2022 ACSBR Computing P1 Solutions

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 16 Secondary 4 Express Computing 7155/01 Anglo-Chinese School (Barker Road) PRELIMINARY EXAMINATION 2022 SECONDARY FOUR EXPRESS COMPUTING PAPER 1 ANSWER KEY

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 17 Secondary 4 Express Computing 7155/01 1 The diagram show four types of computer or network identifiers and eight examples that they could be represented on the right. Draw one line between each identifier to its correct representation. Identifiers Example of Representation • 2001:db8::20:17:bad:c0de • 55 IPv4 • • H4-7G-09-E0-D2-5Z (invalid due to G and Z characters) MAC • • 129.126.67.97 Port number • • 3A (invalid as port number is only denary) IPv6 • • 108.F5.153.AF (invalid as IPv4 only has denary numbers) • F4-7B-09-E0-D3-54 • 2010:db8::20::b2d:134 (invalid as IPv6 should have no more than one set of double colons) [4]

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 18 Secondary 4 Express Computing 7155/01 2 (a) Convert the binary number 101 1011 into a denary and hexadecimal number. Denary: 91 Hexadecimal: 5B [2] (d) Convert the denary number 1698 into hexadecimal number. Show your working. Divide by 16 1698 2 2 106 10 A 6 6 6 0 6A2 [2] (e) Explain why hexadecimal numbers are commonly used to represent binary numbers. Hexadecimal format is quite compact and thus much easier to read/understand compared to the long binary strings of 1's and 0's No marks for single point of short/compact or easy to read [1]

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 19 Secondary 4 Express Computing 7155/01 3 Computer memory is measured in terms of the number of bytes. (c) (i) Explain what is meant by the term byte? A byte is a unit of data made up of eight bits. [1] (ii) State the number of bytes in 5 mebibytes (MiB). 5 × 1024ଶ = 5,242,880 bytes [1] (d) (i) Optical and solid-state are two common types of storage media. Give two differences between these two types of storage media. 1 Data is stored as very small pits or indentations that can be read or written by a laser for optical media. For solid -state, data is stored in electronic circuits called “flash memory” that have no moving parts 2 Optical media are vulnerable to scratches and fingerprints while solid -state media are not as vulnerable to drops, mechanical shocks, scratches or fingerprints. [2] (ii) State another type of storage media. Magnetic [1] Cloud storage not accepted as cloud storage are also classified as magnetic or solid- state storage at server end. 4 Data collection is the first of four stages in the data life cycle. (a) Describe any two data collection activities. 1 Any of the two activities: performing interviews, making observations, conducting surveys, collation and organising of data on spreadsheets etc. 2 [2] (b) List any two other stages in the data life cycle. 1 Any of the two stages: Data processing, Data analysis or Data distribution 2 [2]

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 20 Secondary 4 Express Computing 7155/01 5 Intellectual property are creations that have value. They can exist physically but also purely as data with no physical form. (a) The table shows three scenarios of Intellectual Property offences. Tick () one or more boxes in each row to indicate if the offence is copyright infringement, plagiarism or both. Scenario Copyright Infringement Plagiarism Taking a friend’s source code and submitting it for a coding competition without seeking his permission.  Downloading and installing a “cracked” version of a game without paying for it.  Downloading research information from the internet and submitting it without any modification as your own for a homework assignment.   [3] (b) Draw one or more lines from each description on the left to the type of software it applied to on the right. Illegal to copy, modify and distribute • Protected under copyright • • Public Domain Do not have to pay for use • • Free and Open Source Not protected under copyright • • Proprietary Can legally copy, modify and distribute • [3] (c) Describe one way to avoid plagiarism when using public domain information in your research. Acknowledge or cite the authors appropriately [1]

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 21 Secondary 4 Express Computing 7155/01 6 An alarm, Y, sends a signal (Y = 1) when certain fault conditions in a chemical process are detected. The inputs are: Input Binary Condition A 0 Acidity <= 5 1 Acidity > 5 T 0 Temperature < 150 ºC 1 Temperature >= 150 ºC M 0 Mixer is off 1 Mixer is on The alarm, Y, returns a value of 1 if: either temperature >= 150 ºC AND mixer is OFF or acidity > 5 AND temperature < 150 ºC (a) Draw a logic circuit for the system. Y = (T AND NOT M) OR (A AND NOT T) [4] (b) Complete the truth table for this alarm system. A T M Y 0 0 0 0 0 0 1 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1 0 1 mark for correct outputs in each 2 consecutive rows [4]

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 22 Secondary 4 Express Computing 7155/01 7 A programmer is creating a new computer game. In the game, the user’s avatar (a game character) moves through the virtual world trying to catch and rear cute monsters.  The game will display a menu that will let the user create a new player or login as a returning player.  If the user chooses a new player, an avatar is created with name, gender and costume.  If the user chooses returning player, the game accesses the saved file and starts from where it was last saved.  The user makes the avatar move within a virtual world.  The game is auto-saved.  The user can click on cute monsters roaming in the virtual world and encounter them to catch them  The user can also access his/her collection of cute monsters and interacts with individual monsters via hugging, playing and/or feeding candies. (c) The decomposition technique can be used to create smaller, more manageable modules of the program. One of these modules is the menu. Identify and describe five other modules that can be decomposed from the problem. Module 1 new player / avatar creation module – create an avatar with name, gender and costume Module 2 returning player module – load saved game and start game from saved point Module 3 game save module – auto saving of game Module 4 movement module – movement of avatar within the virtual world Module 5 encounter module – catching of cute monsters Other possible modules include: interaction module – interaction with individual monsters via hugging, playing etc. collection module – list collection of cute monsters in inventory map module – chart virtual world with roaming cute monsters Do not assume beyond information provided beyond the question. [5] (d) State two other problem-solving techniques. 1 Pattern recognition 2 Generalisation [2]

Anglo-Chinese School (Barker Road) Preliminary Examination 2022 23 Secondary 4 Express Computing 7155/01 8 Technology has enabled rapid healthcare changes all around the world. (a) Describe two economic benefits to healthcare using technology. Any two of the benefits: • 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 tran sfer potentially sensitive medical information over the Internet. • There is also