Other Definitions
ascii (dict)

Ascii

 
  !"#$%&'()*+,-./0123456789:;<=>? 
 @ABCDEFGHIJKLMNOPQRSTUVWXYZ\^_ `abcdefghijklmnopqrstuvwxyz
  
 
/pre>  
Overview
 Like other character representation computer codes, ASCII specifies a correspondence between digital bit patterns and the symbols/glyphs of a written language, thus allowing digital devices to communicate with each other and to process, store, and communicate character-oriented information. The ASCII character encoding, or a compatible extension (see below), is used on nearly all common computers, especially personal computers and workstations. The preferred MIME name for this encoding is "US-ASCII".  ASCII is, strictly, a seven-bit code, meaning that it uses the bit patterns representable with seven binary digits (a range of 0 to 127 decimal) to represent character information. At the time ASCII was introduced, many computers dealt with eight-bit groups (bytes or, more specifically, octets) as the smallest unit of information; the eighth bit was commonly used as a parity bit for error checking on communication lines or other device-specific functions. Machines which did not use parity typically set the eighth bit to zero, though some systems such as PRIME machines running PRIMOS set the eighth bit of ASCII characters to one.  ASCII does not specify any way to include information about the conceptual structure or appearance of a piece of text. That requires other standards, such as those specifying markup languages. Conceptual structure can be included using XML and appearance can be specified by using HTML for relatively simple things, SGML for more complex things, or PostScript, Display PostScript, or TeX for advanced layout and font control.  ASCII was first published as a standard in 1963 by the American Standards Association (ASA), which later became ANSI. ASCII-1963 lacked the lowercase letters, and had an up-arrow (↑) instead of the caret (^) and a left-arrow (←) instead of the underscore (_). The 1967 version added the lowercase letters, changed the names of a few control characters and moved the two controls ACK and ESC from the lowercase letters area into the control codes area. There are many variations of ASCII, but its present, most widely-used form is ANSI X3.4-1986, also standardized as ECMA-6, ISO/IEC 646:1991 International Reference Version, ITU-T Recommendation T.50 (09/92), and Request for Comments RFC 20. It is embedded in its probable replacement, Unicode, as the 'lowest' 128 characters. ASCII is considered by some the most successful software standard ever promulgated.  Historically, ASCII developed from telegraphic codes and its first commercial use was as a 7-bit teleprinter code promoted by Bell data services. The Bell System had been planning to use a 6-bit code derived from Fieldata that added punctuation and lower-case letter to the earlier 5-bit Baudot teleprinter code but was persuaded to instead join the ASA subcommittee that was developing ASCII. Baudot helped in the automation of sending and receiving of telegraphic messages, and took many features from Morse code; it was however, a constant length code unlike Morse code. Compared to earlier telegraph codes, the proposed Bell code and ASCII were both reordered for more convenient sorting (ie, alphabetization) of lists, and added features for devices other than teleprinters. Some ASCII features, including the 'ESCape sequence', were due to Bob Bemer.  
ASCII control characters
 The first thirty-two codes (numbers 0–31 decimal) in ASCII are reserved for control characters: codes that were not originally intended to carry information, but rather to control devices (such as printers) that make use of ASCII. For example, character 10 represents the "line feed" function (which causes a printer to advance its paper), and character 27 represents the "escape" key found on the top left of common keyboards.  Code 127 (all seven bits on) is another special character known as "delete" or "rubout". Though its function is similar to that of other control characters, this pattern was used so that it could be used to "erase" a section of paper tape, a popular storage medium until the 80s, by punching all possible holes at a particular character position.  Many of the ASCII control codes are to mark data packets, or to control a data transmission protocol (e.g. ENQuiry "any stations out there?", ACKnowledge, Negative AcKnowledge, Start Of Header, Start Of Text, End Of Text, etc). ESCape and SUBstitute permit a communications protocol to, for instance, mark binary data so that if it contains codes with the same pattern as a protocol character, the code will be processed as data.  The separator characters (Record Separator, etc.) were intended for use with magnetic tape systems.  XON and XOFF are common interpretations of two of the Device Control characters and are generally used to throttle data flow to a slow device, such as a printer, from a fast device, such as a computer so data does not overrun and get lost.  Early users of ASCII adopted some of the control codes to represent "meta-information" such as end-of-line, start/end of a data element, and so on. These assignments often conflict, so part of the effort in converting data from one format to another is making the correct meta-information transformations. For example, the character(s) representing end-of-line ("new line") in text data files/streams vary from operating system to operating system. When moving files from one system to another, these characters must be recognized as end-of-line markers and converted appropriately.  {| border="1" cellpadding="2" cellspacing="0" 
 
 
 
inary
 
Decimal
 
Hex
 
Abbreviation
 
Printable
Representation
 
Keyboard
Access
 
Name/Meaning 
 
 
 
000 0000
 
align="center"|0
 
align="center"|00
 
align="center"|NUL
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␀
 
^@
 
Null character 
 
 
 
000 0001
 
align="center"|1
 
align="center"|01
 
align="center"|SOH
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␁
 
^A
 
Start of Header 
 
 
 
000 0010
 
align="center"|2
 
align="center"|02
 
align="center"|STX
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␂
 
^B
 
Start of Text 
 
 
 
000 0011
 
align="center"|3
 
align="center"|03
 
align="center"|ETX
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␃
 
^C
 
End of Text 
 
 
 
000 0100
 
align="center"|4
 
align="center"|04
 
align="center"|EOT
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␄
 
^D
 
End of Transmission 
 
 
 
000 0101
 
align="center"|5
 
align="center"|05
 
align="center"|ENQ
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␅
 
^E
 
Enquiry 
 
 
 
000 0110
 
align="center"|6
 
align="center"|06
 
align="center"|ACK
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␆
 
^F
 
Acknowledgement 
 
 
 
000 0111
 
align="center"|7
 
align="center"|07
 
align="center"|BEL
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␇
 
^G
 
Bell 
 
 
 
000 1000
 
align="center"|8
 
align="center"|08
 
align="center"|BS
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␈
 
^H
 
Backspace 
 
 
 
000 1001
 
align="center"|9
 
align="center"|09
 
align="center"|HT
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␉
 
^I
 
Horizontal Tab 
 
 
 
000 1010
 
align="center"|10
 
align="center"|0A
 
align="center"|LF
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␊
 
^J
 
Line feed 
 
 
 
000 1011
 
align="center"|11
 
align="center"|0B
 
align="center"|VT
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␋
 
^K
 
Vertical Tab 
 
 
 
000 1100
 
align="center"|12
 
align="center"|0C
 
align="center"|FF
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␌
 
^L
 
Form feed 
 
 
 
000 1101
 
align="center"|13
 
align="center"|0D
 
align="center"|CR
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␍
 
^M
 
Carriage return 
 
 
 
000 1110
 
align="center"|14
 
align="center"|0E
 
align="center"|SO
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␎
 
^N
 
Shift Out 
 
 
 
000 1111
 
align="center"|15
 
align="center"|0F
 
align="center"|SI
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␏
 
^O
 
Shift In 
 
 
 
001 0000
 
align="center"|16
 
align="center"|10
 
align="center"|DLE
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␐
 
^P
 
Data Link Escape 
 
 
 
001 0001
 
align="center"|17
 
align="center"|11
 
align="center"|DC1
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␑
 
^Q
 
Device Control 1 — oft. XON  
 
 
 
001 0010
 
align="center"|18
 
align="center"|12
 
align="center"|DC2
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␒
 
^R
 
Device Control 2 
 
 
 
001 0011
 
align="center"|19
 
align="center"|13
 
align="center"|DC3
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␓
 
^S
 
Device Control 3 — oft. XOFF 
 
 
 
001 0100
 
align="center"|20
 
align="center"|14
 
align="center"|DC4
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␔
 
^T
 
Device Control 4 
 
 
 
001 0101
 
align="center"|21
 
align="center"|15
 
align="center"|NAK
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␕
 
^U
 
Negative Acknowledgement 
 
 
 
001 0110
 
align="center"|22
 
align="center"|16
 
align="center"|SYN
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␖
 
^V
 
Synchronous Idle 
 
 
 
001 0111
 
align="center"|23
 
align="center"|17
 
align="center"|ETB
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␗
 
^W
 
End of Trans. Block 
 
 
 
001 1000
 
align="center"|24
 
align="center"|18
 
align="center"|CAN
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␘
 
^X
 
Cancel 
 
 
 
001 1001
 
align="center"|25
 
align="center"|19
 
align="center"|EM
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␙
 
^Y
 
End of Medium 
 
 
 
001 1010
 
align="center"|26
 
align="center"|1A
 
align="center"|SUB
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␚
 
^Z
 
Substitute 
 
 
 
001 1011
 
align="center"|27
 
align="center"|1B
 
align="center"|ESC
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␛
 
^[ or ESC
 
Escape 
 
 
 
001 1100
 
align="center"|28
 
align="center"|1C
 
align="center"|FS
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␜
 
^\
 
File Separator 
 
 
 
001 1101
 
align="center"|29
 
align="center"|1D
 
align="center"|GS
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␝
 
^]
 
Group Separator 
 
 
 
001 1110
 
align="center"|30
 
align="center"|1E
 
align="center"|RS
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␞
 
^^
 
Record Separator 
 
 
 
001 1111
 
align="center"|31
 
align="center"|1F
 
align="center"|US
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␟
 
^_
 
Unit Separator 
 
 
 
111 1111
 
align="center"|127
 
align="center"|7F
 
align="center"|DEL
 
align="center" style="font-family:'lucida sans unicode','arial unicode ms'"|␡
 
^?, Delete, or Backspace
 
Delete
 
}  In the table above, the fifth column contains glyphs reserved for representing control codes in a data stream, ie, when they must be printed or displayed rather than (or in addition to) causing action; your browser, (i.e., your HTML user agent) may require the installation of additional fonts in order to display them.  The sixth column shows the key combinations traditionally used to input control characters from a keyboard. In this column, a caret ("^") represents the "Control"/"Ctrl" key, which must be held down while pressing the next key, e.g. "^Z" means to hold down Ctrl while pressing the Z key. This notation is also sometimes used by software as a printable representation of control characters that could not be processed.  In some systems on the Internet, there is a history of the DEL control code being converted to BS in transit to a remote server. If the code was received in a text editor that did not know what do with it, the result was often "^H" appearing where the user intended to delete previous characters. "^H" persists in messages today as a deliberate humorous device, e.g. "there's a sucker^H^H^H^H^H^H potential customer born every minute". (A variant of this is the use of "^W", which in some text editors means "delete previous word". The example sentence would therefore also work as "there's a sucker^W potential customer born every minute", which is easier to both write and read.)  
ASCII printable characters
 Code 32 is the "space" character, denoting the space between words, which is produced by the large space bar of a keyboard. Codes 33 to 126 are called the printable characters, which represent letters, digits, punctuation marks, and a few miscellaneous symbols.  Seven bit ASCII provided seven "national" characters and, if the combined hardware and software permit, can use overstrikes to simulate some additional international characters: a BackSpace can be followed with the grave accent (which the American and British standards, but only the American and British standards, also call "opening single quotation mark"), a tilde, or a breath mark (inverted vel).  {| border="0" cellspacing="0" cellpadding="0" 
 
 
 
{| border="1" cellspacing="0" cellpadding="2" 
 
 
 
inary
 
Decimal
 
Hex
 
Graphic 
 
 
 
010 0000
 
align="center"|32
 
align="center"|20
 
align="center"|(blank) (␠) 
 
 
 
010 0001
 
align="center"|33
 
align="center"|21
 
align="center"|! 
 
 
 
010 0010
 
align="center"|34
 
align="center"|22
 
align="center"|" 
 
 
 
010 0011
 
align="center"|35
 
align="center"|23
 
align="center"|# 
 
 
 
010 0100
 
align="center"|36
 
align="center"|24
 
align="center"|$ 
 
 
 
010 0101
 
align="center"|37
 
align="center"|25
 
align="center"|% 
 
 
 
010 0110
 
align="center"|38
 
align="center"|26
 
align="center"|& 
 
 
 
010 0111
 
align="center"|39
 
align="center"|27
 
align="center"|' 
 
 
 
010 1000
 
align="center"|40
 
align="center"|28
 
align="center"|( 
 
 
 
010 1001
 
align="center"|41
 
align="center"|29
 
align="center"|) 
 
 
 
010 1010
 
align="center"|42
 
align="center"|2A
 
align="center"|* 
 
 
 
010 1011
 
align="center"|43
 
align="center"|2B
 
align="center"|+ 
 
 
 
010 1100
 
align="center"|44
 
align="center"|2C
 
align="center"|, 
 
 
 
010 1101
 
align="center"|45
 
align="center"|2D
 
align="center"|- 
 
 
 
010 1110
 
align="center"|46
 
align="center"|2E
 
align="center"|. 
 
 
 
010 1111
 
align="center"|47
 
align="center"|2F
 
align="center"|/ 
 
 
 
011 0000
 
align="center"|48
 
align="center"|30
 
align="center"|0 
 
 
 
011 0001
 
align="center"|49
 
align="center"|31
 
align="center"|1 
 
 
 
011 0010
 
align="center"|50
 
align="center"|32
 
align="center"|2 
 
 
 
011 0011
 
align="center"|51
 
align="center"|33
 
align="center"|3 
 
 
 
011 0100
 
align="center"|52
 
align="center"|34
 
align="center"|4 
 
 
 
011 0101
 
align="center"|53
 
align="center"|35
 
align="center"|5 
 
 
 
011 0110
 
align="center"|54
 
align="center"|36
 
align="center"|6 
 
 
 
011 0111
 
align="center"|55
 
align="center"|37
 
align="center"|7 
 
 
 
011 1000
 
align="center"|56
 
align="center"|38
 
align="center"|8 
 
 
 
011 1001
 
align="center"|57
 
align="center"|39
 
align="center"|9 
 
 
 
011 1010
 
align="center"|58
 
align="center"|3A
 
align="center"|: 
 
 
 
011 1011
 
align="center"|59
 
align="center"|3B
 
align="center"|; 
 
 
 
011 1100
 
align="center"|60
 
align="center"|3C
 
align="center"|< 
 
 
 
011 1101
 
align="center"|61
 
align="center"|3D
 
align="center"|= 
 
 
 
011 1110
 
align="center"|62
 
align="center"|3E
 
align="center"|> 
 
 
 
011 1111
 
align="center"|63
 
align="center"|3F
 
align="center"|?
 
}
 
 
 
 {| border="1" cellspacing="0" cellpadding="2" 
 
 
 
inary
 
Decimal
 
Hex
 
Graphic 
 
 
 
100 0000
 
align="center"|64
 
align="center"|40
 
align="center"|@ 
 
 
 
100 0001
 
align="center"|65
 
align="center"|41
 
align="center"|A 
 
 
 
100 0010
 
align="center"|66
 
align="center"|42
 
align="center"|B 
 
 
 
100 0011
 
align="center"|67
 
align="center"|43
 
align="center"|C 
 
 
 
100 0100
 
align="center"|68
 
align="center"|44
 
align="center"|D 
 
 
 
100 0101
 
align="center"|69
 
align="center"|45
 
align="center"|E 
 
 
 
100 0110
 
align="center"|70
 
align="center"|46
 
align="center"|F 
 
 
 
100 0111
 
align="center"|71
 
align="center"|47
 
align="center"|G 
 
 
 
100 1000
 
align="center"|72
 
align="center"|48
 
align="center"|H 
 
 
 
100 1001
 
align="center"|73
 
align="center"|49
 
align="center"|I 
 
 
 
100 1010
 
align="center"|74
 
align="center"|4A
 
align="center"|J 
 
 
 
100 1011
 
align="center"|75
 
align="center"|4B
 
align="center"|K 
 
 
 
100 1100
 
align="center"|76
 
align="center"|4C
 
align="center"|L 
 
 
 
100 1101
 
align="center"|77
 
align="center"|4D
 
align="center"|M 
 
 
 
100 1110
 
align="center"|78
 
align="center"|4E
 
align="center"|N 
 
 
 
100 1111
 
align="center"|79
 
align="center"|4F
 
align="center"|O 
 
 
 
101 0000
 
align="center"|80
 
align="center"|50
 
align="center"|P 
 
 
 
101 0001
 
align="center"|81
 
align="center"|51
 
align="center"|Q 
 
 
 
101 0010
 
align="center"|82
 
align="center"|52
 
align="center"|R 
 
 
 
101 0011
 
align="center"|83
 
align="center"|53
 
align="center"|S 
 
 
 
101 0100
 
align="center"|84
 
align="center"|54
 
align="center"|T 
 
 
 
101 0101
 
align="center"|85
 
align="center"|55
 
align="center"|U 
 
 
 
101 0110
 
align="center"|86
 
align="center"|56
 
align="center"|V 
 
 
 
101 0111
 
align="center"|87
 
align="center"|57
 
align="center"|W 
 
 
 
101 1000
 
align="center"|88
 
align="center"|58
 
align="center"|X 
 
 
 
101 1001
 
align="center"|89
 
align="center"|59
 
align="center"|Y 
 
 
 
101 1010
 
align="center"|90
 
align="center"|5A
 
align="center"|Z 
 
 
 
101 1011
 
align="center"|91
 
align="center"|5B
 
align="center"|[ 
 
 
 
101 1100
 
align="center"|92
 
align="center"|5C
 
align="center"|\ 
 
 
 
101 1101
 
align="center"|93
 
align="center"|5D
 
align="center"|] 
 
 
 
101 1110
 
align="center"|94
 
align="center"|5E
 
align="center"|^ 
 
 
 
101 1111
 
align="center"|95
 
align="center"|5F
 
align="center"|_
 
}
 
 
 
 {| border="1" cellspacing="0" cellpadding="2" 
 
 
 
inary
 
Decimal
 
Hex
 
Graphic 
 
 
 
110 0000
 
align="center"|96
 
align="center"|60
 
align="center"|` 
 
 
 
110 0001
 
align="center"|97
 
align="center"|61
 
align="center"|a 
 
 
 
110 0010
 
align="center"|98
 
align="center"|62
 
align="center"|b 
 
 
 
110 0011
 
align="center"|99
 
align="center"|63
 
align="center"|c 
 
 
 
110 0100
 
align="center"|100
 
align="center"|64
 
align="center"|d 
 
 
 
110 0101
 
align="center"|101
 
align="center"|65
 
align="center"|e 
 
 
 
110 0110
 
align="center"|102
 
align="center"|66
 
align="center"|f 
 
 
 
110 0111
 
align="center"|103
 
align="center"|67
 
align="center"|g 
 
 
 
110 1000
 
align="center"|104
 
align="center"|68
 
align="center"|h 
 
 
 
110 1001
 
align="center"|105
 
align="center"|69
 
align="center"|i 
 
 
 
110 1010
 
align="center"|106
 
align="center"|6A
 
align="center"|j 
 
 
 
110 1011
 
align="center"|107
 
align="center"|6B
 
align="center"|k 
 
 
 
110 1100
 
align="center"|108
 
align="center"|6C
 
align="center"|l 
 
 
 
110 1101
 
align="center"|109
 
align="center"|6D
 
align="center"|m 
 
 
 
110 1110
 
align="center"|110
 
align="center"|6E
 
align="center"|n 
 
 
 
110 1111
 
align="center"|111
 
align="center"|6F
 
align="center"|o 
 
 
 
111 0000
 
align="center"|112
 
align="center"|70
 
align="center"|p 
 
 
 
111 0001
 
align="center"|113
 
align="center"|71
 
align="center"|q 
 
 
 
111 0010
 
align="center"|114
 
align="center"|72
 
align="center"|r 
 
 
 
111 0011
 
align="center"|115
 
align="center"|73
 
align="center"|s 
 
 
 
111 0100
 
align="center"|116
 
align="center"|74
 
align="center"|t 
 
 
 
111 0101
 
align="center"|117
 
align="center"|75
 
align="center"|u 
 
 
 
111 0110
 
align="center"|118
 
align="center"|76
 
align="center"|v 
 
 
 
111 0111
 
align="center"|119
 
align="center"|77
 
align="center"|w 
 
 
 
111 1000
 
align="center"|120
 
align="center"|78
 
align="center"|x 
 
 
 
111 1001
 
align="center"|121
 
align="center"|79
 
align="center"|y 
 
 
 
111 1010
 
align="center"|122
 
align="center"|7A
 
align="center"|z 
 
 
 
111 1011
 
align="center"|123
 
align="center"|7B
 
align="center"|{ 
 
 
 
111 1100
 
align="center"|124
 
align="center"|7C
 
align="center"|| 
 
 
 
111 1101
 
align="center"|125
 
align="center"|7D
 
align="center"|} 
 
 
 
111 1110
 
align="center"|126
 
align="center"|7E
 
align="center"|~
 
}
 
  
   Note how uppercase characters can be converted to lowercase by adding 32 to their ASCII value; in binary, this can be accomplished simply by setting the sixth-least significant bit to 1.  
Aliases for ASCII
  RFC 1345, published in June 1992, and the IANA registry of character sets, ongoing, recognize the following case-insensitive aliases for ASCII as being suitable for use on the Internet:  
 
 ANSI_X3.4-1968 (canonical name)
 
 ANSI_X3.4-1986
 
 ASCII
 
 US-ASCII (preferred MIME name)
 
 us
 
 ISO646-US
 
 ISO_646.irv:1991
 
 iso-ir-6
 
 IBM367
 
 cp367
 
 csASCII
 
  Of these, only the aliases US-ASCII and ASCII are widely used. They are often found in the optional "charset" parameter in the Content-Type header of some MIME messages, in the equivalent "meta" element of some HTML documents, and in the encoding declaration part of the prolog of some XML documents.  
Variants of ASCII
 As computer technology spread throughout the world, many variations of ASCII were developed by corporations and standards bodies in order to facilitate the expression of non-English languages that still used Roman-based alphabets. Some of these variations can be considered to be ASCII extensions, although the term is sometimes misapplied to cover all variants, including those that don't preserve ASCII's character map in the 7-bit range.  ISO 646 (1972) was the first attempt to remedy the English bias, although it created compatibility problems, since it was still a seven-bit character set. No additional codes were available, so some were re-assigned in language-specific variants. It was thus impossible to know what character was represented by a code without knowing what variant was in use, and text processing systems were generally able to cope with only one variant, anyway.  Eventually, improved technology brought out-of-band means to represent the information formerly encoded in the eighth bit of each byte, freeing this bit to add another 128 additional character codes for new assignments. For example, IBM developed eight-bit code pages, such as code page 437, which replaced the control characters with graphic symbols such as smiley faces, and mapped additional graphic characters to the upper 128 bytes. These code pages were supported in hardware by IBM PC manufacturers, as well as in operating systems such as DOS.  Eight-bit standards such as ISO/IEC 8859 were true extensions of ASCII, leaving the original character mapping intact and just adding additional values above the 7-bit range. This enabled a broader range of languages to be represented, but these standards were still plagued with incompatibilities and limitations. Still, ISO/IEC 8859-1 and original 7-bit ASCII are the most common character encodings in use today.  Unicode and ISO/IEC 10646: the Universal Character Set, have a much wider array of characters, and their various encoding forms are rapidly supplanting ISO/IEC 8859 and ASCII in many environments. While ASCII is defined in terms of 7-bit codes, Unicode and the UCS are defined in terms of relatively abstract "code points": non-negative integer numbers that can be mapped, using different encoding forms and schemes, to sequences of 1 or more 8-bit bytes. To permit backward compatibility, Unicode and the UCS assign the first 128 code points to the same characters as ASCII. ASCII can therefore be thought of as being a 7-bit encoding scheme for a very small subset of Unicode and the UCS. The popular UTF-8 encoding form prescribes the use of one to four 8-bit code values for each code point character, and is identical to ASCII for the code values below 128. Other encoding forms such as UTF-16 resemble ASCII in how they represent the first 128 characters of Unicode, but tend to use 16 or 32 bits per character, so they are not entirely compatible without conversions.  The portmanteau word ASCIIbetical has evolved to describe the collation of data in ASCII code order rather than "standard" alphabetical order (which requires some tricky computation, and varies with language).  ASCII contains many characters which were not commonly used, or at least spoken of, outside of the computing context; the ";popularization" of these characters required that names be agreed upon for them. See the pronunciation guide in the external links, below.  ASCIIZ or ASCIZ is an abbreviation used to refer to a null-terminated ASCII string.  
See also
 Related topics: 
 
ASCII art
 
Binary and text files
 
EBCDIC
 
Extended ASCII
 
ISCII
 
ISO 646
 
ISO 8859
 
Textfiles.com
 
Unicode
 
UTF-8
 
VISCII
 
   Computer (family)-specific ASCII variants: 
 
ATASCII
 
PETSCII
 
ZX Spectrum character set
 
   ASCII in space: 
 
Asteroid 3568 ASCII
 
  
External links
 
 
 Color coded ASCII chart with binary, octal, decimal, and hex values
 
 Standard ECMA-6: 7-bit Coded Character Set 6th edition (December 1991)
 
 IANA Registry: C0 Set of ISO 646
 
 IANA Registry: ISO 646, USA Version X3.4 — 1968
 
 Jargon File: ASCIIbetical
 
 Bob Bemer's home page some historical notes about ASCII from one of its designers
 
 A pronunciation guide for ASCII characters (some are more whimsical than others; see especially the end of the list)
 
 Annotated History of Character Codes by Tom Jennings, World Power Systems
 
 Learning by Simulations Interactive simulation of ASCII encoding
 
  
  ASCII is also a name of one of the oldest and most prestigious computer magazines published in Japan. See ASCII (magazine)
 
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andre agassi
austro asiatic languages
afro asiatic languages
andorra
arithmetic mean
american football conference
al gore
animal farm
amphibian
alaska
architecture (disambiguation)
agriculture
aldous huxley