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ASCII (/ ˈ æ s k iː / ⓘ ASS-kee), [3]: 6 an acronym for American Standard Code for Information Interchange, is a character encoding standard for electronic communication. . ASCII codes represent text in computers, telecommunications equipment, and other devic
In 1973, ECMA-35 and ISO 2022 [18] attempted to define a method so an 8-bit "extended ASCII" code could be converted to a corresponding 7-bit code, and vice versa. [19] In a 7-bit environment, the Shift Out would change the meaning of the 96 bytes 0x20 through 0x7F [a] [21] (i.e. all but the C0 control codes), to be the characters that an 8-bit environment would print if it used the same code ...
For example, an ASCII (or extended ASCII) scheme will use a single byte of computer memory, while a UTF-8 scheme will use one or more bytes, depending on the particular character being encoded. Alternative ways to encode character values include specifying an integer value for a code point, such as an ASCII code value or a Unicode code point.
The control code ranges 0x00–0x1F ("C0") and 0x7F originate from the 1967 edition of US-ASCII.The standard ISO/IEC 2022 (ECMA-35) defines extension methods for ASCII, including a secondary "C1" range of 8-bit control codes from 0x80 to 0x9F, equivalent to 7-bit sequences of ESC with the bytes 0x40 through 0x5F.
The NULL character (code 0) is represented by Ctrl-@, "@" being the code immediately before "A" in the ASCII character set. For convenience, some terminals accept Ctrl-Space as an alias for Ctrl-@. In either case, this produces one of the 32 ASCII control codes between 0 and 31.
Initially defined as part of ASCII, the default C0 control code set is now defined in ISO 6429 (ECMA-48), making it part of the same standard as the C1 set invoked by the ANSI escape sequences (although ISO 2022 allows the ISO 6429 C0 set to be used without the ISO 6429 C1 set, and vice versa, provided that 0x1B is always ESC). This is used to ...
A code point is a value or position of a character in a coded character set. [10] A code space is the range of numerical values spanned by a coded character set. [10] [12] A code unit is the minimum bit combination that can represent a character in a character encoding (in computer science terms, it is the word size of the character encoding).
A wide character refers to the size of the datatype in memory. It does not state how each value in a character set is defined. Those values are instead defined using character sets, with UCS and Unicode simply being two common character sets that encode more characters than an 8-bit wide numeric value (255 total) would allow.