CODEPAGE and KEYB affect the operation of DOS-based programs. If, whilst at a command prompt, a character other than "@" appears when the "@" button is pressed, some attention to codepages is required.
The following lines are typical entries in CONFIG.SYS:
device=C:\WINDOWS\COMMAND\display.sys con=(ega,,1) Country=044,437,C:\WINDOWS\COMMAND\country.sys
...and the following in AUTOEXEC.BAT:
mode con codepage prepare=((437) C:\WINDOWS\COMMAND\ega.cpi) mode con codepage select=437 keyb uk,,C:\WINDOWS\COMMAND\keyboard.sys
The last line loads the correct driver for the UK keyboard, whilst all of the other lines load the UK character sets for display & print purposes.
Note: Windows has a habit of resetting the codepage number to 850 (rather than 437) every time it is updated or reloaded.