ZHSS 2020 Computing P1 Solution

Setter: Mr. Calvin Heng Vetter: Mr. Low Kee Ley This question paper consists of 13 printed pages including this cover page. ZHONGHUA SECONDARY SCHOOL PRELIMINARY EXAMINATION 2020 SECONDARY 4 EXPRESS Candidate’s Name Class Register Number MODEL ANSWER TOS COMPUTING 7155/01 Paper 1 18 September 2020 2 hours Additional Materials: NIL READ THESE INSTRUCTIONS FIRST Write your index number and name on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all the questions. Write your answers in this question booklet. Give non-exact numerical answers correct to 3 significant figures, or 1 decimal place in the case of angles in degrees, unless a different level of accuracy is specified in the question. The use of a scientific calculator is expected, where appropriate. You are reminded of the need for clear presentation in your answers. At the end of the presentation, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. The total number of marks for this paper is 80. For Examiner’s Use:

2 1 (a) Convert 8 bits into GB. 8 bits = 1 byte 1byte x 10-3 x 10-3 x 10-3 = 1.00 x 10-9 GB (3sf) KB MB GB [1] (b) Convert 64 Terabytes into KB. 64 x 103 x 103 x 103 = 64 x 109 = 6.40 x 1010 KB (3sf) GB MB KB [1] 2 Draw a line to match the terms to its correct description. Terms Description DoS Attack l Cookie l l A small piece of data used by websites to store personal information on a user’s web browser. Encryption l l Hidden program that secretly collects personal information. Phishing l l Flooding network with useless traffic, making the network slow or inaccessible. Software piracy l l Sending fake or spoof emails. Spyware l [4]

3 3 Fill in the blanks with the helping words. ALU APPLICATION RAM CPU ROM UTILITY (a) RAM is high speed, volatile memory. (b) The accumulator stores intermediate results of calculations in the ALU . (c) Antivirus software is an example of UTILITY a software. (d) ROM tells the CPU how to boot up. [4] 4 Fiona is a graphic designer for a publishing company. The image editing software that she uses represents each unique colour as a six digit hexadecimal code. (a) As a power of 16, how many possible unique colours could Fiona use? (workings must be shown clearly) 6 digits of 16 possibilities: = 16 x 16 x 16 x 16 x 16 x 16 = 16,777,216 colours [2] (b) Explain one benefit to programmers of using hex codes to represent the different colours. It would be easier to remember the hexadecimal code for a particular colour BECAUSE Hexad