TM 1-1510-225-10 3B-166 LRU's including CBIT, IBIT, and bus status failures for later examination by maintenance personnel.  To save this status data to the data cartridge, first access the Data  Loader  pages  and  then  press  the   STAT  SAVE line  select  key  twice.    The  failed  history  file  contains start  and  end  dates  of  the  record.    A  new  fail  history record will begin whenever the crew saves the status data to the cartridge. (5)   Zeroizing System Data. The Lock/Zeroize  page  permits  selective  blanking  of  data within  CDU  nonvolatile  memory  and  the  data  loader cartridge.    In  addition  to  selective  blanking,  a  single key commands a master zeroize of all data stored in the system, including, V/UHF HAVE QUICK data, and the GPS selective availability/anti-spoofing     keys.   Figure 3B-136 and Table 3B -101 show the Lock/Zeroize   page   and   its   associated   operation   in blanking different portions of system memory. A   ZERO   ALL   command   will   erase   all   system data.    Flight  plan  zeroization  and  erasure  will  delete the  active  waypoint.    Following  flight  plan  zeroization, guidance  will  be  indeterminate  and  revert  to  a  wings- level configuration. (6)   Locking    the    System.        The    FMS-800 provides  a  system  lock  function  to  prevent  improper investigation   or   tampering   of   system   data   while  the aircraft   is   on   the   ground.      The   system   lock,   when activated   with   a   password   entry,   disables   the   CDU function   keys   with   the   exception   of   two   line   select keys.    One  unlocks  the  system  with  the  entry  of  the same password and one that performs a zeroization of system data. To lock the system, access the lock/zeroize page Figure    3B-136    and    Table    3B-101,    enter    a    three- character  password  in  the  scratchpad,  and  press  the LOCK  line  select  key.    Both  CDU's  will  display  the lock/zeroize page and display the LOCKED annunciation,   indication   the   system   is   locked.      No function keys or line select keys (other than the LOCK and  ZERO  ALL)  are  operational  at  this  point.    Once the system is locked, it can only be unlocked and the full   functionality   restored   to   the   CDU's  by  either  re- entering the same password in the scratchpad of the CDU    and    pressing    the    LOCK    line    select    key    or pressing the   ZERO  ALL  line  select  key  twice  on  the CDU to zeroize system data. Figure 3B-136.  Zeroizing or Locking Up System Data NOTE A zeroize command involving the CDU will erase  any  associated  nonvolatile  memory in the CDU. All    functions    on    this    page    will    delete significant  amounts  of  data  stored  in  the CDU or other subsystem nonvolatile memory.      They   all   require   confirmation prior  to  execution  by  pressing  the  same key   a   second   time   to   acknowledge   the confirmation message.