 +_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] HIRAM THOMPSON     ]    PASS PROGRAM NOTE        ]       107971     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE (X)  USER NOTE ( ) ] DATE:  11/27/95  ]
 ] SSOAS/(281)335-2238]      RELEASE NOTE( )        ] REV A: 06/20/97  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI-24 THRU OI-27              ]  CREW (X)  GROUND (X)  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW (X)  GNC ( )  VU ( )  SM/PL ( )] ALL                             ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: MMU                                              ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: SBIO                                           ]
 ]_____________________________________________________________________]
 ] TITLE:                                                              ]
 ]             FALSE OFF/BUSY MMUX MESSAGE POSSIBLE                    ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ] DURING CERTAIN MASS MEMORY OPERATIONS WHICH REQUIRE TWO OR MORE     ]
 ] SEPARATE MMU I/O TRANSACTIONS, IT IS POSSIBLE FOR THE FSW TO CAUSE  ]
 ] THE MMU OPERATION TO FAIL WITH AN "OFF/BSY MMUX" INDICATION.  THIS  ]
 ] IS CAUSED BY A PREMATURE INDICATION OF I/O COMPLETE FOR ONE MMU     ]
 ] TRANSACTION PRIOR TO THE INITIATION OF A SUBSEQUENT MMU             ]
 ] TRANSACTION INITIATED BY AN APPLICATION PROGRAM.  FOR THIS PROBLEM  ]
 ] TO OCCUR, THE FIRST MMU I/O TRANSACTION MUST COMPLETE (APPROX.      ]
 ] 200 MICROSECONDS) PRIOR TO THE BEGINNING OF A CS SYNC CYCLE (SIP    ]
 ] CYCLES 2, 6, 10, 14, 18, & 22).  THIS IS A LOW PROBABILITY PROBLEM, ]
 ] BUT IS UNPREDICTABLE DUE TO THE ASYNCHRONOUS REQUEST FOR MMU        ]
 ] OPERATIONS, CPU AND I/O LOADING (OPS AND ACTIVITY DEPENDENT), AND   ]
 ] TYPE OF MMU OPERATION REQUESTED.                                    ]
 ]                                                                     ]
 ] IT IS POSSIBLE FOR THE ANOMALY TO OCCUR ON THE FOLLOWING: SM        ]
 ] CHECKPOINTS, TFL LOADS, MM PATCH, TCS SEQ FROM MMU (FIRST SEQUENCE  ]
 ] REQUEST ONLY), AND OPS OVERLAYS WHICH REQUIRE TWO PHASE OVERLAYS    ]
 ] (EXCLUDING G1 OPS OVERLAY WITH G3 ARCHIVE) FROM MMU.                ]
 ]                                                                     ]
 ] CURRENTLY, THE SM CHECKPOINT IS MOST EXPOSED TO THIS ANOMALY.       ]
 ] EXPOSURE DURING AN OPS TRANSITION IS CONSIDERABLY LESS THAN         ]
 ] CHECKPOINTS SINCE CPU AND I/O PROCESSING IS SIGNIFICANTLY REDUCED   ]
 ] DURING OPS OVERLAY PROCESSING.                                      ]
 ]                                                                     ]
 ]                  - CONTINUED ON SUPPLEMENT PAGE -                   ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]SSOAS:ANDREW L. KLAUSMAN  DATE 07/22/97]                             ]
 ]     -------------------      ---------]                             ]
 ]ASD:    W. R. PRUETT      DATE 07/22/97]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 10/29/97 ]
 ]PF MGR:KAYLENE F. KINDT   DATE 07/23/97]------------------- -------- ]
 ]       -----------------      ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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 +_____________________________________________________________________
 ]                                                                     ]
 ]                       SUPPLEMENTAL SHEET                            ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] AUTHOR:            ]                             ] DR:              ]
 ] HIRAM THOMPSON     ]    PASS PROGRAM NOTE        ]       107971     ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE (X)  USER NOTE ( ) ] DATE:  11/27/95  ]
 ] SSOAS/(281)335-2238]      RELEASE NOTE( )        ] REV A: 06/20/97  ]
 ]____________________]_____________________________]__________________]
 ] TITLE:                                                              ]
 ]             FALSE OFF/BUSY MMUX MESSAGE POSSIBLE                    ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ]                                                                     ]
 ] THE GENERIC SIGNATURE OF THIS CONDITION IS:                         ]
 ]   - AN "OFF/BUSY MMUX" MESSAGE                                      ]
 ]   - AND A BCE 27 I/O ERROR WILL BE LOGGED                           ]
 ]                                                                     ]
 ] FOR THE SM CHECKPOINT, THE FOLLOWING WILL ALSO BE NOTED:            ]
 ]   - AN "S60 CHECKPOINT FAIL" MESSAGE                                ]
 ]   - SPEC 60 (SM TABLE MAINT) WILL DISPLAY "FAIL UNIQ"               ]
 ]   - SM DOWNLIST PARAMETERS V92J1090C (CHECKPOINT R/W STATUS) AND    ]
 ]     V92J1091C (CHECKPOINT FAIL QUALIFIER) WILL HAVE VALUES OF 4     ]
 ]     AND 3 RESPECTIVELY                                              ]
 ]   - AND THE I/O ERROR LOGGED AS MENTIONED ABOVE WILL HAVE AN OPCODE ]
 ]     VALUE OF 5                                                      ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ]                                                                     ]
 ] RETRY THE REQUESTED MASS MEMORY OPERATION.  FOR OVERLAYS, THE       ]
 ] AUTOMATIC RETRY WILL BE SUCCESSFUL.                                 ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]                                                                     ]
 ]_____________________________________________________________________]
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