
63
Table 21 – Reset Phase Table
FINAL SECTOR
TRANSFERRED TO
HOST
Less than EOT
Equal to EOT
Less than EOT
Equal to EOT
Less than EOT
Equal to EOT
Less than EOT
Equal to EOT
MT
HEAD
ID INFORMATION AT RESULT PHASE
H
NC
C + 1
NC
NC
NC
C + 1
NC
NC
NC
NC
LSB
NC
NC
C + 1
LSB
C
NC
R
N
NC
NC
NC
NC
NC
NC
NC
NC
0
0
R + 1
01
R + 1
01
R + 1
01
R + 1
01
1
1
0
1
NC: No Change, the same value as the one at the beginning of command execution.
LSB: Least Significant Bit, the LSB of H is complemented.
Write Data
After the Write Data command has been issued, the FDC loads the head (if it is in the unloaded state),
waits the specified head load time if unloaded (defined in the Specify command), and begins reading
ID fields. When the sector address read from the diskette matches the sector address specified in the
command, the FDC reads the data from the host via the FIFO and writes it to the sector's data field.
After writing data into the current sector, the FDC computes the CRC value and writes it into the CRC
field at the end of the sector transfer. The Sector Number stored in "R" is incremented by one, and the
FDC continues writing to the next data field. The FDC continues this "Multi-Sector Write Operation".
Upon receipt of a terminal count signal or if a FIFO over/under run occurs while a data field is being
written, then the remainder of the data field is filled with zeros. The FDC reads the ID field of each
sector and checks the CRC bytes. If it detects a CRC error in one of the ID fields, it sets the IC code in
Status Register 0 to "01" (abnormal termination), sets the DE bit of Status Register 1 to "1", and
terminates the Write Data command.
The Write Data command operates in much the same manner as the Read Data command. The
following items are the same. Please refer to the Read Data Command for details:
Transfer Capacity
EN (End of Cylinder) bit
ND (No Data) bit
Head Load, Unload Time Interval
ID information when the host terminates the command
Definition of DTL when N = 0 and when N does not = 0
Write Deleted Data
This command is almost the same as the Write Data command except that a Deleted Data Address
Mark is written at the beginning of the Data Field instead of the normal Data Address Mark. This
command is typically used to mark a bad sector containing an error on the floppy disk.