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 <Fn+Esc>
                and RESUME <any key> operation.  This will reset the cursor
                without the user losing any information.