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(a)A string of 200 characters is to be transmitted over a serial
data transmission line.
How many bits will be transmitted in each of the following modes?(Show
your
working.)
(i)Synchronous data transmission with 4 SYN characters;message begun
with STX character and ended with EOT character.[3 marks ]
(ii)Asynchronous transmission with 1 start bit and 2 sto bits.[3 marks
]
(b)Describe the main characteristics of twisted air cable.Explain
why it is ‘twisted ’and give one typical use.[3 marks ]
(c)There are two modern standards for high-speed communications between
desktop computers and peripherals —USB and SCSI.
USB uses a thin cable with just a few wires,and a very simple 4-in
connector.It
achieves a maximum data rate of 12 Mbps.SCSI uses a fat cable with
many wires,and a 50-pin connector.It can achieve data rates up to
40 Mbps.
Use your knowledge of serial and parallel connections to explain how
these standards differ in their basic design,and how this affects
their performance.USB cables are often longer than SCSI cables.Explain
why this is.[6 marks ]
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