The US-ASCII Character Set
The First 128 Unicode Characters.
©2004, Bob Beeman
Updated 2004-09-19 SU
Read More Important Notice

The character set commonly used on the internet for European languages is known as ISO-8859. This standard was issued by the "International Standards Organization" and is copies are available only for purchase. Ten alphabets are currently available, all of which have US-ASCII as characters 0 through 127. ISO 8859 Latin-1 supports Western European languages, but there are nine others. One of the best attempts to capture the various character sets is RFC-1345, available from the Internet Engineering Task Force (IETF) for the price of a mouse click.

The most modern method of encoding the thousands of characters from all living (and a number of dead) languages is the Unicode" character set. Unicode is the universally accepted code for the world, and is supported by all major computer hardware and software vendors. Again, the first 128 characters of Unicode are the old original US-ASCII characters. The tilde character: "~" from Spanish), is also included in US-ASCII. The vast majority of characters in US-ASCII are not specific to the US, and include many characters used everywhere - for example the Arabic numerals:   0 1 2 3 4 5 6 7 8 9   the common math symbols:   + - * / =   and many common and not so common symbols:   . , / ? ' " ; : [ ] { } \ | ! @ # $ % ^ & * ( ) - _   including the "space" character (#32 decimal or 0x20 in Hex) used to separate words.

This page, your computer (Mac, PC, or Linux) and most of the English-language text that you encounter on the internet use this character set. The table below shows the decimal and Hexadecimal (base 16) character number, what each one looks like in your browser. There is additional information about the first 32 characters and character 127. Character "0" is not usually considered a legal character, and the HTML code may show through.

There is an excellent article on US-ASCII at Wikipedia.

Decimal 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Hexadecimal x00 x01 x02 x03 x04 x05 x06 x07 x08 x09 x0A x0B x0C x0D x0E x0F
Your Browser            
Kbd ctrl- ^@ ^A ^B ^C ^D ^E ^F ^G ^H ^I ^J ^K ^L ^M ^N ^O

Decimal 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Hexadecimal x10 x11 x12 x13 x14 x15 x16 x17 x18 x19 x1A x1B x1C x1D x1E x1F
Your Browser                  
Kbd ctrl- ^P ^Q ^R ^S ^T ^U ^V ^W ^X ^Y ^Z ^[ ^\ ^] ^^ ^_

Decimal 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Hexadecimal x20 x21 x22 x23 x24 x25 x26 x27 x28 x29 x2A x2B x2C x2D x2E x2F
Your Browser   ! " # $ % & ' ( ) * + , - . /

Decimal 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
Hexadecimal x30 x31 x32 x33 x34 x35 x36 x37 x38 x39 x3A x3B x3C x3D x3E x3F
Your Browser   0 1 2 3 4 5 6 7 8 9 : ; < = > ?

Decimal 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79
Hexadecimal x40 x41 x42 x43 x44 x45 x46 x47 x48 x49 x4A x4B x4C x4D x4E x4F
Your Browser   @ A B C D E F G H I J K L M N O

Decimal 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95
Hexadecimal x50 x51 x52 x53 x54 x55 x56 x57 x58 x59 x5A x5B x5C x5D x5E x5F
Your Browser   P Q R S T U V W X Y Z [ \ ] ^ _

Decimal 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111
Hexadecimal x60 x61 x62 x63 x64 x65 x66 x67 x68 x69 x6A x6B x6C x6D x6E x6F
Your Browser   ` a b c d e f g h i j k l m n o

Decimal 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127
Hexadecimal x70 x71 x72 x73 x74 x75 x76 x77 x78 x79 x7A x7B x7C x7D x7E x7F
Your Browser   p q r s t u v w x y z { | } ~ 


The first 32 US-ASCII / Unicode Characters - Control and Special
The usual keyboard combination is to hold down the control-key
(shown here as "^") simultaneously with a letter or symbol.
Decimal Hexadecimal Designation Keys Meaning
0 x00 NUL ^@ Null - Not generally considered a legal character.
1 x01 SOH ^A Start Of Header
2 x02 STX ^B Start of TeXt
3 x03 ETX ^C End of TeXt - Still used to interrupt processes in UNIX
4 x04 EOT ^D End Of Transmission
5 x05 ENQ ^E ENQuiry
6 x06 ACK ^F ACKnowledge
7 x07 BEL ^G BELl - On old Teletype Machines when you sent this it rang a bell at the other end, hence the name.
8 x08 BS ^H Back Space
9 x09 HT ^I Horizontal Tab - usually just called a "tab".
10 x0A LF ^J Line Feed
11 x0B VT ^K Vertical Tab
12 x0C FF ^L Form Feed
13 x0D CR ^M Carriage Return
14 x0E SO ^N Shift Out
15 x0F SI ^O Shift In
16 x10 DLE ^P Data Link Enable
17 x11 DC1 ^Q Device Control 1
18 x12 DC2 ^R Device Control 2
19 x13 DC3 ^S Device Control 3
20 x14 DC4 ^T Device Control 4
21 x15 NAK ^U Negative Acknowledgement - "I know you sent something, but either I didn't understand it, or I can't do that."
22 x16 SYN ^V SYNchronization
23 x17 ETB ^W End of Text Block
24 x18 CAN ^X CANcel
25 x19 EM ^Y End of Medium - The end of a paper tape, for example.
26 x1A SUB ^Z SUBstitute
27 x1B ESC ^[
ESCape - The escape key at the upper left of your keyboard usually sends this, assuming that it isn't just captured by the running program and mapped to something else.
28 x1C FS ^\ File Separator
29 x1D GS ^] Group Separatorr
30 x1E RS ^^ Record Separator
31 x1F US ^_ Unit Separator
127 x7F DEL ^_ DELete or Rub Out. Often used to delete characters on a paper tape.

More information about "US-ASCII"
Most of the first 32 characters are obsolescent now. They harken back to the time when single characters were used on data links to start and stop peripherals, indicate the end of paper tapes, eject pages from printers, ring a bell at the other end of the link, and generally control things remotely. The computing world has moved on, but a number of these characters are still widely used, including "Backspace", "Carriage Return", "Line Feed", "Tab: and "escape". Some of them are generally referred to by their alternative names (Control-C for example) and are used in UNIX terminal sessions and for other mostly "techie" purposes.

The use of these characters in UNIX sessions is one reason why Macs (unlike most PCs) have separate "Control" and "Apple/Command" keys. You use the "Apple/Command" key for things like "Copy" (Command-C), "Paste" (Command-V), and "Cut" (Command-X). You use the "Control" key so that you can type "Control Characters" in terminal sessions. On a Mac, this allows the UNIX terminal window and other such "tech toys" to use the normal key combinations for functions like "Cut and Paste" without compromising the ability to type control characters when required. Since Windows has only the "Control" key, there are potential conflicts in some cases, but these are minimized by the fact that Windows generally doesn't support UNIX conventions or utilities.

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©2004, Bob Beeman
That means that although it is copyrighted, it is intended for you to use for education or entertainment. You may use it yourself, copy and redistribute it, or even put it on your own website. I ask only that you not make any changes. If you reuse any of the code, make sure to list me as one of your sources.

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