A code page is simply a character set. Code page support was added to
DOS 3.3 to make it possible for DOS to be translated into international
languages. DOS also makes it possible for a program to be written in a
"language-independent" manner; for instance, there are DOS functions which
help you to sort a list of text strings that contain international
characters such as É and Ç.
Code page support provides a "behind-the-scenes" way to process non-
English keystrokes and a way to reprogram EGA and VGA adapters to display
certain characters that are not defined by standard IBM-compatible
hardware. It also provides some limited printer font-definition support.
Code pages (character sets) defined and supported in DOS include:
437 US et.al.
850 Multilingual (Latin I)
852 Slavic (Latin II)
863 Canadian French
866 Norwegian and Danish
Here is some information relevant to code pages:
■ The CONFIG.SYS file contains a COUNTRY= directive which selects a
default code page and country information file. See also fn 65H.
■ One or more DEVICE= directives in CONFIG.SYS install 'code page
aware' device drivers DISPLAY.SYS or PRINTER.SYS.
■ The '.CPI' files that come with DOS contain 'Code Page Information'
for a selected device. See Code Page Font Files.
■ The Nlsfunc command installs code page switching (optionally
overriding the country information file set in CONFIG.SYS) and must
be used before any code page activities take place.
■ The Mode and Chcp commands (3.3+) can prepare and select a code page.
You can perform the same functions as Mode via fn 440cH (but it is a
pain). And you can use fn 6602H to activate a prepared code page.
■ When you 'prepare' a code page via the Mode command, the information
in the .CPI file is used to redefine a font. For instance, the '$'
character can be changed into the '£' character. This takes place at
the device driver level via Fn 44H (IOCTL) commands. For the EGA,
the appropriate INT 10H BIOS calls are made to redefine the character
set. For a printer, a character set can be downloaded into it and
selected as the default.
Code Page Font Files describes the layout of the font-definition files
used by code page aware device drivers.
See Also: National Language Support
fn 44H (IOCTL functions)
fn 66H (code page switching)
Code Page Font Files