Digital encoding of APL symbols: Difference between revisions

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==Character sets==

Due to its origins on [[IBM]] [[IBM Selectric typewriter|Selectric]]-based [[teleprinter]]s, APL symbols have traditionally been represented on the wire{{jargon inline|date=August 2025}} using a unique, non-standard character set. In the 1960s and 1970s, few terminal devices existed which could reproduce them, the most popular ones being the [[IBM 2741]] and [[IBM 1050]] fitted with a specific APL print head. Over time, with the universal use of high-quality graphic display, printing devices and [[Unicode]] support, the APL character font problem has largely been eliminated.

===Character repertoire===

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====Code page 907====

'''Code page 907''' is used by the IBM 3812, like [[code page 906]].

{|{{chset-table-header1|Code page 907<ref name="cpgid907">{{citation|mode=cs1 |archive-url=https://web.archive.org/web/20170803005351/http://www-03.ibm.com/systems/resources/systems_i_software_globalization_pdf_cp00907z.pdf |archive-date=2017-08-03 |url=http://www-03.ibm.com/systems/resources/systems_i_software_globalization_pdf_cp00907z.pdf |title=Code Page 00907 |author=IBM |author-link=IBM}}</ref>}}

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Homologous uses of 47 include the "SD" (diacritic) series GCGID SD470000 for "Line Below/Discontinuous Underscore"<ref name="cs969">{{cite web |url=https://public.dhe.ibm.com/software/globalization/gcoc/attachments/CS00969.txt |title=OCR B |id=GCSGID 00969 |publisher=[[IBM]]}}</ref>—i.e. [[macron below]], distinct from the ASCII underscore which is SP090000 ("Underline/Continuous Underscore")<ref name="cp1252"/>—and the "A" ([[Arabic script|Arabic letter]]) series GCGID AD470009 for the [[ḏāl]],<ref name="cp1256pdf">{{cite web |url=https://public.dhe.ibm.com/software/globalization/gcoc/attachments/CP01256.pdf |title=Windows, Arabic (PDF) |id=CPGID 01256 |publisher=[[IBM]]}}</ref> for example. Unicode's [[Latin Extended Additional]] block includes the following capital "Line Below" characters with the macron below diacritic, for Semitic transcription (it includes a pre-composed ẖ only in lowercase):

* {{unichar|E7001E06|LATIN CAPITAL LETTER vendB withWITH strokeLINE BELOW}}

* {{unichar|1E0E|LATIN CAPITAL LETTER D WITH LINE BELOW}}

* {{unichar|1E34|LATIN CAPITAL LETTER K WITH LINE BELOW}}

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==Keyboard layout==

NoteThere theare mnemonics associating an APL character with a letter: {{keypress|?}} (''question mark'') on {{keypress|Q}}, {{keypress|⋆}} (''power'') on {{keypress|P}}, {{keypress|ρ}} (''rho'') on {{keypress|R}}, {{keypress|⊥}} (''base value'') on {{keypress|B}}, {{keypress|⊤}} (''eNcode'') on {{keypress|N}}, {{keypress|∣}} (''modulus'') on {{keypress|M}} and so on. This makes it easier for an English-language speaker to type APL on a non-APL keyboard, providing one has visual feedback on one's screen. Also, decals have been produced for attachment to standard keyboards, either on the front of the keys or on the top of them.

[[Image:APL-keybd2.svg|600px|thumb|center|APL keyboard layout.<ref>

A more up-to-date keyboard diagram, applicable for APL2 and other modern implementations, is available at WikensOnline '''[http://www.wickensonline.co.uk/apl/union-large.png Union APL large keyboard layout for Windows] {{webarchive |url=https://web.archive.org/web/20120310113525/http://www.wickensonline.co.uk/apl/union-large.png |date=March 10, 2012 }}''', '''[http://www.wickensonline.co.uk/apl-unicomp.html actual photo + diagram here] {{webarchive |url=https://web.archive.org/web/20150403042056/http://www.wickensonline.co.uk/apl-unicomp.html |date=April 3, 2015 }}''' and '''[http://www.sudleyplace.com/APL/Keyboard.ahtml NARS2000 APL keyboard layout here]'''.</ref>]]