To represent text in a computer system, we give each character its own special number. This number is called its code. We can then store this code in the computer using binary ones and zeros.
ASCII stands for American Standard Code for Information Interchange.
ASCII code allows computers to understand how to represent text. In ASCII, each character (letter, number, symbol or control character) is represented by a binary value. Extended ASCII is a version that supports representation of 256 different characters. This is because extended ASCII uses eight bits to represent a character as opposed to seven in standard ASCII (where the 8th bit is used for error checking).
The maximum number of characters that can be represented in extended ASCII is 256.
As an example, the ASCII code for uppercase A is 65.
Character
Code
Representation Binary
A
65
01000001
Character
A
Code
65
Representation Binary
01000001
Control characters and printable characters
Extended ASCII represents both control characters and printable characters.
Control characters are used to perform actions rather than to display a printable character on screen. Easily understood examples include 'Escape', 'Backspace' and 'Delete'.
Printable characters are used to show a character on screen. Letters, symbols, numbers and punctuation marks are all examples of printable characters.
Code
Character
Code
Character
Code
Character
Code
Character
0
Null
66
B
132
ä
198
ã
1
Start of Header
67
C
133
à
199
Ã
2
Start of Text
68
D
134
å
200
╚
3
End of Text
69
E
135
ç
201
╔
4
End of Trans.
70
F
136
ê
202
╩
5
Enquiry
71
G
137
ë
203
╦
6
Acknowledegment
72
H
138
è
204
╠
7
Bell
73
I
139
ï
205
═
8
Backspace
74
J
140
î
206
╬
9
Horizontal Tab
75
K
141
ì
207
¤
10
Line feed
76
L
142
Ä
208
ð
11
Vertical Tab
77
M
143
Å
209
Ð
12
New page
78
N
144
É
210
Ê
13
Return
79
O
145
æ
211
Ë
14
Shift out
80
P
146
Æ
212
ı
15
Shift in
81
Q
147
ô
213
ı
16
Data link escape
82
R
148
ö
214
Í
17
Device control 1
83
S
149
ò
215
Î
18
Device control 2
84
T
150
û
216
Ï
19
Device control 3
85
U
151
ù
217
┘
20
Device control 4
86
V
152
ÿ
218
┌
21
Negative acknowl.
87
W
153
Ö
219
█
22
Synchronous idle
88
X
154
Ü
220
▄
23
End of trans. block
89
Y
155
ø
221
¦
24
Cancel
90
Z
156
£
222
Ì
25
End of medium
91
[
157
Ø
223
▀
26
Substitute
92
\
158
×
224
Ó
27
Escape
93
]
159
ƒ
225
ß
28
File separator
94
^
160
á
226
Ô
29
Group separator
95
_
161
í
227
Ò
30
Record separator
96
'
162
ú
228
õ
31
Unit Separator
97
a
163
ñ
229
Õ
32
Space
98
b
164
ñ
230
µ
33
!
99
c
165
Ñ
231
þ
34
”
100
d
166
ª
232
Þ
35
#
101
e
167
º
233
Ú
36
$
102
f
168
¿
234
Û
37
%
103
g
169
®
235
Ù
38
&
104
h
170
¬
236
ý
39
’
105
i
171
½
237
Ý
40
(
106
j
172
¼
238
¯
41
)
107
k
173
¡
239
´
42
*
108
l
174
«
240
43
+
109
m
175
»
241
±
44
,
110
n
176
░
242
‗
45
-
111
o
177
▒
243
¾
46
.
112
p
178
▓
244
¶
47
/
113
q
179
│
245
§
48
0
114
r
180
┤
246
÷
49
1
115
s
181
Á
247
¸
50
2
116
t
182
Â
248
°
51
3
117
u
183
À
249
¨
52
4
118
v
184
╣
250
·
53
5
119
w
185
║
251
¹
54
6
120
x
186
║
252
³
55
7
121
y
187
╗
253
²
56
8
122
z
188
╝
254
■
57
9
123
{
189
¢
255
nbsp
58
:
124
|
190
¥
59
;
125
}
191
┐
60
˂
126
~
192
└
61
=
127
_
193
┴
62
˃
128
Ç
194
┬
63
?
129
ü
195
├
64
@
130
é
196
─
65
A
131
â
197
┼
Code
0
Character
Null
Code
66
Character
B
Code
132
Character
ä
Code
198
Character
ã
Code
1
Character
Start of Header
Code
67
Character
C
Code
133
Character
à
Code
199
Character
Ã
Code
2
Character
Start of Text
Code
68
Character
D
Code
134
Character
å
Code
200
Character
╚
Code
3
Character
End of Text
Code
69
Character
E
Code
135
Character
ç
Code
201
Character
╔
Code
4
Character
End of Trans.
Code
70
Character
F
Code
136
Character
ê
Code
202
Character
╩
Code
5
Character
Enquiry
Code
71
Character
G
Code
137
Character
ë
Code
203
Character
╦
Code
6
Character
Acknowledegment
Code
72
Character
H
Code
138
Character
è
Code
204
Character
╠
Code
7
Character
Bell
Code
73
Character
I
Code
139
Character
ï
Code
205
Character
═
Code
8
Character
Backspace
Code
74
Character
J
Code
140
Character
î
Code
206
Character
╬
Code
9
Character
Horizontal Tab
Code
75
Character
K
Code
141
Character
ì
Code
207
Character
¤
Code
10
Character
Line feed
Code
76
Character
L
Code
142
Character
Ä
Code
208
Character
ð
Code
11
Character
Vertical Tab
Code
77
Character
M
Code
143
Character
Å
Code
209
Character
Ð
Code
12
Character
New page
Code
78
Character
N
Code
144
Character
É
Code
210
Character
Ê
Code
13
Character
Return
Code
79
Character
O
Code
145
Character
æ
Code
211
Character
Ë
Code
14
Character
Shift out
Code
80
Character
P
Code
146
Character
Æ
Code
212
Character
ı
Code
15
Character
Shift in
Code
81
Character
Q
Code
147
Character
ô
Code
213
Character
ı
Code
16
Character
Data link escape
Code
82
Character
R
Code
148
Character
ö
Code
214
Character
Í
Code
17
Character
Device control 1
Code
83
Character
S
Code
149
Character
ò
Code
215
Character
Î
Code
18
Character
Device control 2
Code
84
Character
T
Code
150
Character
û
Code
216
Character
Ï
Code
19
Character
Device control 3
Code
85
Character
U
Code
151
Character
ù
Code
217
Character
┘
Code
20
Character
Device control 4
Code
86
Character
V
Code
152
Character
ÿ
Code
218
Character
┌
Code
21
Character
Negative acknowl.
Code
87
Character
W
Code
153
Character
Ö
Code
219
Character
█
Code
22
Character
Synchronous idle
Code
88
Character
X
Code
154
Character
Ü
Code
220
Character
▄
Code
23
Character
End of trans. block
Code
89
Character
Y
Code
155
Character
ø
Code
221
Character
¦
Code
24
Character
Cancel
Code
90
Character
Z
Code
156
Character
£
Code
222
Character
Ì
Code
25
Character
End of medium
Code
91
Character
[
Code
157
Character
Ø
Code
223
Character
▀
Code
26
Character
Substitute
Code
92
Character
\
Code
158
Character
×
Code
224
Character
Ó
Code
27
Character
Escape
Code
93
Character
]
Code
159
Character
ƒ
Code
225
Character
ß
Code
28
Character
File separator
Code
94
Character
^
Code
160
Character
á
Code
226
Character
Ô
Code
29
Character
Group separator
Code
95
Character
_
Code
161
Character
í
Code
227
Character
Ò
Code
30
Character
Record separator
Code
96
Character
'
Code
162
Character
ú
Code
228
Character
õ
Code
31
Character
Unit Separator
Code
97
Character
a
Code
163
Character
ñ
Code
229
Character
Õ
Code
32
Character
Space
Code
98
Character
b
Code
164
Character
ñ
Code
230
Character
µ
Code
33
Character
!
Code
99
Character
c
Code
165
Character
Ñ
Code
231
Character
þ
Code
34
Character
”
Code
100
Character
d
Code
166
Character
ª
Code
232
Character
Þ
Code
35
Character
#
Code
101
Character
e
Code
167
Character
º
Code
233
Character
Ú
Code
36
Character
$
Code
102
Character
f
Code
168
Character
¿
Code
234
Character
Û
Code
37
Character
%
Code
103
Character
g
Code
169
Character
®
Code
235
Character
Ù
Code
38
Character
&
Code
104
Character
h
Code
170
Character
¬
Code
236
Character
ý
Code
39
Character
’
Code
105
Character
i
Code
171
Character
½
Code
237
Character
Ý
Code
40
Character
(
Code
106
Character
j
Code
172
Character
¼
Code
238
Character
¯
Code
41
Character
)
Code
107
Character
k
Code
173
Character
¡
Code
239
Character
´
Code
42
Character
*
Code
108
Character
l
Code
174
Character
«
Code
240
Character
Code
43
Character
+
Code
109
Character
m
Code
175
Character
»
Code
241
Character
±
Code
44
Character
,
Code
110
Character
n
Code
176
Character
░
Code
242
Character
‗
Code
45
Character
-
Code
111
Character
o
Code
177
Character
▒
Code
243
Character
¾
Code
46
Character
.
Code
112
Character
p
Code
178
Character
▓
Code
244
Character
¶
Code
47
Character
/
Code
113
Character
q
Code
179
Character
│
Code
245
Character
§
Code
48
Character
0
Code
114
Character
r
Code
180
Character
┤
Code
246
Character
÷
Code
49
Character
1
Code
115
Character
s
Code
181
Character
Á
Code
247
Character
¸
Code
50
Character
2
Code
116
Character
t
Code
182
Character
Â
Code
248
Character
°
Code
51
Character
3
Code
117
Character
u
Code
183
Character
À
Code
249
Character
¨
Code
52
Character
4
Code
118
Character
v
Code
184
Character
╣
Code
250
Character
·
Code
53
Character
5
Code
119
Character
w
Code
185
Character
║
Code
251
Character
¹
Code
54
Character
6
Code
120
Character
x
Code
186
Character
║
Code
252
Character
³
Code
55
Character
7
Code
121
Character
y
Code
187
Character
╗
Code
253
Character
²
Code
56
Character
8
Code
122
Character
z
Code
188
Character
╝
Code
254
Character
■
Code
57
Character
9
Code
123
Character
{
Code
189
Character
¢
Code
255
Character
nbsp
Code
58
Character
:
Code
124
Character
|
Code
190
Character
¥
Code
Character
Code
59
Character
;
Code
125
Character
}
Code
191
Character
┐
Code
Character
Code
60
Character
˂
Code
126
Character
~
Code
192
Character
└
Code
Character
Code
61
Character
=
Code
127
Character
_
Code
193
Character
┴
Code
Character
Code
62
Character
˃
Code
128
Character
Ç
Code
194
Character
┬
Code
Character
Code
63
Character
?
Code
129
Character
ü
Code
195
Character
├
Code
Character
Code
64
Character
@
Code
130
Character
é
Code
196
Character
─
Code
Character
Code
65
Character
A
Code
131
Character
â
Code
197
Character
┼
Code
Character
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