    AST RESEARCH, INC.             TECHNICAL BULLETIN # 0932                6-6-94

                                  ASCENTIA 900N CURSOR DRIFT

    PROBLEM:        The trackstick controller has an imbedded calibration routine
                    to compensate for temperature variations within the system.
                    The user can cause the cursor to drift by touching the
                    trackstick during the calibration window.

    CAUSE:          The calibration routine monitors the activity of the
                    trackstick.  If there is no trackstick activity for eight
                    seconds, the controller will initiate the calibration, which
                    takes approximately one millisecond to complete.  If a user
                    touches the trackstick during this one millisecond, the
                    calibration routine will try to compensate for the voltage
                    difference it has just detected, causing the cursor to drift.

    SYSTEMS
    AFFECTED:            AST                                            REVISION
                    PART NUMBER     DESCRIPTION                         LEVEL
                    501299-2XX      ASCENTIA 900N 4/50 COLOR-10         All
                    501300-3XX      ASCENTIA 900N 4/50 COLORPLUS-9      All
                    501302-2XX      ASCENTIA 900N 4/75 COLOR-10         All
                    501304-3XX      ASCENTIA 900N 4/75 COLORPLUS-10     All

    SOLUTION:       The user can reset the device by invoking a SUSPEND
                    and RESUME  operation.  This will reset the cursor
                    without the user losing any information.