DISK DRIVE OPERATION
5.2.2.4The Disk ECC Control Block
The SID2001 supports a programmable 10-way interleaved Reed-Solomon ECC. The code is capable of correcting up to ten 3 bytes, one 30 bytes bursts in hardware up to or 60 bytes correction with erasure pointer. The Disk ECC block also supports 32 bits of ESN (Embedded Sector Number) to the ECC generator to allow for greater data integrity in a headerless environment. Error detection and correction is handled in the Disk Control block. Automatic on-the-fly hardware correction will take place for up to three symbols in error per interleave. Correction is guaranteed to complete before the ECC Field of the sector following the sector where the error occurred utilizing standard ATA size sectors. Optional burst limiting can be used to decrease the probability on misdetection and mis-correction. An added feature of the SID2001 ECC block is the ability to log corrected ECC errors.
5.2.2.5Frequency Synthesizer
The frequency synthesizer is a clock frequency generation circuit used to generate a DSP clock, AT disk controller and servo clock from the External Reference clock input.
5.2.2.6Power Management
Power management features are incorporated into each block of the SID2001. 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.
5.2.3 Read/Write IC
The Read/Write IC, shown in Figure 5-3 provides read/write-processing functions for the drive. The Read/Write IC receives the RD GATE and WR GATE signals, write data, and servo AGC and gates from the Interface Controller. The Read/Write IC sends decoded read data and the read reference clock. It receives write data from the Interface Controller.
The 88C5200 is a sampled-data digital PRML channel designed to work with a disk controller and a read/write preamplifier to provide the signal processing elements required to build a state
of the art high density, high speed disk drive. The 88C5200 implements a noise predictive, PRML Viterbi read channel (supporting) zone-bit recording ,
