Hitachi HTS542525K9SA00 Specifications page 87

Bit Definitions
BSY Busy. Bit BSY=1 whenever the device is accessing the registers. The host should not read or write
any registers when BSY=1. If the host reads any register when BSY=1, the contents of the Status
Register will be returned.
DRDY Device Ready. RDY=1 indicates that the device is capable of responding to a command. RDY
(RDY) will be set to zero during power on until the device is ready to accept a command. If the device
detects an error while processing a command, RDY is set to zero until the Status Register is read
by the host, at which time RDY is set back to one.
DF Device Fault. This product does not support DF bit. DF is always zero.
DSC Device Seek Complete. If DSC=1, it indicates that a Seek has completed and the device head is
settled over a track. Bit DSC is set to 0 by the device just before a Seek begins. 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. When the device enters into or is in Standby
mode or Sleep mode, this bit is set by the device in spite of the drive not spinning up.
DRQ Data Request. Bit DRQ=1 indicates that the device is ready to transfer a word or byte of data
between the host and the device. The host should not write the Command register when DRQ=1.
CORR Corrected Data. Always 0
(COR)
IDX Index. IDX=1 once per revolution. Because IDX=1 only for a very short time during each revolu-
tion, the host may not see it set to 1 even if the host is continuously reading the Status Register.
Therefore the host should not attempt to use IDX for timing purposes.
ERR Error. ERR=1 indicates that an error occurred during execution of the previous command. The
Error Register should be read to determine the error type. The device sets bit ERR=0 when the
next command is received from the host.
Deskstar 7K160 Hard Disk Drive Specification
73