 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] SMS: B28622      ]
 ] S. VENITSKY        ]    BFS PROGRAM NOTE         ] DR:  106209      ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE: RID     ] OPS NOTE ( )  USER NOTE (X) ] DATE: 05/24/91   ]
 ] (213) 922-1921     ]      RELEASE NOTE ( )       ]                  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] 8C AND SUBS                   ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]           MAJOR SOFTWARE AREA:            ] OPS MODES AFFECTED:     ]
 ]BSL( ) BSS(X) GNC( ) SEQ( ) SM/SP( ) IPL( )]   0, 1, 3, 6            ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: BOS                                              ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: MG038101/3.1.2.2.2  PAYLOAD BUSSES (PL1-2)     ]
 ]_____________________________________________________________________]
 ] TITLE:  ERROR IN PAYLOAD I/O FAULT DISPLAY                          ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ] IF THERE IS PAYLOAD SUPPORT PROCESSING AND AFTER AN MDM HAS FAILED, ]
 ] THE IDENTIFICATION OF THE FAILED PIECE OF HARDWARE (BUS AND/OR MDM) ]
 ] CAN BE OBSCURED ON THE PL BUSES UNDER THE FOLLOWING CIRCUMSTANCES:  ]
 ]                                                                     ]
 ] 1) IF A FLEX MDM WAS INSTALLED AND FAILED, THE ERROR MESSAGE 'I/O   ]
 ]    ERROR PL1' OR 'I/O ERROR PL2' INDICATES WHICH BUS THE FLEX MDM   ]
 ]    WAS ASSIGNED TO.                                                 ]
 ]                                                                     ]
 ] 2) IF A PF MDM HAS FAILED AND AFTER PORT MODING HAS BEEN INVOKED,   ]
 ]    AND THE FOLLOWING ERROR MESSAGES ARE RECEIVED 'I/O ERROR PL1'    ]
 ]    AND 'I/O ERROR PL2'.                                             ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] USER RESPONSE:                                                      ]
 ]                                                                     ]
 ] THE GROUND CAN DETERMINE WHICH PIECE OF HARDWARE FAILED (MDM OR BUS)]
 ] BY EXAMINING THE I/O ERROR LOG AND THE DOWNLIST PAYLOAD SUPPORT     ]
 ] BYPASS BITS FOR THE NUMBER OF A POSSIBLY FAILED BCE ELEMENT         ]
 ] AND/OR FAILED BCE.                                                  ]
 ]                                                                     ]
 ] THE CREW CAN DETERMINE WHICH PIECE OF HARDWARE FAILED (MDM OR BUS)  ]
 ] BY EXAMINING THE 'GNC SYS SUMM 1' DISPLAY FOR THE DOWN ARROW NEXT   ]
 ] TO THE MDM PF1 OR PF2 THAT HAS BEEN BYPASSED.                       ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]RI: <S> C. PURTELL            05/29/91 ]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:   W. R. PRUETT      DATE 05/30/91]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 05/30/91 ]
 ]PF MGR:  D. STEPHENSON    DATE 05/30/91]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_____________________________________________________________________]
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