JYSS 2019 P1

JUNYUAN SECONDARY SCHOOL PRELIMINARY EXAMINATION 2019 SECONDARY FOUR EXPRESS CANDIDATE NAME CLASS INDEX NUMBER COMPUTING 7155/01 Paper 1 3 Sep 2019 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 15 printed pages and 1 blank page. [Turn over For Examiner’s use

2 1 (a) A computer has 2048 MB of RAM. How many GB of RAM does the computer have? Show your working. .................................................................................................................................................. .................................................................................................................................................. .................................................................................................................................................. ..............................GB [2] (b) Describe one item that is stored in RAM. .................................................................................................................................................. .................................................................................................................................................. ............................................................................................................................................ [2] (c) Explain two ways that RAM is different to ROM. 1............................................................................................................................................... ................................................................................................................................................. ................................................................................................................................................. 2............................................................................................................................................... ................................................................................................................................................. ........................................................................................................................................... [2]

3 4E Computing P1 2019 Prelim [Turn over 2 Five security terms and six statements are listed below. Draw a line to match the security term with the most appropriate statement. Security term Statement Gathers information by monitoring key presses on a user’s keyboard; the information is relayed back to the originator of the software. Cookie Provides a secure connection between web browsers and websites allowing secure transmission of private data. Pharming Uses rules and criteria, set by the user, to help protect a network or system from unauthorised access. Phishing Legitimate-looking email is sent in the hope of gathering personal information; it requires the user to click. Spyware A message given to a web browser by a web server; it is stored in a text file; the message is then sent back to the server each time the browser requests a page from the server. Firewall Malicious code installed on the hard drive of a user’s computer; this code will redirect the user to a fake website without the user’s knowledge. [5]

4 3 Match the three descriptions below using the following list of types of software. Open courseware Freeware Free and open source software Proprietary software Shareware Description Type of Software (a) Users can download this software free of charge, but they cannot modify the source code in any way. (b) Users can study the software source code and modify it, where necessary, to meet their own needs, without breaking copyright laws. (c) Users can obtain a free trial version of the software, but this often does not contain all the features of the full version. [3] 4 Hexadecimal codes are used in MAC addresses. (a) State what is meant by the term MAC. .......................................................................................................................................... [1] (b) Explain what the hexadecimal code in a MAC address represents. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ ........................................................................................................................................... [2]

5 4E Computing P1 2019 Prelim [Turn over 5 (a) Convert the following two hexadecimal numbers into binary: F A 7 D 3 E [4] (b) Now perform the AND (logic) operation on each corresponding pair of binary bits in the two numbers from part (a). [2] (c) Convert your answer in part (b) into hexadecimal. ................................................................................................................................................ ........................................................................................................................................... [2] (d) Hexadecimal numbers are often used by computer programmers to represent binary values. Explain why computer programmers may choose to use hexadecimal numbers. ................................................................................................................................................ ................................................................................................................................................ ................................................................................................................................................ .......................................................................................................................................... [2] F A 7 D 3 E

6 6 A greenhouse uses a system to monitor the conditions that plants need to grow. The inputs to the system are: Input Binary value Condition W 1 Window is open 0 Window is closed T 1 Temperature >=26 °C 0 Temperature <26 °C H 1 Humidity >=50% 0 Humidity <50% The system will sound an alarm when certain conditions are detected. Alarm (X) will sound (=1) when: window is closed and temperature >=26 °C or temperature <26 °C and humidity >=50% (a) Write a Boolean statement that matches the description of the logic required. X = ………………………………………………………………………….………………………...