There are a
number of different systems for representing binary information in physical
systems. Here are a few.
- A voltage signal with zero (0) corresponding
to 0 volts and one (1) corresponding to five or
three volts.
- A sinusoidal signal with zero corresponding to some
frequency, and one corresponding to some other frequency.
- A current signal with zero corresponding to 4
milliamps and one corresponding to 20 milliamps.
- And one last way is to use switches, OPEN for
"0" and CLOSED for "1".
- (And there are more ways!)
