Western Digital Corporation

Robert Ellis Caddy, Jr

Robert L Cloke

David Price Turner

Michael R Spaur

A system for polling a preamplifier unit to remotely determine pre-established parametric values in a disk drive is disclosed. The disk drive comprises a controller, a preamplifier, and a plurality of transducers. The system for polling the preamplifier comprises means in the controller for generating a succession of serial bit characters each representative of a different pattern. A means is provided for successively transferring said serial bit characters from the controller to the preamplifier unit. A plurality of individual bit lines are provided in the preamplifier unit representative of at least one parametric value. A means is included in the preamplifier unit for comparing each serial bit pattern character received with said plurality of individual bit lines, and for generating a match signal when a serial bit pattern character received matches the plurality of individual bit lines. A means is provided for transferring the match signal from the preamplifier unit to the controller.

Polling a preamplifier within a disk drive to remotely determine pre-established parametric values

A disk drive comprising a plurality of read/write transducers, a programmable preamplifier, and a controller for furnishing control and data signals to the programmable preamplifier and for receiving data signals therefrom, is disclosed. The programmable preamplifier comprising a write data input circuit for receiving data signals to be supplied to a transducer, a read data output circuit for manifesting data signals supplied to said preamplifier unit by a transducer, and a transducer interface circuit for providing write data signals to a transducer and receiving read data signals from a transducer. The programmable preamplifier further comprises a multiplexer comprising a first multiplexer input connected to receive a first internal digital signal, a second multiplexer input connected to receive a second internal digital signal, a control input connected to receive a control signal for selecting between the first and second internal digital signals, and a multiplexer output for outputting the selected first or second internal digital signal. The multiplexer output is connected to an output terminal of the programmable preamplifier. The programmable preamplifier comprises a serial interface circuit for receiving serially presented control signals from the associated controller, including the control signal for selecting between the first and second internal digital signals.

Disk drive comprising a programmable preamplifier including a

A disk drive preamplifier unit includes a serial interface circuit for receiving serially formatted control signals from an associated disk drive controller. The control signals contain several types of information, including head select, write current magnitude, bias for MR transducers, gain magnitude for a variable gain amplifier, and test and mode information. The preamplifier unit incorporates several test circuits in addition to the usual write unsafe detector circuit, and a multiplexer controlled by the mode control signals from the serial interface unit is used to select which test circuit or detector is coupled to a common test output terminal whose signals are coupled back to the controller for further processing. The preamplifier can be used to remotely test the head population of the head disk assembly, to measure the MR bias current through any of the MR transducers and to signal the controller in response to polling characters when a match is obtained between a character and preestablished multi-bit parameter information fixed in the preamplifier unit. A write current generator is shared by the write transducers and the MR bias test circuit, with a current scaling unit used to provide different current ranges from the common source. The preamplifier unit affords remote control and testing which can be adapted to evolving systems using firmware changes alone.

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Oronoco, MN, United States of America

Robert Ellis Caddy, Jr