Abstract: A logical-to-physical head map is built upon each power up of a disc drive. After powering the controller and disc drive spindle motor, a bias current is iteratively supplied to the read heads in succession. A representation of the voltage across each read head is stored in a fault register for comparison to a threshold and a “good” or “bad” fault status is stored for each head. A logical-to-physical head map is defined based on the number of logical heads, which in turn is based on the disc drive serial number. Each of the logical heads in the logical-to-physical head map is associated to a respective one of the heads having a “good” fault status to construct the logical-to-physical head map in the controller memory.

Abstract: A method of, system, modules, and computer readable media for generating a defect error log on a disc in a disc drive is disclosed. All defective sector addresses of all defective sectors on the disc are identified and stored in the memory. At least two defective sectors identified are adjacent to each other circumferentially or radially or in both directions. The at least two sector addresses of adjacent defective sectors are merged into a defect error entry. Merging refers to a conversion (or encoding) of the multi sector addresses into a defect error entry. The converted defect error entry is then stored in the defect error log.

Abstract: A disc drive production process automatically configures the disc drive to a suitable capacity based upon the data transfer capability of each of the head/disc surface combinations in the drive. The error rate of each of the head/disc surface combinations is determined as a function of the bit density of the disc surface. Based on the data transfer capability of the head/disc surface combinations, one of three drive configuration schemes is selected. A variable BPI (bits per inch) scheme reduces the data rate of a weak head/disc surface combination while increasing the data rate of a strong head/disc surface combination. If the drive contains one very weak head/disc surface combination, a head depopulation scheme disables the very weak head. If the drive contains two or more very weak heads, a de-frequency scheme reduces the overall capacity of the drive.

Abstract: A system, method, and device for moving a plurality of heads in a disk drive is disclosed. The system comprises hard disks, read/write heads for reading from or writing to the hard disks, a voice coil motor for moving the plurality of heads, a voice coil motor driver for energizing the voice coil motor, a voltage clamp device for regulating a voltage across the voice coil motor, and a park voltage source. The voltage clamp device comprises a transistor, a switch, and a resistive divider network. During head parking, a park voltage source activates the voltage clamp device, which clamps the voltage across the voice coil motor to a fixed value, resulting in movement of the voice coil and heads towards a park location with fixed velocity.