NASS 2020 P1 Solution

Sec 4E Computing Prelim Exam 2020 Marking Scheme 1 (a) Amount of data Size in bytes 2.4 MB 2 400 000 5 GiB 5 × 10243 (b) Processing speed: The 3 GHz processor chip will be able to execute more instructions and run faster as compared to the 900 MHz processor chip. Cost: The 3 GHz processor chip will likely be more expensive as compared to the 900 MHz processor chip. (c) Data is entered using an input device and converted into a form that the computer can understand. This data may be temporarily stored in a processor register. Instructions from the running application are then interpreted. These instructions involving logical operations may require the data to be processed by the processor’s Arithmetic Logic Unit. The control unit may then redirect the processed data to an output device for display in a form that users can understand. 2 (a) It is usually not legal to copy, modify or distribute proprietary software whereas users are given freedom to change, copy, study and share a free and open-source software. (b) 1. Check and follow the website’s terms and conditions. Many websites state the terms and conditions for using the site’s content, such as whether copying, downloading or hyperlinking to any materials is permitted. 2. Limit reproduction of a copyrighted work to 10% (for educational purposes only). The reproduced work should not be modified and must be properly cited to avoid plagiarism. 3. Consider using public domain material instead.

Like public domain software, some works are released to the public domain on purpose or are so old that their copyrights have expired. Although these materials can be copied without the need to seek permission, it is still necessary to acknowledge or cite the authors appropriately to avoid plagiarism. (Any 2) 3 (a) On the positive side, 1) 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. This gives patients who are located in remote places or have limited mobility better access to healthcare. 2) the use of video conferencing allows families and friends to still keep in touch with one another even when they are not allowed to visit one another. (Any 1) On the negative side, 1) some patients find the use of robots and other technology in healthcare impersonal and mistrust the ability of machines to provide proper healthcare. 2) inaccurate medical advice or the misuse of information from the Internet can potentially cause people to make dangerous decisions based on incorrect diagnoses. (Any 1) (b) 1) Threatening or urgent tone saying that the banking has been suspended. 2) Message was not addressed to any specific name, indicating that it could have been mass-sent. 3) The link attached did not seem like a legitimate link from the bank. 4) Unlikely that a bank will request for personal information through an SMS. 5) Any answer that is logical. (Any 2)

4 (a) B3: text B5: currency (b) =PMT($B$8/12,18,$B$6) (c) =PPMT($B$8/12,A29,18,$B$6) (d) =IPMT($B$8/12,A12,18,$B$6) (e) - Highlight cell range C12:C29 and select Conditional Formatting - Define cell rules to highlight cells that have value smaller than ($50) with a red background. 5 (a) NAND Gate (b) X = A NAND ((A NOR B) OR (B AND (NOT C))) 1m per correct logic gate A B C

(c) X = A NAND ((A NOR B) OR (B AND (NOT C))) A B C (A NOR B) (B AND (NOT C) (A NOR B) OR (B AND (NOT C)) X 0 0 0 1 0 1 1 0 0 1 1 0 1 1 0 1 0 0 1 1 1 0 1 1 0 0 0 1 1 0 0 0 0 0 1 1 0 1 0 0 0 1 1 1 0 0 1 1 0 1 1 1 0 0 0 1 1 mark for each correct 2 rows 6 (a) Binary Denary 0001001110 78 0110110111 439 1000000001 513 (b) Split the binary number into 4-digit groups [1] Add leading zeroes to the first group if it does not have 4 digits [1] 0001 1011 0111 Convert each group of 4 binary digits into the hexadecimal digit [1] 0001 1 1011 B 0111 7 Hexadecimal value: 1B716 [1]

(c) Uses fewer characters // shorter – 10 bits are represented by 2 hexadecimal digits. One from any below: Easier to read / write / understand Less likely to make mistakes // less error prone Easier to debug (d) RGB colour codes IPv6 MAC address Memory Dump [Any one above]

7 Term Description Ethernet Media Access Control (MAC) Wireless access point (WAP) 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 area 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. Router 8 (a) (i) 1m for each correct box (ii) load saved squad input player’s scores display players’ scores upload photos save players’ records [any 4 above] (b) Variable String Integer Float List players ! player_name ! player_age ! manage squad add player edit name remove player create new squad

player_height ! (c) (i) Format check and range check (ii) valid_goals goals OUTPUT false -3 “Enter goals” , “Invalid entry” 54 “Enter goals” , “Invalid entry” true 20 “Enter goals” (iii) Test case condition Test data Normal 3, 28 Error “Three”, “ “ Boundary -1, 0, 40, 41

(d)

9 (a) Number 5 5 8 6 1 8 7 0 1 7 4 4 0 7 9 Double alternate digit 10 5 16 6 2 8 14 0 2 7 8 4 0 7 18 Result 1 5 7 6 2 8 5 0 2 7 8 4 0 7 9 Total = 9 + 7 + 0 + 4 + 8 + 7 + 2 + 0 + 5 + 8 + 2 + 6 + 7 + 5 + 1 = 71 71 x 9 = 639 639 / 10 = 63 remainder 9 Check digit = 9 (b) INPUT num result = 0 digit = 0 [1m] num_length = length of num [1m] FOR x = 1 to num_length [1m] digit = num % 10 [1m] IF x%2 == 0 [1m] digit *=2 ENDIF IF digit > 9 [1m] digit -=9 ENDIF NEXT result *=9 result = result%10 [1m] *** End of Paper ***