ascii table wikipedia

These were positioned to maximize the Hamming distance between their bit patterns.[3]:243–245. For example, a Swedish programmer mailing another programmer asking if they should go for lunch, could get "N{ jag har sm|rg}sar" as the answer, which should be "Nä jag har smörgåsar" meaning "No I've got sandwiches". The Telnet protocol defined an ASCII "Network Virtual Terminal" (NVT), so that connections between hosts with different line-ending conventions and character sets could be supported by transmitting a standard text format over the network. Other schemes, such as markup languages, address page and document layout and formatting. ASCII (pronounced az-kee, ass-key if American), is a table of characters for computers.It is binary code used by electronic equipment to handle text using the English alphabet, numbers, and other common symbols.ASCII is an abbreviation for American Standard Code for Information Interchange. The committee voted to use a seven-bit code to minimize costs associated with data transmission. For other uses, see, ASCII chart from a pre-1972 printer manual. In a shifted code, some character codes determine choices between options for the following character codes. Lowercase letters were therefore not interleaved with uppercase. It allows compact encoding, but is less reliable for data transmission, as an error in transmitting the shift code typically makes a long part of the transmission unreadable. Size of this PNG preview of this SVG file: Add a one-line explanation of what this file represents, (SVG file, nominally 1,000 × 812 pixels, file size: 1.5 MB), copyrighted, dedicated to the public domain by copyright holder, released into the public domain by the copyright holder, https://simple.wikipedia.org/wiki/File:ASCII-Table.svg. Paper tape was a very popular medium for long-term program storage until the 1980s, less costly and in some ways less fragile than magnetic tape. ASCII-code order is also called ASCIIbetical order. 2, and the ,< .> pairs were used on some keyboards (others, including the No. [35][36] Because of this, DEC video terminals (by default) sent the DEL code for the key marked "Backspace" while the key marked "Delete" sent an escape sequence, while many other terminals sent BS for the Backspace key. Below is the ASCII character table and this includes descriptions of the first 32 non-printing characters. will show up incorrectly. Sometimes someone talks about a file or document in ASCII, meaning it is in plain text. The entire carriage had to be pushed (returned) to the right in order to position the left margin of the paper for the next line. You can look up ASCII number for a character. The code includes definitions for 128 characters: most of these are the printable characters of the alphabet such as abc, ABC, 123, and ?&!. [16] The X3.2.4 task group voted its approval for the change to ASCII at its May 1963 meeting. [3]:435 The indecision did not last long: during May 1963 the CCITT Working Party on the New Telegraph Alphabet proposed to assign lowercase characters to sticks[a][14] 6 and 7,[15] and International Organization for Standardization TC 97 SC 2 voted during October to incorporate the change into its draft standard. (RU), a reserved device control (DC0), synchronous idle (SYNC), and acknowledge (ACK). Kaypro CP/M computers used the "upper" 128 characters for the Greek alphabet. The PDP-6 monitor,[35] and its PDP-10 successor TOPS-10,[36] used Control-Z (SUB) as an end-of-file indication for input from a terminal. The "escape" character (ESC, code 27), for example, was intended originally to allow sending other control characters as literals instead of invoking their meaning. Original file ‎(SVG file, nominally 1,000 × 812 pixels, file size: 1.5 MB). Ο ascii αναπτύχθηκε υπό την αιγίδα μίας επιτροπής του Αμερικανικού Οργανισμού Τυποποίησης, ονόματι επιτροπή x3, από την υποεπιτροπή της, x3.2 (αργότερα x3l2), και αργότερα από την ομάδα εργασίας x3.2.4 αυτής της υποεπιτροπής. The original ASCII standard used only short descriptive phrases for each control character. They proposed a 9-track standard for magnetic tape, and attempted to deal with some punched card formats. See also YUSCII (Yugoslavia). A list of all the userful characters in the ASCII table. TWX originally used the earlier five-bit ITA2, which was also used by the competing Telex teleprinter system. Subject to change any time. I have also approved recommendations of the Secretary of Commerce [Luther H. Hodges] regarding standards for recording the Standard Code for Information Interchange on magnetic tapes and paper tapes when they are used in computer operations. There are also control characters that cannot be printed but instead control how text is processed, to start a new line for example. On some systems Control-S retains its meaning but Control-Q is replaced by a second Control-S to resume output. The proper name for systems that use 8 bits is called extended ASCII. pair also dates to the No. DEC operating systems (OS/8, RT-11, RSX-11, RSTS, TOPS-10, etc.) The /? ASCII codes represent text in computers, telecommunications equipment, and other devices. Any special markups for bold or centered text, etc. [11] Ninety-five of the encoded characters are printable: these include the digits 0 to 9, lowercase letters a to z, uppercase letters A to Z, and punctuation symbols. The Internet Assigned Numbers Authority (IANA) prefers the name US-ASCII for this character encoding. Other representations might be used by specialist equipment, for example ISO 2047 graphics or hexadecimal numbers. However, it would require all data transmission to send eight bits when seven could suffice. Eventually, as 8-, 16- and 32-bit (and later 64-bit) computers began to replace 12-, 18- and 36-bit computers as the norm, it became common to use an 8-bit byte to store each character in memory, providing an opportunity for extended, 8-bit relatives of ASCII. From Simple English Wikipedia, the free encyclopedia. To keep options available for lowercase letters and other graphics, the special and numeric codes were arranged before the letters, and the letter A was placed in position 41hex to match the draft of the corresponding British standard. Click on a date/time to view the file as it appeared at that time. By the time so-called "glass TTYs" (later called CRTs or terminals) came along, the convention was so well established that backward compatibility necessitated continuing the convention. However, the four years that elapsed between the publication of ASCII-1963 and ISO's first acceptance of an international recommendation during 1967[57] caused ASCII's choices for the national use characters to seem to be de facto standards for the world, causing confusion and incompatibility once other countries did begin to make their own assignments to these code points. [citation needed], The use of ASCII format for Network Interchange was described in 1969. The X3 committee made other changes, including other new characters (the brace and vertical bar characters),[18] renaming some control characters (SOM became start of header (SOH)) and moving or removing others (RU was removed). 8, Task Group X3.2.4, December 17 and 18, 1963, "Specific Criteria", attachment to memo from R. W. Reach, "X3-2 Meeting – September 14 and 15", September 18, 1961, United States of America Standards Institute, International Organization for Standardization, Comité Consultatif International Téléphonique et Télégraphique, "American Standard Code for Information Interchange, ASA X3.4-1963", "An annotated history of some character codes or ASCII: American Standard Code for Information Infiltration", "Correct classification of RFC 20 (ASCII format) to Internet Standard", "7-bit character sets: Revisions of ASCII", "INCITS 4-1986[R2012]: Information Systems - Coded Character Sets - 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII)", "INCITS 4-1986[R2017]: Information Systems - Coded Character Sets - 7-Bit American National Standard Code for Information Interchange (7-Bit ASCII)", "Re: editor and word processor history (was: Re: RTF for emacs)", "PDP-10 Reference Handbook, Book 3, Communicating with the Monitor", "Technical and human engineering problems in connecting terminals to a time-sharing system", "First-Hand: Chad is Our Most Important Product: An Engineer's Memory of Teletype Corporation", "Bemer meets Europe (Computer Standards) – Computer History Vignettes", "Memorandum Approving the Adoption by the Federal Government of a Standard Code for Information Interchange", Pine.SUN.3.91.961220100220.13180C-100000@duncan.cs.utk.edu, "Chapter 13: Special Areas and Format Characters", "The Babel of Codes Prior to ASCII: The 1960 Survey of Coded Character Sets: The Reasons for ASCII", "On the Early Development of ASCII – The History of ASCII", "C0 Controls and Basic Latin – Range: 0000–007F", Unicode control, format and separator characters, https://en.wikipedia.org/w/index.php?title=ASCII&oldid=988965688, All Wikipedia articles written in American English, Articles with unsourced statements from March 2020, Articles with unsourced statements from June 2016, Articles with unsourced statements from May 2019, Creative Commons Attribution-ShareAlike License, ASA X3.4-1965 (approved, but not published, nevertheless used by, All uppercase come before lowercase letters; for example, "Z" precedes "a", Digits and many punctuation marks come before letters, This page was last edited on 16 November 2020, at 08:10. A list of all the useful characters in the ASCII table. File:ASCII-Table.svg licensed with PD-self 2008-06-27T18:26:29Z AnonMoos 1000x812 (1576490 Bytes) fixing truncation of rows at bottom; 2007-04-14T00:04:17Z ZZT32 1052x744 (1576527 Bytes) A list of all the userful characters in the ASCII table. When Gary Kildall created CP/M he was inspired by some command line interface conventions used in DEC's RT-11. ASCII (pronounced az-kee, ass-key if American), is a table of characters for computers. Atari 8-bit computers and Galaksija computers also used ASCII variants. Furthermore, the ASCII extensions have also been mislabelled as ASCII. Points which represented a different character in previous versions (the 1963 version and/or the 1965 draft) are shown boxed. [9] That document was formally elevated to an Internet Standard in 2015.[10]. ASCII reserves the first 32 codes (numbers 0–31 decimal) for control characters: codes originally intended not to represent 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. Many of the non-alphanumeric characters were positioned to correspond to their shifted position on typewriters; an important subtlety is that these were based on mechanical typewriters, not electric typewriters. ASCII currently defines codes for 128 characters: 33 are non-printing characters, and 95 are printable characters. In the X3.15 standard, the X3 committee also addressed how ASCII should be transmitted (least significant bit first),[3]:249–253[26] and how it should be recorded on perforated tape. This technique became adopted by several early computer operating systems as a "handshaking" signal warning a sender to stop transmission because of impending overflow; it persists to this day in many systems as a manual output control technique. Goes up to 0x7F. Znaki s kodami od 0 do 31 so kontrolni znaki, znaki od 32 do 126 pa so izpisljivi, glej tabelo spodaj: dvojiško desetiško Goes up to 0x7F. The IBM PC defined 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. Since the space character is considered an invisible graphic (rather than a control character)[3]:223[46] it is listed in the table below instead of in the previous section. A list of all the useful characters in the ASCII table. Instead there was a key marked RUB OUT that sent code 127 (DEL). ASCII codes represent text in computers, telecommunications equipment, and other devices.Most modern character-encoding schemes are based on ASCII, although they support many additional characters. [49], On March 11, 1968, U.S. President Lyndon B. Johnson mandated that all computers purchased by the United States Federal Government support ASCII, stating:[50][51][52]. The @ symbol was not used in continental Europe and the committee expected it would be replaced by an accented À in the French variation, so the @ was placed in position 40hex, right before the letter A. [32] 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. é, ñ, ß, Ł), currency symbols (e.g. The standards committee decided against shifting, and so ASCII required at least a seven-bit code. [1] ASCII (/ˈæskiː/ (listen) ASS-kee),[3]:6 abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. 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. The first edition of the standard was published in 1963,[4][5] underwent a major revision during 1967,[6][7] and experienced its most recent update during 1986. [17] Locating the lowercase letters in sticks[a][14] 6 and 7 caused the characters to differ in bit pattern from the upper case by a single bit, which simplified case-insensitive character matching and the construction of keyboards and printers. This allows digital devices to communicate with each other and to process, store, and communicate character-oriented information such as written language. 2, did not shift , (comma) or . Goes up to 0x7F. Even more importantly, forward compatibility is ensured as software that recognizes only 7-bit ASCII characters as special and does not alter bytes with the highest bit set (as is often done to support 8-bit ASCII extensions such as ISO-8859-1) will preserve UTF-8 data unchanged. If the file has been modified from its original state, some details may not fully reflect the modified file. [a][14] The parentheses could not correspond to 9 and 0, however, because the place corresponding to 0 was taken by the space character. Many other countries developed variants of ASCII to include non-English letters (e.g. [3]:215, 236 §4. The PETSCII code Commodore International used for their 8-bit systems is probably unique among post-1970 codes in being based on ASCII-1963, instead of the more common ASCII-1967, such as found on the ZX Spectrum computer. used both characters to mark the end of a line so that the console device (originally Teletype machines) would work. To include all these, and control characters compatible with the Comité Consultatif International Téléphonique et Télégraphique (CCITT) International Telegraph Alphabet No. [41][42] This adds complexity to implementations of those protocols, and to other network protocols, such as those used for E-mail and the World Wide Web, on systems not using the NVT's CR-LF line-ending convention.[43][44]. .mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .id-lock-free a,.mw-parser-output .citation .cs1-lock-free a{background:linear-gradient(transparent,transparent),url("//upload.wikimedia.org/wikipedia/commons/6/65/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited a,.mw-parser-output .id-lock-registration a,.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:linear-gradient(transparent,transparent),url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription a,.mw-parser-output .citation .cs1-lock-subscription a{background:linear-gradient(transparent,transparent),url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:linear-gradient(transparent,transparent),url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}RFC 2822 refers to control characters that do not include carriage return, line feed or white space as non-whitespace control characters. For example, Canada had its own version that supported French characters. 2 (1878), the first typewriter with a shift key, and the shifted values of 23456789- were "#$%_&'() – early typewriters omitted 0 and 1, using O (capital letter o) and l (lowercase letter L) instead, but 1! In C library and Unix conventions, the null character is used to terminate text strings; such null-terminated strings can be known in abbreviation as ASCIZ or ASCIIZ, where here Z stands for "zero". Over time this meaning has been co-opted and has eventually been changed. [30] Mechanical typewriters followed the standard set by the Remington No. 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). Standard ASCII is still commonly used, particularly in computer software and HTML files. Earlier versions of ASCII used the up arrow instead of the caret (5Ehex) and the left arrow instead of the underscore (5Fhex).[5][47]. [3]:243, 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?" ASCII was developed in the 1960's and was based on earlier codes used by telegraph systems. IBM's PC DOS (also marketed as MS-DOS by Microsoft) inherited the convention by virtue of being loosely based on CP/M,[38] and Windows inherited it from MS-DOS. There are 95 printable characters in total.[m]. Operating systems such as DOS supported these code pages, and manufacturers of IBM PCs supported them in hardware. ASCII was the most common character encoding on the World Wide Web until December 2007, when UTF-8 encoding surpassed it; UTF-8 is backward compatible with ASCII.[53][54][55]. The original Macintosh OS, Apple DOS, and ProDOS, on the other hand, used carriage return (CR) alone as a line terminator; however, since Apple replaced these operating systems with the Unix-based macOS operating system, they now use line feed (LF) as well. [28], The committee debated the possibility of a shift function (like in ITA2), which would allow more than 64 codes to be represented by a six-bit code. Many more of the control codes have been given meanings quite different from their original ones. For example, character 10 represents the "line feed" function (which causes a printer to advance its paper), and character 8 represents "backspace". The Macintosh defined Mac OS Roman and Postscript also defined a set, both of these contained both international letters and typographic punctuation marks instead of graphics, more like modern character sets. (full stop) so they could be used in uppercase without unshifting). C trigraphs were created to solve this problem for ANSI C, although their late introduction and inconsistent implementation in compilers limited their use. Before ASCII was developed, the encodings in use included 26 alphabetic characters, 10 numerical digits, and from 11 to 25 special graphic symbols. [3]:247–248 ASCII was subsequently updated as USAS X3.4-1967,[6][19] then USAS X3.4-1968, ANSI X3.4-1977, and finally, ANSI X3.4-1986.[8][20]. This discrepancy from typewriters led to bit-paired keyboards, notably the Teletype Model 33, which used the left-shifted layout corresponding to ASCII, not to traditional mechanical typewriters. Most modern character-encoding schemes are based on ASCII, although they support many additional characters. Thus, in ASCII ! Originally based on the English alphabet, ASCII encodes 128 specified characters into seven-bit integers as shown by the ASCII chart above. Eight bits allows for 256 characters. Often a web site that has fields for entering text will only take ASCII text. "#$% were placed in the second stick,[a][14] positions 1–5, corresponding to the digits 1–5 in the adjacent stick. [2]. When a Teletype 33 ASR equipped with the automatic paper tape reader received a Control-S (XOFF, an abbreviation for transmit off), it caused the tape reader to stop; receiving Control-Q (XON, "transmit on") caused the tape reader to resume. The assumption that no key sent a BS caused Control+H to be used for other purposes, such as the "help" prefix command in GNU Emacs.[37]. 2 (ITA2) standard of 1924,[27][28] FIELDATA (1956[citation needed]), and early EBCDIC (1963), more than 64 codes were required for ASCII. The main deviations in ASCII order are: An intermediate order converts uppercase letters to lowercase before comparing ASCII values. Unix and Unix-like systems, and Amiga systems, adopted this convention from Multics. .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}  Letter   Number   Punctuation   Symbol   Other   Undefined   Character changed from 1963 version and/or 1965 draft, ASCII was first used commercially during 1963 as a seven-bit teleprinter code for American Telephone & Telegraph's TWX (TeletypeWriter eXchange) network. [48] Because of his extensive work on ASCII, Bemer has been called "the father of ASCII". One could class some of these variations as "ASCII extensions", although some misuse that term to represent all variants, including those that do not preserve ASCII's character-map in the 7-bit range. 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 became neglected. It was only meant for English and doesn't work well for most other languages. ASCII was developed a long time ago and now the non-printing characters are rarely used for their original purpose. Telnet used ASCII along with CR-LF line endings, and software using other conventions would translate between the local conventions and the NVT. 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. The X3.2 subcommittee designed ASCII based on the earlier teleprinter encoding systems. The American Standard Code for Information Interchange (ASCII) was developed under the auspices of a committee of the American Standards Association (ASA), called the X3 committee, by its X3.2 (later X3L2) subcommittee, and later by that subcommittee's X3.2.4 working group (now INCITS). Like other character encodings, ASCII specifies a correspondence between digital bit patterns and character symbols (i.e. The Unix terminal driver could only use one code to erase the previous character, this could be set to BS or DEL, but not both, resulting in a long period of annoyance where users had to correct it depending on what terminal they were using (shells that allow line editing, such as ksh, bash, and zsh, understand both). A historically common and still prevalent convention uses the ETX code convention to interrupt and halt a program via an input data stream, usually from a keyboard. This solves the problem for languages that are based on the Latin alphabet, although not all extended ASCII systems are the same. ASCII is an abbreviation for American Standard Code for Information Interchange. The ISO/IEC 8859 standard (derived from the DEC-MCS) finally provided a standard that most systems copied (at least as accurately as they copied ASCII, but with many substitutions). It is binary code used by electronic equipment to handle text using the English alphabet, numbers, and other common symbols. To simplify matters plain text data streams, including files, on Multics[39] used line feed (LF) alone as a line terminator. There is no real formatting control (for bold or Italics, etc.) [40] The File Transfer Protocol adopted the Telnet protocol, including use of the Network Virtual Terminal, for use when transmitting commands and transferring data in the default ASCII mode. I, the copyright holder of this work, release this work into the. The first 128 characters must be the same as for ASCII and the rest are usually used for alphabetic letters with accents, for example like É, È, Î and Ü. ASCII does not have diacritics (marks that are added to a letter, like the dots (umlauts) above vowels in German, or the tilde (~) above the 'n' for the 'ñ' used in Spanish). This was accommodated by removing _ (underscore) from 6 and shifting the remaining characters, which corresponded to many European typewriters that placed the parentheses with 8 and 9. American Standard Code for Information Interchange, Američki standardni znakovnik za razmjenu informacija ili Američki standardni znakovnik za razmjenu obavijesti) način je kodiranja znakova temeljen na engleskoj abecedi.ASCII-kodovima predstavlja se tekst u računalima, komunikacijskoj opremi i drugim napravama koje obrađuju tekst pisan engleskim jezikom. Digital Equipment Corporation developed the Multinational Character Set (DEC-MCS) for use in the popular VT220 terminal as one of the first extensions designed more for international languages than for block graphics. Electric typewriters, notably the IBM Selectric (1961), used a somewhat different layout that has become standard on computers – following the IBM PC (1981), especially Model M (1984) – and thus shift values for symbols on modern keyboards do not correspond as closely to the ASCII table as earlier keyboards did. ITA2 were in turn based on the 5-bit telegraph code Émile Baudot invented in 1870 and patented in 1874. [34] Teletypes were commonly used for the less-expensive computers from Digital Equipment Corporation, so these systems had to use the available key and thus the DEL code to erase the previous character. Most early home computer systems developed their own 8-bit character sets containing line-drawing and game glyphs, and often filled in some or all of the control characters from 0 to 31 with more graphics. Subject to change any time. In modern use, an ESC sent to the terminal usually indicates the start of a command sequence usually in the form of a so-called "ANSI escape code" (or, more properly, a "Control Sequence Introducer") from ECMA-48 (1972) and its successors, beginning with ESC followed by a "[" (left-bracket) character. The ambiguity this caused was sometimes intentional, for example where a character would be used slightly differently on a terminal link than on a data stream, and sometimes accidental, for example with the meaning of "delete". Some English words borrowed from other languages use these marks as well, like resumé (see Appendix:English words with diacritics). This was more important years ago when connections were often noisy. ASCII, stands for American Standard Code for Information Interchange.It's a 7-bit character code where every single bit represents a unique character. [54], ISO/IEC 4873 introduced 32 additional control codes defined in the 80–9F hexadecimal range, as part of extending the 7-bit ASCII encoding to become an 8-bit system.[58]. [8] Compared to earlier telegraph codes, the proposed Bell code and ASCII were both ordered for more convenient sorting (i.e., alphabetization) of lists, and added features for devices other than teleprinters. Until the introduction of PC DOS in 1981, IBM had no hand in this because their 1970s operating systems used EBCDIC instead of ASCII and they were oriented toward punch-card input and line printer output on which the concept of carriage return was meaningless. 2), and rearranged mathematical symbols (varied conventions, commonly -* =+) to :* ;+ -=. ASCII (od engl. Some operating systems such as CP/M tracked file length only in units of disk blocks and used Control-Z to mark the end of the actual text in the file. Unfortunately, requiring two characters to mark the end of a line introduces unnecessary complexity and questions as to how to interpret each character when encountered alone. Probably the most influential single device on the interpretation of these characters was the Teletype Model 33 ASR, which was a printing terminal with an available paper tape reader/punch option. The code itself was patterned so that most control codes were together and all graphic codes were together, for ease of identification. Also look up a character for ASCII number. ASCII was developed in the 1960's and was based on earlier codes used by telegraph systems.