Abstract: An intelligent hard disk drive subsystem including control circuitry and disk drive storage media along with drive mechanics in a combination including a standardized interface between the intelligent subsystem and a host computer wherein the data is buffered, serialized, deserialized, conditioned, precompensated, and located within the media, all under the control of a microprocessor within the subsystem. A method of formatting the media is provided which eliminates the need for a track 0 sensing switch, and which provides for formatted guard bands on the disk. The formatting process locates the head through a sequence of writing, indexing, and reading, until a stop is located by the fact that the head reads what it has just written.

Abstract: A disk drive control system including servo sectors written on a disk, with each sector containing three sets of marker pulses arranged so that three adjacent marker pulses from each of the sets spans two tracks. The pulses each comprise high frequency sinusoidal signals. Servo control depends upon the pulse amplitudes sensed by the read/write head while traversing a servo sector. The system includes an amplifier to rectify and amplify the high frequency signals, a sample-and-hold circuit to hold at least three value representative of the amplified high frequency signals, and synchronizing means to synchronize the sample-and-hold circuit such that the first value sampled and held is representative of the amplitude of the first pulse read in a servo sector, the second value sampled and held is representative of the amplitude of the second pulse read in the servo sector, and so forth. A multiplexing circuit provides multiplexed signals sequentially representative of values sampled.

Abstract: A disk drive system includes a mechanism for positioning a movable transducer member in the absence of electrical power to the drive system. The mechanism includes a ferromagnetic lever arm pivotably positioned to engage a movable transducer member and, by such engagement, to move the transducer to a predetermined location. An electromagnet attracts the lever arm to a position clear of the movable transducer member in the presence of electrical power to the drive system, and a spring moves the lever arm into engagement with the movable transducer member when the electromagnet is not energized.

Abstract: A disk drive control system includes servo sectors written on a disk, with each sector containing three sets of marker pulses arranged so that three adjacent marker pulses from each of the sets spans two tracks. Positional control utilizes a function comprising a ratio whose denominator value represents the sum of the amplitudes of the two largest amplitude marker pulses detected by the read/write head while traversing a servo sector and who numerator represents the differences in amplitude between said two largest amplitude marker pulses.