Abstract: A method and an apparatus for providing a RAID 1 controller subsystem are provided. According to the invention, data or commands issued by a host system and addressed to a transport master are provided to a system bus interface. The system bus interface simultaneously provides the data or commands to the transport master and to a transport slave. The data or commands are then passed to the first and second devices substantially simultaneously. In a normal RAID 1 mode of operation, data retrieved from the first device is passed to the host system by the transport master. In a failover RAID 1 mode of operation, the data retrieved from the first device is not provided to the transport master. Instead, a multiplexer is operated to provide the transport master with the data retrieved from the second device. The invention also allows the controller to operate in a non-RAID 1 mode.

Abstract: A method and an apparatus for providing a RAID 1 controller subsystem are provided. According to the invention, data or commands issued by a host system and addressed to a transport master are provided to a system bus interface. The system bus interface simultaneously provides the data or commands to the transport master and to a transport slave. The data or commands are then passed to the first and second devices substantially simultaneously. In a normal RAID 1 mode of operation, data retrieved from the first device is passed to the host system by the transport master. In a failover RAID 1 mode of operation, the data retrieved from the first device is not provided to the transport master. Instead, a multiplexer is operated to provide the transport master with the data retrieved from the second device. The invention also allows the controller to operate in a non-RAID 1 mode.

Abstract: A wideband tunable (programmable) filter includes first-order and second-order filter circuits employing bipolar transistors. The bandwidth of the filter circuits are set by the product of the dynamic emitter resistance of the transistors and directly coupled on-chip capacitances. The filter bandwidth is inversely proportional to the time constant. To adjust the resonant frequency of the filter networks, emitter currents are varied, which in turn controls the emitter resistances. As the resonant frequency of the filter network is varied, the gain and normalized frequency response of the various output nodes remain constant. In the second-order configuration, the damping ratio of the filter is set using "positive" feedback, for a Q of greater than one-half, with a loop gain of less than one. Temperature compensation is accomplished by use of a temperature "dependent" voltage network.

Abstract: Methods and circuitry for generating sector and data cell timing frequencies for banded variable frequency sector disc drive systems with dedicated plus embedded servo positioning systems which have the timing signals synchronized to servo track information written on a dedicated surface of the disc.

Abstract: A thin film magnetic read/write head is conditioned by (i) causing the head to perform a first operation (e.g., a read operation), (ii) determining if the first operation was performed acceptably, and (iii) if not, causing the head to perform a second operation (e.g., a write operation) that is capable of increasing the likelihood that the head will be able to perform the first operation acceptably.

Abstract: An analog amplifier multiplexer for a data system in which a plurality of differential signal channels are multiplexed onto a pair of differential signal lines includes a differential amplifier connected to each pair of differential signal lines which are to be multiplexed and a current switch connected to each differential amplifier which ensures that an individual differential amplifier will amplify the differential signal applied to it only when it is selected to do so by a selection signal. The selection signal and the current switch ensure that only one differential amplifier amplifies its corresponding differential signal and supplies it to an additional circuitry at any one time.