Parallel Mode is the way the internal transfer of binary data takes place inside a computer. Serial Mode is the predominant method of transferring information in data communications.

1. BY
AJAL.A.J
FACULTY – METS
Transmission Mode

2. INTRODUCTION

4. Transmission Modes
Parallel Mode is the way the internal transfer
of binary data takes place inside a
computer.
Serial Mode is the predominant method of
transferring information in data
communications.

5. Transmission Modes
Parallel Mode
Serial Mode

6. Baseband Transmission
Digital transmission is the transmission of
electrical pulses. Digital information is
binary in nature in that it has only two
possible states 1 or 0.
Digital signals are commonly referred to as
baseband signals.
In order to successfully send and receive a
message, both the sender and receiver
have to agree how often the sender can
transmit data (data rate).

7.  Parallel
 Bits in a group are sent simultaneously, each using a separate link
 n wires are used to send n bits at one time
 Advantage: speed
 Disadvantage: cost; limited to short distances

8.  Serial
 Transmission of data one bit at a time using only one single link
 Advantage: reduced cost
 Disadvantage: requires conversion devices
 Methods: Asynchronous
Synchronous

9. Asynchronous Transmission
 Transfer of data with start and stop bits and a variable time interval
between data units
 Timing is unimportant
 Start bit alerts receiver that new group of data is arriving
 Stop bit alerts receiver that byte is finished
 Synchronization achieved through start/stop bits with each byte
received  Requires additional overhead (start/stop bits)
 Slower, ideal for low-speed communication when gaps may occur
during transmission (ex: keyboard)
 Cheap and effective

10. Asynchronous Transmission

11. In asynchronous transmission, weIn asynchronous transmission, we
send 1 start bit (0) at the beginningsend 1 start bit (0) at the beginning
and 1 or more stop bits (1s) at the endand 1 or more stop bits (1s) at the end
of each byte. There may be a gapof each byte. There may be a gap
between each byte.between each byte.
Note:Note:

12. Asynchronous here meansAsynchronous here means
“asynchronous at the byte level,” but“asynchronous at the byte level,” but
the bits are still synchronized; theirthe bits are still synchronized; their
durations are the same.durations are the same.
NoteNote::

13. Synchronous Transmission
 Requires constant timing relationship
 Bit stream is combined into longer frames, possibly containing
multiple bytes
 Any gaps between bursts are filled in with a special sequence of
0s and 1s indicating idle
 Advantage: speed, no gaps or extra bits
 Byte synchronization accomplished by data link layer

14. Synchronous Transmission

15. In synchronous transmission,In synchronous transmission,
we send bits one after another withoutwe send bits one after another without
start/stop bits or gaps.start/stop bits or gaps.
It is the responsibility of the receiver toIt is the responsibility of the receiver to
group the bits.group the bits.
Note:Note: