Int 2F Fn 4B52  - Keyrus V7.3 - Api                                        [K]

   AX = 4B52h ('KR')
   BL = function number
       00h installation check

       Return: AL = 82h if installed
               BH = major version number
               BL = minor version number
               ES destroyed
       01h get driver status

       Return: AL??? = current status (see #2511)
       02h set driver state
       AL = new driver state (see #2511)
       03h blank screen (if blanking enabled when TSR was loaded)
       04h unblank screen
       4Ch switch to English keyboard mode
       90h switch to Russian keyboard mode

Return:

Bitfields for KeyRus driver status:
Bit(s) Description (Table 2511)
 1-0   language mode
   00 Latin
   01 Russian
   10 Alternative
   11 unused
 2 allow character loading (if disabled, use ROM fonts)
 3 English keyboard support
 7-4   used internally (read-only)