There are only 26 symbols in English. Shakespeare has used only these symbols and written great dramas. To venture into math and accountancy, we need 10 more symbols (numbers). For science and technology, we still needed more symbols. And we borrowed them from Greek and Latin. Also, we require punctuation for clarity. That is human weakness, we need more and more symbols to understand a concept or a message. But the nature has coded all the information using only four symbols (chemicals) in the DNA. But only two symbols are enough to represent any info. in today's machines and digital devices.
ACOUSTIC - MORSE CODE
In those days, Morse code were used for instant and emergency communications (Telegram). Morse code consists of only 2 symbols dot and dash. Dot means a sound signal of short duration. Dash means a sound signal of long duration. All the 26 alphabets were represented using these dots and dashes. The messages were transmitted using sound signals through telegraphic devices.
Next, 0 and 1 (binary numbers) were used as two symbols and digital revolution was born. These binary numbers can easily take many avatars. Let us see them one by one.
ELECTRICAL REPRESENTATION
Just ON, OFF states of a switch can represent 0 and 1. High or low voltage and high or low current can stand for binary numbers. This principle is widely used in electrical circuits.
MAGNETIC
In a hard disk or drive, magnetization and demagnetization represent Binary states. They still store vast amount of data in computers.
ELECTRONIC
The tiny electronic devices diode, transistors etc act as auto switch and represent the two states 0 and 1. They are found in every electronic devices.
A charged capacitor can mean 1 and a discharged capacitor means 0. A circuit called "flip-flop" can store 0 or 1 and it can be toggled by a suitable voltage. The amount of charges or electrons in the integrated circuits (IC chips) can be manipulated to represent 0 and 1. All these techniques are adopted in today's digital memories.
MECHANICAL
In CD, DVD and Blu ray disk, tiny "pits" and "pumps" are etched by the laser beam in miles long spiral track. Those pits and pumps are read as zeros and ones.
OPTICAL
Every product, we buy has the bar code. A thin black bar may represent zero and thick bar may stand for one. (There are several standards).
The numbers 0 to 9 are easily coded using the bars (like Morse code) and printed on the product. The scanner can read the bar-code using laser light and fetch the company and product info. from the internet.
Below, the 'ones' indicate diamond shape.
0011100
0111110
0011100
0001000
Below, glowing LEDs indicate 'walking man'. Here, switched-on LED stand for 1; switched-off LED for 0.
As shown above, the binary numbers can create figures, messages etc. This principle is used in traffic signals and display boards. They contain array or matrix of LEDs. For a figure, the LEDs in the particular positions are lighted up and remaining LEDs are switched-off.
ATOMIC
An electron spinning in one direction said to represent 1 and the electron spinning in opposite direction is zero. A light photon can also represent binary states. These are called "qubits" and is the basis of quantum computing.
Thus Bi-states takes many formats. They can easily be manipulated, transmitted, stored and yield for any kind of coding.
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