Function  1Fh Get Default Drive Parameter Block  
 *  Same as function call 32h (below), except that the table is accessed from  
    the default drive 
entry   AH      1Fh 
	other registers unknown 
return  AL      00h     no error 
		0FFh    error 
	DS:BX   points to DOS Disk Parameter Block for default drive. 
note 1) Unknown vector returned in ES:BX. 
     2) For DOS 2.x and 3.x, this just invokes Int\21f\32 (undocumented, Read
        DOS Disk Block) with DL=0