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| Character is one of information exchange terms, it is used to denote some symbolic data, used in the processing procedure of the character of letters, numbers and decimal point, symbols and the function character, CNC system only accept binary information, people put the character encoding, so that each character corresponds to a 8 bit binary number, the code called code, now the most widely used code has two kinds of standards, the international organization for standardization of ISO standard and USA Electronic Industries Association EIA standard, which is named as ISO code and EIA code.
