1+_____________________________________________________________________
 ] AUTHOR:            ]                             ] DR:              ]
 ] PAUL M. TICE       ]    PASS PROGRAM NOTE        ]       33619      ]
 ]____________________]                             ]__________________]
 ] ORG/PHONE:         ] OPS NOTE ( )  USER NOTE (X) ] DATE: AUG. 1987  ]
 ] IBM/282-7297       ]      RELEASE NOTE( )        ] REV B: 02/12/93  ]
 ]____________________]_____________________________]__________________]
 ] OI/FLIGHT EFFECTIVITY:        ]  USER AFFECTED:                     ]
 ] OI-21 AND SUBS                ]  CREW (X)  GROUND ( )  DUMP ONLY ( )]
 ]_______________________________]_____________________________________]
 ]        MAJOR SOFTWARE AREA:       ] OPS MODES AFFECTED:             ]
 ]SSW (X)  GNC ( )  VU ( )  SM/PL ( )]  ALL                            ]
 ]_____________________________________________________________________]
 ] SOFTWARE SUB-AREA: ANNUNCIATION                                     ]
 ]_____________________________________________________________________]
 ] PRINCIPAL FUNCTIONS: SANU                                           ]
 ]_____________________________________________________________________]
 ] TITLE:  GARBLED MESSAGE ON DISPLAY MESSAGE LINE                     ]
 ]_____________________________________________________________________]
 ] DESCRIPTION:                                                        ]
 ] IT IS POSSIBLE FOR AN ERROR MESSAGE TO BECOME GARBLED WITH          ]
 ] PORTIONS OF TWO MESSAGES BEING DISPLAYED. ONE OF THE MESSAGES       ]
 ] WILL BE AN ILLEGAL ENTRY MESSAGE WHILE THE OTHER MESSAGE CAN        ]
 ] BE ANY FAULT MESSAGE.                                               ]
 ]                                                                     ]
 ] THIS SITUATION CAN OCCUR ONLY IF ALL OF THE FOLLOWING CONDITIONS    ]
 ] EXIST:                                                              ]
 ] A.  THE ANNUNCIATION MESSAGE PROCESSOR MUST PROCESS A FAULT         ]
 ]     MESSAGE ON ONE CYCLE AND A CLASS 5 MESSAGE (E.G., ILLEGAL       ]
 ]     ENTRY) ON THE NEXT CYCLE.                                       ]
 ]                                                                     ]
 ] B.  THE CYCLIC DISPLAY UPDATE PROCESSOR, WHICH NORMALLY RUNS TWICE  ]
 ]     AS FREQUENTLY AS THE ANNUNCIATION PROCESSOR, MUST CYCLE OVERRUN ]
 ]     (GPC ERROR 020D) TO SUCH AN EXTENT THAT THE ANNUNCIATION        ]
 ]     MESSAGE PROCESSOR ANNUNCIATES BOTH MESSAGES IN BETWEEN CYCLIC   ]
 ]     DISPLAY UPDATE CYCLES.                                          ]
 ]                                                                     ]
 ] C.  THE PHASING OF THE ABOVE PROCESSES HAS TO LINE UP SO THAT THE   ]
 ]     ANNUNCIATION MESSAGE PROCESSOR UPDATES THE MESSAGE LINE BUFFER  ]
 ]     AT THE EXACT INSTANT THAT CYCLIC DISPLAY UPDATE PROCESSOR I/O   ]
 ]     OPERATION FOR THAT DEU IS ACTUALLY TRANSMITTING DATA.           ]
 ]                                                                     ]
 ] (ALSO REFERENCE DR55324)                                            ]
 ]_____________________________________________________________________]
 ]USER RESPONSE:                                                       ]
 ] RECOGNIZE THAT THE SYSTEM HAS REJECTED THE MOST RECENT KEYBOARD     ]
 ] ENTRY AS ILLEGAL AND RESPOND ACCORDINGLY. DEPRESSING MSG RESET      ]
 ] KEY WILL CAUSE THE FAULT MESSAGE TO BE DISPLAYED WITHOUT THE SPLIT  ]
 ] MESSAGE CONDITION.                                                  ]
 ]_____________________________________________________________________]
 ]CONCURRENCE:                           ]APPROVAL:                    ]
 ]IBM:   JEAN L. ZOPHY      DATE 04/13/93]                             ]
 ]    --------------------      ---------]                             ]
 ]FDSD:   W. R. PRUETT      DATE 04/15/93]                             ]
 ]     -------------------      ---------] DARRELL E. STAMPER 04/28/93 ]
 ]PF MGR:  ERIC C. BINGHAM  DATE 04/13/93]------------------- -------- ]
 ]       ------------------     ---------] CHAIRMAN, SASCB      DATE   ]
 ]_______________________________________]_____________________________]
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