Computer memory saves all data in digital form. There is no way to store characters directly. Each character has its digital code equivalent: ASCII code (for American Standard Code for Information Interchange). Basic ASCII code represented characters as 7 bits (for 128 possible characters, numbered from 0 to 127). In the 1960s, the ASCII code was adopted as the new standard. With it, characters can be coded using 8 bits for 256 possible characters.
What is the ASCII code chart?
Codes 0 to 31 are not used for characters They are called control characters because they are used for actions like:
- Carriage return (CR).
- Bell (BEL).
Codes 65 to 90 stand for uppercase letters, and codes 97 to 122 stand for lowercase letters (Changing the 6th-bit switches uppercase to lowercase; this is equivalent to adding 32 to the ASCII code in base-10.)
ASCII character chart
|Character||ASCII Code||Hexadecimal Code|
|SOH (Start of heading)||1||01|
|STX (Start of text)||2||02|
|ETX (End of text)||3||03|
|EOT (End of transmission)||4||04|
|TAB (Horizontal tabulation)||9||09|
|LF (Line Feed)||10||0A|
|VT (Vertical tabulation)||11||0B|
|FF (Form feed)||12||0C|
|CR (Carriage return)||13||0D|
|SO (Shift out)||14||0E|
|SI (Shift in)||15||0F|
|DLE (Data link escape)||16||10|
|DC1 (Device control 1)||17||11|
|DC2 (Device control 2)||18||12|
|DC3 (Device control 3)||19||13|
|DC4 (Device control 4)||20||14|
|NAK (Negative acknowledgement)||21||15|
|SYN (Synchronous idle)||22||16|
|ETB (End of transmission block)||23||17|
|EM (End of medium)||25||19|
|FS (File separator)||28||1C|
|GS (Group separator)||29||1D|
|RS (Record separator)||30||1E|
|US (Unit separator)||31||1F|
Extended ASCII Character Chart
ASCII Code was developed for use with the English language. It does not have accented characters, or language-specific characters. To encode such a character, a different code system is needed. ASCII code was extended to 8 bits (a byte) in order to be able to encode more characters (this is also known as Extended ASCII Code). This code assigns the values 0 to 255 (coded as 8 bits, that is, 1 byte) to uppercase and lowercase letters, digits, punctuation marks and other symbols (including accented characters, in the code iso-latin1).
Extended ASCII code is not standardized, and varies depending on which platform is used.
The two most commonly used extended ASCII character sets are:
- OEM Extended ASCII Code: it was built into the first IBM PCs.
- ANSI Extended ASCII CODE: it is used by recent operating systems
What is the EBCDIC code?
Developed by IBM, EBCDIC code (short for Extended Binary-Coded Decimal Interchange Code) is used for encoding characters with 8 bits. Though widespread on IBM computers, it has not been as successful as ASCII code.
What is unicode?
Unicode is a 16-bit character encoding system developed in 1991. Unicode can express any character as a 16-bit code, regardless of operating system or programming language.
It includes almost all current alphabets (among them Arabic, Armenian, Cyrillic, Greek, Hebrew, and Latin) and is compatible with ASCII code.