18-bit computing: Difference between revisions

Revision as of 02:44, 22 August 2019

Revision as of 08:50, 11 September 2019

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18-bit machines use a variety of character encodings.

The [[DEC Radix-50]], called Radix 50₈ format, packs three characters plus two bits in each 18-bit word.<ref>{{Cite manual|title=PDP-9 Utility Programs--Advanced Software System--Programmer's Reference Manual|last=|first=|publisher=[[Digital Equipment Corporation]]|year=1968|isbn=|___location=Maynard, Massachusetts|url=http://www.bitsavers.org/pdf/dec/pdp9/DEC-9A-GUAB-D_UTILITIES.pdf|archive-date=January 25, 2019|dead-url-status=nolive|archive-url=https://web.archive.org/web/20190125062212/http://www.bitsavers.org/pdf/dec/pdp9/DEC-9A-GUAB-D_UTILITIES.pdf|page=A1-1|chapter=Linking Loader|pages=}}</ref>

The Teletype packs three characters in each 18-bit word; each character a 5-bit [[Baudot code]] and an upper-case bit.<ref name="pdp7" />

The [[DEC SIXBIT]] format packs three characters in each 18-bit word,<ref name="pdp7">{{Cite manual|title=PDP-7 Symbolic Assembler Programming Manual|last=|first=|publisher=[[Digital Equipment Corporation]]|year=1965|isbn=|___location=Maynard, Massachusetts|pages=6, 38–39|url=http://bitsavers.trailing-edge.com/pdf/dec/pdp7/PDP-7_AsmMan.pdf|archive-url=https://web.archive.org/web/20170523224514/http://bitsavers.trailing-edge.com/pdf/dec/pdp7/PDP-7_AsmMan.pdf|archive-date=May 23, 2017|dead-url-status=nolive|access-date=June 18, 2015}}</ref> each 6-bit character obtained by stripping the high bits from the 7-bit [[ASCII]] code, which folds lowercase to uppercase letters.

==References==