 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] C. WOHL            ]    PASS PROGRAM NOTE        ]        104404    ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE (X)  USER NOTE ( ) ] DATE:  02/20/91  ]
 ] SSOAS/(281)335-2197]      RELEASE NOTE( )        ] REV E: 12/04/97  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ]  OI-22 THRU OI-28             ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW (X)  GNC ( )  VU ( )  SM/PL ( )] G9, G1                          ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: I/O, FTS                                         ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: SBIO                                           ]
 ]_____________________________________________________________________]
 ] TITLE:  LOSS OF REDUNDANT SET I/O ERROR INFORMATION                 ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:  A "FAKE MSC TIMEOUT (T/O)" OCCURS WHEN A BCE PROGRAM  ]
 ] TAKES SLIGHTLY LONGER TO SUCCESSFULLY COMPLETE THAN THE TIME        ]
 ] ALLOCATED FOR THE I/O TRANSACTION.  A "PSEUDO T/O" OCCURS WHEN I/O  ]
 ] IS REQUESTED ON A MASKED BUS. NEITHER OF THESE CONDITIONS RESULT IN ]
 ] AN I/O ERROR LOG ENTRY.                                             ]
 ]                                                                     ]
 ] I/O ERROR INFORMATION IN A REDUNDANT SET GPC CAN BE ERRONEOUSLY     ]
 ] CLEARED (I.E. LOST) IN THE FOLLOWING SCENARIO:                      ]
 ]                                                                     ]
 ] 1) A COMMFAULTABLE I/O TRANSACTION COMPLETES WITH A REAL I/O ERROR. ]
 ] 2) A TIMER INTERRUPTS I/O COMPLETION PROCESSING AND INITIATES       ]
 ]    ANOTHER COMMFAULTABLE I/O TRANSACTION WITH A HIGHER PRIORITY.    ]
 ] 3) THE HIGHER PRIORITY I/O COMPLETES WITH A FAKE MSC T/O OR PSEUDO  ]
 ]    T/O. (ERROR INFORMATION FOR THE FIRST TRANSACTION IS LOST.)      ]
 ]                                                                     ]
 ] IF ALL GPCS EXCEPT ONE IN AN RS DETECT A FAKE MSC T/O ON THE HIGHER ]
 ] PRIORITY I/O, AND IF THIS OCCURS ON THE 2ND CONSECUTIVE ERROR OF    ]
 ] THE LOWER PRIORITY I/O, THE SINGLE GPC NOT DETECTING THE FAKE MSC   ]
 ] T/O WILL FTS DUE TO A FALSE NON-UNIVERSAL I/O ERROR ON THE LOWER    ]
 ] PRIORITY I/O TRANSACTION.  THIS CAN OCCUR ONLY IN G9.  IF ALL GPCS  ]
 ] DETECT A FAKE MSC T/O OR PSEUDO T/O ON THE HIGHER PRIORITY I/O THEN ]
 ] COMMFAULT INFORMATION FOR THE LOWER PRIORITY I/O WILL BE LOST FOR   ]
 ] ONE I/O CYCLE (AFFECTED I/O TRANSACTIONS: SRB DATA ACQUISITION FOR  ]
 ] DOWNLIST IN G9 AND G1, PF LOW RATE READS FOR DOWNLIST IN G9, AND G9 ]
 ] PSP AND PDI SWITCH MATRIX & BITE STATUS REGISTER READS VIA SPEC 62.)]
 ]_____________________________________________________________________]
 ] USER RESPONSE:  IF A FAIL TO SYNC OCCURS, NORMAL FTS PROCEDURES     ]
 ] SHOULD BE FOLLOWED.  NO ACTION IS NEEDED IF A TRANSIENT LOSS OF     ]
 ] COMMFAULT STATUS OCCURS SINCE THE ERRING I/O TRANSACTION SHOULD BE  ]
 ] BYPASSED ON A SUBSEQUENT I/O CYCLE.                                 ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]SSOAS:  JOHN MAGLEY       DATE 01/13/98]                             ]
 ]      ------------------      ---------]                             ]
 ]ASD:    ERIC C. BINGHAM   DATE 01/20/98]                             ]
 ]      ------------------      ---------] DARRELL E. STAMPER 01/26/98 ]
 ]PF MGR: KAYLENE F. KINDT  DATE 01/20/98]------------------- -------- ]
 ]       ------------------     ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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