ASCII code

We have discussed about the alphanumeric codes in a different article. We now know that these codes are used to represent different data, letters, numbers by distinguish symbols and characters, that’s why they are called alphanumeric codes. We also know that there are three types of alphanumeric codes, those are ASCII code, EBCDIC codes and Unicode, among which the first one is the most popular and used in maximum areas. And we will discuss about it in this article.

About the ASCII code

The name of the code ASCII stands for American Standard Code for Information Interchange and this is pronounced as ‘ask-ee’. They are used to represent alphanumeric data in computers, communication equipment in electronic device to represent the input and output in a more scientific manner. In 1967 this code was first published as a standard. From then it is constantly being updated and revised. In 1986 the latest version was called and published as ANSI X3.4. It is able to represent 27 = 128 codes as it is a seven bit code. Currently a total number of 95 printable characters are represented by this code including 26 upper case letters (A - Z), 26 lower case letters (a - z), 10 numerals (0 - 9) and there are 33 special characters which include mathematical symbols, punctuation marks and space characters. The latest development in the field of ASCII code is the development of 8 bit code which is known as US ASCII-8 or ASCII-8. As it is an 8 bit code it can represent 28 = 256 characters. The tabulated form of the ASCII code is given below.

Table ASCII code.

DEC OCT HEX BIN Symbol HTML Number Description
0 0 0 0 NUL &# 000; Null char
1 1 1 1 SOH &# 001; Start of Heading
2 2 2 10 STX &# 002; Start of Text
3 3 3 11 ETX &# 003; End of Text
4 4 4 100 EOT &# 004; End of Transmission
5 5 5 101 ENQ &# 005; Enquiry
6 6 6 110 ACK &# 006; Acknowledgment
7 7 7 111 BEL &# 007; Bell
8 10 8 1000 BS &# 008; Back Space
9 11 9 1001 HT &# 009; Horizontal Tab
10 12 0A 1010 LF &# 0 10 ; Line Feed
11 13 0B 1011 VT &# 0 11 ; Vertical Tab
12 14 0C 1100 FF &# 0 12 ; Form Feed
13 15 0D 1101 CR &# 0 13 ; Carriage Return
14 16 0E 1110 SO &# 0 14 ; Shift Out / X-On
15 17 0F 1111 SI &# 0 15 ; Shift In / X-Off
16 20 10 10000 DLE &# 0 16 ; Data Line Escape
17 21 11 10001 DC1 &# 0 17 ; Device Control 1 (oft. XON)
18 22 12 10010 DC2 &# 0 18 ; Device Control 2
19 23 13 10011 DC3 &# 0 19 ; Device Control 3 (oft. XOFF)
20 24 14 10100 DC4 &# 0 20 ; Device Control 4
21 25 15 10101 NAK &# 0 21 ; Negative Acknowledgement
22 26 16 10110 SYN &# 0 22 ; Synchronous Idle
23 27 17 10111 ETB &# 0 23 ; End of Transmit Block
24 30 18 11000 CAN &# 0 24 ; Cancel
25 31 19 11001 EM &# 0 25 ; End of Medium
26 32 1A 11010 SUB &# 0 26 ; Substitute
27 33 1B 11011 ESC &# 0 27 ; Escape
28 34 1C 11100 FS &# 0 28 ; File Separator
29 35 1D 11101 GS &# 0 29 ; Group Separator
30 36 1E 11110 RS &# 0 30 ; Record Separator
31 37 1F 11111 US &# 0 31 ; Unit Separator
32 40 20 100000 &# 32 ; Space
33 41 21 100001 ! &# 33 ; Exclamation mark
34 42 22 100010 " &# 34 ; Double quotes (or speech marks)
35 43 23 100011 # &# 35 ; Number
36 44 24 100100 $ &# 36 ; Dollar
37 45 25 100101 % &# 37 ; Procenttecken
38 46 26 100110 & &# 38 ; Ampersand
39 47 27 100111 ' &# 39 ; Single quote
40 50 28 101000 ( &# 40 ; Open parenthesis (or open bracket)
41 51 29 101001 ) &# 41 ; Close parenthesis (or close bracket)
42 52 2A 101010 * &# 42 ; Asterisk
43 53 2B 101011 + &# 43 ; Plus
44 54 2C 101100 , &# 44 ; Comma
45 55 2D 101101 - &# 45 ; Hyphen
46 56 2E 101110 . &# 46 ; Period, dot or full stop
47 57 2F 101111 / &# 47 ; Slash or divide
48 60 30 110000 0 &# 48 ; Zero
49 61 31 110001 1 &# 49 ; One
50 62 32 110010 2 &# 50 ; Two
51 63 33 110011 3 &# 51 ; Three
52 64 34 110100 4 &# 52 ; Four
53 65 35 110101 5 &# 53 ; Five
54 66 36 110110 6 &# 54 ; Six
55 67 37 110111 7 &# 55 ; Seven
56 70 38 111000 8 &# 56 ; Eight
57 71 39 111001 9 &# 57 ; Nine
58 72 3A 111010 : &# 58 ; Colon
59 73 3B 111011 ; &# 59 ; Semicolon
60 74 3C 111100 &# 60 ; Less than (or open angled bracket)
61 75 3D 111101 = &# 61 ; Equals
62 76 3E 111110 &# 62 ; Greater than (or close angled bracket)
63 77 3F 111111 ? &# 63 ; Question mark
64 100 40 1000000 @ &# 64 ; At symbol
65 101 41 1000001 A &# 65 ; Uppercase A
66 102 42 1000010 B &# 66 ; Uppercase B
67 103 43 1000011 C &# 67 ; Uppercase C
68 104 44 1000100 D &# 68 ; Uppercase D
69 105 45 1000101 E &# 69 ; Uppercase E
70 106 46 1000110 F &# 70 ; Uppercase F
71 107 47 1000111 G &# 71 ; Uppercase G
72 110 48 1001000 H &# 72 ; Uppercase H
73 111 49 1001001 I &# 73 ; Uppercase I
74 112 4A 1001010 J &# 74 ; Uppercase J
75 113 4B 1001011 K &# 75 ; Uppercase K
76 114 4C 1001100 L &# 76 ; Uppercase L
77 115 4D 1001101 M &# 77 ; Uppercase M
78 116 4E 1001110 N &# 78 ; Uppercase N
79 117 4F 1001111 O &# 79 ; Uppercase O
80 120 50 1010000 P &# 80 ; Uppercase P
81 121 51 1010001 Q &# 81 ; Uppercase Q
82 122 52 1010010 R &# 82 ; Uppercase R
83 123 53 1010011 S &# 83 ; Uppercase S
84 124 54 1010100 T &# 84 ; Uppercase T
85 125 55 1010101 U &# 85 ; Uppercase U
86 126 56 1010110 V &# 86 ; Uppercase V
87 127 57 1010111 W &# 87 ; Uppercase W
88 130 58 1011000 X &# 88 ; Uppercase X
89 131 59 1011001 Y &# 89 ; Uppercase Y
90 132 5A 1011010 Z &# 90 ; Uppercase Z
91 133 5B 1011011 [ &# 91 ; Opening bracket
92 134 5C 1011100 \ &# 92 ; Backslash
93 135 5D 1011101 ] &# 93 ; Closing bracket
94 136 5E 1011110 ^ &# 94 ; Caret - circumflex
95 137 5F 1011111 _ &# 95 ; Underscore
96 140 60 1100000 ` &# 96 ; Grave accent
97 141 61 1100001 a &# 97 ; Lowercase a
98 142 62 1100010 b &# 98 ; Lowercase b
99 143 63 1100011 c &# 99 ; Lowercase c
100 144 64 1100100 d &# 100 ; Lowercase d
101 145 65 1100101 e &# 101 ; Lowercase e
102 146 66 1100110 f &# 102 ; Lowercase f
103 147 67 1100111 g &# 103 ; Lowercase g
104 150 68 1101000 h &# 104 ; Lowercase h
105 151 69 1101001 i &# 105 ; Lowercase i
106 152 6A 1101010 j &# 106 ; Lowercase j
107 153 6B 1101011 k &# 107 ; Lowercase k
108 154 6C 1101100 l &# 108 ; Lowercase l
109 155 6D 1101101 m &# 109 ; Lowercase m
110 156 6E 1101110 n &# 110 ; Lowercase n
111 157 6F 1101111 o &# 111 ; Lowercase o
112 160 70 1110000 p &# 112 ; Lowercase p
113 161 71 1110001 q &# 113 ; Lowercase q
114 162 72 1110010 r &# 114 ; Lowercase r
115 163 73 1110011 s &# 115 ; Lowercase s
116 164 74 1110100 t &# 116 ; Lowercase t
117 165 75 1110101 u &# 117 ; Lowercase u
118 166 76 1110110 v &# 118 ; Lowercase v
119 167 77 1110111 w &# 119 ; Lowercase w
120 170 78 1111000 x &# 120 ; Lowercase x
121 171 79 1111001 y &# 121 ; Lowercase y
122 172 7A 1111010 z &# 122 ; Lowercase z
123 173 7B 1111011 { &# 123 ; Opening brace
124 174 7C 1111100 | &# 124 ; Vertical bar
125 175 7D 1111101 } &# 125 ; Closing brace
126 176 7E 1111110 ~ &# 126 ; Equivalency sign - tilde
127 177 7F 1111111 &# 127 ; Delete

From the table we can see that numbers 0 - 9 are represented with binary values with prefix 0011. In a similar fashion in case of upper-case letters -‘P’ to ‘Z’ are represented by 0101 0000 to 0101 1010, lower-case letters ‘p’ to ‘z’ are represented by 0111 0000 to 0111 1010.