Explaining the ASCII table

By the late 1950’s computers were getting more common, and starting to communicate with each other. There was an urgent need for a standard way to represent text so it could be understood by different electronic devices and computers. This began being a motivation for the development of the ASCII table, based on earlier tables used by teleprinters first published in 1963 . After several revisions, the modern version of the 7-bit ASCII table was recognised as a standard by the American National Standards Institute (ANSI) in the 1960’s. The current version is from 1986, published as ANSI X3.4-1986.

Electronic devices only work with high and low states known as bits witch correspond to binary numbers. ASCII codes are just a stream 1’s and 0’s stored on a computers memory. These codes are used for purposes like transferring information, displaying characters and data storage. each code in the ASCII table correspond to some previously defined character like numbers, alphabets…etc. A single character, whether digit, letter or HTML special character is represented as a code between 0 and 255. This can be represented using 8 bits. However, it is then no longer the classic ASCII sequence with seven bits. Codes with values higher than 127 are not strictly ASCII codes but are commonly used (because each character is stored in bytes and bytes are 8 bit not 7). However these codes called extended ASCII(128 to 255) have different interpretation on different systems, typically according to the code page selected.

The incapability of ASCII text to encode characters from any of the world’s other major languages makes the designers’ choice of 7 bits look more and more like a serious mistake as the use of international networks continues to increase.

Hardware and software from the U.S. still tends to assume that ASCII is the universal character set and that characters have 7 bits. This is a major problem to people who wanted to use a character set suited to their own preferred languages. Though, efforts to solve this problem by proliferating ‘national’ character sets produce pressure to use a smaller subset common to all those in use even though that’s impossible.

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