Abstract: A motion controller including a computer comprising a primary processor or a central processing unit and an input/output communication bus. The primary processor is in communicative connection with the bus and is adapted to communicate with other devices in communicative connection with the bus via the bus. The motion controller also includes at least one secondary processor in communicative connection with the bus. The secondary processor is adapted to execute at least one control algorithm for one or more axes of motion associated therewith. The secondary processor is further adapted to communicate with other devices in communicative connection with the bus via the bus independently of the primary processor (that is, the secondary processor is can effect bus mastering). The operating system of the computer can, for example, be a general purpose operating system.

Abstract: A servomechanism finds an optimum location for a transducer relative to a track on a magnetic disk by sampling signal strength for a plurality of transducer trajectories. By processing the amplitude envelope of the recorded signal through a comparator prior to sampling, the comparator output, rather than the continuous signal envelope, is sampled. In this way a manageable amount of data is produced for tabulating a collection of integers that specify the cross-track distribution of signal strength across the trajectories. The best trajectory is selected and the transducer is moved accordingly to obtain the best playback signal.

Abstract: A video player includes a playback head that repeatedly passes in contact with a circular track on a flexible magnetic disk in order to reproduce a still picture on a video display. By cycling the player into a special quiescent state after a certain interval elapses without user instructions, excessive disk wear is avoided. While in the quiescent state, the disk drive motor is stopped--immobilizing the disk-to-head interface--and the video display is blanked. If user instructions are received while in this state, the disk drive motor is reenergized and the video display is resumed, showing the still picture displayed prior to interruption. If no user instructions are received during a further interval, the player is shut off.