Abstract: An arbitration and data source selection mechanism arbitrating access to a shared communication port between a servo engine and a controller of a disc drive is disclosed. In a preferred embodiment, the arbitration and data source selection mechanism, the shared communication port, the servo engine and the controller collectively share a common die of an application specific integrate circuit (ASIC). Servo control code and control code are each loaded into the ASIC for operation of the disc drive. The servo engine is allowed to hold service of the shared serial port dedicated to the servo control code for any length of time required by the servo engine. During periods of non-use by the servo control code, the servo engine releases the shared serial port to the controller for dedicated use by the control code, for a predetermined period of time.

Abstract: An arbitration and data source selection mechanism arbitrating access to a shared communication port between a servo engine and a controller of a disc drive is disclosed. In a preferred embodiment, the arbitration and data source selection mechanism, the shared communication port, the servo engine and the controller collectively share a common die of an application specific integrate circuit (ASIC). Servo control code and control code are each loaded into the ASIC for operation of the disc drive. The servo engine is allowed to hold service of the shared serial port dedicated to the servo control code for any length of time required by the servo engine. During periods of non-use by the servo control code, the servo engine releases the shared serial port to the controller for dedicated use by the control code, for a predetermined period of time.

Abstract: A system for controlling movement of a head over tracks on a disc in a disc drive includes a servo positioner for positioning the head over a desired track, a sectoring circuit for determining when the head is over a data sector on the desired track, a formatter for controlling data transfers to and from the desired track, and a controller for providing the servo positioner with a track address indicative of the desired track. A track change system is coupled to the formatter and the servo positioner, and provides a direct communication channel between the servo positioner and the formatter. Thus, the data transfer can be carried out utilizing communications between the formatter and the servo positioner, without waiting for the microcontroller to be interrupted.