Fujitsu MHY2250BH Product/Maintenance Manual page 103

(8) Status field
The contents of this field indicate the status of the device. The contents of this
field are updated at the completion of each command. When the BSY bit is 1,
other bits of this field, are invalid.
Bit 7
BSY
- Bit 7: Busy (BSY) bit
This bit is set whenever the Command filed of the shadow block registers for the host
system is accessed.
Then this bit is cleared when the command is completed. However, even if a command is being
executed, this bit is cleared during the PIO data transfer request.
When BSY bit is 1, the host system should not write the shadow block registers. This bit
is set by the device under following conditions:
(a) After COMRESET or SRST is set in the Device Control Field, the BSY bit is set,
then the BSY bit is cleared, when the COMRESET process is completed.
The BSY bit is set for no longer than 15 seconds after the IDD accepts reset.
- Bit 6: Device Ready (DRDY) bit
This bit indicates that the device is capable to respond to a command.
The IDD checks its status when it receives a command. If an error is detected (not ready
state), the IDD clears this bit to 0. This is cleared to 0 at power-on and it is cleared until the
rotational speed of the spindle motor reaches the steady speed.
- Bit 5: Device Write Fault (DF) bit
This bit indicates that a device fault (write fault) condition has been detected.
If a write fault is detected during command execution, this bit is latched and retained until
the device accepts the next command or reset.
- Bit 4: Device Seek Complete (DSC) bit
This bit indicates that the device heads are positioned over a track.
In the IDD, this bit is always set to 1 after the spin-up control is completed.
- Bit 3: Data Request (DRQ) bit
This bit indicates that the device is ready to transfer PIO data of word unit or byte unit
between the host system and the device.
- Bit 2: Always 0
- Bit 1:
Always 0
- Bit 0: Error (ERR) bit
This bit indicates that an error was detected while the previous command was being
executed. The Error field indicates the additional information of the cause for the error.
C141-E262
Bit 6 Bit 5 Bit 4
DRDY DF DSC
5.2 Logical Interface
Bit 3 Bit 2 Bit 1
DRQ 0 0
Bit 0
ERR
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