is slower

is faster

operates at the same speed as parallel adder

is more complicated

2

4

8

16

4

8

16

32

input combination at the time

input combination and the previous output

input combination at that time and the previous input combination

present output and the previous output

to decode information

to select 1 out of N input data sources and to transmit it to single channel

to transit data on N lines

to perform serial to parallel conversion