DOS code pages

DOS code pages were IBM's system for supporting multiple languages on the PC before Unicode. CP437 (the original IBM PC page) covered US English plus box-drawing characters. CP850 replaced some box-drawing with Western European accented letters. CP866 served Russian, CP869 served Greek, and CP862 served Hebrew.

Switching code pages in DOS required the CHCP command and a matching font in CONFIG.SYS. A file created under CP437 would display wrong characters if opened under CP850 - there was no metadata in text files to indicate which code page was used. This is the same class of problem that UTF-8 eventually solved. See the Windows code pages comparison and character sets reference for modern equivalents.