SST 2022 S4 Computing Prelim P1

SECONDARY 4 PRELIM EXAMINATION COMPUTING Paper 1 Written 7155/01 26 August 2022 (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 18 printed pages. For Examiner’s Use 1 4 2 9 3 4 4 9 5 9 6 6 7 6 8 3 9 8 10 5 11 6 12 11 Total /80

Page 2 of 18 1 Draw a line to match the types of computer security threats with their respective descriptions. [4] Description • A computer program that runs automatically and attempts to spread by sending copies of itself to other computers without the need to attach itself to an existing program. • A hidden program that secretly collects personal information about its users and transmits this information to attackers without the users’ knowledge. • The use of emails and fake websites that appear to be from reputable companies in order to steal personal information such as passwords and credit card numbers from users. • A computer program that pretends to be a harmless file or useful application. Once it is run, it does something harmful such as giving intruders unauthorised access to the computer instead. • The interception of requests sent from a computer to a legitimate website and redirection to a fake website to steal personal data or credit card details. • A computer program that attaches itself to a normally harmless program and modifies it. Types of computer security threats (a) Pharming • (b) Spyware • (c) Trojan horse • (d) Worm •

Page 3 of 18 [Turn over 2 In computer networks, MAC addresses are very important and used extensively. 20:17:0B:AD:C0:BE is an example of a MAC address in hexadecimal. (a) What does the acronym MAC stand for? ..................................................................................................................................... [1] (b) State what MAC addresses are used for. ..................................................................................................................................... ..................................................................................................................................... [1] (c) Identify what the first six and last six hexadecimal digits of a MAC address represent. First six digits: ........................................................................................................... Last six digits: ........................................................................................................... [2] (d) Convert (AD)16 to a binary number. Show your working. Answer: …………………………………… [2] (e) Convert (BE)16 to a denary number. Show your working. Answer: …………………………………… [2] (f) Other than networks, describe one other area where hexadecimals is used. …………..................................................................................................................... ..................................................................................................................................... ……………................................................................................................................. ..................................................................................................................................... [1]

Page 4 of 18 3 The rise of technology has transformed the entertainment sector greatly. Describe two advantages and two disadvantages of the impact of technology on entertainment. Advantage 1 ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... Advantage 2 ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... Disadvantage 1 ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... Disadvantage 2 ..................................................................................................................................... ..................................................................................................................................... ..................................................................................................................................... [1] [1] [1] [1]

Page 5 of 18 [Turn over 4(a) Draw the logic circuit to represent the following Boolean statement. Do not simplify the statement. X = (A NAND B) OR (NOT B NOR C) [4] (b) Complete the truth table for the Boolean statement X = (A NAND B) OR (NOT B NOR C) A B C Working Space X 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 [4] (c) Simplify X with just the use of three logic gates or less. X = .................................................................................................................................... [1] AA B CC X

Page 6 of 18 5(a) Convert the following amounts of data into the unit indicated below. (i) 100 TiB = …………………… GiB (ii) 65536 kB = …………………… KiB [1] [1] (b) The table below shows some computer hardware. Tick (✓) one or more boxes in each row to indicate if the hardware is an input, output, or storage device. Input device Output device Storage device Touch screen monitor ROM Scanner [3] (c) Describe the functions of the following parts of a computer: (i) Control unit ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... [2] (ii) Address bus ................................................................................................................................... .....................................................................................................