Author: Mike Shkolnik

How to read the code page of system?

Answer:

Sometimes in run-time you must detect the current values of code page. 

To detect the code page of Windows operation system you must call the GetACP 
function from Windows API. 

This function will return the value: 
874 Thai 
932 Japan 
936 Chinese (PRC, Singapore) 
949 Korean 
950 Chinese (Taiwan, Hong Kong) 
1200 Unicode (BMP of ISO 10646) 
1250 Windows 3.1 Eastern European 
1251 Windows 3.1 Cyrillic 
1252 Windows 3.1 Latin 1 (US, Western Europe) 
1253 Windows 3.1 Greek 
1254 Windows 3.1 Turkish 
1255 Hebrew 
1256 Arabic 
1257 Baltic 

If you needs to read the code page of "DOS" sessions, you must call the GetOEMCP 
function from Windows API. 
This function will return the value: 

437 MS-DOS United States 
708 Arabic (ASMO 708) 
709 Arabic (ASMO 449+, BCON V4) 
710 Arabic (Transparent Arabic) 
720 Arabic (Transparent ASMO) 
737 Greek (formerly 437G) 
775 Baltic 
850 MS-DOS Multilingual (Latin I) 
852 MS-DOS Slavic (Latin II) 
855 IBM Cyrillic (primarily Russian) 
857 IBM Turkish 
860 MS-DOS Portuguese 
861 MS-DOS Icelandic 
862 Hebrew 
863 MS-DOS Canadian-French 
864 Arabic 
865 MS-DOS Nordic 
866 MS-DOS Russian (former USSR) 
869 IBM Modern Greek 
874 Thai 
932 Japan 
936 Chinese (PRC, Singapore) 
949 Korean 
950 Chinese (Taiwan, Hong Kong) 
1361 Korean (Johab) 

Also you can check the valids of code page. For example, 
1   
2   if IsValidCodePage(866) then
3     ShowMessage('Correct MS-DOS russian code page')