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DISK DRIVE OPERATION
SpinPoint V40 Product Manual
52
6.3.4.10 Status Register (1F7h)
This register contains the drive status. The contents of this register are updated at the completion of each
command. When BSY is cleared, the other bits in this register are valid within 400 nsec. If BSY=1, no other
bits in this register are valid. If the host reads this register when an interrupt is pending, it is considered to be
the interrupt acknowledge. Any pending interrupt is cleared whenever this register is read.
NOTE: If Drive 1 is not detected as present, Drive 0 clears the Drive 1 Status register to 00h (indicating that
the drive is Not Ready).
7 6 5 4 3 2 1 0
BSY DRDY DWF DSC DRQ CORR IDX ERR
• BSY (Busy) is set whenever the drive has access to the Command Block registers. The host should not
access the Command Block registers when BSY=1. When BSY=1, a read of any Command Block
register returns the contents of the Status register. This bit is set by the drive under the following
circumstances:
a) Within 400 nsec after the negation of RESET- or after SRST has been set in the Device Control
register.
b) Within 400 nsec of a host write of the Command register with a Read, Read Long, Read Buffer,
Seek, Recalibrate, Initialize Drive Parameters, Read Verify, Identify Drive, or Execute Drive
Diagnostic command.
c) Within 5 µsec following transfer of 512 bytes of data during execution of a Write, Format Track, or
Write Buffer command, or 512 bytes of data and the appropriate number of ECC bytes during the
execution of a Write Long command.
• DRDY (Drive Ready) indicates that the drive is capable of responding to a command. When there is an
error, this bit does not change until the host reads the Status register. Then the bit again indicates the
current readiness of the drive. This bit clears at power-on and remains clear until the drive is ready to
accept a command.
• DWF (Drive Write Fault) indicates the current write fault status. When an error occurs, this bit is not
changed until the Status register is read by the host, at which time the bit again indicates the current write
fault status.
• DSC (Drive Seek Complete) indicates that the drive heads have settled over a track. When an error
occurs, this bit is not changed until the Status register is read by the host, at which time the bit again
indicates the current Seek Complete status.
• DRQ (Data Request) indicates that the drive is ready to transfer a word or byte of data between the host
and the drive.
• CORR (Corrected Data) indicates that a correctable data error was encountered and the data has been
corrected. This condition does not terminate a data transfer.
• IDX (Index) is set once per disk revolution.
• ERR (Error) indicates that an error occurred during execution of the previous command. The bits in the
Error register have additional information regarding the cause of the error.