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6.12DIAGNOSTICS
The drive has extensive diagnostic capabilities, including those described below:
6.12.1Power On Self Test (POST)
The disk drive performs a
If the drive passes the
The drive diagnostics test the following:
•RAM and ROM chips
•Buffer memory
•Gate array chips
•Read/write encoding circuits
•Basic servo functions
After a SELECTION TIME following
6.12.2Periodic Self-Adjustments
During normal drive operation, certain periodic functions occur automatically so the drive can verify and maintain the integrity of its operations and optimize performance. The operations performed include those listed below.
•Move/Switch idle heads
•Adaptive seek profile calibration
•ROM checksum
Such periodic functions can make the drive appear to be active when no commands are outstanding, because the drive appears to be seeking. Periodic calibrations occur only after the drive has been inactive for 30 seconds.
Note: If a media access command is received during a calibration, the drive aborts the calibration process and acts on the command.
If desired, calibrations can be suspended to reduce drive overhead by setting the Manual Calibration bit in the (Vendor) Special Function Control page. If this is done, manual calibrations can still be initiated by performing a REZERO UNIT command.