The operating system interface routines use absolute SCSI element
    addresses, instead of zero relative address as used by the higher
    level functions. A zero based element address can be converted to
    an absolute address by adding the element base address from the
    robot_info_t structure. For example, the absolute slot address
    can be found by adding slot_start to the relative slot address:

     int  slot ;
     robot_info_t robot_info ;

     /*
      * An relative starting address.
      */
     slot = 3 ;

     /*
      * Becoming an absolute address.
      */
     slot += robot_info.slot_start ;