(By the way, the superscript I used above (⁸) is a Unicode character that uses 2 bytes (hex code: 2078.) This is called a variable-width encoding, and there are two main ones in Unicode. But we don't always need 4 bytes a simple 5-character string like "hello" would take 20 bytes! There has to be some way we can use only the minimum number of bytes each character needs. And it does! A single Unicode codepoint can be up to four bytes. For an encoding like Unicode to support more than 256, it has to go beyond one-byte characters. One byte = 8 bits, which means a byte can only hold 256 (2⁸) characters. It has tons of codepoints still available to be assigned to new characters. Unicode is maintained by the Unicode Consortium, and its character mapping system is more complex than ASCII's. Unicode is the "modern" character set, supporting over 1 million possible codepoints, and is the reason why your computer or phone can render emoji and characters from other languages correctly. ISO-8859-1 (also called "Latin1") is an "extended ASCII" charset it adds a few non-English characters like ß to the basic ASCII set, bringing it up to about 200 characters (and 8 bits). We got more character sets, like ISO-8859-1 and Unicode. But we'll focus on ASCII and friends because they started with English and the Latin/Western alphabet. There are other character sets designed for other languages. Also, it's the " American Standard Code for Information Interchange", so it makes sense that they focused on English characters. ASCII was based on the existing telegraphing system, and at the time, they figured they only needed 7 bits, which can only hold 128 (2⁷) numbers. The answer is an intersection of old tech (the telegraph) and new (the computer). And there are also mathematical symbols (±), and (today) emoji.Īside: Why does ASCII support only 128 characters? That mostly covers the English language, but many languages use other characters (like 大).
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