Encoding on the Internet

2: ASCII Encoding

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Standing for "American Standard Code for Information Interchange", this was the first attempt to provide a character exchange standard. When it was invented in the 1960's, computing limitations limited the set to 2^⁷ or 128 characters. For more information on how ASCII was developed, you can read this article at CNN.com.

ASCII Chart

Characters number 1-31 are old control characters designed for teletype machines.



ASCII Numeric Values 32-127

Num Char 32   33 ! 34 " 35 # 36 $ 37 % 38 & 39 ' 40 ( 41 ) 42 * 43 + 44 , 45 - 46 . 47 /

Num Char 48 0 49 1 50 2 51 3 52 4 53 5 54 6 55 7 56 8 57 9 58 : 59 ; 60 < 61 = 62 > 63 ?

Num Char 64 @ 65 A 66 B 67 C 68 D 69 E 70 F 71 G 72 H 73 I 74 J 75 K 76 L 77 M 78 N 79 O

Num Char 80 P 81 Q 82 R 83 S 84 T 85 U 86 V 87 W 88 X 89 Y 90 Z 91 [ 92 \ 93 ] 94 ^ 95 _

Num Char 96 ` 97 a 98 b 99 c 100 d 101 e 102 f 103 g 104 h 105 i 106 j 107 k 108 l 109 m 110 n 111 o

Num Char 112 p 113 q 114 r 115 s 116 t 117 u 118 v 119 w 120 x 121 y 122 z 123 { 124 | 125 } 126 ~ 127 DEL

 

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Properties of ASCII

ASCII is structured as followed

• Characters #0-31 are old teletype command or control codes
• Character #32 is a blank space
• Characters #48-57 are numerals
• Characters# 65-90 are capital letters
• Characters #97-122 are lower case letters
• The rest are different types of punctuation
• Numeric position determines alphabetic order

  NOTE: Sometimes the character number in an encoding scheme is called a code point.

Additional charts can be found at the following Web sites, among others.

• Fincher - www.fincher.org/Utilities/Ascii.shtml
• Memorial University of Newfoundland - web.cs.mun.ca/~michael/c/ascii-table.html
• University of Wisconsin - www.neurophys.wisc.edu/comp/docs/ascii.html

  NOTE: Some charts may list the decimal number (base-10) as well the hexadecimal (base-16) number and octal (base-8) number. In most cases, you would use the decimal number.

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Deficiencies of ASCII

ASCII is notoriously U.S.centric and did not provide for common Western European symbols such as the British £ symbol, accented letters (e.g. ñ, é, ü), or even the ¢ symbol. In addition, it is a 7-bit code restricted to 128 (2⁷) characters, which is too few characters for the many languages which use accents in their spelling.

However, ASCII has been the default standard since its inception, and is an encoding standard available to almost all modern computers all over the world.

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This Web page maintained by Teaching and Learning with Technology, a unit of Information Technology Services. For questions or comments on this Web page, please contact Elizabeth J. Pyatt (ejp10@psu.edu).

Unicode character names and hexadecimal entity codes are taken from the public Unicode Character Charts.

Last Modified: Thursday, 26-Jul-2007 16:00:30 EDT