Code page: Difference between revisions

Revision as of 17:24, 15 April 2004

Revision as of 16:57, 17 May 2004

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[[fr:Page de code]]

'''Code page''' is the traditional [[International Business Machines|IBM]] term used for a specific variant of character codingencoding fortable [[computer]]s. Although the(a basismapping of manybinary characterinteger sets is [[ASCII]]values, ASCIIoften was0 athrough seven bit code255, with the 8-bit representation of ASCII either setting the top bit to zero or using it as a [[parity bit]]. Using this bit for data doubled the size of the possiblespecific character set, allowing another 128 characters to be added. No standardor existedglyph) for these "[[Extended ASCII|extended character setscomputer]]",s. and IBM referred to the variants as code pages.

Although the basis of many character sets is [[ASCII]], ASCII was a seven bit code, with the 8-bit representation of ASCII either setting the top bit to zero or using it as a [[parity bit]]. Using this bit for data doubled the size of the possible character set, allowing another 128 characters to be added. No standard existed for these ‘[[Extended ASCII|extended character sets]]’, and IBM referred to the variants as code pages (as it had always done for variants of EBCDIC encodings).

Although IBM maintained a myriad of code pages, the term has in general use taken on the meaning character coding for the [[IBM PC]]. Since the original IBM PC code page was not really designed for international use, several incompatible variants emerged:

Although IBM maintained a myriad of code pages, the term has in generalwider use taken on the meaning character coding for the [[IBM PC]]. Since the original IBM PC code page was not really designed for international use, several incompatible variants emerged:

* 437 -- Original PC extended character set

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The most notable of these is the [[windows-1252]] code page, which contains a range of [[typography|typographical]] punctuation characters in character positions which were reserved for [[control character]]s in the [[ISO 8859-1]] "latin-1" code page.

Many Microsoft products produce characters in these ranges automatically, notably with "‘smartquotes"’. This means that other software has to choose between

* not interoperating with documents produced with Microsoft applications

* mis-rendering the text in question

* adding full support for the Microsoft code pages, in effect making Microsoft's implementation thea de facto standard.

These code pages are often viewed as part of Microsoft'’s [[embrace, extend and extinguish]] strategy towards open standards. Fortunately, the transition to full [[Unicode]] support now offers standards-based applications the possibility of full interoperability with the [[character repertoire]] of these documents without giving up standards compliance on output.

== See also ==