AT INTERFACE and ATA COMMANDS
WA31273A / WA32543A / WA33203A / WA32163A / WA31083A / WA32162A 6-15
•
HS3 through HS0
contain the binary coded address of the head to be selected in
CHS
mode (e.g. if HS3 through HS0 are 0011b, respectively, head 3 will be selected. HS3 is
the most significant bit). In
LBA
mode this register contains bits 24-27 of the LBA. At
command completion, this register is updated to reflect the currently selected disk
address.
•
LBA
is the binary coded address mode select. When L=0, disk addressing is by
CHS
mode. When L=1, disk addressing is by
LBA
mode. This bit was set to zero when
ATA drive didn’t supported LBA mode
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 being 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 Register 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
µ
sec 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 clear
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
