Table of Contents
IGCSE Computer Science Topic 2
Easy Level Magic Review Questions – IGCSE Computer Science
Indicate how you would know whether or not a website was secure.
– If the website has a padlock sign on the status bar, then some form of security is used such as https where the s means http over secure.
HTML is made up of structure and presentation. Explain the difference between these two terms.
– Structure: HTML Structure is the essential part of an HTML document that includes the semantics and structural mark-up of the document.
– Presentation: On the other hand, HTML Presentation is the style of the HTML document that includes the elements on what it would look like.
Give two examples of devices which can connected to a computer using a USB connection.
– Example 1: Hard disk reader
– Example 2: External drive
Give the meaning of the term USB.
– USB stands for universal serial bus, and is an asynchronous data transmission method. It is the industry standard for transferring data between computers and electronic devices.
Give one advantage and one disadvantage of using synchronous data transmission.
– Advantage: Faster data transmission compared to asynchronous data transmission.
– Disadvantage: There can be errors when sending data with this method if the timing signals generated by the internal clock is wrong.
Describe how it is possible to ensure that data is received in the correct groups when using synchronous data transmission.
– Synchronous data transmission is a continuous flow of data. The data is paired with timing signals made by an internal clock. This makes sure that the sender and receiver of the data are synchronized with each other. The receiver will count how many bits were sent and will reassemble them into bytes of data. The timing of this kind of data transmission must be very accurate since there were no controlled bits sent with the data.
Describe how it is possible to ensure data arrives correctly identified at its destination when using asynchronous data transmission.
– Asynchronous data transmission refers to data being transmitted in an agreed bit pattern. The data bits are grouped together and sent with controlled bits. This means that the receiver of the data knows when the data starts and ends. This prevents data from being mixed up. If there are no controlled bits, it is impossible to separate groups of data when it arrives.
Data transmitted in both directions, but not at the same times, along a single channel or wire.
– Serial, half-duplex transmission.
Several bits of data transmitted in both directions at the same time over several channels.
– Parallel, duplex transmission.
Data transmitted in one direction only; one bit at a time over a single channel or wire.
– Serial, simplex transmission.
What does URL standfor?
– uniform resource locator
What are the three parts of the URL?
1. protocol used
2. web server’s name
3. file name
Web browser have what features?
– they have a HOME page
– they can store the user’s favourite websites/pages
– they keep a history of the websites the user has visited
– they give the ability to go backwards and forwards to websites opened
Medium Level Magic Review Questions – IGCSE Computer Science
How does web browser work?
– It translates the HTML code from the website and shows the result of translation in the form of videos, images or sound.
Explain how http works?
– When a form of security is used, then this changes to https. The letter s refers to http over secure. A padlock sign can also be seen in the status bar.
– https is slower than http but used when sending sensitive or private data over the internet.
Explain HTML document and CSS?
– The two features of HTML mist be kept separate.
– During design process, author must have HTML document that keeps the structure and actual content and CSS (cascading style sheet) file which contains everything that control the actual presentation of the web page.
What is HTML Presentation?
– It is the style of the document.
– It affects how the document will look and sound.
– Includes the multimedia events.
What is HTML structure?
– The essential part of the HTML document.
– Includes semantics (meaning) and structural markup of the document.
IP address vs MAC address?
– The IP adress gives the location of a device on the internet, while MAC address identifies the device conncected to the internet.
Remember this!
Why is echo check not reliable?
– Because if the two sets of data, it is hard to know whether the error occured during the transmission process or when the data is sent back for checking.
– If not, then echo check is also another way to check whether data was transmitted correctly.
How does echo check work?
When data is sent to another device:
1. This data is sent back to the sender
2. Sender compares the two sets of data to check if there are any errors that occur during transmission
Why is an IPv6 more used nowadays?
– Because of the growth of the internet and the depletion of available IPv4.
– It is a new version and it uses 128 bits for the IP address.
What does Internet Protocol version 4 (IPv4) define?
– It defined an IP address as a 32 bit number.
What does it mean to write in semantic markup?
– It means to create web content that is both human and computer readible.
Why is writing semantic markup mandatory?
To make out website:
– Accessible to all visitors
– achive a high search engine ranking
– available to all visitors from around the world
– interface effectively with other web services
Hard Level Magic Review Questions – IGCSE Computer Science
What is a markup language?
– Is a computer language that uses tags to define elements within a document.
– Human readable as it uses standar words, not programming syntax.
What is intenet protocol?
– HTTP is the core protocol that governs transmission of data via the internet. It works as request-response action. This means that a client makes a request that web server responds to.
What is web browser or internet browser?
– A program that allows computer user to visit, retrieve and display the information that webpage contains.
What is web server?
– A computer that hosts a website. It may host many websites.
What is ISP?
– Stands for internet service provider.
– Company that provides us with access to the internet, using the connection provided by the ISP.
Define firewalls?
– System that protects unauthorised access to or from a computer or network.
Define hacking?
– Gaining unauthorised access to a computer network.
Define spyware?
– Software that collects user’s information through the internet.
Define virus?
– Software designed to corrupt computer and the files on it.
Define malware?
– Software designed to damage a computer.
Define hacker?
– A person who tries to gain unauthorised access to a computer or network.
Explain Automaic repeat request?
– Set of rules for error control when transmitting data.
– Uses acknowledgement = message sent by receiver indicating that the data has been sent correctly
– and timeout = the time allowed to elapse before acknowledgement is received
– If receiver detects are error with data packet, it automatically sneds a request to the sender to resend the packet.
Explain check digits?
– Used on identification numbers like barcodes, ISBN.
– Calculation is performed using the digits in the identification number and a check digit is added at the end of the number as a result.
– Computer will perform same calculation and compare the result with the check digit.
Explain parity check?
– Uses parity bit to ensure data has been sent accurately.
– Can use odd or even parity.
– First 7 bits of the byte is the data itself, the bit is the parity bit.
Explain checksum?
– Way to check if data has been changed or corrupted after transmission.
– Data sent in block with an additional value (the number of bits being sent) at the end of the block.
What are the different error detection and correction methods?
– Checksum
– Parity check
– Check digit
– Automatic Repeat Request
– Echo check
What are the disadvantages of USB?
– Maximum cable length is only 5 metres.
– Current transmission rate is less than 500 megabits per second.
– Older USB standard may not be supported in the future.
What are the benefits of USB?
– Device is automatically detected and appropriate device driver is loaded.
– Connection only fits one way, preventing incorrect connections from being made.
– Industry standard, so considerable support is available to users.
– Many different data transmission rates are supported.
– Newer USB standards is backwards compatible with older USB standards.
Explain what happens when device is plugged into a computer using one of the USB ports?
– Computer automatically detects that a device is present
– Device is automatically recognised and appropriate device driver is loaded to make communcation between computer and device easier
– If new device is detected, computer will look for appropriate device driver. If not available, user is prompted to download the appropriate software.
USB cable consists of?
– four wire shielded cable
– two of the wires are used for power and the earth
– two of the wires are used in the data transmission
Common Exam Style Questions
Define USB?
– Stands for Universal Serial Bus.
– Asynchronous serial data transmission method.
– The standard method of transferring data between computer and different devices.
Explain synchronous?
– Continuous stream of data.
– Data is accompanied by timing signals generated by an internal clock.
– Ensures that sender and reciver are synchronized with each other.
– Receiver counts how many bits of data has been sent and groups them into bytes.
– Timing must be accurate since no control bits is sent.
– Faster method than asynchronous so used in important issue like in network communication.
Explain asynchronous?
– Refers to data being sent in an agreed bit pattern.
– Data bits are grouped together and sent with control bits.
– This allows the receiver to know where the data starts and ends.
– Prevents data from being mixed up.
– Without control bits, it is impossible to separate groups of data as they arrived.
What are the two methods of synchronization?
– Asynchronous
– Synchronous
Explain half-duplex transmission?
– Data is sent to both direction, but only one direction at a time.
– Ex: walkie-talkie
Explain duplex transmission?
– Data is sent in both directions at the same time.
– Ex: telephone conversation.
Explain simplex transmission?
– Data is sent in one direction only at a time.
– Ex: television broadcast.
What are the three types of data transmission direction?
– Simplex transmission
– Duplex transmission
– Half-duplex transmission
Define interference?
– Disturbance that can occur in the signals when sending data that may corrupt it.
Explain parallel transmission?
– Uses multiple wires to transfer bits of data.
– Used over short distances.
– High cost as multiple wires needed.
– Faster transmission as data is sent simultaneously over multiple wires.
– Less safe transmission as errors can occur when collating the bits together as they are sent simultaneosly.
Explain serial transmission?
– Use a single wire to transfer bits of data.
– Used over long distances.
– Low cost since only one wire is needed.
– Slower transmission as data is sent one bit at a time over a single wire.
– Safer transmission as it is easier to accurately collate the bits together as they are sent one at a time
What are the two types of data transmission?
– Serial transmission
– Parallel transmission
What is data transmission?
– The process of sending digital or analog data over a communication medium to one or more computing, network, communication or electronic device.
– Enables the transfer and communication of devices in a point to point, point to multipoint and multipoint to multipoint environment.
– Also known as digital transmission or digital communication.
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