Abstract: A disk drive provides manufacture test processing of itself after it is installed and operating within a computer system. The tests include flaw mapping, embedded runout compensation and final drive verification and do not interfere with normal operations of the disk drive.

Abstract: A method and apparatus for increasing formatting efficiency of a disk drive is disclosed. In one embodiment, a method for storing data in a disk drive is provided. The disk drive is coupled to a computer via an interface. The method includes the steps of storing data on a disk surface in a disk block having a predetermined length; and, presenting data from the disk drive to the interface as a host block having a predetermined length, wherein the predetermined length of the disk block is equal to N times the predetermined length of the host block, where N is a natural number greater than 1. In one embodiment, a read/modify/write procedure is provided to ensure that data is not lost when a power failure occurs during a write operation when the number of host blocks being written is not a multiple of N.

Abstract: A method and apparatus for dynamically detecting write fault errors is provided. According to the invention, transducer head control parameters are adjusted according to observed events. For instance, off-track events of a certain magnitude may trigger the implementation of a severe shock timer, which lengthens the delay between the off-track event and allowing write operations to resume, as compared to the standard off-track timer. According to another embodiment of the present invention, a lower write fault threshold is implemented following an off-track event of sufficient magnitude. According to yet another embodiment of the present invention, the average or accumulated position error of the transducer head is monitored, and a lower write fault threshold implemented if the average position error exceeds a threshold value.

Abstract: A personal computer hard disk has disk media that comprises a primary portion and a backup portion; both portions are in the same hard disk housing. The backup portion is logically separate from the primary portion, and access to the logically separate backup portion is controlled by a backup access control mechanism. The backup access control mechanism may comprise a manually-actuable mechanism, such as a switch or a jumper, or it may comprise software provided in an ROM forming part of the internal memory of the hard disk.

Abstract: A method and apparatus for controlling the position of a disk drive transducer head relative to a target track are provided. An oversampled control output allows frequencies that are higher than the Nyquist frequency of the servo control system to be filtered. The system initiates a plurality of control outputs during a single sampling period, allowing the use of a single processor interrupt for each sampling period. The outputs initiated during a single sampling period may be of unequal length. In addition, the outputs may be proportioned so that the total control energy provided to the actuator is equal to the control energy that would be provided by control outputs initiated every one-half sampling period.

Abstract: A method and apparatus are disclosed which allow for compensation of repeatable runout in a disk drive when an actuator arm assembly has a relatively high friction to inertia ratio in a pivot bearing assembly. The compensation uses one of two initial runout coefficients, based on a seek length. If the seek length is shorter than a predetermined distance, a current runout coefficient is used to compensate for repeatable runout which is continuously updated throughout a previous seek operation. If the seek length is greater than the predetermined distance, a transient runout coefficient is used to compensate for repeatable runout which is updated following the initial revolutions of the hard disk.

Abstract: A PTP test subsystem of a magnetic disk drive identifies an undesired pole tip protrusion (PTP) condition, and takes steps to prevent problems associated with PTP. A PTP stressing mechanism stresses the disk drive during a PTP test mode to induce a PTP condition. A disk contact detection circuit detects when a head of the disk drive contacts the disk. A PTP write current determining circuit is also provided which comprises a write current level detector to ascertain a write current level at which the disk contact detection circuit detects when the head of the disk drive contacts the disk while the disk drive is stressed during the PTP test mode.

Abstract: A method and apparatus for writing servo information to disks within a disk drive is disclosed. A servo track writer is used to write first servo information to the disks. The disk drive is then sealed, and the read/write heads within the disk drive are used to fill in second servo information. The first servo information includes digital information and A, B, C, and D servo bursts for a first number of tracks on the disks. The first servo information also includes digital information and A and B servo bursts for the remaining tracks on the disks. After the disk drive is sealed in the manufacturing process, the read/write heads within the disk drive fill in the second servo information, which includes C and D servo bursts for the remaining tracks. The read head reads the first servo information in the first number of tracks, and the position of the write head is adjusted based on the first servo information.

Abstract: A disk drive stores data within a single track of a data storage disk at two different lateral positions with respect to the track centerline. The radial distance between the two lateral positions is preferably equal to the lateral offset between the read and write elements of a corresponding dual element transducer for the particular track. In a preferred approach, some of the data sectors within selected tracks are designated to be offset sectors. Data is written to these sectors at the offset position rather than the standard write position for the disk drive. Data can then be moved within a single track of the disk drive without having to perform a microjog operation by reading from a data sector in the standard location and then writing to an offset sector location.

Abstract: A system for positioning a plurality of heads traversing multiple disks in a disk drive system is disclosed herein. The positioning system includes a servo pattern recorded on at least one of the hard disks, the servo pattern having a sequence of servo locations successively recorded along concentric tracks on the disks. Burst zones are also recorded on the hard disks, each burst zone having multiple transitions recorded at staggered separate radial distances from the center of the disks. The positioning system contains means for computing servo burst signal magnitudes based on head position relative to the transitions in each burst zone, and means for calculating a head offset based on differences between the servo burst signal magnitudes and radial displacement of each head in each track. The positioning system transmits a correction signal based on calculated head position, and the output signal has a linear response for any head position on the disk.