2021 BVSS Computing P1 Solutions

1 Marking Scheme Q1 1(a) 1 mark for each correct line. Maximum 4 lines. Description Stage Gather requirements Train users to use the program. Plan solutions Compare the actual output with expected output. Write code Determine the complete set of outputs that is necessary to solve the problem. Test and refine code Write possible algorithms using either flowcharts or pseudo-code. Implement code 1(b) Description • An array is a variable with list of items of the same type that can be indexed. Example • For example, an array can be used to store 40 students’ marks. A repetition / loop can be used to process the array of 40 marks and this makes the program code more concise.

2 Q2 2(a) (i) • Data transfer is typically faster. • Data transfer is typically more secure. (ii) • Users can be connected to a wireless network as long as they are within range of the network coverage. • Low in cost • Easy to configure and manage. 2(b) Network Device Description Network interface card (NIC) NIC provides the hardware interface to enable the transfer of data between a device and a network. Network hub A device that transmits received packets to all connected device. Network bridge A device that constructs a single network by connecting two similar networks together. Router A device that forwards packets between separate networks. Modem A device that is responsible for modulation and demodulation. Wireless Access Point A device that allows other wireless devices to connect to a wired network.

3 Q3 3(a) 1810 x 1024 = 1853440 bytes 3(b) 60416 / 1024 = 59 GiB 3(c) 16 bits = 16 / 8 = 2 bytes 6144 x 2 bytes = 12288 bytes [ 3(d) Random access memory (RAM) • Main memory • Hard disk / Hard drive • Flash memory • Read-only memory (ROM) • Any other correct answer

4 Q4 4(a) 20 student names and 20 student temperatures 4(b) Names of students who have temperature 38 degrees or above and their respective temperatures. 4(c) • Store the 20 student names and temperature data in arrays / lists. • Search for students with temperature 38 degree or above.

5 Q5 5(a) Transfers required memory location from processor to memory. It is unidirectional. 5(b) Transfers data between memory and processor. It is bi-directional. Q6 Description Type of cyberattack A computer program that attaches itself to a normally harmless program and modifies it. Virus A computer program that pretends to be a harmless file or useful application but it can cause unauthorised access to the computer. Trojan horse A computer program that runs automatically and attempts to spread by sending copies of itself to other computers. Worm A small piece of data used by websites to store personal information on a user’s web browser. Cookie [4m]

6 Q7 7(a) The position of a digit in a binary number determines its place value, which is represented by 2N. The place value starts from 20 for the rightmost digit, with the power (N) increasing by 1 for each subsequent digit on the left. Hence, 11010111 (binary) = 27 + 26 + 24 + 22 + 21 + 20 (or = 128 + 64 + 16 + 4 + 2 + 1) = 215 (denary) 7(b) (i) Maximum 3 marks. Award 1 mark for every 2 correct conversions. RGB ode E 9 A 4 B 8 4-bit binary 1110 ………… 1001 ………… 1010 ………… 0100 ………… 1011 ………… 1000 ………… 7(b) (ii) 211 / 16 is 13 remainder 3 13 / 16 is 0 remainder 13 (which is D in hexadecimal) 211 = D3 (hexadecimal) 7(b) (iii) • Memory dumps • Network addresses • ASCII and Unicode • URL encoding

7 Q8 8(a) Maximum 5 marks. i name mass height bmi max person OUTPUT 0 0 ALI 52.5 1.6 20.5 20.5 ALI 1 SARAH 49 1.5 21.8 21.8 SARAH 2 TOMMY 63.5 1.8 19.6 SARAH 22 8(b) (i) WHILE height <= 0 or height > 2.8 OUTPUT “Invalid height! Enter positive height and less than or equal 2.8 m:” INPUT height ENDWHILE [Note: 1m is awarded for appropriate Error message and INPUT statement written.] (ii) Test case condition Test data for height Normal Example: 1.2, 2.5 Error Example: -0.5, -1 Boundary Example: 0, 2.8 = 8(c) Description Validation Check Ensure input data is not too short or too long. Length Check Ensure all the required inputs are provided. Presence Check =

8 Q9 9(a) Any one: subjects, number, count, student_subject, index Note: The variable stated must be same case as given in the question. 9(b) One mark for each error identified. One mark for suggested correction. Error 1 : 03 FOR count = 0 to 50 Correction : FOR count = 0 to 49 [1m] [1m] Error 2 : 06 IF index = -1 Correction : IF index != -1 [1m] [1m] Error 3 : 07 number[index]= number + 1 Correction : number[index]= number[index] + 1 [1m] [1m] Error 4 : 13 OUTPUT subjects[5], number[5] Correction : OUTPUT subjects[count], number[count] [1m] [1m] Corrected Pseudo-code: 01 02 03 04 05 06 07 08 09 10 11 12 13 14 subjects = [bengali, chinese, hindi, malay, tamil, others] number = [0, 0, 0, 0, 0, 0] FOR count = 0 to 49 INPUT student_subject index = find(subjects, student_subject) IF index != -1 number[index]= number[index] + 1 ELSE number[5] = number[5] + 1 ENDIF NEXT FOR count = 0 to 5 OUTPUT subjects[count], number[count] NEXT

9 Q10 10(a) • Technology has enabled telemedicine, which is the use of video conferencing and other technology, for doctors to provide medical consultations and diagnoses over the Internet. • Patients who are located in remote places or have limited mobility has better access to healthcare. 10(b) • Patients may find the use of robots and other technology in healthcare impersonal. • Patients may not trust the ability of machines to provide proper heathcare. • Patients may misuse information from the Internet and make potentially dangerous decisions based on incorrect diagnoses. • Patients may be uncomfortable with the collection of medical data necessary to improve the performance of healthcare-related AI. 10(c) • Technology has created new areas of growth in the healthcare industry, such as the provision of telemedicine solutions to existing healthcare businesses. In particular, many of these solutions provide a way for patients to securely transfer potentially sensitive medical information over the Internet. • There is also an increased focus in automating healthcare processes through the use of robots to dispense medicine and other more menial tasks. This may in turn cause such jobs to disappear from the job market. • The rise of 3D-printing technology has also opened up new opportunities in the building and customisation of prosthetic limbs, hearing aids and dental fixtures. 10(d) • Whether it is acceptable for robots to replace humans in providing certain kind of healthcare. • Whether it is acceptable to transfer private medical information over the Internet.

10 Q11 11(a) Maximum 4 marks. Correct use of NAND gate – 1 mark Correct use of AND gate – 1 mark Correct use of OR gate – 1 mark Correct use of NOT gate – 1 mark 11(b) 11(c) NAND gate (Note: A NAND B) [1m] A B C Working Space X= P OR R P= A NAND B Q= NOT B R = Q AND C 0 0 0 1 1 0 1 0 0 1 1 1 1 1 0 1 0 1 0 0 1 0 1 1 1 0 0 1 1 0 0 1 1 0 1 1 0 1 1 1 1 1 1 1 0 0 0 0 0 1 1 1 0 0 0 0 AG BC CL X