Flashcards in 3.9 Deck (27)
What is serial data transmission?
bits of data sent down 1 at a time over a single wire/line
Very high data transfer rates can be achieved using fibre optic
What is parallel data transmission?
bits of data sent simultaneously over a number of parallel wires/ lines
used in integrated circuits & within RAM
only reliable over short distances
What are the advantages of serial data transmission?
Data can be sent longer distances using serial data transmission
The data doesn't jump lines onto a different line because there are no other lines
Cheaper as fewer wires
What are the advantages of parallel data transmission?
You can send more than one piece of data at a time
What are the disadvantages of serial data transmission?
can only send 1 piece of data at a time
What are the disadvantages of parallel data transmission?
'crosstalk' happens, this is when data crosses lines & interferes with other lines of data
Skewing happens which is when some lines of data take longer to get received because they don't take the most direct route so lag behind the other lines so if received after
What is synchronous transmission?
data transferred at regular intervals & timed by clocking signal to allow constant & reliable transmission
used for time-sensitive transmission
parallel transmission typically uses this
What is asynchronous transmission?
one byte at a time, each character preceded by a start bit alerts receiver & syncs the clock to get ready to receive the data
Baud rate at receiving end needs to be set at the same rate as the sender otherwise data will not be received correctly
What is the purpose of the start & stop bit in asynchronous data transmission?
its purpose is a means of timing or synchronizing the data characters being transmitted.
Without the use of these bits, the sending and receiving systems will not know where one character ends and another begins.
What is baud rate?
is the rate at which information is transferred in a communication channel
'1000 baud' means that the serial port is capable of transferring a maximum of 1000 bits per second.
What is bit rate?
the number of bits per second that can be transmitted along a digital network.
What is bandwidth?
is the capacity of a network to transmit the maximum amount of data from one point to another over a computer network or internet connection in a given amount of time
What is latency?
is an expression of how much time it takes for a packet of data to get from one designated point to another
What is a protocol?
a set of rules or procedures for transmitting data between electronic devices
In order for computers to exchange information, there must be a preexisting agreement as to how the information will be structured & how each side will send & receive it.
What is the difference between baud rate & bit rate?
Bit rate can be higher than baud rate if more than one bit is encoded in each signal chance
What is the relationship between bit rate & bandwidth?
Bit rate is directly proportional to bandwidth
How is a physical star topology laid out roughly?
There is a central hub which every host computer connects to on its own individual wire
How is a logical bus topology laid out?
There are terminators at each end of the backbone of which other host computers link to. There is also one main server which is connected to the backbone wire aswell
What is the difference between physical & logical topologies?
Physical topologies are the hardware(wires) whereas logical topologies are the conceptual way in which data is transmitted
What is peer-to-peer networking?
the 'peers' are computer systems which are connected to every other peer via the Internet
Files can be shared directly between systems on the network without the need of a central server
each computer has equal status
What is client-server networking?
A computer network in which one centralized, powerful computer (the server) is a hub to which many less powerful personal computers (clients) are connected
The clients run programs and access data that are stored on the server
The clients request services from the servers, which provide these services
What is the purpose of WIFI?
a wireless network that is based on international standards
Used to enable devices to connect to a network wirelessly
What components are required for wireless networking?
Wireless network adaptor
Wireless access point
How are wireless networks secured?
Strong encryption of transmitted data using WPA (wifi protected access)/WPA2, SSID (service set identifier) broadcast disabled, MAC (media access control) address white list
What is SSID(Service set identification)?
identify the network ( the name of the network e.g. its name)
its usually followed up by a security key of up to 32 bytes usually a string
What is WPA/WPA2?
are wifi/ security protocols
they encrypt data & make it to that it is unreadable to an unauthorised third party