In computing FOCAL character set refers to a group of 8-bit single bytecharacter sets introduced by Hewlett-Packard since 1979. It was used in several RPNcalculators supporting the FOCAL programming language, like the HP-41C/CV/CX as well as the later HP-42S,[1][2] which was introduced in 1988[1][2] and produced up to 1995. As such, it is also used by SwissMicros' DM41/L, both introduced in 2015, and is implicitly supported by the DM42, introduced in 2017 (although the later calculator utilizes Free42, which is based on Unicode internally).
Character set
The character set is derived from ASCII, but with the control code range and some high bit characters replaced by various special characters.
When Hewlett-Packard introduced the HP-42S in 1988, the FOCAL character set was revised to include more characters, including a number of characters already provided by the HP 82240A infrared thermo printer, which had been introduced in 1986,[5] as part of its extended variant of the 1985 revision of the HP Roman-8 character set,[6][7] although at completely different code points.
There is no code point definition for the euro sign in this character set.
^ abThe glyph at code point 127 (⊦) is called APPEND character in Hewlett-Packard terminology. In the HP-41C/CV/CX and HP-42S series of calculators, it is used to indicate that the following characters will be appended to the alpha register rather than replacing the existing contents of the register.
^The glyph at code point 6 is called GOOSE character in Hewlett-Packard terminology. While U+25B6 (▶) is the preferred Unicode character for maximum cross-compatibility with established RPL character set mappings, Free42 since release 2.0.1 (2017-04-23) maps to U+25B8 (▸) instead. [1]
^Hicks, David G. (2017) [1998]. "HP-41C Synthetic Programming". The Museum of HP Calculators (MoHPC). Archived from the original on 2018-01-06. Retrieved 2018-01-06.
^Hicks, David G. (1997). "Graphic byte code table". The Museum of HP Calculators (MoHPC). Archived from the original on 2018-01-06. Retrieved 2018-01-06.
^HP 82240A Infrared Printer(PDF) (2 ed.). Corvallis, OR, USA: Hewlett Packard, Portable Computer Division. October 1986. HP reorder number 82240-90001 (82240-90008). Archived(PDF) from the original on 2016-08-06. Retrieved 2016-08-06.
^HP 82240B Infrared Printer (1 ed.). Corvallis, OR, USA: Hewlett Packard. August 1989. pp. 17–18. HP reorder number 82240-90014.