Abstract: A method and random number generator are provided for generating random numbers. Under the method, a filter coefficient value that is used by a filter to filter an input signal is set and then compared to a default value for the filter coefficient. At least one bit of the random number is then set based on the comparison between the filter coefficient value and the default value.

Abstract: The present invention pertains to an apparatus and method for recording data in a variable bit density disc drive. The disc drive includes a recording surfaces, each having a corresponding head for recording data on the recording surface. At least one head is operated at a different recording frequency from the other heads, creating a variable bit density for the different recording surfaces. The combination of head recording frequencies is determined following an error testing operation and a unique physdisc lookup table is created based on the determined recording frequencies. The physdisc lookup table is used to allocate data sectors and to convert between logical and physical block addresses.

Abstract: A method is provided for preventing a peripheral device such as an ATA disc drive, which is restricted to use with a designated host, being hot-plugged to another system after the drive is unlocked. Thus, violation of privacy of data (eg. music/video) stored on the drive through a hot-plug attack may be avoided. This is accomplished by maintaining time synchronization between the drive and its designated host so that both devices obtain the same seed from time information to generate a validation number at any time that a read/write command is issued from the host.

Abstract: Methods for improving security in data storage devices are disclosed. The methods include a synchronization method by which an encrypted password, using any known encryption algorithm, keeps changing at each transmission from host to data storage device. Additionally, a security system for implementing the security method is provided.

Abstract: The present invention pertains to an apparatus and method for recording data in a variable bit density disc drive. The disc drive includes a recording surfaces, each having a corresponding head for recording data on the recording surface. At least one head is operated at a different recording frequency from the other heads, creating a variable bit density for the different recording surfaces. The combination of head recording frequencies is determined following an error testing operation and a unique physdisc lookup table is created based on the determined recording frequencies. The physdisc lookup table is used to allocate data sectors and to convert between logical and physical block addresses.

Abstract: The present invention pertains to an apparatus and method for recording data in a data storage medium. The data storage medium includes a number of discs, each having at least one recording surface. Each recording surface is associated with a read/write head that records and accesses data from the surface. Each recording surface is partitioned into a number of zones. Each zone is vertically aligned with a same zone on each surface of each disc. The zone boundaries on all surfaces of the disc drive are the same. The recording frequency for each zone on all surfaces can differ for each read/write head in order to compensate for a read/write head that cannot meet the BPI error rate threshold.

Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to said base and a device for moving the actuator assembly. The disc drive includes servo circuitry and a controller for controlling movement of the actuator and head switches during track seek operations. The disc drive determines the average seek time for each head and also measures the amount of time for a head switch from the transducer head having the shortest average seek time to all the other transducing heads in the disc drive. When a seek is performed, the controller in the disc drive determines if the shortest average seek time plus the seek time from the transducing head to the transducing head on the surface containing the target track and sector is less than the average seek time of the head on the surface having the target track and sector.

Abstract: The present invention provides a method of describing defects that requires less memory space than conventional methods. Entries of a first defect table are sorted according to the type of track layout, or zones. They are then grouped into clusters. Each cluster is characterized by a set of new parameters, including a starting sector, a scratch parameter, a span parameter, and an angle parameter. The new parameters are stored in a second table, replacing the corresponding entries in the first table. In this manner, a single entry in the second table replaces one or more entries in the first table with one entry in the first table.

Abstract: The present invention pertains to an apparatus and method for recording data in a data storage medium. The data storage medium includes a number of discs, each having at least one recording surface. Each recording surface is associated with a read/write head that records and accesses data from the surface. Each recording surface is partitioned into a number of zones. Each zone is vertically aligned with a same zone on each surface of each disc. The zone boundaries on all surfaces of the disc drive are the same. The recording frequency for each zone on all surfaces can differ for each read/write head in order to compensate for a read/write head that cannot meet the BPI error rate threshold.