ASCII
ASCII is a redirect to this article. For other meanings, see ASCII (disambiguation).
The American Standard Code for Information Interchange (ASCII, alternatively US-ASCII, often pronounced [ˈæski], German "Amerikanischer Standard-Code für den Informationsaustausch") is a 7-bit character encoding; it corresponds to the US variant of ISO 646 and serves as the basis for later character set encodings based on more bits.
The ASCII code was first approved by the American Standards Association (ASA) on June 17, 1963 as standard ASA X3.4-1963 and substantially updated in 1967/1968 and most recently in 1986 (ANSI X3.4-1986) by its successor institutions and is still in use today. The character encoding defines 128 characters, consisting of 33 non-printable as well as the following 95 printable characters, starting with the space character:
Letters as 7-bit code ASCII Dec Hex Binary 65 41 (0)100 0001 66 42 (0)100 0010 67 43 (0)100 0011 … … … … 90 5A (0)101 1010 Each character is assigned a bit pattern consisting of 7 bits. Since each bit can take on two values, there are 27 = 128 different bit patterns, which can also be interpreted as the integers 0-127 (hexadecimal 00h-7Fh). The eighth bit, which is not used for ASCII, can be used for error correction purposes (parity bit) on the communication lines or for other control tasks. Today, however, it is almost always used to extend ASCII to an 8-bit code. These extensions are largely compatible with the original ASCII, so that all characters defined in ASCII are also encoded by the same bit patterns in the various extensions. The simplest extensions are encodings with language-specific characters that are not contained in the basic Latin alphabet, cf. below. ASCII character table, hexadecimal numbering Code …0 …1 …2 …3 …4 …5 …6 …7 …8 …9 …A …B …C …D …E …F 0… NUL SOH STX ETX EOT ENQ ACK BEL BS HT LF VT FF CR SO SI 1… DLE DC1 DC2 DC3 DC4 NAC SYN ETB CAN EM SUB ESC FS GS RS US 2… SP # $ % + , - 3… 1 2 3 4 5 6 7 8 9 < > 4… A B C D E F G H I J K L M N O 5… P Q R S T U V W X Y Z [ \ ] _ 6… ` a b c d e f g h i j k l m n o 7… p q r s t u v w x y z { } DEL The first 32 ASCII character codes (from 00hex to 1Fhex) are reserved for control characters; see there for the explanation of the abbreviations in the table to the right (or above). These characters are not characters, but are (or were) used to control devices that use ASCII (such as printers). Control characters are, for example, carriage return for line feed or Bell (the bell); their definition is historical. Code 20hex (SP) is the space or blank character used in a text as a space and separator between words and is created on the keyboard by the space bar. The codes 21hex to 7Ehex stand for printable characters which include letters, digits and punctuation marks (punctuation marks, word signs). The letters are only lowercase and uppercase letters of the Latin alphabet. Letter variants used in non-English languages - for example, the German umlauts - are not included in the ASCII character set. Similarly, typographically correct dashes and quotation marks are absent; typography is limited to the typewriter set. The purpose was information exchange, not print typesetting. Code 7Fhex (all seven bits set to one) is a special character which is also called a delete character (DEL). This code used to be used like a control character in order to be able to subsequently delete an already punched character on punched tape or punched cards by setting all bits, i.e. by punching out all seven marks. This was the only way to erase, since once holes were made they could not be undone. Areas without holes (i.e. with the code 00hex) were found mainly at the beginning and end of a strip of holes (NUL). For this reason, only 126 characters belonged to the actual ASCII, because no character codes corresponded to the bit patterns 0 (0000000) and 127 (1111111). The code 0 was later interpreted in the programming language C as "end of string"; the character 127 was assigned various graphic symbols.
Coding
A B C Z Composition
Questions and Answers
Q: What is ASCII?
A: ASCII is a table of characters for computers, which uses binary code to handle text using the English alphabet, numbers, and other common symbols.Q: What does ASCII stand for?
A: ASCII stands for American Standard Code for Information Interchange.Q: When was ASCII developed?
A: ASCII was developed in the 1960s.Q: How many characters are included in the code?
A: The code includes definitions for 128 characters, which are assigned numbers from 0 to 127.Q: How many bits does it take to represent an ASCII character?
A: It takes 7 binary digits (bits) to represent an ASCII character.Q: Does an ASCII computer file use one byte per character?
A: Yes, an ASCII computer file uses one byte per character, with 8 bits per byte.
Q: Is standard ASCII still commonly used today? A: Yes, standard ASCI is still commonly used today, particularly in computer software and HTML files.
