FREE THOUGHT · FREE SOFTWARE · FREE WORLD

ASCII Chart

Wanted to stick this here for a reference, mostly for me. I use ASCII alot in bash, preg_matches, preg_replace, etc..

Linux Function to print ASCII Chart

ascii chartThis function will print a 256 ASCII Character Chart.

function aa_pascii ()
{
    local p=;
    for i in {1..256};
    do
        p="  $i";
        echo -e "${p: -3} \\0$(( $i / 64 * 100 + $i % 64 / 8 * 10 + $i % 8 ))";
    done | cat -t | column -c$(( ${COLUMNS:-80} / 2 ))
}

History of ASCII

The American Standard Code for Information Interchange (ASCII) was developed under the auspices of a committee of the American Standards Association, called the X3 committee, by its X3.2 (later X3L2) subcommittee, and later by that subcommittee's X3.2.4 working group. The ASA became the United States of America Standards Institute or USASI and ultimately the American National Standards Institute.

The X3.2 subcommittee designed ASCII based on earlier teleprinter encoding systems. Like other character encodings, ASCII specifies a correspondence between digital bit patterns and character symbols (i.e. graphemes and control characters). This allows digital devices to communicate with each other and to process, store, and communicate character-oriented information such as written language. Before ASCII was developed, the encodings in use included 26 alphabetic characters, 10 numerical digits, and from 11 to 25 special graphic symbols. To include all these, and control characters compatible with the Comité Consultatif International Téléphonique et Télégraphique (CCITT) International Telegraph Alphabet No. 2 (ITA2) standard, Fieldata, and early EBCDIC, more than 64 codes were required for ASCII.

The committee debated the possibility of a shift key function (like the Baudot code), which would allow more than 64 codes to be represented by six bits. In a shifted code, some character codes determine choices between options for the following character codes. It allows compact encoding, but is less reliable for data transmission; an error in transmitting the shift code typically makes a long part of the transmission unreadable. The standards committee decided against shifting, and so ASCII required at least a seven-bit code.

The committee considered an eight-bit code, since eight bits (octets) would allow two four-bit patterns to efficiently encode two digits with binary coded decimal. However, it would require all data transmission to send eight bits when seven could suffice. The committee voted to use a seven-bit code to minimize costs associated with data transmission. Since perforated tape at the time could record eight bits in one position, it also allowed for a parity bit for error checking if desired. Eight-bit machines (with octets as the native data type) that did not use parity checking typically set the eighth bit to 0.

The code itself was patterned so that most control codes were together, and all graphic codes were together, for ease of identification. The first two columns (32 positions) were reserved for control characters. The "space" character had to come before graphics to make sorting easier, so it became position 20hex; for the same reason, many special signs commonly used as separators were placed before digits. The committee decided it was important to support upper case 64-character alphabets, and chose to pattern ASCII so it could be reduced easily to a usable 64-character set of graphic codes. Lower case letters were therefore not interleaved with upper case. To keep options available for lower case letters and other graphics, the special and numeric codes were arranged before the letters, and the letter "A" was placed in position 41hex to match the draft of the corresponding British standard. The digits 0–9 were arranged so they correspond to values in binary prefixed with 011, making conversion with binary-coded decimal straightforward.

Many of the non-alphanumeric characters were positioned to correspond to their shifted position on typewriters. Thus #, $ and % were placed to correspond to 3, 4, and 5 in the adjacent column. The parentheses could not correspond to 9 and 0, however, because the place corresponding to 0 was taken by the space character. Since many European typewriters placed the parentheses with 8 and 9, those corresponding positions were chosen for the parentheses. The @ symbol was not used in continental Europe and the committee expected it would be replaced by an accented À in the French variation, so the @ was placed in position 40hex next to the letter A.

The control codes felt essential for data transmission were the start of message (SOM), end of address (EOA), end of message (EOM), end of transmission (EOT), "who are you?" (WRU), "are you?" (RU), a reserved device control (DC0), synchronous idle (SYNC), and acknowledge (ACK). These were positioned to maximize the Hamming distance between their bit patterns.

With the other special characters and control codes filled in, ASCII was published as ASA X3.4-1963, leaving 28 code positions without any assigned meaning, reserved for future standardization, and one unassigned control code. There was some debate at the time whether there should be more control characters rather than the lower case alphabet. The indecision did not last long: during May 1963 the CCITT Working Party on the New Telegraph Alphabet proposed to assign lower case characters to columns 6 and 7, and International Organization for Standardization TC 97 SC 2 voted during October to incorporate the change into its draft standard. The X3.2.4 task group voted its approval for the change to ASCII at its May 1963 meeting. Locating the lowercase letters in columns 6 and 7 caused the characters to differ in bit pattern from the upper case by a single bit, which simplified case-insensitive character matching and the construction of keyboards and printers.

The X3 committee made other changes, including other new characters (the brace and vertical line characters), renaming some control characters (SOM became start of header (SOH)) and moving or removing others (RU was removed). ASCII was subsequently updated as USASI X3.4-1967, then USASI X3.4-1968, ANSI X3.4-1977, and finally, ANSI X3.4-1986 (the first two are occasionally retronamed ANSI X3.4-1967, and ANSI X3.4-1968).

The X3 committee also addressed how ASCII should be transmitted (least significant bit first), and how it should be recorded on perforated tape. They proposed a 9-track standard for magnetic tape, and attempted to deal with some forms of punched card formats.

ASCII itself was first used commercially during 1963 as a seven-bit teleprinter code for American Telephone & Telegraph's TWX (TeletypeWriter eXchange) network. TWX originally used the earlier five-bit Baudot code, which was also used by the competing Telex teleprinter system. Bob Bemer introduced features such as the escape sequence. His British colleague Hugh McGregor Ross helped to popularize this work—according to Bemer, "so much so that the code that was to become ASCII was first called the Bemer-Ross Code in Europe". Because of his extensive work on ASCII, Bemer has been called "the father of ASCII."

On March 11, 1968, U.S. President Lyndon B. Johnson mandated that all computers purchased by the United States federal government support ASCII, stating:

I have also approved recommendations of the Secretary of Commerce regarding standards for recording the Standard Code for Information Interchange on magnetic tapes and paper tapes when they are used in computer operations. All computers and related equipment configurations brought into the Federal Government inventory on and after July 1, 1969, must have the capability to use the Standard Code for Information Interchange and the formats prescribed by the magnetic tape and paper tape standards when these media are used.

Other international standards bodies have ratified character encodings such as ISO/IEC 646 that are identical or nearly identical to ASCII, with extensions for characters outside the English alphabet and symbols used outside the United States, such as the symbol for the United Kingdom's pound sterling (£). Almost every country needed an adapted version of ASCII, since ASCII suited the needs of only the USA and a few other countries. For example, Canada had its own version that supported French characters. Other adapted encodings include ISCII (India), VISCII (Vietnam), and YUSCII (Yugoslavia). Although these encodings are sometimes referred to as ASCII, true ASCII is defined strictly only by ANSI standard.

ASCII was incorporated into the Unicode character set as the first 128 symbols, so the ASCII characters have the same numeric codes in both sets. This allows UTF-8 to be backward compatible with ASCII, a significant advantage.

ASCII control characters

ASCII reserves the first 32 codes (numbers 0–31 decimal) for control characters: codes originally intended not to represent printable information, but rather to control devices (such as printers) that make use of ASCII, or to provide meta-information about data streams such as those stored on magnetic tape. For example, character 10 represents the "line feed" function (which causes a printer to advance its paper), and character 8 represents "backspace". RFC 2822 refers to control characters that do not include carriage return, line feed or white space as non-whitespace control characters. Except for the control characters that prescribe elementary line-oriented formatting, ASCII does not define any mechanism for describing the structure or appearance of text within a document. Other schemes, such as markup languages, address page and document layout and formatting.

The original ASCII standard used only short descriptive phrases for each control character. The ambiguity this caused was sometimes intentional (where a character would be used slightly differently on a terminal link than on a data stream) and sometimes accidental (such as what "delete" means).

Probably the most influential single device on the interpretation of these characters was the Teletype Model 33 ASR, which was a printing terminal with an available paper tape reader/punch option. Paper tape was a very popular medium for long-term program storage until the 1980s, less costly and in some ways less fragile than magnetic tape. In particular, the Teletype Model 33 machine assignments for codes 17 (Control-Q, DC1, also known as XON), 19 (Control-S, DC3, also known as XOFF), and 127 (Delete) became de facto standards. Because the keytop for the O key also showed a left-arrow symbol (from ASCII-1963, which had this character instead of underscore), a noncompliant use of code 15 (Control-O, Shift In) interpreted as "delete previous character" was also adopted by many early timesharing systems but eventually became neglected.

The use of Control-S (XOFF, an abbreviation for transmit off) as a "handshaking" signal warning a sender to stop transmission because of impending overflow, and Control-Q (XON, "transmit on") to resume sending, persists to this day in many systems as a manual output control technique. On some systems Control-S retains its meaning but Control-Q is replaced by a second Control-S to resume output.

Code 127 is officially named "delete" but the Teletype label was "rubout". Since the original standard did not give detailed interpretation for most control codes, interpretations of this code varied. The original Teletype meaning, and the intent of the standard, was to make it an ignored character, the same as NUL (all zeroes). This was useful specifically for paper tape, because punching the all-ones bit pattern on top of an existing mark would obliterate it. Tapes designed to be "hand edited" could even be produced with spaces of extra NULs (blank tape) so that a block of characters could be "rubbed out" and then replacements put into the empty space.

As video terminals began to replace printing ones, the value of the "rubout" character was lost. DEC systems, for example, interpreted "Delete" to mean "remove the character before the cursor" and this interpretation also became common in Unix systems. Most other systems used "Backspace" for that meaning and used "Delete" to mean "remove the character at the cursor". That latter interpretation is the most common now.

Many more of the control codes have been given meanings quite different from their original ones. The "escape" character (ESC, code 27), for example, was intended originally to allow sending other control characters as literals instead of invoking their meaning. This is the same meaning of "escape" encountered in URL encodings, C language strings, and other systems where certain characters have a reserved meaning. Over time this meaning has been co-opted and has eventually been changed. In modern use, an ESC sent to the terminal usually indicates the start of a command sequence, usually in the form of a so-called "ANSI escape code" (or, more properly, a "Control Sequence Introducer") beginning with ESC followed by a "[" (left-bracket) character. An ESC sent from the terminal is most often used as an out-of-band character used to terminate an operation, as in the TECO and vi text editors. In graphical user interface (GUI) and windowing systems, ESC generally causes an application to abort its current operation or to exit (terminate) altogether.

The inherent ambiguity of many control characters, combined with their historical usage, created problems when transferring "plain text" files between systems. The best example of this is the newline problem on various operating systems. Teletype machines required that a line of text be terminated with both "Carriage Return" (which moves the printhead to the beginning of the line) and "Line Feed" (which advances the paper one line without moving the printhead). The name "Carriage Return" comes from the fact that on a manual typewriter the carriage holding the paper moved while the position where the keys struck the ribbon remained stationary. The entire carriage had to be pushed (returned) to the right in order to position the left margin of the paper for the next line.

DEC operating systems (OS/8, RT-11, RSX-11, RSTS, TOPS-10, etc.) used both characters to mark the end of a line so that the console device (originally Teletype machines) would work. By the time so-called "glass TTYs" (later called CRTs or terminals) came along, the convention was so well established that backward compatibility necessitated continuing the convention. When Gary Kildall cloned RT-11 to create CP/M he followed established DEC convention. Until the introduction of PC-DOS in 1981, IBM had no hand in this because their 1970s operating systems used EBCDIC instead of ASCII and they were oriented toward punch-card input and line printer output on which the concept of "carriage return" was meaningless. IBM's PC-DOS (also marketed as MS-DOS by Microsoft) inherited the convention by virtue of being a clone of CP/M, and Windows inherited it from MS-DOS.

Unfortunately, requiring two characters to mark the end of a line introduces unnecessary complexity and questions as to how to interpret each character when encountered alone. To simplify matters, plain text files on Multics, Unix and Unix-like systems, and Amiga systems use line feed (LF) alone as a line terminator. The original Macintosh OS, on the other hand, used carriage return (CR) alone as a line terminator; however, since Apple replaced it with the Unix-based OS X operating system, they now use line feed (LF) as well.

Transmission of text over the Internet, for protocols as E-mail and the World Wide Web, uses both characters.

Operating systems such as some older DEC operating systems, along with CP/M, tracked file length only in units of disk blocks and used Control-Z (SUB) to mark the end of the actual text in the file. For this reason, EOF, or end-of-file, was used colloquially and conventionally as a three-letter acronym (TLA) for Control-Z instead of SUBstitute. For a variety of reasons, the end-of-text code, ETX aka Control-C, was inappropriate and using Z as the control code to end a file is analogous to it ending the alphabet, a very convenient mnemonic aid.

In C library and Unix conventions, the null character is used to terminate text strings; such null-terminated strings can be known in abbreviation as ASCIZ or ASCIIZ, where here Z stands for "zero".

ASCII CODES

Codes 0 through 31 and 127 (decimal) are unprintable control characters. Code 32 (decimal) is a nonprinting spacing characer. Codes 33 through 126 (decimal) are printable graphic characters.

Binary 		Oct 	Dec 	Hex Glyph
010 0000 	040 	32 		20
010 0001 	041 	33 		21 	!
010 0010 	042 	34 		22 	"
010 0011 	043 	35 		23 	#
010 0100 	044 	36 		24 	$
010 0101 	045 	37 		25 	%
010 0110 	046 	38 		26 	&
010 0111 	047 	39 		27 	'
010 1000 	050 	40 		28 	(
010 1001 	051 	41 		29 	)
010 1010 	052 	42 		2A 	*
010 1011 	053 	43 		2B 	+
010 1100 	054 	44 		2C 	,
010 1101 	055 	45 		2D 	-
010 1110 	056 	46 		2E 	.
010 1111 	057 	47 		2F 	/
011 0000 	060 	48 		30 	0
011 0001 	061 	49 		31 	1
011 0010 	062 	50 		32 	2
011 0011 	063 	51 		33 	3
011 0100 	064 	52 		34 	4
011 0101 	065 	53 		35 	5
011 0110 	066 	54 		36 	6
011 0111 	067 	55 		37 	7
011 1000 	070 	56 		38 	8
011 1001 	071 	57 		39 	9
011 1010 	072 	58 		3A 	:
011 1011 	073 	59 		3B 	;
011 1100 	074 	60 		3C 	<
011 1101 	075 	61 		3D 	=
011 1110 	076 	62 		3E 	>
011 1111 	077 	63 		3F 	?
100 0000 	100 	64 		40 	@
100 0001 	101 	65 		41 	A
100 0010 	102 	66 		42 	B
100 0011 	103 	67 		43 	C
100 0100 	104 	68 		44 	D
100 0101 	105 	69 		45 	E
100 0110 	106 	70 		46 	F
100 0111 	107 	71 		47 	G
100 1000 	110 	72 		48 	H
100 1001 	111 	73 		49 	I
100 1010 	112 	74 		4A 	J
100 1011 	113 	75 		4B 	K
100 1100 	114 	76 		4C 	L
100 1101 	115 	77 		4D 	M
100 1110 	116 	78 		4E 	N
100 1111 	117 	79 		4F 	O
101 0000 	120 	80 		50 	P
101 0001 	121 	81 		51 	Q
101 0010 	122 	82 		52 	R
101 0011 	123 	83 		53 	S
101 0100 	124 	84 		54 	T
101 0101 	125 	85 		55 	U
101 0110 	126 	86 		56 	V
101 0111 	127 	87 		57 	W
101 1000 	130 	88 		58 	X
101 1001 	131 	89 		59 	Y
101 1010 	132 	90 		5A 	Z
101 1011 	133 	91 		5B 	[
101 1100 	134 	92 		5C 	
101 1101 	135 	93 		5D 	]
101 1110 	136 	94 		5E 	^
101 1111 	137 	95 		5F 	_
110 0000 	140 	96 		60 	`
110 0001 	141 	97 		61 	a
110 0010 	142 	98 		62 	b
110 0011 	143 	99 		63 	c
110 0100 	144 	100 	64 	d
110 0101 	145 	101 	65 	e
110 0110 	146 	102 	66 	f
110 0111 	147 	103 	67 	g
110 1000 	150 	104 	68 	h
110 1001 	151 	105 	69 	i
110 1010 	152 	106 	6A 	j
110 1011 	153 	107 	6B 	k
110 1100 	154 	108 	6C 	l
110 1101 	155 	109 	6D 	m
110 1110 	156 	110 	6E 	n
110 1111 	157 	111 	6F 	o
111 0000 	160 	112 	70 	p
111 0001 	161 	113 	71 	q
111 0010 	162 	114 	72 	r
111 0011 	163 	115 	73 	s
111 0100 	164 	116 	74 	t
111 0101 	165 	117 	75 	u
111 0110 	166 	118 	76 	v
111 0111 	167 	119 	77 	w
111 1000 	170 	120 	78 	x
111 1001 	171 	121 	79 	y
111 1010 	172 	122 	7A 	z
111 1011 	173 	123 	7B 	{
111 1100 	174 	124 	7C 	|
111 1101 	175 	125 	7D 	}
111 1110 	176 	126 	7E 	~

THE NON PRINTING CHARACTERS

000   or   �  =
001   or     = 	
002   or     = 	
003   or     = 	
004   or     = 	
005   or     = 	
006   or     = 	
007   or     = 	
008   or     = 	
009   or   	  =
010   or   
  =
011   or     =
012   or     = 	
013   or   
  =
014   or     = 	
015   or     = 	
016   or     = 	
017   or     = 	
018   or     = 	
019   or     = 	
020   or     = 	
021   or     = 	
022   or     = 	
023   or     = 	
024   or     = 	
025   or     = 	
026   or     = 	
027   or     = 	
028   or     = 	
029   or     = 	
030   or     = 	
031   or     = 	
032   or      = 	 

SPECIAL CHARACTERS

033   or   !  = 	!
034   or   "  = 	"
035   or   #  = 	#
036   or   $  = 	$
037   or   %  = 	%
038   or   &  = 	&
039   or   '  = 	'
040   or   (  = 	(
041   or   )  = 	)
042   or   *  = 	*
043   or   +  = 	+
044   or   ,  = 	,
045   or   -  = 	-
046   or   .  = 	.
047   or   /  = 	/

NUMERIC CHARACTERS

048   or   0  = 	0
049   or   1  = 	1
050   or   2  = 	2
051   or   3  = 	3
052   or   4  = 	4
053   or   5  = 	5
054   or   6  = 	6
055   or   7  = 	7
056   or   8  = 	8
057   or   9  = 	9

ADDITIONAL SPECIAL CHARACTERS

058   or   :  = 	:
059   or   ;  = 	;
060   or   <  = 	<
061   or   =  = 	=
062   or   >  = 	>
063   or   ?  = 	?
064   or   @  = 	@

CAPITALIZED or UPPER CASE CHARACTERS

065   or   A  = 	A
066   or   B  = 	B
067   or   C  = 	C
068   or   D  = 	D
069   or   E  = 	E
070   or   F  = 	F
071   or   G  = 	G
072   or   H  = 	H
073   or   I  = 	I
074   or   J  = 	J
075   or   K  = 	K
076   or   L  = 	L
077   or   M  = 	M
078   or   N  = 	N
079   or   O  = 	O
080   or   P  = 	P
081   or   Q  = 	Q
082   or   R  = 	R
083   or   S  = 	S
084   or   T  = 	T
085   or   U  = 	U
086   or   V  = 	V
087   or   W  = 	W
088   or   X  = 	X
089   or   Y  = 	Y
090   or   Z  = 	Z

ADDITIONAL SPECIAL CHARACTERS

091   or   [  = 	[
092   or   \  = 	
093   or   ]  = 	]
094   or   ^  = 	^
095   or   _  = 	_
096   or   `  = 	`

LOWER CASE CHARACTERS

097   or   a  = 	a
098   or   b  = 	b
099   or   c  = 	c
100   or   d  = 	d
101   or   e  = 	e
102   or   f  = 	f
103   or   g  = 	g
104   or   h  = 	h
105   or   i  = 	i
106   or   j  = 	j
107   or   k  = 	k
108   or   l  = 	l
109   or   m  = 	m
110   or   n  = 	n
111   or   o  = 	o
112   or   p  = 	p
113   or   q  = 	q
114   or   r  = 	r
115   or   s  = 	s
116   or   t  = 	t
117   or   u  = 	u
118   or   v  = 	v
119   or   w  = 	w
120   or   x  = 	x
121   or   y  = 	y
122   or   z  = 	z

EXTENDED ASCII CHARACTERS

123   or   {  = 	{
124   or   |  = 	|
125   or   }  = 	}
126   or   ~  = 	~
127   or     = 	
128   or   €  = 	€
129   or     = 	
130   or   ‚  = 	‚
131   or   ƒ  = 	ƒ
132   or   „  = 	„
133   or   …  = 	…
134   or   †  = 	†
135   or   ‡  = 	‡
136   or   ˆ  = 	ˆ
137   or   ‰  = 	‰
138   or   Š  = 	Š
139   or   ‹  = 	‹
140   or   Œ  = 	Œ
141   or     = 	
142   or   Ž  = 	Ž
143   or     = 	
144   or     = 	
145   or   ‘  = 	‘
146   or   ’  = 	’
147   or   “  = 	“
148   or   ”  = 	”
149   or   •  = 	•
150   or   –  = 	–
151   or   —  = 	—
152   or   ˜  = 	˜
153   or   ™  = 	™
154   or   š  = 	š
155   or   ›  = 	›
156   or   œ  = 	œ
157   or     = 	
158   or   ž  = 	ž
159   or   Ÿ  = 	Ÿ
160   or      =
161   or   ¡  = 	¡
162   or   ¢  = 	¢
163   or   £  = 	£
164   or   ¤  = 	¤
165   or   ¥  = 	¥
166   or   ¦  = 	¦
167   or   §  = 	§
168   or   ¨  = 	¨
169   or   ©  = 	©
170   or   ª  = 	ª
171   or   «  = 	«
172   or   ¬  = 	¬
173   or   ­  = 	­
174   or   ®  = 	®
175   or   ¯  = 	¯
176   or   °  = 	°
177   or   ±  = 	±
178   or   ²  = 	²
179   or   ³  = 	³
180   or   ´  = 	´
181   or   µ  = 	µ
182   or   ¶  = 	¶
183   or   ·  = 	·
184   or   ¸  = 	¸
185   or   ¹  = 	¹
186   or   º  = 	º
187   or   »  = 	»
188   or   ¼  = 	¼
189   or   ½  = 	½
190   or   ¾  = 	¾
191   or   ¿  = 	¿
192   or   À  = 	À
193   or   Á  = 	Á
194   or   Â  = 	Â
195   or   Ã  = 	Ã
196   or   Ä  = 	Ä
197   or   Å  = 	Å
198   or   Æ  = 	Æ
199   or   Ç  = 	Ç
200   or   È  = 	È
201   or   É  = 	É
202   or   Ê  = 	Ê
203   or   Ë  = 	Ë
204   or   Ì  = 	Ì
205   or   Í  = 	Í
206   or   Î  = 	Î
207   or   Ï  = 	Ï
208   or   Ð  = 	Ð
209   or   Ñ  = 	Ñ
210   or   Ò  = 	Ò
211   or   Ó  = 	Ó
212   or   Ô  = 	Ô
213   or   Õ  = 	Õ
214   or   Ö  = 	Ö
215   or   ×  = 	×
216   or   Ø  = 	Ø
217   or   Ù  = 	Ù
218   or   Ú  = 	Ú
219   or   Û  = 	Û
220   or   Ü  = 	Ü
221   or   Ý  = 	Ý
222   or   Þ  = 	Þ
223   or   ß  = 	ß
224   or   à  = 	à
225   or   á  = 	á
226   or   â  = 	â
227   or   ã  = 	ã
228   or   ä  = 	ä
229   or   å  = 	å
230   or   æ  = 	æ
231   or   ç  = 	ç
232   or   è  = 	è
233   or   é  = 	é
234   or   ê  = 	ê
235   or   ë  = 	ë
236   or   ì  = 	ì
237   or   í  = 	í
238   or   î  = 	î
239   or   ï  = 	ï
240   or   ð  = 	ð
241   or   ñ  = 	ñ
242   or   ò  = 	ò
243   or   ó  = 	ó
244   or   ô  = 	ô
245   or   õ  = 	õ
246   or   ö  = 	ö
247   or   ÷  = 	÷
248   or   ø  = 	ø
249   or   ù  = 	ù
250   or   ú  = 	ú
251   or   û  = 	û
252   or   ü  = 	ü
253   or   ý  = 	ý
254   or   þ  = 	þ
255   or   ÿ  = 	ÿ

This page contains content from article and is released under the CC-BY-SA.

Linux ASCII Unicode

 

 

Comments