communication

Question 1

name four different types of data transmission

Answer 1

simplex, duplex, half duplex, full duplex

Question 2

what is the definition of simplex data transmission

Answer 2

data is transmitted one way only

Question 3

what is the definition of duplex data transmission

Answer 3

two or more connected devices that can communicate with one another in both directions

Question 4

what is the definition of half duplex data transmission

Answer 4

data is transmitted both ways but not at the same time

Question 5

what is the definition of full duplex data transmission

Answer 5

data is transmitted both ways at the same time

Question 6

state the two differences between serial and parallel data transmission

Answer 6

serial transmission - one bit is sent at a time over a single wire
sends data externally between devices
parallel transmission - multiple bits are sent at the same time using multiple wires
sends data internally

Question 7

give an example of serial transmission

Answer 7

computer to printer

Question 8

give an example of parallel transmission

Answer 8

computer to modern

Question 9

give an advantage of serial transmission

Answer 9

reliable over long distances

less errors since it only uses one wire

Question 10

give an advantage of parallel transmission

Answer 10

• faster than serial transmission

- more reliable over short distances

Question 11

what are the reasons for using serial transmission to connect devices to a PC

Answer 11

• single wire means less chance of errors
• a single wire is cheaper
• reliable over long distances

Question 12

what does USB stand for

Answer 12

universal serial bus

Question 13

what is USB

Answer 13

it is used as a data transmission method

Question 14

what kind of transmission do USB use

Answer 14

asynchronous serial transmission

Question 15

what are the advantages of USB

Answer 15

the devices are automatically detected
they only fit one way so they cannot be connected incorrectly
backward compatible
supports different transmission speeds

Question 16

what are the three factors that need to be considered when transmitting data?

Answer 16

• direction of data transmission
• method of data transmission
• method of synchronisation between two devices

Question 17

give an example of half-duplex transmission

Answer 17

a phone conversation between two people but only one person is speaking at a time

Question 18

when is parallel transmission usually use in the internal electronics of a computer system?

Answer 18

pathways between the CPU and the memory use it

integrated circuits, buses use this form of transmission

Question 19

what is asynchronous data transmission?

Answer 19

when data is sent in an agreed bit pattern
data bits (1 and 0) are sent together with control bits
having control bits mean that the receiver knows when the data starts and when it ends
this prevents the data being mixed up

Question 20

what is synchronous data transmission?

Answer 20

when the data is sent in a continuous stream (without being grouped)
data is sent with timing signals generated by an internal clock
this makes sure that the sender and the reciever are synchronised with eachother

Question 21

how does synchronous data transmission work?

Answer 21

the receiver counts how many bits (1 and 0) were sent

this is reassembled into bytes of data

Question 22

what is a disadvantage of synchronous data transmission?

Answer 22

the timing must be accurate since it doesn’t have any control bits

Question 23

what is an advantage of synchronous data transmission?

Answer 23

it is faster than asynchronous which is why its used for important issues (eg network communication)

Question 24

what does a USB cable consist of?

Answer 24

• four wired shielded cable
• two of the wires are used for power and earth
• two of the wires are used for data transmission

Question 25

state the disadvantages of USB

Answer 25

maximum cable length is 5 metres

older USB standard may not be compatible in the future