INT 41h                  Fixed disk parameters

        This vector points to a data region containing the parameters
        required for the fixed disk drive. The Power-on routines initialize
        the vector to point to the parameters contained in the ROM disk
        routines. Theese default parameters represent the specified values
        for a plain vanilla fixed disk drive. Changing this parameter block
        may be neccesary to reflect the specifications of the actual Fixed
        disk drive(s) attached.