Maxtor D540X-4K - Manual (Page 55)

Basic Principles of Operation
Maxtor D540X-4K 20.4/40.0/60.0/80.0 GB AT 5-7
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The Buffer Controller supports a 1.75 MB buffer. The 16-bit width implementation
provides a 60 MB/s maximum buffer bandwidth. This increased bandwidth allows the
µProcessor to have direct access to the buffer, eliminating the need for a separate
µProcessor RAM IC.
The Buffer Controller supports both drive and host address rollover and reloading, to
allow for buffer segmentation. Drive and host addresses may be separately loaded for
automated read/write functions.
The Buffer Controller operates under the direction of the µProcessor.
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The Servo Processor in the Read Write Channel ASIC provides servo data recovery
and burst demodulation to extract the actuator position information. This information
is processed in the controller ASIC/microprocessor, and a control signal is output to
the VCM in the Power ASIC. This controls the current in the actuator coil which
controls the position of the actuator.
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The Read/Write interface allows the integrated µprocessor, disk controller to
communicate with the Read/Write chip.
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The ATA Interface Controller portion of the ASIC provides data handling, bus
control, and transfer management services for the ATA interface. Configuration and
control of the interface is accomplished by the µController across the MAD bus. Data
transfer operations are controlled by the Buffer Controller module.
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The Motor Controller controls the spindle and voice coil motor (VCM) mechanism
on the drive.
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The Read/Write ASIC integrates an Advanced Partial Response Maximum
Likelihood (PRML) processor, a selectable code rate Encoder-Decoder (ENDEC),
and a Servo Processor with data rates up to 270 MHz (259 Mb/s). Programming is
done through a fast 40 MHz serial interface. The controller and data interface through
an 8-bit wide data interface. The Read/Write ASIC is a low power 3.3 Volts, single
supply, with selective power down capabilities.
The Read/Write ASIC comprises 12 main functional modules (described below):
• Pre-Compensator
• Variable Gain Amplifier (VGA)
• Butterworth Filter
• FIR Filter