From voltages to XML

Hi Folks,

Once upon a time there was a device containing a continuous stream of voltages. Along came a clever fellow who decided to:

• Discretize the continuous stream of voltages into parts, which he called “bits”.
• Bits with a voltage at or above a certain level, he represented with the number 1. Bits below the level, he represented with the number 0.

After doing so, here is what he had:

11110001000101011110000110000101101101011100000110110001100101001111100100100001100101011011000110110001101111001011000010000001110111011011110111001001101100011001000011110000101111010001010111100001100001011011010111000001101100011001010011111000001010

For reasons no one quite knows, the fellow decided to break up this long string of zeroes and ones (which he referred to as a “binary string”) into groups of 8. He treated each group as representing a number and converted each number to a base 16 value (hexadecimal). After doing so, here is what he had:

3C 45 78 61 6D 70 6C 65 3E 48 65 6C 6C 6F 2C 20 77 6F 72 6C 64 3C 2F 45 78 61 6D 70 6C 65 3E 0A

The fellow was uncomfortable dealing with hexadecimal values and decided to let each pair of hexadecimal digits (hex digits) represent a character:

Hex 3C shall be represented by the character <
Hex 45 shall be represented by the character E
Hex 78 shall be represented by the character x
Hex 61 shall be represented by the character a
…

He was far more systematic than I show here, but you get the idea. This mapping from hex to characters he called an “encoding”. After doing the encoding, he had this:

<Example>Hello, world</Example>

He called this XML.

/Roger