Get default drive parameter block (INT 21h, 1Fh - internal)

        Entry:
          AH = 1Fh
        Return:
          AL = 00h No Error
               FFh Error
          DS:BX = pointer to DOS Drive Parameter Block (DDPB)

      Note: This just invokes function 32h with DL = 0.
            DOS 4.x returns a different block