JWSS 2018 P1

Setter: Mr V Surya Class Index Number Name: Jurong West Secondary School Preliminary Examinations 2018 COMPUTING 7155/01 Secondary Four Express 27 August 2018 Paper 1 0800 – 1000 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces provided 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. Do not use 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 marks for this paper is 80. This document consists of 14 printed pages. After checking of answer script Checked by Signature Date Student 80 _________________________________________________________________________________

2 JWSS Preliminary Examinations 2018 Computing (7155/01) Secondary 4 Express Answer all questions 1 Draw a line to match the computer parts to the correct description. 2 Cloud services allow users to run programs and access data anywhere over the Internet without having to be at a particular physical location. Describe two safety measures you can take to prevent unauthorised access to your private information when using cloud services. (a) Safety measure 1 ……………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. (b) Safety measure 2 ……………………………………………………………….. …………………………………………………………………………………….. …………………………………………………………………………………….. [2] Control Unit ALU Secondary Storage Collection of wires for transporting data from one part to another Stores large amount of data that will not be lost when power is interrupted Part of the processor that follows instructions and decides when the data should be stored, received or transmitted Part of the processor that processes data by performing basic mathematical and logical operations [4] CPU Bus ROM

3 JWSS Preliminary Examinations 2018 Computing (7155/01) Secondary 4 Express 3 Insert five of the following words about network devices and components, in the correct place in the text below. client network hub router SSID modem server network bridge port The ……………..…………… number is used together with an IP address to uniquely identify a program that is running on a network. The ……………..…………… is a device that connects multiple devices to the same network and transmits received packets to all connected devices. The ……………..…………… is a device that converts digital signals to analog signals and vice-versa. The ……………..…………… is a 32-bit string that identifies a wireless access point and all devices connected to it. The ……………..…………… is a device that forwards packets between separate networks. [5] 4 When we use a programming language, the source code must be translated into machine code before it can be run. Identify two ways by which source code can be translated into machine code and give an advantage of each method. Method 1 .……………………………………………………………………………. Advantage …….……………………………………………………………….…….. ………………….……………………………………………………………….…….. Method 2 …………………………………………………………………………….. Advantage …….……………………………………………………………….…….. …………....…….……………………………………………………………………... [4]

4 JWSS Preliminary Examinations 2018 Computing (7155/01) Secondary 4 Express 5 A meteorologist wants to find out the day and temperature recorded, for the hottest day in the month of January, which contains 31 days. State the inputs and outputs required for this problem. Inputs ………………………………………………………………………………... ………….…………………………………………………………………………….. Outputs …………………………………………………………………………….... ………….…………………………………………………………………………….. State two examples of inputs where it may not be possible to find the hottest day in the month of January. Example 1 ……………...…………………………………………………….……. ………………….……………………………………………………………….…… Example 2 ……………...…………………………………………………….……. ………………….……………………………………………………………….…… [6] 6 Sequence data types allow you to store multiple values in an ordered, organised and efficient fashion. (a) State two sequence data types in Python. (i) ………...…………………….……………………………………………… (ii) ………...…………………….……………………………………………… [2] (b) State two non-sequence data types in Python. (i) ………...…………………….……………………………………………… (ii) ………...…………………….……………………………………………… [2]

5 JWSS Preliminary Examinations 2018 Computing (7155/01) Secondary 4 Express 7 Data can be corrupted due to a number of reasons. (a) Describe how the following causes can contribute to data corruption and provide a preventive measure for each cause. (i) Human error ...…………….……………………………………………… ….…………………………………………………………………………... Preventive Measure ...…………………………………………………… ….…………………………………………………………………………... [2] (ii) Power failure ...…………….……………………………………………… ….…………………………………………………………………………... Preventive Measure ...…………………………………………………… ….…………………………………………………………………………... [2] (b) To ensure integrity of data during network transmission, parity checks are commonly used for error-checking. (i) The word “be” was sent across the internet. Assuming an odd parity system was used, state if there were any errors in the transmission for each character. Data received Was there an error? ASCII character at destination (Indicate Yes / No) b 01100010 …………………….…… e 01100101 …………………………. [2] (ii) State one limitation of parity checks. ….…………………………………………………………………………... ….…………………………………………………………………………... [1]

6 JWSS Preliminary Examinations 2018 Computing (7155/01) Secondary 4 Express 8 A topology describes the physical layout of a network. Understanding the topology is essential to designing a network. (a) State three common types of network topology. ………………………………………………………………………………….… ………………………………………………………………………………….… ………………………………………………………………………………….… [3] (b) A businessman intends to set up a company in town and wants to have a secure LAN in the office. He has around 150 staff working in the same office and another 25 staff working from offsite locations. The staff need to share files and connect to the printers. He also plans to expand his business in the next five years. (i) Which network topology is most suitable in this case? Why? Choice .…………………….……………………………………………… Reason .…………………………………………………………………… ….…………………………………………………………………………... [2] (ii) State two advantages of a client-server network over a P2P network. Advantage 1 ………………………………………………………............ ……………………………………………………………………................ Advantage 2 ………………………………………………………............ ………………………………………………………………………………. [2]

7 JWSS Preliminary Examinations 2018 Computing (7155/01) Secondary 4 Express 9 In order to locate or identify a particular component on a network, an IP (Internet Protocol) address is used along with a MAC (Media Access Control) address. (a) State the difference in operation between an IP address and a MAC address. …………….…………………………………………………………………....… …………….…………………………………………………………………..….. …………….…………………………………………………………………..….. [2] (b) The following is a valid IPv4 denary address. 12.97.19.155 Convert the IPv4 denary address into a 32-bit binary address. …………….…………………………………………………………………….… …………….…………………………………………………………………….… …………….…………………………………………………………………….… …………….…………………………………………………………………..…... [2] (c) The following is a valid MAC hexadecimal address. 20:17:0B:AD:C0:DE (i) Identify the number of bits represented by the MAC address. ……….………………………………………………………………….