go to previous page   go to home page   go to next page hear noise highlighting

Answer:

On or Off.


Advantages of Binary 2: Unambiguous Signals

Binary Devices in Old North Church

Unambiguous Signals: It is easy to tell if a light is on or off. Exactly how bright it is does not matter if all that matters is "on" or "off."

Consider Paul Revere, waiting for news of the attack of the British troops. He is expecting to see a signal lantern in the tower of Old North Church telling him how the British are attacking:

1.32456 if by land, 1.71922 if by sea.

The signal shines out! ...and Paul Revere's famous ride is delayed for several hours as he tries to figure out just how bright that signal is.

Lack of ambiguity is a tremendous advantage. The signal that Paul Revere was actually waiting for that night in 1775 was:

One (lantern) if by land, and two (lanterns) if by sea.

...an easily interpreted signal. All Paul Revere had to do was count. Such signals are called discrete because they have a fixed number of definite states. Sometimes the word digital is used to mean the same thing.


QUESTION 6:

Could an abacus be regarded as a digital computer?


go to previous page   go to home page   go to next page