There are 94 printable ASCII characters, numbered 33 to 126 (decimal) in the original code.

American Standard Code for Information Interchange (ASCII), pronounced /ˈæski/^[1] is a character encoding based on the English alphabet. A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page The modern English alphabet consists of 26 letters derived from the Latin alphabet: History See also History of the ASCII codes represent text in computers, communications equipment, and other devices that work with text. For other uses see Character. In Computer and machine-based Telecommunications terminology a character is a unit of A computer is a Machine that manipulates data according to a list of instructions. Most modern character encodings — which support many more characters than did the original — have a historical basis in ASCII. A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page

Historically, ASCII developed from telegraphic codes and its first commercial use was as a seven-bit teleprinter code promoted by Bell data services. A bit is a binary digit, taking a value of either 0 or 1 Binary digits are a basic unit of Information storage and communication Work on ASCII began in 1960. The first edition of the standard was published in 1963,^[2] a major revision in 1967, and the most recent update in 1986. Compared to earlier telegraph codes, the proposed Bell code and ASCII were both reordered for more convenient sorting (i. e. , alphabetization) of lists, and added features for devices other than teleprinters. Some ASCII features, including the "ESCape sequence", were due to Robert Bemer. Robert William Bemer ( February 8, 1920 &ndash June 22, 2004) was a computer scientist best known for his work at IBM during the late

ASCII includes definitions for 128 characters: 33 are non-printing, mostly obsolete control characters that affect how text is processed; 94 are printable characters (excluding the space). In Computing and Telecommunication, a control character or non-printing character is a Code point (a Number) in a In writing a space () is a blank area that is devoid of content which separates words letters numbers and punctuation The ASCII character encoding^[3] — or a compatible extension — is used on nearly all common computers, especially personal computers and workstations. A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated A workstation, such as a Unix workstation, RISC workstation or Engineering workstation, is a high-end Microcomputer

History

US ASCII 1967 Code Chart was structured with two columns of control characters, a column with special characters, a column with numbers, and four columns of letters

The American Standard Code for Information Interchange (ASCII) was developed by a committee of the American Standards Association, called the X3 committee. The ASA became the United States of America Standards Institute or USASI^[4] and ultimately the American National Standards Institute.

The X3 committee designed ASCII based on earlier teleprinter encoding systems. A teleprinter ( Like other character encodings, ASCII specifies a correspondence between digital bit patterns and character symbols (i. A character encoding consists of a code that pairs a sequence of characters from a given character set (sometimes incorrectly referred to as Code page For other uses see Character. In Computer and machine-based Telecommunications terminology a character is a unit of e. graphemes and control characters). In Typography, a grapheme is the fundamental unit in written language. In Computing and Telecommunication, a control character or non-printing character is a Code point (a Number) in a This allows digital devices to communicate with each other and to process, store, and communicate character-oriented information such as written language. A digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for The encodings in use before ASCII included 26 alphabetic characters, 10 numerical digits, and from 11 to 25 special graphic symbols. The modern English alphabet consists of 26 letters derived from the Latin alphabet: History See also History of the In Mathematics and Computer science, a digit is a symbol (a number symbol e To include control characters compatible with the Comité Consultatif International Téléphonique et Télégraphique standard, Fieldata and early EBCDIC, more than 64 codes were required. In Computing and Telecommunication, a control character or non-printing character is a Code point (a Number) in a The ITU Telecommunication Standardization Sector ( ITU-T) coordinates standards for telecommunications on behalf of the International Telecommunication Fieldata was a pioneering computer project run by the US Army Signal Corps in the late 1950s that intended to create a single standard for collecting and distributing Extended Binary Coded Decimal Interchange Code ( EBCDIC) is an 8- Bit Character encoding ( Code page) used on IBM mainframe Operating

The committee debated the possibility of a shift key function (like the Baudot code), which would allow more than 64 codes to be represented by six bits. The shift key is a Modifier key on a keyboard, used to type capital letters and other alternate "upper" characters The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII, and the root predecessor to International Telegraph In a shifted code, some character codes determine choices between options for the following character codes. This allows compact encoding, but is less reliable for data transmission; an error in transmitting the shift code typically makes a long part of the transmission unreadable. The standards committee decided against shifting, and so ASCII required at least a seven-bit code. ^[5]

The committee considered an eight-bit code, since eight bits would allow two four-bit patterns to efficiently encode two digits with binary coded decimal. In Computing and electronic systems binary-coded decimal ( BCD) is an encoding for decimal numbers in which each digit is represented by its own binary However this would require all data transmission to send eight bits when seven could suffice. The committee voted to use a seven-bit code to minimize costs associated with data transmission. Since perforated tape at the time could record eight bits in one position, this also allowed for a parity bit for error checking if desired. Error detection If an odd number of bits (including the parity bit are changed in transmission of a set of bits then parity bit will be incorrect and will thus indicate ^[6] Machines with octets as the native data type that did not use parity checking typically set the eighth bit to 0. In Computing, an octet is a grouping of eight Bits Octet, with the only exception noted below always refers to an entity having exactly eight ^[7]

The code itself was structured so that most control codes were together, and all graphic codes were together. The first two columns (32 positions) were reserved for control characters. ^[8] The "space" character had to come before graphics to make sorting algorithms easy, so its became position 32. In writing a space () is a blank area that is devoid of content which separates words letters numbers and punctuation In Computer science and Mathematics, a sorting algorithm is an Algorithm that puts elements of a list in a certain order. ^[9] The committee decided it was important to support the upper case 64-character alphabets, and chose to structure ASCII so it could easily be reduced to a usable 64-character set of graphic codes. Capital letters or majuscules pronunciation /məˈdʒʌskyuls ˈmædʒəˌskyuls/ in the Roman alphabet A, B, C, D, ^[10] Lower case letters were therefore not interleaved with upper case. Lower case (also lower-case or lowercase) minuscule, or small letters are the smaller form of letters as opposed to upper To keep options for lower case letters and other graphics open, the special and numeric codes were placed before the letters, and the letter 'A' was placed in position 65 to match the draft of the corresponding British standard. ^[11] The digits 0–9 were placed so they correspond to values in binary prefixed with 0011, making conversion with binary-coded decimal straightforward. In Computing and electronic systems binary-coded decimal ( BCD) is an encoding for decimal numbers in which each digit is represented by its own binary

Many of the non-alphanumeric characters were positioned to correspond to their shifted position on typewriters. Thus #, $ and % were placed to correspond to 3, 4, and 5 in the adjacent column. The parentheses could not correspond to 9 and 0, however, because the place corresponding to 0 was taken by the space character. Since many European typewriters placed the parentheses with 8 and 9, these correspnding positions were chosen for the parentheses. The @ symbol was not used in continental Europe and the committee expected it would be replaced by an accented À in France, so the @ was placed in position 64 next to the letter A. ^[12]

The control codes felt essential for data transmission were the start of message (SOM), end of address (EOA), end of message (EOM), end of transmission (EOT), "who are you?" (WRU), "are you?" (RU), a reserved device control (DC0), synchronys idle (SYNC), and acknowledge (ACK). These were positioned to maximize the Hamming distance between their bit patterns. Examples The Hamming distance between 1011101 and 1001001 ^[13]

With the other special characters and control codes filled in, ASCII was published as ASA X3. 4-1963, leaving 28 code positions without assigned meaning, reserved for future standardization. ^[14] This version did not specify codes for lower case characters because there was some debate there should be more control characters instead. ^[15] In late 1963 the International Organization for Standardization voted to assign lower case characters to columns 6 and 7. The X3 committee incorporated this decision, locating the lowercase letters so they differ in bit pattern from the upper case by a single bit. This simplified case-insensitive character matching. Text sometimes exhibits case sensitivity; that is words can differ in meaning based on differing use of uppercase and lowercase letters The X3 committee made other changes, including other new characters (the curly bracket characters), renaming some control characters (SOM became start of header (SOH)) and moving or removing others (RU was removed). ^[16] ASCII was subsequently updated as USASI X3. 4-1967, then USASI X3. 4-1968, ANSI X3. 4-1977, and finally, ANSI X3. 4-1986.

The X3 committee also addressed how ASCII should be transmitted (low bit first), and how it should be recorded on perforated tape. They proposed a 9-track standard for magnetic tape, and attempted to deal with some forms of punched card formats. The IBM System/360, released in 1964 introduced what is now generally known as 9 track tape.

ASCII itself first entered commercial use in 1963 as a seven-bit teleprinter code for American Telephone & Telegraph's TWX (Teletype Wide-area eXchange) network. Before proposing a merge request please see Talk and see if the merger you propose has recently been made and TWX originally used the earlier five-bit Baudot code, which was also used by the competing Telex teleprinter system. The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII, and the root predecessor to International Telegraph Bob Bemer introduced features such as the escape sequence. Robert William Bemer ( February 8, 1920 &ndash June 22, 2004) was a computer scientist best known for his work at IBM during the late ^[2] His British colleague Hugh McGregor Ross helped to popularize this work — according to Bemer, "so much so that the code that was to become ASCII was first called the Bemer-Ross Code in Europe". Hugh McGregor Ross (born August 31, 1917 in Nairobi, Kenya) is an early pioneer in the history of British Computing. ^[17]

On March 11, 1968, U. Events 1425 BC - Thutmose III, Pharaoh of Egypt, dies (according to the Low Chronology of the 18th Dynasty Year 1968 ( MCMLXVIII) was a Leap year starting on Monday (link will display full calendar of the Gregorian calendar. S. President Lyndon B. Johnson mandated that all computers purchased by the United States federal government support ASCII, stating:

I have also approved recommendations of the Secretary of Commerce regarding standards for recording the Standard Code for Information Interchange on magnetic tapes and paper tapes when they are used in computer operations. All computers and related equipment configurations brought into the Federal Government inventory on and after July 1, 1969, must have the capability to use the Standard Code for Information Interchange and the formats prescribed by the magnetic tape and paper tape standards when these media are used. "July 1st" redirects here For the Ayumi Hamasaki song see H (song. Year 1969 ( MCMLXIX) was a Common year starting on Wednesday (link will display full calendar of the Gregorian calendar. ^[18]

Other international standards bodies have ratified character encodings such as ISO/IEC 646 that are identical or nearly identical to ASCII, with extensions for characters outside the English alphabet and symbols used outside the United States, such as the symbol for the United Kingdom's pound sterling (£). ISO 646 is an ISO standard that since 1972 has specified a 7- Bit character code from which several national standards are derived The modern English alphabet consists of 26 letters derived from the Latin alphabet: History See also History of the The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located The Pound Sterling ( symbol £; ISO code: GBP) subdivided into 100 pence (singular penny) is the Currency Almost every country needed an adapted version of ASCII since ASCII only suited the needs of the USA and a few other countries. For example, Canada had its own version that supported French. Other adapted encodings include ISCII (India), VISCII (Vietnam), and YUSCII (Yugoslavia). Indian Script Code for Information Interchange ( ISCII) is a coding scheme for representing various writing systems of India. The Vietnamese Standard Code for Information Interchange ( VISCII) is a Character set comprising the Vietnamese alphabet, Punctuation, and other YUSCII was an informal name for JUS IB1002 national variant of ISO 646, 7- Bit Latinic character encoding standard, and used in Yugoslavia Although these encodings are sometimes referred to as ASCII, true ASCII is strictly defined only by ANSI standard.

ASCII has been incorporated into the Unicode character set as the first 128 symbols, so the ASCII characters have the same numeric codes in both sets. In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's This allows UTF-8 to be backward compatible with ASCII, a significant advantage. UTF-8 (8- Bit UCS / Unicode Transformation Format) is a variable-length Character encoding for Unicode. In Technology, especially Computing (irrespective of platform a product is said to be backward compatible when it is able to take the place of an older product

Asteroid 3568 ASCII is named after the character encoding. 3568 ASCII is a small main belt Asteroid discovered by Marguerite Laugier in 1936.

ASCII control characters

Main article: Control character

ASCII reserves the first 32 codes (numbers 0–31 decimal) for control characters: codes originally intended not to carry printable information, but rather to control devices (such as printers) that make use of ASCII, or to provide meta-information about data streams such as those stored on magnetic tape. In Computing and Telecommunication, a control character or non-printing character is a Code point (a Number) in a In Computing and Telecommunication, a control character or non-printing character is a Code point (a Number) in a For example, character 10 represents the "line feed" function (which causes a printer to advance its paper), and character 8 represents "backspace". Control characters that do not include carriage return, line feed or white space are called non-whitespace control characters. ^[19] Except for the control characters that prescribe elementary line-oriented formatting, ASCII does not define any mechanism for describing the structure or appearance of text within a document. Other schemes, such as markup languages, address page and document layout and formatting. A markup language is an Artificial language using a set of annotations to text that give instructions regarding the structure of text or how it is to be displayed

The original ASCII standard used only short descriptive phrases for each control character. The ambiguity this left was sometimes intentional (where a character would be used slightly differently on a terminal link than on a data stream) and sometimes more accidental (such as what "delete" means).

Probably the most influential single device on the interpretation of these characters was the ASR-33 Teletype series, which was a printing terminal with an available paper tape reader/punch option. Introduced about 1963, Teletype Corporation 's ASR33 was a very popular model of Teleprinter. Punched tape or paper tape is a largely obsolete form of Data storage, consisting of a long strip of paper in which holes are punched to store data Paper tape was a very popular medium for long-term program storage up through the 1980s, lower cost and in some ways less fragile than magnetic tape. In particular, the Teletype 33 machine assignments for codes 17 (Control-Q, DC1, also known as XON), 19 (Control-S, DC3, also known as XOFF), and 127 (DELete) became de-facto standards. Because the keytop for the O key also showed a left-arrow symbol (from ASCII-1963, which had this character instead of underscore), a noncompliant use of code 15 (Control-O, Shift In) interpreted as "delete previous character" was also adopted by many early timesharing systems but eventually faded out.

The use of Control-S (XOFF, an abbreviation for "transmit off") as a handshaking signal warning a sender to stop transmission because of impending overflow, and Control-Q (XON, "transmit on") to resume sending, persists to this day in many systems as a manual output control technique. On some systems Control-S retains its meaning but Control-Q is replaced by a second Control-S to resume output.

Code 127 is officially named "delete" but the Teletype label was "rubout". Since the original standard gave no detailed interpretation for most control codes, interpretations of this code varied. The original Teletype meaning, and the intent of the standard, was to make it an ignored character, the same as NUL (all zeroes). This was specifically useful for paper tape, because punching the all-ones bit pattern on top of an existing mark would obliterate it. Punched tape or paper tape is a largely obsolete form of Data storage, consisting of a long strip of paper in which holes are punched to store data Tapes designed to be "hand edited" could even be produced with spaces of extra NULs (blank tape) so that a block of characters could be "rubbed out" and then replacements put into the empty space.

As video terminals began to replace printing ones, the value of the "rubout" character was lost. DEC systems, for example, interpreted "Delete" to mean "remove the character before the cursor," and this interpretation also became common in Unix systems. Most other systems used "Backspace" for that meaning and used "Delete" as it was used on paper tape, to mean "remove the character after the cursor". That latter interpretation is the most common today.

Many more of the control codes have taken on meanings quite different from their original ones. The "escape" character (code 27), for example, was originally intended to allow sending other control characters as literals instead of invoking their meaning. This is the same meaning of "escape" encountered in URL encodings, C language strings, and other systems where certain characters have a reserved meaning. Over time this meaning has been coopted and has eventually drifted. In modern use, an ESC sent to the terminal usually indicates the start of a command sequence, usually in the form of an ANSI escape code. ANSI escape codes are used to control text formatting and other output options on Text terminals In this context ANSI refers to the ANSI X3 An ESC sent from the terminal is most often used as an "out of band" character used to terminate an operation, as in the TECO and vi text editors. TECO (pronounced /tee'koh/ originally an acronym for T ape E ditor and CO rrector, but later T ext E ditor and CO vi is a screen-oriented Text editor written by Bill Joy in 1976 for an early BSD release

The inherent ambiguity of many control characters, combined with their historical usage, created problems when transferring "plain text" files between systems. The clearest example of this is the newline problem on various operating systems. In Computing, a newline (also known as a line break or end-of-line / EOL character is a special character or sequence of characters An operating system (commonly abbreviated OS and O/S) is the software component of a Computer system that is responsible for the management and coordination On printing terminals there is no question that you terminate a line of text with both "Carriage Return" and "Linefeed". The first returns the printing carriage to the beginning of the line and the second advances to the next line without moving the carriage. However, requiring two characters to mark the end of a line introduced unnecessary complexity and questions as to how to interpret each character when encountered alone. To simplify matters, plain text files on Unix and Amiga systems use line feeds alone to separate lines. Similarly, older Macintosh systems, among others, use only carriage returns in plain text files. Various DEC operating systems used both characters to mark the end of a line, perhaps for compatibility with teletypes, and this de facto standard was copied in the CP/M operating system and then in MS-DOS and eventually Microsoft Windows. Digital Equipment Corporation was a pioneering American company in the Computer industry A teleprinter ( CP/M (Control Program for Microcomputers is an Operating system originally created for Intel 8080 / 85 based Microcomputers by Gary Kildall MS-DOS (short for M icro' s' oft D isk O perating S ystem is an Operating system commercialized by Microsoft. Microsoft Windows is a series of Software Operating systems and Graphical user interfaces produced by Microsoft. Transmission of text over the Internet, for protocols as E-mail and the World Wide Web, uses both characters. The Internet is a global system of interconnected Computer networks Electronic mail, often abbreviated to e-mail, email, or originally eMail, is a Store-and-forward method of writing sending receiving The World Wide Web (commonly shortened to the Web) is a system of interlinked Hypertext documents accessed via the Internet.

The DEC operating systems, along with CP/M, tracked file length only in units of disk blocks and used Control-Z (SUB) to mark the end of the actual text in the file (also done for CP/M compatibility in some cases in MS-DOS, though MS-DOS has always recorded exact file-lengths). Text strings ending with the null character are known as ASCIZ or C strings. In Computer programming and some branches of Mathematics, a string is an ordered Sequence of Symbols. The null character (also null terminator) is a character with the value zero present in the ASCII and Unicode character sets and available In computing a C string is a character sequence stored as a one-dimensional character Array and terminated with a Null character ('\0' In computing a C string is a character sequence stored as a one-dimensional character Array and terminated with a Null character ('\0'

ASCII printable characters

Code 32, the "space" character, denotes the space between words, as produced by the space-bar of a keyboard. In writing a space () is a blank area that is devoid of content which separates words letters numbers and punctuation The "space" character is considered an invisible graphic rather than a control character. ^[20] Codes 33 to 126, known as the printable characters, represent letters, digits, punctuation marks, and a few miscellaneous symbols.

Seven-bit ASCII provided seven "national" characters and, if the combined hardware and software permit, can use overstrikes to simulate some additional international characters: in such a scenario a backspace can precede a grave accent (which the American and British standards, but only those standards, also call "opening single quotation mark"), a backtick, or a breath mark (inverted vel). Pitch The grave accent was first used in the polytonic orthography of Ancient Greek, where it occurred only on the last syllable of a word in cases where the

Aliases

A June 1992 RFC^[21] and the IANA registry of character sets^[22] recognize the following case-insensitive aliases for ASCII as suitable for use on the Internet:

Of these, only the aliases "US-ASCII" and "ASCII" have achieved widespread use. Multipurpose Internet Mail Extensions ( MIME) is an Internet standard that extends the format of e-mail to support text in Character One often finds them in the optional "charset" parameter in the Content-Type header of some MIME messages, in the equivalent "meta" element of some HTML documents, and in the encoding declaration part of the prologue of some XML documents. Multipurpose Internet Mail Extensions ( MIME) is an Internet standard that extends the format of e-mail to support text in Character HTML, an initialism of HyperText Markup Language, is the predominant Markup language for Web pages It provides a means to describe the structure Don't change "Extensible"

Variants

As computer technology spread throughout the world, different standards bodies and corporations developed many variations of ASCII in order to facilitate the expression of non-English languages that used Roman-based alphabets. One could class some of these variations as "ASCII extensions", although some misuse that term to cover all variants, including those that do not preserve ASCII's character-map in the 7-bit range. The term extended ASCII (or high ASCII) describes Eight-bit or larger Character encodings that include the standard seven- Bit

The PETSCII Code used by Commodore International for their 8-bit systems is probably unique among post-1970 codes in being based on ASCII-1963 instead of the far more common ASCII-1967, such as found on the ZX Spectrum computer. PETSCII ( PET S tandard C ode of I nformation I nterchange) also known as CBM ASCII, is the variation of the Commodore, the commonly used name for Commodore International, was a US-American Electronics company based in West Chester Pennsylvania The ZX Spectrum character set is the variant of ASCII used in the British Sinclair Spectrum computers Atari and Galaksija computers also used ASCII variants. The ATASCII character set from ATA RI S tandard C ode for I nformation I nterchange, alternatively AT ARI The Galaksija (pronounced Galaxiya, meaning Galaxy) was originally a build-it-yourself Computer designed by Voja Antonić

Incompatibility vs interoperability

ISO/IEC 646 (1972), the first attempt to remedy ASCII's English language bias, created compatibility problems, since it remained a 7-bit character set. ISO 646 is an ISO standard that since 1972 has specified a 7- Bit character code from which several national standards are derived It made no additional codes available, so it reassigned some in language-specific variants. Escape codes were defined to indicate which national variant applied to a piece of text, but these were rarely used, so it was often impossible to know what variant to work with and therefore which character a code represented, and text-processing systems could generally cope with only one variant anyway.

A German, French, or Swedish, etc. , programmer had to get used to
ä aÄiÜ='Ön'; ü
or similar, instead of
{ a[i]='\n'; }

Eventually, improved technology brought out-of-band means to represent the information formerly encoded in the eighth bit of each byte, freeing this bit to add another 128 additional character-codes for new assignments. Out-of-band is a technical term with different uses in Communications and Telecommunication.

For example, IBM developed 8-bit code pages, such as code page 437, which replaced the control-characters with graphic symbols such as smiley faces, and mapped additional graphic characters to the upper 128 positions. International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology Code page is the traditional IBM term used to map a specific set of characters to numerical Code point values. IBM PC or MS-DOS Code page 437, often abbreviated CP437 and also known as DOS-US, OEM-US or sometimes misleadingly referred The smiley, smiley face, or happy face, is a stylized representation of a smiling human face commonly represented as a yellow circle with two dots representing Operating systems such as DOS supported these code-pages, and manufacturers of IBM PCs supported them in hardware. DOS, short for "Disk Operating System" is a shorthand term for several closely related Operating systems that dominated the IBM PC compatible market Digital Equipment Corporation developed the Multinational Character Set (DEC-MCS) for use in the popular VT220 terminal. Digital Equipment Corporation was a pioneering American company in the Computer industry The Multinational Character Set is a Character encoding created by Digital Equipment Corporation for use in the popular VT220 terminal. The VT220 was a terminal produced by Digital Equipment Corporation from 1983 to 1987. A computer terminal is an electronic or electromechanical hardware device that is used for entering data into and displaying data from a Computer or a Computing

Eight-bit standards such as ISO/IEC 8859 (derived from the DEC-MCS) and Mac OS Roman developed as true extensions of ASCII, leaving the original character-mapping intact, but adding additional character definitions after the first 128 (i. ISO/IEC 8859 is a joint ISO and IEC standard for 8-bit Character encodings for use by computers Mac OS Roman is a Character encoding primarily used by Mac OS to represent text e. , 7-bit) characters. This enabled representation of characters used in a broader range of languages. But these standards continued to suffer from incompatibilities and limitations. Still, ISO-8859-1 (Latin 1), its variant Windows-1252 (often mislabeled as ISO-8859-1), and the original 7-bit ASCII remain the most common character encodings in use today. ISO 8859-1, more formally cited as ISO/IEC 8859-1 is part 1 of ISO/IEC 8859, a standard Character encoding of the Latin alphabet. Windows-1252 (also known as WinLatin1) is a Character encoding of the Latin alphabet, used by default in the legacy components of Microsoft Windows

Unicode

Unicode and the ISO/IEC 10646 Universal Character Set (UCS) have a much wider array of characters, and their various encoding forms have begun to supplant ISO/IEC 8859 and ASCII rapidly in many environments. In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's The Universal Character Set (UCS defined by the ISO / IEC 10646 International Standard, is a standard set of characters upon which While ASCII is limited to 128 characters, Unicode and the UCS support more characters by separating the concepts of unique identification (using natural numbers called code points) and encoding (to 8-, 16- or 32-bit binary formats, called UTF-8, UTF-16 and UTF-32). In Mathematics, a natural number (also called counting number) can mean either an element of the set (the positive Integers or an UTF-8 (8- Bit UCS / Unicode Transformation Format) is a variable-length Character encoding for Unicode. In Computing, UTF-16 (16- Bit Unicode Transformation Format is a variable-length Character encoding for Unicode, capable of encoding UTF-32 (or UCS-4) is a protocol for encoding Unicode characters that uses exactly 32 Bits for each Unicode Code point.

To permit backward compatibility, the 128 ASCII and 256 ISO-8859-1 (Latin 1) characters are assigned Unicode/UCS code points that are the same as their codes in the earlier standards. Therefore, ASCII can be considered a 7-bit encoding scheme for a very small subset of Unicode/UCS, and, conversely, the UTF-8 encoding forms are binary-compatible with ASCII for code points below 128, meaning every properly encoded ASCII file is also a valid UTF-8 file. The other encoding forms resemble ASCII in how they represent the first 128 characters of Unicode, but use 16 or 32 bits per character, so they require conversion for compatibility.

Order

Collation of data is sometimes done in ASCII-code order rather than "standard" alphabetical order. The main deviations are:

• capitals come before lowercase letters, i. e. "Z" before "a"
• characters in extended character sets such as "é" come after "z"

The slang expression ASCIIbetical is sometimes used for this order. Slang is the use of highly informal Words and expressions that are not considered standard in the speaker's Dialect or Language. ^[23] In programming, alphanumeric sorting means to sort by numeric value, without regard of any character set. An alphanumerically sorted array of bytes will appear ASCIIbetically when viewed in an ASCII-compatible character set.

A refined version of this order converts uppercase letters to lowercase before comparing ASCII values.

References

1. ^ Audio pronunciation for ASCII. Mirriam Webster. Accessed 2008-04-14.
2. ^ ^{a b} Mary Brandel (July 6, 1999). 1963: The Debut of ASCII: CNN. Cable News Network, usually referred to by its Initialism CNN, is a major English language Television network founded in 1980 by Ted Turner Accessed 2008-04-14.
3. ^ International Organization for Standardization (December 1, 1975). "The set of control characters for ISO 646". Internet Assigned Numbers Authority Registry. Alternate U. S. version: [1]. Accessed 2008-04-14.
4. ^ Mackenzie, p. 211.
5. ^ Decision 4. Mackenzie, p. 215.
6. ^ Decision 5. Mackenzie, p. 217.
7. ^ Sawyer A. Sawyer and Steven George Krantz (January 1, 1995). A Tex Primer for Scientists. CRC Press. ISBN 0-8493-7159-7. p. 13.
8. ^ Decision 8,9. Mackenzie, p. 220.
9. ^ Decision 10. Mackenzie, p. 237.
10. ^ Decision 14. Mackenzie, p. 228.
11. ^ Decision 18. Mackenzie, p. 238.
12. ^ Mackenzie, p. 243.
13. ^ Mackenzie, p. 243-245.
14. ^ Mackenzie, p. 66.
15. ^ Mackenzie, p. 435.
16. ^ Mackenzie, p. 247-8.
17. ^ Bob Bemer (n. Robert William Bemer ( February 8, 1920 &ndash June 22, 2004) was a computer scientist best known for his work at IBM during the late d. ). Bemer meets Europe. Trailing-edge. com. Accessed 2008-04-14. Employed at IBM at that time
18. ^ Lyndon B. Johnson (March 11, 1968). International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology Memorandum Approving the Adoption by the Federal Government of a Standard Code for Information Interchange. The American Presidency Project. Accessed 2008-04-14.
19. ^ RFC 2822 (April 2001). "NO-WS-CTL".
20. ^ Mackenzie, p. 223.
21. ^ RFC 1345 (June 1992).
22. ^ ^{a b} Internet Assigned Numbers Authority (May 14, 2007). "Character Sets". Accessed 2008-04-14.
23. ^ ASCIIbetical definition. PC Magazine. PC Magazine (sometimes referred to as PC Mag) is a Computer magazine that is published monthly in the United States (until 2008 it was published Accessed 2008-04-14.

Further reading

• G. S. Robinson & C. Cargill. "History and impact of computer standards", Computer Vol. 29, no. 10, October 1996, pp.  79-85.  
• American National Standards Institute, et al (1977). American National Standard Code for Information Interchange. The Institute.  
• Charles E. Mackenzie (1980). Coded Character Sets: History and Development. Addison-Wesley.  

External links

• A history of ASCII, its roots and predecessors by Tom Jennings, October 29, 2004 (accessed December 17, 2005)
• ASCII Chart, how to send documents "in ASCII", etc
• Interactive AJAX-style ASCII (and Unicode) Decoder Table
• Online Encoder/Decoder for ASCII, HEX, Binary, Base64, etc with MD2, MD4, MD5, SHA1+2, CRC, and other hashing algorithms
• The ASCII subset of Unicode