ASCII code. The ASCII code (acronym in English for American S tandard C ode for Information Interchange according to abbreviationfinder) is the model or pattern of characters to be used during the exchange of information based on the Latin alphabet as used in modern English and other Western languages.
History
The ASCII code was developed in the field of telegraphy and was first used commercially as a teleprinting code powered by Bell Data Services. Bell had planned to use a six-bit code, derived from Fieldata, that added punctuation and lowercase letters to the older Baudot teleprinting code, but they were persuaded to join the American Standards Agency (ASA) subcommittee, which had started to develop the ASCII code.
Baudot helped automate the sending and receiving of telegraphic messages, and borrowed many features from Morse code; however, unlike Morse code, Baudot used codes of constant length. Compared to earlier telegraph codes, the code proposed by Bell and ASA resulted in a more convenient rearrangement for ordering lists (especially since it was ordered alphabetically) and added features such as the ‘escape sequence’.
The American Standards Agency (ASA), which would later become the American National Standards Institute (Ansi), first published the ASCII code in 1963. The ASCII published in 1963 had an arrow pointing up (↑) in place of the circumflex (^) and an arrow pointing to the left instead of the underscore (_).
The 1967 version added the lowercase letters, changed the names of some control codes, and moved both the ACK and ESC control codes from the lowercase letters area to the control codes area.
ASCII was updated accordingly and published as ANSI X3.4-1968, ANSI X3.4-1977]], and finally ANSI X3.4-1986.
Other standards bodies have published character codes that are identical to ASCII. These character codes are often referred to as ASCII, even though ASCII is strictly defined by the ASA/ ANSI standards only:
– The European Computer Manufacturers Association (ECMA) published editions of its ASCII clone, ECMA-6 in 1965, 1967, 1970, 1973, 1983, and 1991. The 1991 edition is identical to ANSI X3.4-1986.
– The International Organization for Standardization (ISO) published its version, ISO 646 (later ISO/IEC 646) in 1967, 1972, 1983 and 1991. In particular, ISO 646: 1972 established a set of country-specific versions where punctuation characters were replaced with non-English characters. ISO/IEC 646: 1991 The International Reference Version is the same as in ANSI X3.4-1986.
– The International Telecommunications Union (ITU) published its version of ANSI X3.4-1986, ITU Recommendation T.50, in 1992.
In the early 1970s, a version was published as CCITT Recommendation V.3.
– DIN published a version of ASCII as the DIN 66003 standard in 1974.
– The Internet Engineering Task Force (IETF) published a version in 1969 as RFC 20, and established the standard version for the Internet, based on ANSI X3.4-1986, with the publication of RFC 1345 in 1992.
– The IBM version of ANSI X3.4-1986 was published in the IBM technical literature as code page 367.
The ASCII Code
A computer’s memory stores all information in digital format. There is no way to store characters directly. Each of the characters has an equivalent digital code. This is called an ASCII (American Standard Code for Information Interchange) code. The basic ASCII code represented characters using 7 bits (for 128 possible characters, numbered 0 through 127).
– Codes 0 to 31 are not used for characters. These are called control characters as they are used for actions such as Carriage Return (CR) or Bell (BEL)
– Codes 65 to 90 represent upper case letters.
– Codes 97 to 122 represent lowercase letters
(If we change the 6th bit, it goes from uppercase to lowercase; this is equivalent to adding 32 to the ASCII code in decimal base).
ASCII control characters
ASCII reserves the first 32 codes (decimal numbers 0-31) for control characters: codes originally intended not to carry printable information, but rather to control devices (for example 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 makes the printer advance its paper), and character 8 represents the “backspace key”.
Control characters that do not include carriage return, line feed, or white space are called non-whitespace control characters. Except for 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 format.
The original ASCII standard used only short descriptive phrases for each control character. The ambiguity this left was sometimes intentional (where a character would be used slightly differently in a terminal link than in a data stream) and sometimes more accidental (such as what “delete” means).
ASCII printable characters
Code 32, “space” character, denotes the space between words, as produced by the spacer on a keyboard. The “space” character is considered an invisible graphic rather than a control character.[20] Codes 33 through 126, known as the printable characters, represent letters, digits, punctuation marks, and some miscellaneous symbols.
Seven-bit ASCII provided seven “national” characters and, if the combined hardware and software allow, can use overstrikes to simulate some additional international characters: in such a scenario a backspace key can precede a backtick (which the Americans and British standards, but only those standards, also call “opening single quotes”), a backtick, or a breath mark (inverted vel).
| Binary | Oct | dec | hex | glyph | Binary | Oct | dec | hex | glyph | Binary | Oct | dec | hex | glyph | ||
| 010 0000 010 0001 010 0010 010 0011 010 0100 010 0101 010 0110 010 0101 010 010 010 010 010 1010 010 1011 010 1100 010 1101 010 1110 010 1111 011 0000 011 0001 011 011 011 011 011 011 011 011 011 011 011 0111 011 1000 011 1001 011 1010 011 1011 011 1100 011 1101 011 1110 011 1111 |
40 41 42 43 44 45 46 47 50 51 52 53 54 55 56 57 60 61 62 63 64 65 66 67 70 71 72 73 74 75 76 77 |
32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 |
20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2nd 2E 2F 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F |
␠ ! ” # $ % & ‘ ( ) * + , – . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? |
100 0000 100 0001 100 0010 100 0011 100 0100 100 0101 100 0110 100 0111 100 1000 100 1001 100 1010 100 1011 100 1100 100 1101 100 1110 100 1111 101 0000 101 0001 101 0010 101 0011 101 0100 101 0101 101 0110 101 0111 101 1000 101 1001 101 1010 101 1011 101 1100 101 1101 101 1110 101 1111 |
100 101 102 103 104 105 106 107 110 111 112 113 114 115 116 117 120 121 122 123 124 125 126 127 130 131 132 133 134 135 7 136 |
64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 |
40 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 50 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F |
@ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ \ ] ^ _ |
110 0000 110 0001 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 110 111 111 111 111 111 111 0011 111 111 0000 111 0011 111 111 111 0000 111 0011 111 111 111 0000 111 0011 111 111 111 111 0011 111 0100 111 0101 111 0110 111 0111 111 1000 111 1001 111 1010 111 1011 111 1100 111 1101 111 1110 |
140 141 142 143 144 145 146 147 150 151 152 153 154 155 156 157 160 161 162 163 164 165 166 167 170 171 172 173 174 175 176 |
96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 |
60 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E |
` a b c d e f g h i j k l m n o p q r s t u v W x y z { | } ~ |
ASCII art
The ASCII character code is the support of a minority artistic discipline, ASCII art, which consists of composing images using printable ASCII characters. The resulting effect has been compared to pointillism, as images produced with this technique are generally appreciated in more detail when viewed from a distance.
ASCII art began as an experimental art, but it soon became popular as a means of representing images on media incapable of processing graphics, such as teletypes, terminals, emails, or some printers. Although you can manually compose ASCII art using a text editor, you can also automatically convert images and videos to ASCII using software, such as the popular Aalib library (freely licensed). Aalib is supported by some graphic design programs, games and video players.
