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Unicode does not have millions of code points anymore. It is limited to 17 planes of 65536 characters each, about 1.1 million. |
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{{other uses}}
{{Distinguish|text=MS [[Windows-1252]] or other types of [[
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{{Use mdy dates|date=June 2013|cs1-dates=y}}
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| classification = [[ISO/IEC 646|ISO/IEC 646 series]]
}}
'''ASCII''' ({{IPAc-en|audio=En-us-ASCII.ogg|ˈ|æ|s|k|iː}} {{respell|ASS|kee}}),<ref name="Mackenzie_1980">{{cite book |url=https://textfiles.meulie.net/bitsaved/Books/Mackenzie_CodedCharSets.pdf |title=Coded Character Sets, History and Development |series=The Systems Programming Series |author-last=Mackenzie |author-first=Charles E. |date=1980 |edition=1 |publisher=[[Addison-Wesley Publishing Company, Inc.]] |isbn=978-0-201-14460-4 |lccn=77-90165 |pages=6, 66, 211, 215, 217, 220, 223, 228, 236–238, 243–245, 247–253, 423, 425–428, 435–439 |access-date=2019-08-25 |archive-url=https://web.archive.org/web/20160526172151/https://textfiles.meulie.net/bitsaved/Books/Mackenzie_CodedCharSets.pdf |archive-date=May 26, 2016 |url-status=live |df=mdy-all }}</ref>{{rp|6}} an acronym for '''American Standard Code for Information Interchange''', is a [[character encoding]] standard for electronic communication. ASCII codes represent text in computers, [[telecommunications equipment]], and other devices. Because of technical limitations of computer systems at the time it was invented, ASCII has just 128 [[code point]]s, of which only 95 are {{Pslink|printable characters}}, which severely limited its scope. Modern computer systems have evolved to use [[Unicode]], which has
The [[Internet Assigned Numbers Authority]] (IANA) prefers the name '''US-ASCII''' for this character encoding.<ref name="IANA_2007">{{cite web|website=Internet Assigned Numbers Authority (IANA)|date=May 14, 2007|url=https://www.iana.org/assignments/character-sets|title=Character Sets|access-date=2019-08-25}}</ref>
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Despite being an American standard, ASCII does not have a code point for the [[Cent (currency)|cent]] (¢). It also does not support [[English terms with diacritical marks]] such as [[résumé]] and [[jalapeño]], or [[proper nouns]] with diacritical marks such as [[Beyoncé]].
==<span class="anchor" id="1963"></span><span class="anchor" id="1965"></span><span class="anchor" id="1967"></span><span class="anchor" id="1968"></span><span class="anchor" id="1977"></span><span class="anchor" id="1986"></span><span class="anchor" id="1992"></span><span class="anchor" id="1997"></span><span class="anchor" id="2002"></span><span class="anchor" id="2007"></span><span class="anchor" id="2012"></span><span class="anchor" id="2017"></span><span class="anchor" id="2022"></span>History==
[[File:ASCII1963-infobox-paths.svg|thumb|upright=1.25|right|ASCII (1963). [[Control Pictures]] of equivalent controls are shown where they exist, or a grey dot otherwise.]]
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]]). The ASA later became the United States of America Standards Institute (USASI)<ref name="Mackenzie_1980"/>{{rp|211}} and ultimately became the [[American National Standards Institute]] (ANSI).
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The X3 committee made other changes, including other new characters (the [[brace (punctuation)|brace]] and [[vertical bar]] characters),<ref>Report of Meeting No. 8, Task Group X3.2.4, December 17 and 18, 1963</ref> renaming some control characters (SOM became start of header (SOH)) and moving or removing others (RU was removed).<ref name="Mackenzie_1980"/>{{rp|247–248}} ASCII was subsequently updated as USAS X3.4-1967,<ref name="ASCII-1967"/><ref name="Winter_2010">{{cite web |title=US and International standards: ASCII |url=http://homepages.cwi.nl/~dik/english/codes/stand.html#ascii |author-first=Dik T. |author=Winter |date=2010 |orig-year=2003 |url-status=dead |archive-url=https://web.archive.org/web/20100116001012/http://homepages.cwi.nl/~dik/english/codes/stand.html#ascii |archive-date=2010-01-16}}</ref> then USAS X3.4-1968,<ref name="ASCII-1968">{{cite tech report |title=USA Standard Code for Information Interchange, USAS X3.4-1968 |url=https://archive.org/details/enf-ascii-1968-1970/ |publisher=[[United States of America Standards Institute]] |date=October 10, 1968}}</ref> ANSI X3.4-1977, and finally, ANSI X3.4-1986.<ref name="ASCII-1986"/><ref name="Salste_2016">{{cite web |title=7-bit character sets: Revisions of ASCII |author-first=Tuomas |author-last=Salste |publisher=Aivosto Oy |date=January 2016 |id={{URN|nbn|fi-fe201201011004}} |url=http://www.aivosto.com/vbtips/charsets-7bit.html#body |access-date=2016-06-13 |url-status=live |archive-url=https://web.archive.org/web/20160613145224/http://www.aivosto.com/vbtips/charsets-7bit.html#body |archive-date=2016-06-13}}</ref>
===Revisions
* ASA
* ASA X3.4-1965 (approved, but not published, nevertheless used by [[IBM 2260]] & [[IBM 2265|2265]] Display Stations and [[IBM 2848]] Display Control)<ref name="Mackenzie_1980"/>{{rp|423, 425–428, 435–439}}<ref name="SA_215">{{cite journal |title=Information<!-- Title of issue, not title of article --> |date=September 1966 |volume=215 |number=3 |type=special edition |journal=[[Scientific American]] |jstor=e24931041 }}</ref><ref name="Winter_2010"/><ref name="Salste_2016"/>
* USAS
* USAS X3.4-1968
* ANSI
* ANSI X3.4-1986<ref name="ASCII-1986"/><ref name="Salste_2016"/>
* ANSI X3.4-1986 (R1992)
* ANSI X3.4-1986 (R1997)
* ANSI INCITS 4-1986 (R2002)<ref name="Korpela_2014">{{cite book |title=Unicode Explained – Internationalize Documents, Programs, and Web Sites |author-first=Jukka K. |author-last=Korpela |edition=2nd release of 1st |date=2014-03-14 |orig-year=2006-06-07 |publisher=[[O'Reilly Media, Inc.]] |isbn=978-0-596-10121-3 |page=118}}</ref>
* ANSI INCITS 4-1986 (R2007)
*
*
* INCITS 4-1986 (R2022)<ref>https://webstore.ansi.org/standards/incits/incits1986r2022</ref>
In the X3.15 standard, the X3 committee also addressed how ASCII should be transmitted ([[least significant bit]] first)<ref name="Mackenzie_1980"/>{{rp|249–253}}<ref name="X3.15-1966">{{citation |title=Bit Sequencing of the American National Standard Code for Information Interchange in Serial-by-Bit Data Transmission |id=X3.15-1966 |date=1966 |publisher=[[American National Standards Institute]] (ANSI)}}</ref> and recorded on perforated tape. They proposed a [[9-track]] standard for magnetic tape and attempted to deal with some [[punched card]] formats.
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==<span class="anchor" id="Code chart"></span><span class="anchor" id="ASCII printable code chart"></span><span class="anchor" id="ASCII printable characters"></span>Character set==
[[File:ASCII Table (suitable for printing).svg|thumb]]
{|{{chset-table-header1|ASCII (1977/1986)}}
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:<code>{ a[i] = '\n'; }</code>
[[C trigraph]]s were created to solve this problem for [[ANSI C]], although their late introduction and inconsistent implementation in compilers limited their use. Many programmers kept their computers on
In Japan and Korea, still {{As of|2021|alt=as of the 2020s|post=,|df=US}} a variation of ASCII is used, in which the [[backslash]] (5C hex) is rendered as ¥ (a [[Yen sign]], in Japan) or ₩ (a [[Won sign]], in Korea). This means that, for example, the file path C:\Users\Smith is shown as C:¥Users¥Smith (in Japan) or C:₩Users₩Smith (in Korea).
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{{Main|Extended ASCII}}{{See also|ISO/IEC 8859|UTF-8}}
<!-- to be mentioned [[USASCII-8]] -->
Eventually, as 8-, [[16-bit computing|16-]], and [[32-bit computing|32-bit]] (and later [[64-bit computing|64-bit]]) computers began to replace [[12-bit computing|12-]], [[18-bit computing|18-]], and [[36-bit computing|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. In most cases these developed as true extensions of ASCII, leaving the original character-mapping intact, but adding additional character definitions after the first 128 (i.e., 7-bit) characters. ASCII itself remained a seven-bit code: the term "extended ASCII" has no official status.
For some countries, 8-bit extensions of ASCII were developed that included support for characters used in local languages; for example, [[ISCII]] for India and [[VISCII]] for Vietnam. [[Kaypro]] [[CP/M]] computers used the "upper" 128 characters for the Greek alphabet.{{citation needed|date=November 2023}}
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IBM defined [[code page 437]] for the [[IBM PC]], replacing the control characters with graphic symbols such as [[Emoticon|smiley faces]], and mapping additional graphic characters to the upper 128 positions.<ref>{{cite book |url=http://www.bitsavers.org/pdf/ibm/pc/pc/6025008_PC_Technical_Reference_Aug81.pdf |title=Technical Reference |at=Appendix C. Of Characters Keystrokes and Color |edition=First |date=August 1981 |series=Personal Computer Hardware Reference Library |publisher=IBM}}</ref> [[Digital Equipment Corporation]] developed the [[Multinational Character Set]] (DEC-MCS) for use in the popular [[VT220]] [[computer terminal|terminal]] as one of the first extensions designed more for international languages than for block graphics. [[Apple Inc.|Apple]] defined [[Mac OS Roman]] for the Macintosh and [[Adobe Inc.|Adobe]] defined the [[PostScript Standard Encoding]] for [[PostScript]]; both sets contained "international" letters, typographic symbols and punctuation marks instead of graphics, more like modern character sets.
The [[ISO/IEC 8859]] standard (derived from the DEC-MCS) provided a standard that most systems copied (or at least were based on, when not copied exactly). A popular further extension designed by Microsoft, [[Windows-1252]] (often mislabeled as [[ISO-8859-1]]), added the typographic punctuation marks needed for traditional text printing. ISO-8859-1, Windows-1252, and the original 7-bit ASCII were the most common character
[[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.<ref name="Unicode-5.0_2006">{{cite book |author=The Unicode Consortium |editor-first=Julie D. |editor-last=Allen |title=The Unicode standard, Version 5.0 |date=2006-10-27 |publisher=[[Addison-Wesley Professional]] |location=Upper Saddle River, New Jersey, US |isbn=978-0-321-48091-0 |chapter-url=http://unicode.org/book/ch13.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://unicode.org/book/ch13.pdf |archive-date=2022-10-09 |url-status=live |access-date=2015-03-13 |chapter=Chapter 13: Special Areas and Format Characters |page=314}}</ref>
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