INT 2F - KeyRus v7.3 - API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes.
	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 #02825)
	    02h set driver state
		AL = new driver state (see #02825)
	    03h blank screen (if blanking enabled when TSR(Terminate and Stay Resident) A program which remains in memory after terminating in order to provide services to other programs or the user.  The name comes from the name of the DOS function call used to remain in memory after termination. 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 02825)
 1-0	language mode
	00 Latin
	01 Russian
	10 Alternative
	11 unused
 2	allow character loading (if disabled, use ROM(Read-Only Memory) A memory for program storage which may not be changed by the program as it runs. fonts)
 3	English keyboard support
 7-4	used internally (read-only)