BLSS 2018 Computing P1 Solution

2018 Prelim – 4E Computing 1 Answer Scheme 1. ● Processor registers: Extremely fast but small data storage spaces that are used directly by the ALU and control unit. ● Random access memory (RAM) or main memory: Where data and instructions are stored temporarily (volatile) so that they can be quickly accessed by the processor when needed. ● Read-only memory (ROM): Store data and instructions that rarely need to change or would be needed for a computer to start up are stored. Data stored on ROM cannot be easily changed and remains there regardless of whether the power supply is switched on. ● External memory storage or secondary storage: Where large amounts of data are stored, such as in a hard disk or hard drive. 1. (a) ● Difference 1: A wired network is a network of devices connected by a physical medium, such as cables. Whereas a wireless network is a network of devices in which signals are transmitted without the use of a physical medium. The transmission is in the form of electromagnetic waves, such as radio waves. ● Difference 2 : Data transfer is typically faster and more secure in a wired network. In a wireless network, users can be connected only if they are within range of the network coverage. Obstacles such as walls or metal frames can reduce the strength of Wi-Fi signals.

2018 Prelim – 4E Computing 2 2 (b) Advantage and disadvantage explained. 1 mark for each

2018 Prelim – 4E Computing 3 2. (a) = COUNTIF(B4:B17, “>2”)

2018 Prelim – 4E Computing 4 (b) = (B4+1)*$C$1 (c) Text, Currency 3 (a) 1111 1111 , 28 – 1 = 255 (b) B -> 1011 3 -> 0011 Ans: 1011 0011 (c) 26 = 21+ 23 + 24 Ans: 0001 1010 3. (a) Any two ● Poor data authentication ● Poor data access control or authorisation ● Poor understanding of privacy policies (b) Any two points

2018 Prelim – 4E Computing 5

2018 Prelim – 4E Computing 6 4. a) Two economic effects (accept any possible answer):

2018 Prelim – 4E Computing 7 • The price of music albums, television programmes and films would go up to compensate for the loss in sales due to piracy. • There would be fewer music albums, television programmes and films produced as people would find it increasingly difficult to make money from doing so. b) Siti’s actions are considered to be copyright infringement as she did not have explicit permission from the copyright owner to copy the television series onto her hard drive. c) Music may be downloaded legally without copyright infringement as long as the copyright owner has given permission for the downloading to occur. For instance, the copyright owner may allow a music file to be downloaded from a legitimate online music store as long as payment is made. Alternatively, the music file can be placed under a Creative Commons licence, which explicitly gives everyone permission to download the file as long as certain conditions are met. 7(a) Data validation - Process of ensuring that the input data supplied to a system