What is serial transmission and give an example
Serial transmission sends and receives data one bit at a single communication channel or wire e.g usb
What is parallel transmission and give an example
A method of data transfer where multiple bits are sent simultaneously across multiple wires. The more wires there are, the more data can be sent at any one time. e.g internal computer buses
Difference between serial transmission and parallel transmission
Serial Transmission
Less crosstalk because only one channel is used.* Reliable over long distances since there is no timing skew between bits.* Cheaper and simpler cabling (fewer wires and connectors).* Higher practical speeds with modern technologies but traditionally slower because bits are sent one at a time
Parallel Transmission
Multiple bits sent simultaneously, so it can be faster over short distances.* Timing skew – bits may arrive at slightly different times.* Not reliable over long distances.* More expensive and bulky cabling due to multiple wires.
What is sychronous transmission and give an example
A method where data is sent continuously in blocks or frames with the sender and receiver synchronised by a shared clock signal. e.g ethernet communications on networks
what happens when two devices are not synchronised
*If the two devices are not synchronised then data could be lost during transmission.
What is asynchronous transmission with an example
A method where data is sent one character at a time, and each character is framed with start and stop bits so the receiver knows where the data begins and ends. No shared clock signal is required.
What are the features of a start bit
( 3marks)
The start bit signals the beginning of a data packet or character.
It alerts the receiving device that data is about to be transmitted so it can begin reading the incoming bits at the correct time.
Usually represented by a 0
Allows the receiver to synchronise its timing with the incoming data.
what are the features of a stop bit
The stop bit signals the end of the data packet or character.
It tells the receiving device that the transmission of that character has finished.
Usually represented by a 1
Gives the receiver time to process the character before the next one arrives.
difference between synchronous transmission and asynchronous transmission
Synchronous Transmission
Faster data transfer speeds* More efficient (no start/stop bits for each character)* Suitable for large continuous data transfers. More complex hardware required
Asynchronous Transmission
Simpler and cheaper to implement* No shared clock required* Suitable for irregular or small transmissions. Slower due to start and stop bits* Less efficient because extra bits are added* Not suitable for large continuous data transfers
What is band width and what is it measured in .
The maximum data transfer capacity of a network or channel, usually measured in bits per second (bps).
What is bit rate
the number of bits that are transmitted over the medium per second. Bit rate is directly proportional to bandwidth
What is the difference between bit rate and baud rate
Baud rate
Number of signal changes per second on a communication channel.
Bit Rate
Number of bits transmitted per second.Bit rate = Baud rate × number of bits per signal change
One signal change can carry multiple bits using advanced encoding
What is baud rate
The number of signal changes per second in a communication channel
What is Latency
Latency is the time delay between an action being started and its results being seen.
What is a handshake
Handshaking establishes a connection between two devices and establishes the rules under which they will communicate.
what is protocol
*A protocol is a set of rules. agreed for communications between computer systems
Types of protocol
*TCP/IP (Transmission Control Protocol/Internet Protocol) is actually two protocols that are usually referred to as one and relate to the set of rules that govern the transmission of data around the Internet.
*HTTP (Hypertext Transfer Protocol) is the set of rules governing the exchange of the different types of file that make up displayable web pages.
*FTP (File Transfer Protocol) is similar to HTTP in that it provides the rules for the
transfer of files on the Internet.
The system sends the data over a long distance using serial communication.
Explain why serial communication is more appropriate in this instance than parallel communication.
Eliminates risk of desynchronisation (between data signals)
Bits transmitted together may arrive at different time
State three advantage of serial data transmission over parallel data transmission.
the hardware required for transmission wiring is cheaper
No data skew
No cross talk
Easier to impement
Better for long distatnce
State the purpose of the stop bit in asynchronous serial transmission.
Provides time for the receiver to process the received data
State the purpose of the start bit in asynchronous serial transmission
. to synchronise the receiver and transmitter clocks
What is a physical star topology and how does it work
A network in which all devices are connected to a central hub, The hub acts as a central point for data transfer. (star)
When a device sends data, it is transmitted to the central hub.
The hub forwards the data to the intended recipient device.
Each device has a dedicated connection to the hub, so one cable failure only affects the device connected to that cable.
logical bus topology
A network in which all devices are connected to a single communication line (bus). Data is sent along the bus and is received by all devices, but only the intended recipient processes it.
What are the two different networking between hosts
Peer to peer
Client server