MFSS 2019 P1 Solution

2019 Computing Sec 4 Prelim Paper 1 Marking Guide Qn Answer & Marking Guide 1a A1: Text B1: Currency B2: Percentage 1bi Correct formula and arguments =PMT($B$2/12, $B$3, $B$1) 1bii Correct formula and arguments =SUM(D8:D11) 1biii Correct formula and arguments, accept arguments from other columns =COUNT(C8:C11) 2ai One mark for correct answer, one mark for correct working. 1001 1011 2aii One mark for correct answer, one mark for correct working. BE 2aiii One mark for correct answer, one mark for correct working. 205 2b As memory dumps are usually large, … …the hexadecimal number system is ideal for displaying bytes in a compact manner.

2 3a one mark for each correct column GrpA GrpB X Count Check Output [] [] 2 1 [2, ] 3 2 1 [2,3] 4 1 3 1 [4] 5 2 0 4 1 3 2 2 1 [2,3,5] 6 1 5 1 4 2 [4,6] 7 3 0 6 1 5 2 4 3 3 1 2 1 [2,3,5,7] 8 1 7 1 6 2 5 3 [4,6,8] 0 4 0 [2,3,5,7] [4,6,8] 3b Separate… …prime and composite numbers into two lists.

3 4 5 iteration repeating selection sequence fixed 6a Arithmetic logic unit (ALU): processes data by performing basic mathematical and logical operations 6b Control unit: follows instructions and decides when data should be stored, received or transmitted by different parts of the computer 6c “multi-core” processors contain multiple processing units inside a single package. … … These “multi-core” processors can perform more than one instruction at the same time, and thus are more powerful than “single-core” processors. 7a Positive: • On the positive side, the Internet has enabled diverse cultures to interact and share ideas with each other. Social networking sites have also allowed users to remain connected with friends, family and colleagues even over long distances. Negative: • On the negative side, some people use the Internet to reinforce their existing opinions or to spread rumours and misinformation. 7b Any two from: • The rise of self-driving vehicles is likely to open new areas of growth Term Description Ethernet Media Access Control (MAC) Router Wireless access point (WAP) Internet Protocol (IP) A device responsible for modulation and demodulation. A device that forwards packets between separate networks. The most commonly used wired network protocol for local and metropolitan are networks. A device that provides connection between wireless devices up to 100 metres away and can connect to wired networks. Sequence of bytes that is used to identify a computer or device on the internet. Sequence of bytes (usually permanent in nature) that is used to identify a particular network interface card.

4 in the travel industry. Singapore is one of the first countries where self-driving cars are being tested, and if successful, the technology will likely revolutionise the motor industry. • There are also multiple new companies that offer on-demand rides via mobile applications. These developments have led to sweeping changes in the taxi service industry as well as employment opportunities for taxi drivers. • Mapping technology is also another area of growth with an increased focus on making 3D maps and geospatial data more accessible and useful to travellers. 7c • Is it acceptable for robots to replace humans in providing certain kinds of healthcare? • Is it acceptable to transfer private medical information over the Internet? Also accept other suitable answers 8ai NOR 8aii AND 8bi one mark for each term separated by OR X = A AND C OR B AND C OR NOT A AND NOT C, or X = A AND C OR B AND C OR A NOR C 8bii one mark for every two correct rows A B C Working Space X 0 0 0 1 0 0 1 0 0 1 0 1 0 1 1 1 1 0 0 0 1 0 1 1 1 1 0 0 1 1 1 1 8biii one mark for AC sub-circuit one mark for BC sub-circuit one mark for NOT A and NOT C one mark for use of two OR to collate results

5 9a Odd 9b 0000 1010 1101 1110 9c one mark for each point 1 to 4. 1. ASCII value for H is 72. 2. Looking at first byte, which is H. 3. Convert first 7 bits to denary = 72. 4. Therefore, party bit is appended. 5. To confirm, perform the same on another byte that did not suffer transmission error. 9d Use of Checksum. … …A checksum is a calculated value that is sent together with the data. At the destination, the checksum is recalculated and compared to the sent checksum value. 10 one mark for each correct identification, one mark for each correct correction Line 4 WHILE Num is not equal to 0 Line 10 Flag[Count] = TRUE Line 17 IF Flag[Count] == TRUE THEN Line 18 OUTPUT Large[Count]

6 11 - Input two numbers - Checking for smaller of the two… - …Correct initialization of loop counter - Use of Loop… - with correct management for correct number of iterations - Check for factor(% = 0)… - …with correct use of AND or otherwise - Output result Sample Algo: INPUT x, y IF x > y THEN Check = y ELSE Check = x WHILE Check > 0 IF x % Check = 0 AND y % Check THEN OUTPUT Check Check = 0 ENDIF Check = Check - 1 ENDWHILE