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.

DECOCTHEXBINSymbolHTML NumberDescription
0000NULNull char
1111SOH Start of Heading
22210STXStart of Text
33311ETXEnd of Text
444100EOTEnd of Transmission
81081000BSBack Space
91191001HT Horizontal Tab
10120A1010LF Line Feed
11130B1011VT Vertical Tab
12140C1100FF Form Feed
13150D1101CR Carriage Return
14160E1110SOShift Out / X-On
15170F1111SIShift In / X-Off
16201010000DLEData Line Escape
17211110001DC1Device Control 1 (oft. XON)
18221210010DC2Device Control 2
19231310011DC3Device Control 3 (oft. XOFF)
20241410100DC4Device Control 4
21251510101NAKNegative Acknowledgement
22261610110SYNSynchronous Idle
23271710111ETBEnd of Transmit Block
25311911001EMEnd of Medium
28341C11100FSFile Separator
29351D11101GSGroup Separator
30361E11110RSRecord Separator
31371F11111USUnit Separator
324020100000 Space
334121100001!!Exclamation mark
344222100010""Double quotes (or speech marks)
394727100111''Single quote
405028101000((Open parenthesis (or open bracket)
415129101001))Close parenthesis (or close bracket)
46562E101110..Period, dot or full stop
47572F101111//Slash or divide
60743C111100< <Less than (or open angled bracket)
62763E111110> >Greater than (or close angled bracket)
63773F111111??Question mark
64100401000000@@At symbol
65101411000001AAUppercase A
66102421000010BBUppercase B
67103431000011CCUppercase C
68104441000100DDUppercase D
69105451000101EEUppercase E
70106461000110FFUppercase F
71107471000111GGUppercase G
72110481001000HHUppercase H
73111491001001IIUppercase I
741124A1001010JJUppercase J
751134B1001011KKUppercase K
761144C1001100LLUppercase L
771154D1001101MMUppercase M
781164E1001110NNUppercase N
791174F1001111OOUppercase O
80120501010000PPUppercase P
81121511010001QQUppercase Q
82122521010010RRUppercase R
83123531010011SSUppercase S
84124541010100TTUppercase T
85125551010101UUUppercase U
86126561010110VVUppercase V
87127571010111WWUppercase W
88130581011000XXUppercase X
89131591011001YYUppercase Y
901325A1011010ZZUppercase Z
911335B1011011[[Opening bracket
931355D1011101]]Closing bracket
941365E1011110^^Caret - circumflex
96140601100000``Grave accent
97141611100001aaLowercase a
98142621100010bbLowercase b
99143631100011ccLowercase c
100144641100100ddLowercase d
101145651100101eeLowercase e
102146661100110ffLowercase f
103147671100111ggLowercase g
104150681101000hhLowercase h
105151691101001iiLowercase i
1061526A1101010jjLowercase j
1071536B1101011kkLowercase k
1081546C1101100llLowercase l
1091556D1101101mmLowercase m
1101566E1101110nnLowercase n
1111576F1101111ooLowercase o
112160701110000ppLowercase p
113161711110001qqLowercase q
114162721110010rrLowercase r
115163731110011ssLowercase s
116164741110100ttLowercase t
117165751110101uuLowercase u
118166761110110vvLowercase v
119167771110111wwLowercase w
120170781111000xxLowercase x
121171791111001yyLowercase y
1221727A1111010zzLowercase z
1231737B1111011{{Opening brace
1241747C1111100||Vertical bar
1251757D1111101}}Closing brace
1261767E1111110~~Equivalency sign - tilde

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.


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