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Flashcards in Data transmission and internet Deck (15):

Simplex data transmission:

What is it? Where is it applied?

Simplex data transmission is a unidirectional method of transmitting data - from sender to receiver.

This method of communication can be seen between computers and printers, remote controls and televisions, radio stations to radio (devices).


What is half-duplex d.t.? Where is it used?

Half-duplex transmission is a bidirectional, non-simultaneous method of communication.

Eg. communication over a walkie-talkie or intercom.


What is full-duplex d.t.? Where is it used?

Full duplex is a directional, simultaneous method of data transmission.

EG. talking over a telephone, router to device communication.


What is serial data transmission?
Where is it applied?
When is it used? (2)
Advantages and disadvantages (4, 1)

It is sending bits of data, sequentially over a single channel or wire.

eg. communication between a modem and computer; USBs

It is used for long-distance communications for small amounts of data.

Adv. - data trans. is more accurate as it doesn't arrive asynchronized.

Lesser space is required, since only one wire is used. This means that the wire can be easily distanced from surrounding obstructions.

Crosstalk - a signal in a channel causing undesired effects to signals in other channels - scan be easily avoided.

It is cheaper than parallel data transmission.

Disadv. - Slower than parallel.


What is parallel data transmission?
Where is it used?
When is it used? (3)
Advantages and disadvantages (2, 4)

Several bits of data are transmitted across several channels/wires simultaneously.

Printer to computer; interface communication (eg. Skype), com. between Cpu and memory; ICs to communication with computer

When data needs to be sent quickly; data that is time sensitive (eg. a document to be sent before 6 am); large amounts of data.

Advantages : Data is sent faster
Easier to program.

Disadv. - Data may be out of sync since it is transmitted over several wires - can be noticed in interfaces - eg. Skype.

More space is required, which means that data can be distorted.

Crosstalk is harder to avoid.

More expensive.


What is asynchronous data transmission?
Where is it used?
When is it used? (2)
Advantages and disadvantages (1, 1)

Data is grouped into bits and sent intermittently in an agreed but pattern, with a start bit and a stop bit.

USB, connect printers to web, communications over telephone lines

Where speed is not a necessity, when data is not time sensitive

A - accuracy - time intervals lets the receiver make sure that the correct bits are sent

D - slower than synchronous d.t.


What is synchronous data transmission?
Where is it used?
When is it used? (2)
Advantages and disadvantages (1, 1)

Data is sent continuously, timed by an internal clock so that the sender and receiver are synchronized.

Network communications (you and internet, Ethernet/Wifi to devices)

When data has to transmitted faster, When data is time sensitive

A - Faster than a.d.t

D - Accuracy - if timing is not properly maintained


What is a USB?

it is a connector sued for connecting the computer to other devices such as printers, external hard drives, and other devices.


What are the advantages and disadvantages of using a USB? (5, 3)

Advs. -

1. Automatic detection of devices and automatic upload of device drivers.

2. One-way connection of wire, so incorrect connection cannot be made.

3. Several transmission rates are available.

4. Support available to users as USB is the industry standard.

5. Self-powered - USB powers the device that is connected to computer.

Disadvantages -

1. Cable length, max is 5 m.
2. D.t. rate limited to less than 5 megabits per second
3. Relatively expensive.


What is parity?

It is a function that checks the accuracy of a string of binary data, depending on whether it is even or odd.


What is a browser?

A software application that allows users to access websites on their computers. They translate the HTML code of websites and display the result of the translation.


What is the role of an ISP?

An internet service provider is a company that provides users with access to the internet.


What is the meaning of http?
How is it different from https?

Hypertext transfer protocol is the protocol that the world wide web uses, and it dictates how data is formatted and transmitted, and the responses of web servers and browsers to various commands.

Https is the protocol used for communication that is encrypted.


What is an IP address?

Internet protocol address is an address given to each device over the internet that lets the device communicate over the network.

eg. 930.234.451.3


What is the difference between structure and presentation of HTML language?

Structure refers to semantics of the content in the HTML code, as well as its markup.

Presentation refers to the way a document looks - how the text is formatted, etc. - along with the graphics and sound elements used.

, , , are structure tags.
, are presentation tags.