CTSS 2019 P1 Solution

Question Answer 1 Any 3 listed below Capacity, Speed, Portability, Durability, Cost Question Answer 2 The computer loads instructions for performing a power-on self-test (POST) from ROM to ensure that all the hardware components are functioning properly. The computer then loads the basic input/output system (BIOS) from ROM. The BIOS provides basic instructions on how to communicate with hardware components as well as where to look for an operating system. Assuming that an operating system is found on the computer’s hard drive, its data and instructions are then loaded from the hard drive into RAM. Question Answer 3(a) Number of processor cores Speed of the processor 3(b) i. More processor cores to process more instructions ii. Faster speed Question Answer 4(a) Strings, alphabets only 4(b) Format check, to ensure the input is in alphabets only. 4(c) True / Word is a palindrome. False / Word in not a palindrome Question Answer 5(a) Any method (CD7)16 = 3287 5(b) Any method (1101 1011)2 = DB 5(c) Any method (3172)10 = C64 Question Answer

6 One mark for any stated Error 1: Line 2 Correction: Sum = 0 Error 2: Line 5 Correction: IF Number is ODD Error 3: Line 6 Correction: Sum = Sum + Number or Sum += Number Error 4: Line 10 Correction: OUTPUT Sum Question Answer 7 Set to even or odd before data is transmitted If number of ones not even odd after transmission, data has occured Question Answer 8 1 mark each for each loop management 2 marks for turning the turtle 2 marks for moving the turtle forward import turtle bob = turtle.Turtle() bob.shape("turtle") bob.left(90) bob.forward(50) bob.forward(50) for i in range(4): bob.left(90) for i in range(4): bob.forward(50) bob.right(90) 2 Question Answer 8 (a) Phishing 8 (b) Any 2 : Dubious email asking for personal information Email using generic greetings Inaccurate logos Hyperlink and destination link do not match Fake senders with email accounts from Gmail or Yahoo Tone of email is threatening or very urgent 9(c) Any 2: Pharming Spamming

Spyware Trojan Horse Virus Worm 9(d) Cookie • A small piece of data used by websites to store personal information on a user’s web browser • Although usually not malicious in nature, cookies are sometimes misused to collect personal information about users Pharming • 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 • More difficult to detect than phishing as the fake website uses the same address as the real website Phishing • 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 Spamming • The mass distribution of unwanted messages or advertising to email addresses which are collected from sources such as public mailing lists, social networking sites, company websites and personal blogs Spyware • A hidden program that secretly collects personal information about its users and transmits this information to attackers without the users’ knowledge Trojan horse • A computer program that pretends to be a harmless file or useful application • Once a Trojan horse is run, it does something harmful such as giving intruders unauthorised access to the computer instead Virus • A computer program that attaches itself to a normally harmless program and modifies it • When the modified program is run by a user, the virus attaches copies of itself to any other programs it can find, thus “infecting” them Worm • A computer program that runs automatically and attempts to spread by sending copies of itself to other computers • Unlike a virus, a worm does not need to attach itself to an existing program Question Answer 10(a) 4 marks for 8 correct outputs 3 marks for 6 or 7 correct outputs 2 marks for 4 or 5 correct outputs 1 mark for 2 or 3 correct outputs A B C X 0 0 0 1 0 0 1 1 0 1 0 1

0 1 1 1 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 0 10(b) 1 mark for each correct logic gate, with correct inputs. Question Answer 11(a) B4/C4 11(b) E4*C4 11(c) -D4 11(d) -B1 11(e) Left blank or FALSE 11(f) =FV(B4/C4,E4*C4,-D4,-B1) 11(g) -B$1 (adding the $ to lock the cell) Question Answer 12(a) Any 3 below • Keep passwords secret and safe. • Avoid obvious password choices such as birthdates and surnames. • Use passwords that are a mixture of lower-case letters, upper-case letters, numbers and symbols. • Avoid re-using passwords and use unique passwords for each computer or online account. • Update passwords regularly – at least once every 90 days. 12(b) Public key encryption This ensures that the encoded message can be read only by the intended recipient who has the secret key. Question Answer

13 Question Answer 14 Any eight from • Initialization of 2 counters for positive and negative at start • Loop management for 10 repetitions • Input number in array • Checking and updating positive number counter if found • Checking and updating negative number counter if found • Checking for any number above 50 and outputting the index of that number • Printing out how many numbers greater than 0 and how many less than 0