INT 66 - PenDOS - PKEYUS - ???                                                  
	AH = 43h
	BX = ???
	DX = ???
Return: AX = status
	    0000h if AH=41h flag set
	    else
		AH = ???
		AL = ???
		BX = ???
		DX = ???
SeeAlso: AH=41h