Abstract: A high sensitivity MR (GMR) sensor suitable for ultra high density magnetic recording applications. The GMR sensor has two laminated free layers each comprising two AP-coupled ferromagnetic layers separated by an antiparallel coupling (APC) layer. The two free layer structures are separated by a non-magnetic, conducting spacer layer. The sense current flowing in the layers of the sensor provide the bias field to set magnetization directions. The applied magnetic field from the magnetic disk rotates one or both of the two free laminated layers due to the moment difference of the composite AP-coupled layers that form the laminated free layers. In the initial state, with zero applied field, the GMR sensor is in the high resistance state. In the final states, with either polarity applied field, the GMR sensor is in the low resistance state. A unipolar output signal is produced as the GMR sensor switches states.

Abstract: A magnetoresistive read sensor having an MR sensing element in parallel with a flux guide. The flux guide is made of an amorphous alloy having a composition of Co.sub.a Hf.sub.b Nb.sub.c where a is the concentration of Co, b is the concentration of Hf, and c is the concentration of Nb. Co.sub.a Hf.sub.b Nb.sub.c has a high magnetization and is highly resistive which reduces the amount of sense current flowing through the flux guide, thus increasing the amplitude of the signal sensed by the MR sensing element.

Abstract: A method is disclosed for fabricating a high density recording head having a narrow, well-defined second pole tip for recording data with an areal density in the range of 5 gigabits. The second pole tip is connected to a mushroom yoke which extends across underlying insulated coils. The second pole tip and yoke are formed at the same time using conventional photolithographic and plating processes. By using a preselected thickness for the photoresist mask layer over the head body region, an aspect ratio for the photolithographic process of less than 4:1 is achieved in the head pole tip region. However, the thickness of the photoresist mask layer in the head body/yoke region will be less than the desired thickness of the second pole piece, which creates a problem of a void beneath mushroomed overhanging edges. By back-filling the void with an insulating material at the time the head is sealed, the void problem is overcome.

Abstract: A data storage and retrieval system is provided which has extremely high capacity. The system includes a large array of small disk files, and three storage managers for controlling the allocation of data to the array, access to data, and the power status of disk files within the array. The allocation manager chooses the disk files upon which incoming data is written based on the current state of the disk files (active or inactive), the available capacity, and the type of protection desired (i.e. unprotected, RAID, mirrored, etc.). The access manager interprets incoming read requests to determine the location of the stored data. The power manager sequences disk files between active and inactive to provide the storage requested by the access and allocation managers.

Abstract: An Anti-Parallel (AP)-Pinned SV sensor having a free layer separated from an AP-pinned layer by a conducting spacer. The AP-pinned layer includes a first, second and third pinned layers where the first pinned layer is separated from the second and third pinned layers by an anti-parallel coupling layer. An antiferromagnetic (AFM) layer is used to pin the AP-pinned layer magnetizations directions. The first pinned layer is formed over and in contact with the AFM layer. The first and second pinned layers are made of highly resistive material such as NiFeCr and the third pinned layer is made of low resistive material such as cobalt. The use of a highly resistive first and second pinned layers reduces the amount of sense current flowing in the AP-pinned layer as well as eliminating interdifussion at the AFM/first pinned layer interface resulting in larger GMR coefficient, well controlled net moment, highly stable sensor, and reduced read signal asymmetry.

Abstract: An orthogonal magnetoresistive (MR) read sensor is provided having an MR sensing element which is perpendicular to an air bearing surface (ABS) and has an easy axis which is parallel to the ABS. The MR sensor further has top and bottom flux guides in series with the bottom and the top portion of the MR sensing element, respectively The bottom flux guide extends perpendicular from the ABS. Bottom and top leads are connected to the bottom and top flux guides, respectively, in a spaced-apart relationship for conducting a sense current through the MR sensing element. The MR sensing element and the bottom lead are electrically insulated from each other by an insulating layer which is placed between the sensing element and the bottom lead. Electrically insulating the sensing element from the bottom lead makes the sensing efficiency of the sensing element independent of the size of the bottom lead thus improving the performance and manufacturability of the orthogonal MR sensor.

Abstract: A no-ID zone-bit-recording data recording disk drive system having an interface processor and a servo processor is described wherein track seek time is substantially reduced by the following two step seek process. The interface processor converts a logical block address (LBA) to an estimated physical block address (EPBA) using a defect map where the EPBA is communicated to the servo processor. The servo processor uses a zone table and converts the EPBA to an estimated zone-cylinder-head-sector (ZCHS) value which is used to initiate actuator arm movement and moving the appropriate head over the disk in the direction of sought after track. Concurrently with the servo processor computation and actuator arm motion, the interface processor generates an exact PBA and communicates the exact PBA to the servo processor. The servo processor converts the exact PBA to exact ZCHS values and modifies the actuator arm motion so the head can be exactly positioned over the sought after track.

Abstract: A magnetoresistive sensor having end regions separated from a central active region. The central region comprises magnetoresistive material. Each of the end regions comprises a biasing material for longitudinally biasing the magnetoresistive material in the central region. Each of the end regions also include a lead structure formed over the biasing material for receiving electrical current. The lead structure includes a first refractory metal formed over and in contact with the biasing material; a second refractory metal distinct from the first refractory metal and formed over and in contact with the first refractory metal; and a lead conductor layer formed over and in contact with the second refractory metal. The multi-refractory lead structure has an overall resistance that is much lower than a single refractory metal lead structure.

Abstract: An Anti-Parallel (AP)-pinned spin valve (SV) sensor having a free layer disposed between an AP-pinned layer and a pinned layer. The free layer being separated from the AP-pinned layer by a first conducting spacer and separated from the pinned layer by a second conducting spacer layer. The AP-pinned layer includes a first, second and third AP-pinned layers where the first and second AP-pinned layers are separated from the third AP-pinned layer by an anti-parallel coupling layer. The first AP-pinned layer is formed over and in contact with an antiferromagnetic (AFM) layer. The AFM layer is used to pin the AP-pinned layer magnetizations directions.

Abstract: To reduce read and write times for data in a disk drive, the data of a file is rearranged into continuous recording areas on a disk. A file has a host-specified address and a physical address. The physical address corresponds to the recording area on a disk where the file is stored. The host-specified and physical addresses are stored in a conversion table. The controller receives the host-specified address and a command for reading the file. Based on the host-specified address, the controller determines the physical address from the conversion table. Based on the physical address, the controller reads the data from the disk and sends the data to the host. Thereafter, the controller examines the physical address in the conversion table to determine if the data is recorded on a physically continuous recording area on the disk. If not, the data is moved to a physically continuous recording area, and the physical address in the conversion table is updated.

Abstract: A dual spin valve (DSV) magnetoresistive (MR) sensor has a free magnetic layer disposed between first and second pinned magnetic layers. The first pinned layer has two magnetic sublayers separated from each other by an antiparallel spacer. The first magnetic sublayer closer to the free layer has a magnetic moment which is smaller than the magnetic moment of the second magnetic sublayer. The net moment of the magnetic sublayers is chosen to be equal to the magnetic moment of the second pinned layer thus creating a flux closure and substantially minimizing the effect of the demagnetizing forces. By creating a flux closure and current induced magnetic fields, the first and second pinned layers' magnetization are fixed. This is in contrast with conventional dual spin valve sensors using two antiferromagnetic layers to pin the magnetization of the pinned layers.

Abstract: A spin valve magnetoresistive (MR) read sensor is provided wherein the free and pinned layer magnetization are perpendicular to each other under quiescent conditions and the current flowing in the free MR layer is oriented to flow at a substantially 45 degree angle with respect to the free layer magnetization. The flow of the current at the 45 degree angle with respect to the free layer magnetization causes the AMR effect which is present in the free MR layer to be added to the spin valve sensor GMR effect and increases the overall magnetoresistive effect by about 25% to 33%.

Abstract: In a client/server environment, a method and means for reducing the storage requirement in the backup subsystem and further reducing the load on the transmission bandwidth where base files are maintained on the server in a segmented compressed format. When a file is modified on the client, the file is transmitted to the server and compared with the segmented compressed base version of the file utilizing a differencing function but without decompressing the entire base file. A delta file which is the difference between the compressed base file and the modified version of the file is created and stored on a storage medium which is part of the backup subsystem. Alternatively, a copy of frequently accessed base files are maintained on the client in a compressed format. Whenever the client detects that a frequently accessed file has been modified, the modified version of the file is differenced against the base version of that file without decompressing the entire base file and a delta file is generated.

Abstract: A self-biased spin valve (SV) magnetoresistive (MR) sensor is disclosed having a free layer separated from a pinned layer by a spacer1 layer and further having the free layer separated from a keeper layer by a spacer2 layer. The free layer being disposed between the keeper layer and the pinned layer. The keeper layer in combination with the sense current flowing in the sensor is used as a means of pinning the magnetization of the pinned layer. By using the soft keeper layer in combination with the sense current as a means of pinning the pinned layer magnetization as opposed to the use of the conventional antiferromagnetic layer, the SV sensor dependency on the blocking temperature of the antiferromagnetic layer is eliminated.

Abstract: A disk drive system having a magnetoresistive (MR) sensor having four leads, two leads for providing sense current to an MR layer and two leads for providing current to a soft adjacent layer (SAL). The MR layer as well as the hard bias layers are electrically insulated from the SAL by an insulator. The voltages developed across the MR layer (voltages due to the presence of thermal asperities and voltages due to the presence of data fields) and the SAL (voltages due to the presence of thermal asperities) are applied to the inputs of a differential amplifier for substantial elimination of the thermal asperity signal.

Abstract: A disk drive system having a spin valve (SV) magnetoresistive (MR) sensor having four leads, two leads for providing sense current to an SV element and two leads for providing current to an asperity compensation layer (ACL). The SV element as well as the hard bias layers are electrically insulated from the ACL by an antiferromagnetic layer made of an insulating material. The voltages developed across the SV element (voltages due to the presence of thermal asperities and voltages due to the presence of data fields) and the ACL (voltages due to the presence of thermal asperities) are applied to the inputs of a differential amplifier for substantial elimination of the thermal asperity signal.

Abstract: A data processing system having multiple independent paths for communication between a host and a plurality of storage devices where each path has its own queue for servicing requests generated by the host for accessing the storage devices. Each request is assigned a unique sequential ID before it is stored, along with its unique ID, in all the queues. Each storage device has a "mailbox" register where the ID and the status of the latest request being carried out is stored. Queues are serviced and their status updated based on the content of the mailbox in each storage device. The combination of assigning a unique task ID to each request and a "mailbox" register in each storage device allows the queue in each path to be completely out of sync with each of the queues in the other paths without causing data integrity problems, duplication of requests at the device level, or a need for complex locking schemes to keep the queues in sync with each other.

Abstract: The improved disk drive system has an improved actuator arm assembly where the arms are independently and individually insertable and removable from the actuator member. Furthermore, each arm is individually self-locked into the actuator member without the need for external retaining means such as screws, springs, and rings. Since the arms are individually insertable/removable, the arms can be made very thin thereby allowing easy attachment of the head suspension assembly to the arm without the need for swaging, bonding, welding or screw-in. Since the arms can be made very thin, that provides substantial reduction in disk to disk spacing and therefore, substantial reduction in the overall height of a disk drive system.

Abstract: A dual spin valve (DSV) magnetoresistive (MR) sensor has a free magnetic layer disposed between first and second pinned magnetic layers. The first pinned layer has two magnetic sublayers separated from each other by an antiparallel spacer. The first magnetic sublayer closer to the free layer has a magnetic moment which is smaller than the magnetic moment of the second magnetic sublayer. The net moment of the magnetic sublayers is chosen to be equal to the magnetic moment of the second pinned layer thus creating a flux closure and substantially minimizing the effect of the demagnetizing forces. By creating a flux closure and current induced magnetic fields, the first and second pinned layers' magnetization are fixed. This is in contrast with conventional dual spin valve sensors using two antiferromagnetic layers to pin the magnetization of the pinned layers.

Abstract: In a magnetic read/write assembly, a removable fusible-link shorts the magnetoresistive (MR) sensor element to minimize electrical current through the MR sensing element during discharge of static electricity. Other magnetic head assembly elements such as the write coil and MR magnetic shields are also shorted using fusible-links. The fusible-link is removable during the assembly process. The existing terminal pads and wires are used to remove the fusible-link.