Hardware code page: Difference between revisions

Revision as of 09:18, 8 June 2016

Revision as of 10:08, 8 June 2016

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==Support in operating systems==

When operating systems initialize their codepage switching logic, they need to know but have no means to determine the previously active hardware code page.<ref name="Paul_2001_CPSwitchFD"/><ref name="Caldera_1998_USER"/><ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_2001_NWDOSTIP"/> Under [[DOS]] this wasis accomplished by specifying the hardware codepage as a parameter to the [[device driver]]s [[DISPLAY.SYS]] and [[PRINTER.SYS]] (hwcp) in [[CONFIG.SYS]]:

: <tt>[[DEVICE (CONFIG.SYS directive)|DEVICE]]=...\DISPLAY.SYS CON=(type,hwcp,n|(n,m))</tt><ref name="Paul_2001_CPSwitchFD"/><ref name="Caldera_1998_USER"/><ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_2001_NWDOSTIP"/>

If no hardware code page wasis specified, these drivers defaulteddefault either to a dummy code page number 999<ref name="Paul_2001_CPSwitchFD"/><ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_2001_NWDOSTIP"/> or assumedassume the hardware code page to be equal to the [[primary code page]] (the first codepage listed in [[COUNTRY.SYS]] files for a particular country as specified by the CONFIG.SYS [[COUNTRY (CONFIG.SYS directive)|COUNTRY]] directive).<ref name="Paul_2001_CPSwitchFD"/>

In many English-speaking countries, the primary code page is either 437 (f.e. in the US) or 850 (f.e. in the UK, Irland and Canada),<ref name="Paul_1997_NWDOSTIP"/><ref name="Paul_2001_NWDOSTIP"/> so that, without specifying a different codepage, the system would often assume one of these to be the corresponding device's hardware code page as well.<ref name="Paul_2001_CPSwitchFD"/>

==OEM code pages==