2021 SST S4 Computing Prelim P1 Solutions

1 2021 SEC 4 COMPUTING PRELIM PAPER 1 MARKING SCHEME Qn 1 Marking Scheme / Answer (a) Type of bus Description Transports information from memory to processor when reading data from memory Data bus Transports information from memory to processor when writing data to memory Transports information from processor to memory when reading data from memory Address bus Transports information from processor to memory when writing data to memory (b)(i) An input device is a hardware device that allows users to enter data/instructions into a computer (b)(ii) Any two appropriate input device, such as: Web camera, microphone (c)(i) Any sensible answer, such as: Data stored in the RAM is volatile and will be lost once the power supply is interrupted. Since the operating system is required every time the computer is booted up, it is necessary to store it in a non-volatile storage. OR The capacity of the RAM is usually small. The operating system is stored on the hard drive so that the capacity of the RAM is not wasted. (c)(ii) The data and instructions can be quickly accessed by the processors as required.

2 Qn 2 Marking Scheme / Answer Statement IPv4 Address IPv6 Address MAC Address Also known as a physical address. ü Used to direct data transmitted over the Internet to a device. ü ü Used by a switch to forward data to the intended recipient device. ü Represented by more than 4 bytes. ü ü Usually represented in hexadecimal. ü ü Qn 3 Marking Scheme / Answer (a) Any sensible answer, such as: - Benefit: 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. - Drawback: Some people use the Internet to reinforce their existing opinions or to spread rumours and misinformation. (b)(i) Creations of the mind that have value but can exist purely as data with no physical form. (b)(ii) The social media influencer is only guilty of plagiarism. Copyright infringement only applies to content that is copyrighted. As the photo is public domain, it is not copyrighted. However, by passing the photo off as his own, he is guilty of plagiarism.

3 Qn 4 Marking Scheme / Answer (a) Any 2 sensible answers; such as: - 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. - Worm: A computer program that runs automatically and attempts to spread by sending copies of itself to other computers without the need to attach itself to another program first. (b) Updating software regularly will ensure that bugs that were discovered since the last update can be fixed. This will prevent certain malware/worms from exploiting these bugs to