 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] SMS: B28531      ]
 ]    R J CMELAK      ]    BFS PROGRAM NOTE         ] DR:  101898      ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE: D282    ] OPS NOTE ( )  USER NOTE (X) ] DATE: 8/10/88    ]
 ]     310-922-5246   ]      RELEASE NOTE ( )       ] REV A:7/02/92    ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]      OI21 & SUBS              ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]           MAJOR SOFTWARE AREA:            ] OPS MODES AFFECTED:     ]
 ]BSL( ) BSS(X) GNC( ) SEQ( ) SM/SP( ) IPL( )]    1, 3, 6              ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA:  BSS                                             ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS:  MG038101/3.1.9.1                              ]
 ]_____________________________________________________________________]
 ] TITLE: RS SPLIT STANDALONE AFTER I/O RESET                          ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ]  A 2 ON 2 SPLIT IN THE PASS REDUNDANT SET NORMALLY CAUSES BFS       ]
 ]  TO TRACK THE LOWER PAIR. HOWEVER, IF THE BFS HAS EXPERIENCED A     ]
 ]  NON-UNIVERSAL I/O ERROR DUE TO A MIA RCVR PROBLEM ON A FORWARD     ]
 ]  BUS ASSOCIATED WITH THE LOWER PAIR PRIOR TO THE SPLIT, BFS WILL    ]
 ]  TRACK THE HIGHER PAIR. UPON EXECUTION OF BFS I/O RESET, BFS WILL   ]
 ]  ATTEMPT TO REINITIALIZE TRACKING ON THE LOWEST PAIR BASED ON THE   ]
 ]  AFT TRANSFER DATA. DURING THE NEXT TRANSACTION BFS WILL DOWNMODE   ]
 ]  THE STRING WITH THE FAULTY FORWARD BUS (MIA) AND GO STANDALONE     ]
 ]  FOR LACK OF 2 STRINGS TO TRACK. BFS COULD RECOVER TRACK ONLY BY    ]
 ]  RESTRINGING AND THEN AN I/O RESET.                                 ]
 ]                                                                     ]
 ]  NOTE: LOWER PAIR = STRING 1 AND ITS PARTNER                        ]
 ]_____________________________________________________________________]
 ] USER RESPONSE:                                                      ]
 ]                                                                     ]
 ]  DURING A PASS REDUNDANT SET 2 ON 2 SPLIT SITUATION, IF BFS IS      ]
 ]  TRACKING THE HIGH ORDER STRING PAIR AND A LISTEN COMMAND I/O       ]
 ]  ERROR WAS PREVIOUSLY OBSERVED ON ONE OF THE LOW ORDER FLIGHT       ]
 ]  FORWARD STRINGS DO NOT ATTEMPT AN I/O RESET TO BFS UNTIL           ]
 ]  RESTRINGING IS ACCOMPLISHED.                                       ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]RI: <S> J. AGRES          DATE 07/06/92]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:   W. R. PRUETT      DATE 08/11/92]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 08/17/92 ]
 ]PF MGR:  D. STEPHENSON    DATE 08/11/92]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_____________________________________________________________________]
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