Characters have traditionally been stored on computers as six, seven, or eight bit entities. PCs, pretty much universally, have used ASCII, which is technically a seven bit code, stored in 8 bit bytes. Prior to PCs it often seemed that every vendor used their own unique character code. In the past decade, some PC applications have switched to a 16 bit UniCode representation of characters that can describe up to 65536 different entities.
ASCII consists of 32 control codes such as tab and carriage return; 26 Upper Case letters; 26 Lower Case letters; 10 numbers; space and 33 special characters such as comma, period and asterisk. There are also 128 additional characters available by using the unused eighth data bit along with the 128 ASCII values. While most ASCII values are standardized, a few such as "pound" vary in various languages. The 128 additional characters also vary in different languages.
Many languages that nominally use the Roman alphabet use accent marks. Eastern European languages include altered/new characters. Japanese, Arabic, and other languages may use entirely non-roman alphabets. Chinese and Japanese draw from a "palette" of thousands of potential characters.
Code pages define how the 256 "ASCII" characters map onto printable/displayable characters and control characters. They also define how lower case to upper case mappings are done and whether a given mapping holds in both directions. The code page number identifies the characters associated with a code page. The code page itself identifies how Upper and Lower case conversions are done within the character set. Windows NT supports a 16 bit (Double Byte Character Set) code page in addition to the traditional single byte code page.
some code Page Numbers:
Microsoft software recognizes a Country Code, a global code page and a code page for each device. The country code may imply a specific code page. There is a global code page, but different code pages can be set for specific devices.
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