Abstract: A data buffer monitor apparatus which monitors the space availability in WRITE buffer and the number of sectors available for transfer in the READ buffer and generates the OK TO TRANSFER signal. The data buffers monitor apparatus includes a READ buffer monitor, a WRITE buffer monitor and a transfer controller. The READ buffer monitor monitors the total number of sectors stored in the READ buffer, the number of sectors in the READ buffer available for transfer to the host and generates a READ OK TO TRANSFER signal if the sectors for a requested READ operation are store in the READ buffer. The WRITE buffer monitor monitors the total number of sectors in the WRITE buffer and generates a WRITE OK TO TRANSFER signal if the WRITE monitor determines that a requested WRITE operation can be performed.

Abstract: A method is described for testing for slider/disk contact in a disk drive comprising a rotating disk and a head mounted by an actuator for selective positioning of the head over the disk, the head having a slider, and a spindle motor for rotating the disk. The method comprises the steps of providing power to the spindle motor to cause rotation of the disk at a preselected rotational velocity corresponding to a rotational velocity designed for the disk during normal read/write operation, and thereafter withdrawing the power from the spindle motor such that the disk spins down to zero rotational velocity. While the disk spins down to zero rotational velocity, an acoustic coupling is formed between an acoustic emission sensor having an electric output and the spindle motor to provide first electric signals representative of acoustic emissions from the spindle motor, including acoustic emissions caused by slider/disk contact.

Abstract: The present invention provides a disk drive apparatus for use in computer systems and especially in computer systems where size and weight are of paramount concern, such as lap top computer systems. The preferred embodiment of the disk drive apparatus includes a 21/2" magnetic disk that preferably provides 20 to 40 megabytes of storage within a foot print area of approximately 2.8 inches by approximately 4.0 inches. Further, the disk drive apparatus possesses a height dimension of 0.630 inches or less. This height dimension is achieved, in part, by providing a low profile spin motor to rotate the magnetic disk. The low profile spin motor uses high energy magnets that are preferably made of a material that includes a rare earth, such as neodymium or samarium. The disk drive apparatus also employs a rotary actuator having a voice coil assembly of reduced height that is achieved by using the housing as a flux return path for magnet fields produced by the voice coil assembly.

Abstract: A data smoother for a streaming cartridge tape drive including a data separator circuit for generating a clock signal and a second phase-locked loop circuit for removing frequency modulation arising from instantaneous speed variation (ISV) errors. The broad-band data separator follows all of the ISV generated by the cartridge tape drive to permit detection and correction of cell-slippage in a First-In-First-Out (FIFO) circuit, which accepts the data and clock signal from the data separator. The second PLL has a narrow bandwidth filter that smoothes the clock signal and removes all high-frequency ISV modulation from the data as it is clocked out from the FIFO circuit. The MFM data signal is regenerated by a monostable multivibrator in synchronism with the smoothed clock signal.

Abstract: A hard disk drive implemented as a plug-in module has a height of 10 mm and a foot print of 85.6 mm.times.54 mm. The footprint corresponds to the dimensions of memory cards. The disk drive uses a modified suspension in which the load beams are welded to actuator plates, thereby eliminating the use of a stakable suspension. The disk may be a glass substrate having a thickness of approximately 0.381 mm (0.015") or an aluminum substrate having a thickness of approximately 0.635 mm (0.025").

Abstract: A microcontroller managed adaptive control system, including a precompensator and a passive equalizer, is provided to decrease the read error rate of a disk drive. An adaptively controllable programmable precompensator adjusts the timing of data bits being written to a disk recording surface with the timing adjustment being relative to the individual bit timing windows. A novel adaptively controllable programmable equalization circuit is provided to enhance the peak amplitudes of data bits read at high frequencies. A microcontroller is programmed to control the programmable precompensator and equalizer to determine the threshold for and subsequently enable the precompensation of the write data and, independently, the equalization of read data with respect to a given media surface.

Abstract: A read/write head for an information recording apparatus having a liquid bearing lubricant between a rotating storage medium and the read/write head is disclosed. The head is provided an actuator to position the read/write head over the rotating storage medium. The head includes a slider body having at least a first and second regions; and an interface element comprising a transducer interacting with the storage medium and mounted on the first region of the slider body. A relative motion exists between the head and the rotating storage medium and the slider body is supported by the liquid bearing lubricant during such motion, such that the first region of the slider body is supported at a first distance above the storage medium, and the second region of the slider body is supported at a second distance above the storage medium, whereby the first region of the slider body has a substantially higher drag than the second region when the head moves relative to the storage medium.

Abstract: In a disk drive system having two actuators, each said actuator having a plurality of transducers, said system employing a transducer switching procedure for switching between a first presently selected transducer and a second to be selected transducer, an apparatus, associated with the nonpackwriting actuator, for controlling the sensing of an address mark by said second transducer, said apparatus comprising an address mark means for generating an address mark search signal to start an address mark search when an address mark is expected to be read by said first transducers; and an adjusting means connected to said address mark means for altering the time when said address mark means will generate said address mark search signal such that said second transducer will read the next address mark to occur on the track being read by said second transducer after said second transducer is selected.

Abstract: A method for improving the manufacture of an arcuate scan drive. Such drives include a plurality of read/write heads, each head having a gap and being mounted to a rotating drum. The method for manufacture includes: rotating the drum to determine the rotational center point of the drum; specifying a gap width for each gap; specifying a distance from the rotational center point to the head gap; and laser machining each of the head gaps to said gap width such that each head gap is positioned at said distance from the rotational center point of the head.

Abstract: A hard disk drive system operates from a limited power source to provide for the storage of data on the surface of a rotating hard disk media. An embedded controller incorporates a data channel for transferring data with respect to a hard disk media. The controller includes first and second subsections and a power-down circuit for providing separately switchable power from the power source to the first and section subsections. The controller further includes a processor for controlling the power-down circuit. The processor nominally provides a low duty cycle control signal to the power-down circuit for switching the provision of power to the first subsection of the controller.

Abstract: A disk drive including a disk clamp for clamping one or more disks within the disk drive. The clamp is comprised of a dual member construction which provides a substantially uniform contact pressure at the circular line of contact between the clamp and the disk. The clamp includes an inner ring surrounding and fixedly attached to the hub of the disk drive. The inner ring preferably does not contact the disk. An outer ring is provided having a first portion underneath the inner ring and a second portion provided axially outward from the inner ring. The second portion of the outer ring contacts the disk in a substantially circular line of contact. The inner ring further includes a plurality of threaded holes, through which a plurality of set screws are provided. The screws, when sufficiently threaded through the holes, exert a pressure on the outer ring, which pressure is uniformly transmitted to the disks to secure the disks within the drive.

Abstract: A method and apparatus for performing error detection on data transfer through a parallel interface port at a substantially increased data transfer rate with a minimum of handshaking. Blocks of data are transferred between a sending device and a receiving device, and each of the respective devices maintains a checksum. Each checksum comprises an initial value, and added to that value is the value of each data byte transferred through the parallel port interface. After a block of data bytes has been transferred, the checksum maintained by the sending device and the receiving device are compared. If the checksums are equal, no error is assumed to have occurred during the data transfer. If the checksums are not equal, an error is assumed to have occurred during the data transfer, and the data is retransferred with the previously transferred block discarded.

Abstract: A digital phase detector that stores four sequential digital samples in a shift register. The contents of the shift register is evaluated at one half the clock frequency which generated the digital samples. The digital phase detectors predicts what the value should be for each of the two middle samples in the shift register. The predicted value and the actual value of each middle are used to generated a correction signal. The correction signals for the two middle samples are then added to produce a total correction signal which is to be used in controlling the phase and frequency of the voltage controlled oscillator in the phase locked loop generating the clock that controls the generation of the digital samples.

Abstract: The invention provides a track format and a record carrier system for supporting a track architecture where a first field, such as a data field, is split by a second field, like a servo field. The preferred track format includes a split count field that contains information on the location of the second field with respect to the first field. In the preferred embodiment, the split count field is located in the header associated with the data field. The present invention also includes circuitry that reads the split count and uses the split count to discriminate the first field from the second field or the information contained in the first field from the information contained the second field. The invention is particularly useful in modified constant angular velocity (MCAV) magnetic disk systems where constant frequency servo fields are embedded among variable frequency data fields. The present invention is, however, applicable to any kind of record carrier where one field is split by another field.

Abstract: A method is shown for testing a magnetic disk to be used in a disk drive. The method includes the steps of measuring a height profile of an outer radial edge of the disk, using the profile to determine a slope value for each of a pair of radial segments of the disk, calculating a difference value between the slope values of the pair, comparing the difference value to a preselected threshold difference value and indicating when the difference value is equal to or less than the threshold difference value. The threshold value indicates an outer most diameter of the disk where fly height operation for a head is still stable.

Abstract: A network management system includes a domain administrating server (DAS) that stores a virtual catalog representing an overview of all files distributively stored across a network domain currently or in the past. The current and historical file information is used for assisting in auditing or locating files located anywhere in the domain. The current file information is used for assisting in transferring files across the domain. The domain administrating server (DAS) also includes a rule-base driven artificial administrator for monitoring and reacting to domain-wide alert reports and for detecting problematic trends in domain-wide performance based on information collected from the network domain.

Abstract: A method and apparatus for interfacing a SCSI device directly to an Ethernet network utilizes a single board converter for translating information packets in Ethernet format to a SCSI format. In reverse, the same converter translates information from a SCSI device into a format suitable for transmission on an Ethernet bus. The method defines a procedure for receiving, recognizing and translating data bi-directionally between the bus and the SCSI device.

Abstract: A method for dynamically tracking memory resource allocations/deallocations of a program resident in the memory of a network file server is disclosed wherein calls to system memory allocation functions are intercepted and diverted to memory resident tracker routines, interposed between the caller and the called functions to monitor returns from the called functions. Public symbol lists of application program interfaces are scanned for functions to be tracked, and function entry points are taken over by replacing initial instructions of the system functions with jumps to the tracker routines. The tracker routines then call the remainder of the system functions and record the reply before passing control back to the original caller program. Information on allocated blocks is written to ABLK blocks taken from an ABLK free block pool allocated at tracker startup. Subsequent deallocations of the allocated blocks release the same ABLK blocks back to the ABLK free pool.

Abstract: Disclosed is a method and apparatus for guidance of a magnetic head to a predetermined reference position generally used to recalibrate head to media orientation. An electro-magnetic or photosensitive device is provided to accurately and repeatably position a magnetic head carriage to a reference point in order to calibrate the head gap location with respect to parallel tracks across the width of the media. A coarse and fine adjustment method is used to improve the accuracy of establishing the head at the reference position.

Abstract: A disk drive having a read/write head flying at extremely low flying heights, the drive including a disk clamp for clamping one or more disks within the disk drive, with the clamp exerting a substantially uniform pressure at the circular line of contact between the clamp and the disk. The disk clamp includes a raised circular wall around an outer radius of the clamp, which wall is formed as part of and integrally with the rest of the clamp. The wall serves to increase the structural rigidity of the clamp in a single axial section of the clamp, thereby providing a "stress barrier" to the transmission of localized stresses from the screw points. Thus, the pressure exerted by the clamp on the disk is evenly distributed around the entire clamp, and the distortion normally occurring at the inner diameter of the disk with conventional disk clamps is greatly reduced.