SST 2019 Prelim P1

Page 1 of 16 [Turn over SECONDARY 4 PRELIM EXAMINATION COMPUTING Paper 1 Written 7155/01 30 August 2019 (Friday) 2 hours CANDIDATE NAME CLASS INDEX NUMBER READ THESE INSTRUCTIONS FIRST Do not turn over the page until you are told to do so. Write your name, class, and index number in the spaces provided above. Write in dark blue or black pen. You may use a pencil for any diagrams. Do not use staples, paper clips, highlighters, glue or correction fluid/tape. 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 16 printed pages. For Examiner’s Use 1 3 2 5 3 4 4 3 5 3 6 4 7 4 8 7 9 5 10 4 11 10 12 12 13 10 14 6 Total /80

Page 2 of 16 1 Fill in the blanks with the correct word(s) from the following list. address bus arithmetic logic unit control unit central processing unit data bus memory secondary storage process register RAM ROM hard disk (a) The _____________ transfers data between memory and processor. It is bi-directional. Answer: …………………………………… [1] (b) The __________ is the part of the processor that processes data by performing mathematical operations. Answer: …………………………………… [1] (c) The ___________ is where data and instructions that are needed for a computer to start up are stored. Answer: …………………………………… [1] 2 Data is used in a computer program. It can be stored as bytes. (a) What makes up one byte? ..................................................................................................................................... ..................................................................................................................................... [1] (b) Larger amounts of data can be measured in terms of megabytes or mebibytes. Convert one mebibyte to megabytes. ..................................................................................................................................... ..................................................................................................................................... [2] (c) A camera SD card has 64 gigabytes of storage space. If the size of each low resolution image is 500 kilobytes, what is the maximum number of images the SD card can store before it is full? ..................................................................................................................................... ..................................................................................................................................... .................................................................................................................................... [2]

Page 3 of 16 [Turn over 3 Most webpages use the RGB (Red, Green, Blue) colour model. Hues of the three primary colours, red, green and blue, are added in various intensities to give a distinct colour representation which can be described by a colour code comprising 6 hexadecimal digits, #RRGGBB. RR, GG and BB are pairs of hexadecimal digits which represent the intensities of red, green and blue respectively. The intensity of each primary colour ranges from 00 for zero intensity to FF for maximum intensity. Therefore, #000000 represents black and #FFFFFF represents white. (a) Including white and black, how many different colours can the RGB model represent in total? ..................................................................................................................................... ..................................................................................................................................... An object on a webpage has the colour #6B00D3. [1] (b) Convert (6B)16 to a binary number. Show your working. ..................................................................................................................................... ..................................................................................................................................... [1] (c) Convert (D3)16 to a denary number. Show your working. ..................................................................................................................................... ..................................................................................................................................... [2] 4 Jason is a programmer who uses Unicode often in his work. State what Unicode is, what it is used for, and how it is represented in the computer system. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... .................................................................................................................................... [3]

Page 4 of 16 5 Internet Protocol (IP) addresses are used to identify computers on the Internet. There are two versions of IP addresses used today, namely IP version 4 (IPv4) and IP version 6 (IPv6). (a) State the main difference between a IPv4 address and IPv6 address. ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... [2] (b) Explain the need to have IPv6 addresses. ..................................................................................................................................... ..................................................................................................................................... [1] 6 In computer networks, MAC addresses are very important and used extensively. They can be found in Ethernet, Wi-Fi and Bluetooth technologies. 00:0a:95:9d:68:16 is an example of a MAC address. (a) What does the acroymn MAC stand for? ..................................................................................................................................... [1] (b) State why MAC addresses are used. ..................................................................................................................................... ..................................................................................................................................... [1] (c) Identify what the first six and last six hexadecimal digits of a MAC address represent. First six digits: ........................................................................................................... Last six digits: ........................................................................................................... [2]

Page 5 of 16 [Turn over 7 A private clinic holds records of its patients in a database. Apart from the names and medical conditions of the patients, the other fields include: • Date of birth (DD/MM/YYYY) • Gender (Male / Female) • Height in metres • Postal code (6 digits) For each field, suggest a validation check that should be performed to ensure data is entered accu