- ASCII Code Definition: ASCII (American Standard Code for Information Interchange) is a 7-bit code used to represent text and control characters in digital electronics.
- History and Development: ASCII was first standardized in 1967 and updated in 1986 as ANSI X3.4.
- Structure and Representation: ASCII uses 7 bits to represent 128 characters, including letters, digits, and special symbols.
- ASCII Table Overview: The ASCII table shows characters with their corresponding binary, decimal, octal, and hexadecimal values.
- 8-bit ASCII: The extended 8-bit version, US ASCII-8, can represent 256 characters, enhancing its usage in digital electronics.
Alphanumeric codes use symbols and characters to represent data, letters, and numbers.
There are three types of alphanumeric codes: ASCII code, EBCDIC code, and Unicode. ASCII Code is the most commonly used of these (although the others are used in specific situations).
What is ASCII code
ASCII stands for ‘American Standard Code for Information Interchange’ and is pronounced ‘ask-ee’. ASCII code represents alphanumeric data in computers, communication equipment, and electronic devices. It was first published in 1967 and has been regularly updated, with the latest version being ANSI X3.4 in 1986.
ASCII code is a 7 bit code and is hence able to represent 27 = 128 characters. 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 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.
ASCII Code Table
| DEC | OCT | HEX | BIN | Symbol | Description |
| 0 | 0 | 0 | 0 | NUL | Null char |
| 1 | 1 | 1 | 1 | SOH | Start of Heading |
| 2 | 2 | 2 | 10 | STX | Start of Text |
| 3 | 3 | 3 | 11 | ETX | End of Text |
| 4 | 4 | 4 | 100 | EOT | End of Transmission |
| 5 | 5 | 5 | 101 | ENQ | Enquiry |
| 6 | 6 | 6 | 110 | ACK | Acknowledgment |
| 7 | 7 | 7 | 111 | BEL | Bell |
| 8 | 10 | 8 | 1000 | BS | Back Space |
| 9 | 11 | 9 | 1001 | HT | Horizontal Tab |
| 10 | 12 | 0A | 1010 | LF | Line Feed |
| 11 | 13 | 0B | 1011 | VT | Vertical Tab |
| 12 | 14 | 0C | 1100 | FF | Form Feed |
| 13 | 15 | 0D | 1101 | CR | Carriage Return |
| 14 | 16 | 0E | 1110 | SO | Shift Out / X-On |
| 15 | 17 | 0F | 1111 | SI | Shift In / X-Off |
| 16 | 20 | 10 | 10000 | DLE | Data Line Escape |
| 17 | 21 | 11 | 10001 | DC1 | Device Control 1 (oft. XON) |
| 18 | 22 | 12 | 10010 | DC2 | Device Control 2 |
| 19 | 23 | 13 | 10011 | DC3 | Device Control 3 (oft. XOFF) |
| 20 | 24 | 14 | 10100 | DC4 | Device Control 4 |
| 21 | 25 | 15 | 10101 | NAK | Negative Acknowledgement |
| 22 | 26 | 16 | 10110 | SYN | Synchronous Idle |
| 23 | 27 | 17 | 10111 | ETB | End of Transmit Block |
| 24 | 30 | 18 | 11000 | CAN | Cancel |
| 25 | 31 | 19 | 11001 | EM | End of Medium |
| 26 | 32 | 1A | 11010 | SUB | Substitute |
| 27 | 33 | 1B | 11011 | ESC | Escape |
| 28 | 34 | 1C | 11100 | FS | File Separator |
| 29 | 35 | 1D | 11101 | GS | Group Separator |
| 30 | 36 | 1E | 11110 | RS | Record Separator |
| 31 | 37 | 1F | 11111 | US | Unit Separator |
| 32 | 40 | 20 | 100000 | Space | |
| 33 | 41 | 21 | 100001 | ! | Exclamation mark |
| 34 | 42 | 22 | 100010 | “ | Double quotes (or speech marks) |
| 35 | 43 | 23 | 100011 | # | Number |
| 36 | 44 | 24 | 100100 | $ | Dollar |
| 37 | 45 | 25 | 100101 | % | Procenttecken |
| 38 | 46 | 26 | 100110 | & | Ampersand |
| 39 | 47 | 27 | 100111 | ‘ | Single quote |
| 40 | 50 | 28 | 101000 | ( | Open parenthesis (or open bracket) |
| 41 | 51 | 29 | 101001 | ) | Close parenthesis (or close bracket) |
| 42 | 52 | 2A | 101010 | * | Asterisk |
| 43 | 53 | 2B | 101011 | + | Plus |
| 44 | 54 | 2C | 101100 | , | Comma |
| 45 | 55 | 2D | 101101 | – | Hyphen |
| 46 | 56 | 2E | 101110 | . | Period, dot or full stop |
| 47 | 57 | 2F | 101111 | / | Slash or divide |
| 48 | 60 | 30 | 110000 | 0 | Zero |
| 49 | 61 | 31 | 110001 | 1 | One |
| 50 | 62 | 32 | 110010 | 2 | Two |
| 51 | 63 | 33 | 110011 | 3 | Three |
| 52 | 64 | 34 | 110100 | 4 | Four |
| 53 | 65 | 35 | 110101 | 5 | Five |
| 54 | 66 | 36 | 110110 | 6 | Six |
| 55 | 67 | 37 | 110111 | 7 | Seven |
| 56 | 70 | 38 | 111000 | 8 | Eight |
| 57 | 71 | 39 | 111001 | 9 | Nine |
| 58 | 72 | 3A | 111010 | : | Colon |
| 59 | 73 | 3B | 111011 | ; | Semicolon |
| 60 | 74 | 3C | 111100 | < | Less than (or open angled bracket) |
| 61 | 75 | 3D | 111101 | = | Equals |
| 62 | 76 | 3E | 111110 | > | Greater than (or close angled bracket) |
| 63 | 77 | 3F | 111111 | ? | Question mark |
| 64 | 100 | 40 | 1000000 | @ | At symbol |
| 65 | 101 | 41 | 1000001 | A | Uppercase A |
| 66 | 102 | 42 | 1000010 | B | Uppercase B |
| 67 | 103 | 43 | 1000011 | C | Uppercase C |
| 68 | 104 | 44 | 1000100 | D | Uppercase D |
| 69 | 105 | 45 | 1000101 | E | Uppercase E |
| 70 | 106 | 46 | 1000110 | F | Uppercase F |
| 71 | 107 | 47 | 1000111 | G | Uppercase G |
| 72 | 110 | 48 | 1001000 | H | Uppercase H |
| 73 | 111 | 49 | 1001001 | I | Uppercase I |
| 74 | 112 | 4A | 1001010 | J | Uppercase J |
| 75 | 113 | 4B | 1001011 | K | Uppercase K |
| 76 | 114 | 4C | 1001100 | L | Uppercase L |
| 77 | 115 | 4D | 1001101 | M | Uppercase M |
| 78 | 116 | 4E | 1001110 | N | Uppercase N |
| 79 | 117 | 4F | 1001111 | O | Uppercase O |
| 80 | 120 | 50 | 1010000 | P | Uppercase P |
| 81 | 121 | 51 | 1010001 | Q | Uppercase Q |
| 82 | 122 | 52 | 1010010 | R | Uppercase R |
| 83 | 123 | 53 | 1010011 | S | Uppercase S |
| 84 | 124 | 54 | 1010100 | T | Uppercase T |
| 85 | 125 | 55 | 1010101 | U | Uppercase U |
| 86 | 126 | 56 | 1010110 | V | Uppercase V |
| 87 | 127 | 57 | 1010111 | W | Uppercase W |
| 88 | 130 | 58 | 1011000 | X | Uppercase X |
| 89 | 131 | 59 | 1011001 | Y | Uppercase Y |
| 90 | 132 | 5A | 1011010 | Z | Uppercase Z |
| 91 | 133 | 5B | 1011011 | [ | Opening bracket |
| 92 | 134 | 5C | 1011100 | \ | Backslash |
| 93 | 135 | 5D | 1011101 | ] | Closing bracket |
| 94 | 136 | 5E | 1011110 | ^ | Caret – circumflex |
| 95 | 137 | 5F | 1011111 | _ | Underscore |
| 96 | 140 | 60 | 1100000 | ` | Grave accent |
| 97 | 141 | 61 | 1100001 | a | Lowercase a |
| 98 | 142 | 62 | 1100010 | b | Lowercase b |
| 99 | 143 | 63 | 1100011 | c | Lowercase c |
| 100 | 144 | 64 | 1100100 | d | Lowercase d |
| 101 | 145 | 65 | 1100101 | e | Lowercase e |
| 102 | 146 | 66 | 1100110 | f | Lowercase f |
| 103 | 147 | 67 | 1100111 | g | Lowercase g |
| 104 | 150 | 68 | 1101000 | h | Lowercase h |
| 105 | 151 | 69 | 1101001 | i | Lowercase i |
| 106 | 152 | 6A | 1101010 | j | Lowercase j |
| 107 | 153 | 6B | 1101011 | k | Lowercase k |
| 108 | 154 | 6C | 1101100 | l | Lowercase l |
| 109 | 155 | 6D | 1101101 | m | Lowercase m |
| 110 | 156 | 6E | 1101110 | n | Lowercase n |
| 111 | 157 | 6F | 1101111 | o | Lowercase o |
| 112 | 160 | 70 | 1110000 | p | Lowercase p |
| 113 | 161 | 71 | 1110001 | q | Lowercase q |
| 114 | 162 | 72 | 1110010 | r | Lowercase r |
| 115 | 163 | 73 | 1110011 | s | Lowercase s |
| 116 | 164 | 74 | 1110100 | t | Lowercase t |
| 117 | 165 | 75 | 1110101 | u | Lowercase u |
| 118 | 166 | 76 | 1110110 | v | Lowercase v |
| 119 | 167 | 77 | 1110111 | w | Lowercase w |
| 120 | 170 | 78 | 1111000 | x | Lowercase x |
| 121 | 171 | 79 | 1111001 | y | Lowercase y |
| 122 | 172 | 7A | 1111010 | z | Lowercase z |
| 123 | 173 | 7B | 1111011 | { | Opening brace |
| 124 | 174 | 7C | 1111100 | | | Vertical bar |
| 125 | 175 | 7D | 1111101 | } | Closing brace |
| 126 | 176 | 7E | 1111110 | ~ | Equivalency sign – tilde |
| 127 | 177 | 7F | 1111111 | 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.





