BLSS 2019 P1 Solution

BOON LAY SECONDARY SCHOOL PRELIMNARY EXAMINATION 2019 Name ANSWERS [ ] CCA Subject : COMPUTING Paper No : 1 Subject Code : 7155/01 Level : SECONDARY FOUR EXPRESS Date/Day : XX XXX 2019 / XXXDAY Time : XXXX - XXXX Duration : 2 HOURS Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Before you start your exam, check that you have received the correct paper and the number of printed pages are correct. Write your name, index number, and CCA 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 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.

2 BLS/EYE/2019/4E/COMP/7155/01 This document consists of 15 printed pages. 1 (a) Denary numbers are stored as binary numbers inside a computer. (i) Convert the denary number 168 into 8-bit binary. Show your working. ………………………………………………………………………………………………….[1] 1010 1000 (ii) Convert the positive whole binary number 11010011 into a denary number. Show your working. ………………………………………………………………………………………………….[1] 211 (iii) Convert the hexadecimal number AC into its binary representation. Show your working. ………………………………………………………………………………………………….[1] 1010 1100 (b) Hexadecimal numbers are commonly used in file compression techniques and in Media Access Control (MAC) addresses. (i) Calculate the largest numerical value that can be stored by the following numbers. Show your working. A 4-character binary number (1111) : 15 ………………………………………………………………………………………………….[1] A 4-character hexadecimal number (FFFF) : 65535 ………………………………………………………………………………………………….[1]

3 BLS/EYE/2019/4E/COMP/7155/01 (ii) State and describe one other use of the hexadecimal number system. ……………………………………………………………………………………………………. ………………………………………………………………………………………………….[2] RGB colour scheme codes / Memory addresses 2 A computer network is a system of two or more computers that are connected together by a transmission medium for the exchange of data. (a) The diagram below shows how a home network is connected to the Metropolitan Area Network (MAN). (i) Complete the diagram by filling in the appropriate networking devices for the three parts labelled i., ii., and iii. Networking devices: Router, Modem, Bridge, Network Interface Card i. ………………………………………………………………………………………………… ii. ………………………………………………………………………………………………… iii. ………………………………………………………………………………………………[2] MAN i. Home network ii. iii. Server Home terminal Mobile devic