Storage Devices and Network Hardware: Computer Science 0478 (Cambridge O Level / IGCSE)

A desktop computer in a small office is fitted with an internal expansion card so that the computer can join the office's wired network. This card is not the part that stores program instructions permanently, and it is not the device that directs data between different networks. Instead, at the moment this card leaves the factory, it is permanently given a unique address that will never change for as long as the card exists.

Which piece of hardware is being described?

A community radio station wants to keep backup copies of interviews recorded over the last ten years. The station's technician has three types of storage available for the backups: an internal hard disk drive (HDD), a stack of Blu-ray discs, and a solid-state USB flash drive.

(a) Describe how the hard disk drive physically stores each recording. [2]

(b) Describe how a Blu-ray disc physically stores each recording. [2]

(c) Describe how the solid-state USB flash drive physically stores each recording. [2]

A student's laptop has 8 gigabytes of RAM. The student opens a video editor, a web browser with many tabs, and several other applications until all of the RAM is completely full. Instead of crashing or refusing to open anything else, the laptop keeps running, although everything becomes noticeably slower.

(a) Explain what the operating system does, using the laptop's secondary storage, so that it can keep running once RAM is completely full. [2]

(b) State two reasons why the laptop runs more slowly once it starts relying on this, instead of everything fitting in RAM alone. [2]

A family's home network has one router, provided by their internet service provider. A laptop and a smart TV are both connected to this router by network cable, and each device has its own network interface card (NIC) fitted inside it.

(a) State the type of address given to each device's NIC at the moment it is manufactured, and state the number system in which this address is usually written. [2]

(b) The router currently gives the laptop the IP address 192.168.1.5. Next month, the router might give the laptop a completely different IP address instead. Explain why the laptop's IP address is able to change like this, when the address from part (a) never changes. [2]

(c) Give three separate ways in which the router controls how the laptop and the smart TV are able to reach websites on the internet. [3]

A freelance photographer pays a monthly subscription so that every finished photo edit is automatically uploaded to a remote data centre run by a storage company, rather than being kept only on the hard disk drive inside her own laptop. She can open any of her edited photos from a different device, as long as it has an internet connection, but during a weekend at a hotel with no working Wi-Fi, she is unable to open the edits she finished earlier that same day.

Which storage service is being described?

A desktop computer loses power suddenly during a thunderstorm while a student is typing an essay in a word processor. When the power returns, the computer switches itself back on normally and reaches the operating system's login screen within a few seconds, exactly as it always does. However, the essay the student had been typing, which had not yet been saved, has completely disappeared.

(a) State the type of primary storage that was holding the essay while the student was typing it, and explain why this storage lost the essay's content when the power was lost. [2]

(b) State the type of primary storage that allowed the computer to switch itself on and reach the login screen after the power loss, and explain why this storage was not affected by the same power loss. [2]

(c) Give one difference, other than whether contents are lost when power is removed, between these two types of primary storage. [1]

A small design studio has six desktop computers in one office, all connected by network cable to a single piece of network hardware so that they can share files and a printer with each other. This piece of hardware has no connection to any other network and no connection to the internet; its only job is to receive data from one of the six computers and forward it, using the intended recipient's MAC address, only to the one specific computer it is meant for.

Which piece of network hardware is being described?

A small office originally connected its four computers using an old hub. The office manager noticed that whenever one computer sent a large file to a second computer, all four computers' network activity lights flashed at once, and the two computers not involved in the transfer noticeably slowed down while browsing the internet, even though the file was only meant for one of them. The office replaced the hub with a switch that has the same number of ports, and this problem no longer happens.

(a) Explain how the hub handled the incoming file, in a way that caused all four computers to be affected even though the file was intended for only one of them. [2]

(b) Explain how the switch is able to send the same kind of file so that only the intended computer receives it, without affecting the other two computers. [2]

A family's internet service provider installs a single combined networking box in their living room. Two features of this box are relevant here. First, it lets a phone and a tablet join the home network from anywhere in the house without any cable ever being plugged into them, sending and receiving data as radio signals instead. Second, the box is also wired, by a telephone line running outside the house, to equipment belonging to the internet service provider; along this connection, the box converts the family's outgoing digital data into a signal suitable for transmission down the telephone line, and converts incoming signals from the telephone line back into digital data the home network can use.

(a) Name the piece of network hardware responsible for letting the phone and the tablet join the home network without a cable, and describe what it does. [2]

(b) Name the piece of network hardware responsible for converting the family's data for transmission down the telephone line and converting it back again, and describe what it does. [2]

(c) One evening, the connection along the telephone line to the internet service provider develops a fault, but the box itself is still switched on. State, with a reason, whether the phone would still be able to send a photo directly to the tablet over the home network, and whether it would still be able to load a website from the internet. [2]

A network technician needs to add a piece of hardware to a small office network so that staff smartphones and laptops, none of which have an ethernet cable plugged into them, can join the same network as the desktop computers that are already connected by cable. No cable will ever be plugged into the smartphones or laptops themselves.

Which piece of hardware should be added?