographical area Wide area network (WAN) A component that joins similar networks together [6]

4 3 Computers use a character set to convert text into binary numbers. One character set that can be used is ASCII. Each letter in ASCII can also be represented as a denary value. (a) The word CAR has the denary values: C A R 67 65 82 Convert the three denary values into 8-bit binary digits. 67 65 82 [3] (b) Each letter in ASCII can also be represented as a hexadecimal value. The word PEN has the 8-bit binary values: P E N 0101 0000 0100 0101 0100 1110 Convert the three 8-bit binary values into hexadecimal values. 0101 0000 0100 0101 0100 1110 [3]

5 4E Computing P1 2020 Prelim [Turn over 4 An online book seller wants to use a computer to find out the best-selling book title in 2019. There were 200 different books titles for sale in 2019 and the number of copies sold for each book title was different. State the inputs, the outputs and processes required to find the title of the best-selling book and the number of copies sold for this title. Inputs 1 2 Outputs 1 2 Processes 1 2 [6] 5 Insert five of the following words about Computational Thinking in the correct place in the text below. Each word can only be used once. generalisation decomposition pattern recognition smaller larger differences similarities The technique of …………………………….. is a method of breaking down a complex problem or process into …………………………….. parts such that each part is more manageable and easier to understand. The technique of …………………………….. is a method of identifying …………………………….. among two or more items. The technique of …………………………….. is a method of replacing two or more similar items with a single, more common item. [5]

6 6 (a) Draw the logic circuit to represent the following Boolean statement. Do not simplify the statement. X = (A NOR B) OR (NOT C AND B) A B C [4] (b) Complete the truth table for the Boolean statement: X = (A NOR B) OR (NOT C AND 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] X

7 4E Computing P1 2020 Prelim [Turn over 7 A pseudo-code algorithm: • allows a user to input 10 numbers • checks the number of inputs that are within the range of 5 and 25, both inclusive • outputs a message to show the numbers that are within the range • outputs a message to show the numbers that are outside the range. 1 Within_Range = 0 2 Outside_Range = 1 3 FOR Count = 1 to 10 4 OUTPUT "Enter number" 5 INPUT number 6 IF number >= 5 OR number <= 25 THEN 7 Within_Range = Within_Range + 1 8 ELSE 9 Outside_Range = Outside_Range - 1 10 ENDIF 11 Count = Count + 1 12 NEXT Count 13 OUTPUT Within_Range, Outside_Range There are four errors in the given algorithm. State each error and write the correct pseudo-code. Error 1 Correction Error 2 Correction Error 3 Correction Error 4 Correction [8]

8 8 Spywares and Trojan horses are two examples of online security threats to a computer system. (a) Explain what is meant by Spywares and Trojan horses and the threat that each of them pose to a computer system. Spywares Trojan horses [4] (b) (i) Identify one other online security threat to a computer system. [1] (ii) Based on the online security threat that you have identified in (b)(i), describe one security measure that can help to protect a computer system against that threat. [1]

9 4E Computing P1 2020 Prelim [Turn over 9 With the introduction of Home-based Learning, schools have been using technology both in the classrooms as well as outside of the classrooms. (a) Give one positive social impact and one positive economic impact of students using technology in their school. Social impact Economic impact [2] (b) One negative social impact of using technology at home is that students may become addicted to their mobile devices. (i) Give one way that students can avoid getting addicted to their mobile devices. [1] (ii) Give two other negative impacts of using technology in the school. 1 2 [2]

10 10 Consider the following algorithm. 1 Number = 0 2 OUTPUT “Key in Number1: ” 3 INPUT Number1 4 OUTPUT “Key in Number2: ” 5 INPUT Number2 6 IF Number1 > Number2 7 Number = Number1 – Number2 8 ELSE 9 Number = Number2 – Number1 10 ENDIF 11 OUTPUT Number (a) (i) Complete the following trace table for the algorithm. Use the data 6, 4 as input. Number1 Number2 Number Output [4] (ii) State the purpose of the algorithm. [1]