topic 2 - communication and internet tech Flashcards
1
Q
data transmission types (5)
A
- simplex
- duplex
- half-duplex
- full-duplex
- serial
- parallel
2
Q
simplex
A
data transmitted one way only
3
Q
duplex
A
data transmitted in both way
4
Q
half-duplex
A
data transmitted in both ways but not at the same time
5
Q
full-duplex
A
data transmitted in both ways at the same time
6
Q
serial(2)
A
- one bit sent at a time over a single wire (eg. computer to printer)
- used to send data externally between devices
7
Q
parallel (2)
A
- multiple bits sent at the same time using multiple wires
- used to send data internally
8
Q
why use serial instead of parallel when connecting device to PC
A
- single wire reduces the cost
- single wire means less chance of corruption
- more reliable over time
bits still synchronised after transmission
9
Q
asynchronous transmission (2)
A
- Data is sent in form of byte or character
- time interval of transmission is random
10
Q
synchronous transmission (2)
A
- Data is sent in form of blocks or frames
- time interval of transmission is constant
11
Q
USB (7)
A
- universal serial bus
- data transmission method
- uses serial transmission
- device automatically detected
- only fits one way; it cant fit incorrectly
- industry-standard
- backwards-incompatible
12
Q
methods of error-checking (4)
A
- parity check
- checksum
- ARQ; automatic repeat request
- check digit
13
Q
how does parity check work (5)
A
- checks byte of data
- a parity bit is added
- counts num of 1s
- can be odd or even
- if parity incorrect, error is detected
14
Q
when will parity check not work (2)
A
- multiple errors in same byte
- ## 2 bits interchanged
15
Q
how does ARQ (automatic repeat request) work (6)
A
- uses acknowledgement
- check performed on receiving data
- if error detected request sent to respond data
- resend request repeated until data sent correctly
- send an acknowledgement that data is received
- if acknowledgement not received in set time data is resent
