 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] J.L. DICKMAN       ]    PASS PROGRAM NOTE        ]     100520       ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE:  12/15/87  ]
 ] (713) 282-8472     ]      RELEASE NOTE( )        ] REV B: 05/10/90  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI07 AND SUBS                 ]  CREW (X)  GROUND ( )  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW ( )  GNC (X)  VU ( )  SM/PL ( )] G2, G3                          ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: ORBIT, IMU                                       ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: 5.1                                            ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ]        UNEXPECTED ILLEGAL ENTRY WHEN SELECTING IMU ALIGNMENT        ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ]  IT IS POSSIBLE THAT AN IMU TO IMU ALIGNMENT ENTRY (SPEC 21, ITEM   ]
 ] 16) WILL FAIL WITH AN "ILLEGAL ENTRY" FOR NO APPARENT REASON.       ]
 ]                                                                     ]
 ]  THIS WOULD BE THE CASE IF THE BITE TEST 4 MDM INITIALIZATION READ  ]
 ] IS BYPASSED AT OPS 2 OR 3 TRANSITION.  IN THIS SCENARIO THE OUTPUT  ]
 ] DISCRETE THAT INDICATES THE IMU IS "IN OPERATE" IS SET TO ZERO (AND ]
 ] WILL REMAIN ZERO EVEN AFTER AN I/O RESET).  THIS DISCRETE IS USED   ]
 ] TO DETERMINE IF AN IMU SELECTED AS REFERENCE FOR AN IMU ALIGNMENT   ]
 ] IS IN OPERATE MODE.  ANY ALIGNMENTS USING AN IMU WHOSE "IN OPERATE" ]
 ] OUTPUT DISCRETE IS ZERO WILL FAIL WITH AN ILLEGAL ENTRY.            ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]                                                                     ]
 ] ON SPEC 21, SELECT ITEM 4, 5, OR 6 (OPERATE) TO SET THE "IN OPERATE"]
 ] OUTPUT DISCRETE FOR THE REFERENCE IMU AND REPEAT THE ALIGNMENT.     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]IBM:   WYATT COOPER       DATE 06/12/90]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:   SAM ANKNEY        DATE 06/14/90]                             ]
 ]    --------------------      ---------] DARRELL E. STAMPER 07/02/90 ]
 ]PF MGR: J. R. THIBODEAU   DATE 06/28/90]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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