INT 2F C - MDEBUG display driver - INITIALIZE DRIVER                            
	AX = D001h
Return: CF set on error
	AL = driver semaphor
	AH = buffer semaphor
Range:	AH=C0h to AH=FFh, selected by switch or programmatically
Notes:	MDEBUG calls this function after every successful call of the function
	  00h. The function should reset all internal data and the status of
	  the driver. If this function returns an error, MDEBUG will not call
	  the other functions in this popup session.
	MDEBUG can use any two consecutive multiplex numbers between C0h and
	  FFh; the default is D0h for the display driver and D1h for the
	  command driver
SeeAlso: AX=D000h