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ASCII Code

ASCII Code Definitions

Posted on April 14, 2022April 16, 2022 by definitionexplorer

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.

ASCII Code

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