BLSS 2019 P1

BOON LAY SECONDARY SCHOOL PRELIMNARY EXAMINATION 2019 Name [ ] CCA Subject : COMPUTING Paper No : 1 Subject Code : 7155/01 Level : SECONDARY FOUR EXPRESS Date/Day : 17 SEPTEMBER 2019 / TUESDAY Time : 1030 - 1230 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 13 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] (ii) Convert the positive whole binary number 11010011 into a denary number. Show your working. ……………………………………………………………………………………………………. ………………………………………………………………………………………………….[1] (iii) Convert the hexadecimal number AC into its binary representation. Show your working. ……………………………………………………………………………………………………. ………………………………………………………………………………………………….[1] (b) Hexadecimal numbers are commonly used in file compression techniques and in Media Access Control (MAC) addresses. (i) Identify and calculate the largest denary value that can be stored by the following numbers. Show your working. A 4-character binary number ……………………………………………………………………………………………………. ………………………………………………………………………………………………….[1] A 4-character hexadecimal number ……………………………………………………………………………………………………. ………………………………………………………………………………………………….[1]

3 BLS/EYE/2019/4E/COMP/7155/01 (ii) State and describe one other use of the hexadecimal number system. ……………………………………………………………………………………………………. ………………………………………………………………………………………………….[2] 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. ……………………………