View source for APL code page

{{FormatInfo
|formattype=electronic
|subcat=Character encoding
|codepage=293, 907
|image=Aplsym.png
|caption=Some APL symbols
}}

The '''APL code page''' was used in early implementations of [[APL]] on IBM computer systems and terminals. The original version, [[CP293]], was an [[EBCDIC]]-based character set which replaced many of the characters with the specialized ones needed by the [[APL]] programming language; IBM Selectric terminals used ball 2741 to access it. A later [[ASCII]]-based version was IBM code page 907 ([[CP907]]).

"Classic" APL character sets have only uppercase letters in them (normally presented italicized), though newer ASCII- or [[Unicode]]-based sets generally have lowercase available as well, among other characters not part of "purist" APL.

Internally to APL, characters are assigned code positions within what is known as the "Atomic Vector" (⎕IO), which can differ between systems; one such chart can be found starting on page 201 of the [[IBM 5100]] APL manual (page 207 of [http://bitsavers.trailing-edge.com/pdf/ibm/5100/SA21-9213-0_IBM_5100aplRef.pdf this PDF version]).

Traditionally, some APL characters with distinct meanings were formed by backspacing and overstriking other characters (originally on a printing terminal). For instance, the "quote quad" is formed by overstriking the "quad" (a rectangular shape) with a single quote. These composite characters now have separate code positions in the Unicode set.

== References ==
* [http://en.wikipedia.org/wiki/APL_%28codepage%29 APL codepage (Wikipedia)]
* [http://www.wickensonline.co.uk/apl-transcoding.html APL <-> Unicode transcoding in Java]
* [https://web.archive.org/web/20180308155523/http://www-01.ibm.com/software/globalization/ccsid/ccsid293.html IBM code page 293 official page (archived copy)]
* [ftp://ftp.software.ibm.com/software/globalization/gcoc/attachments/CS00380.pdf IBM code page 293 chart]
* [https://web.archive.org/web/20170803005351/http://www-03.ibm.com/systems/resources/systems_i_software_globalization_pdf_cp00907z.pdf IBM code page 907 chart (archived copy)]
* [http://unicode.org/charts/PDF/U2300.pdf Unicode technical symbols chart (includes many APL characters)]
* [https://apl385.com/fonts/ Downloadable APL fonts]

[[Category:IBM]]