Product manual

DISK DRIVE OPERATION
Spinpoint M9TU-USB 3.0 Product Manual REV 1.0
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5.2.2.2 The Buffer Control Block
The Buffer Control block manages the flow of data into and out of the buffer. Significant automation
allows buffer activity to take place automatically during read/write operations between the host and the disk.
This automation works together with automation within the Host Interface Control and Disk Control blocks to
provide more bandwidth for the local microprocessor to perform non-data flow functions.
The buffer control circuitry keeps track of buffer full and empty conditions and automatically works with the
Disk Control block to stop transfers to or from the disk when necessary. In addition, transfers to or from the
host are automatically stopped or started based on buffer full or empty status.
Additional functionality is provided in the Buffer Control block through the following features:
• Increased automation to support minimal latency read operations with minimal latency.
• Capability to support the execution of multiple consecutive Auto-Write commands without loss of data
due to overwriting of data.
• Auto write pointer.
• A disk sector counter that can monitor the transfers between the disk and buffer.
• Read/Write cache support.
5.2.2.3 The Disk Control Block
The Disk Control block manages the flow of data between the disk and the buffer. Many flexible features and
elements of automation have been incorporated to complement the automation contributed by the Host and Buffer
blocks.
The Disk Control block consists of the programmable sequencer (Disk Sequencer), CDR/data split logic, disk
FIFO, fault tolerant sync detect logic, and other support logic.
The programmable sequencer contains a 32-by-4 byte programmable SRAM and associated control logic, which
is programmed by the user to automatically control all single track format, read, and write operations. From within
the sequencer micro program, the Disk Control block can automatically deal with such real time functions as
defect skipping, servo burst data splitting, branching on critical buffer status and data compare operations. Once
the Disk Sequencer is started, it executes each word in logical order. At the completion of the current instruction
word, it either continues to the next instruction, continues to execute some other instruction based upon an internal
or external condition having been met, or it stops.
During instruction execution or while stopped, registers can be accessed by the DSP to obtain status
information reflecting the Disk Sequencer operations taking place.
5.2.2.4 The Disk ECC Control Block
The Disk Control Block supports a programmable LDPC code. Error detection and correction is handled in
the Disk Control block. Automatic on-the-fly hardware correction will take place. Correction is guaranteed to
complete before the parity bits of the sector following the sector where the error occurred utilizing standard
ATA size sectors.
5.2.2.5 Power Management
Power management features are incorporated into each block of the Spinpoint M9TU-USB 3.0. This allows
the designer to tailor the amount of power management to the specified design. Other power management
features include:
• Independent power management control for each block.
• DSP block powered down and up when needed.
• Disk Sequencer and associated disk logic powered up when the Disk Sequencer is started.
• Weak pull-up structure on input pins to prevent undesirable power consumption due to floating CMOS
inputs.