56
Verify
The Verify command is used to verify the data
stored on a disk.
This command acts exactly
like a Read Data command except that no data
is transferred to the host. Data is read from the
disk and CRC is computed and checked against
the previously-stored value.
Because data is not transferred to the host, TC
(pin
89) cannot be used to terminate this
command.
By setting the EC bit to "1", an
implicit TC will be issued to the FDC. This
implicit TC will occur when the SC value has
decremented
to 0 (an SC value of 0 will
verify 256 sectors). This command can also be
terminated by setting the EC bit to "0" and the
EOT value equal to the final sector to be
checked. If EC is set to "0", DTL/SC should be
programmed to 0FFH.
Refer to Table 23 and
Table 24 for information concerning the values
of MT and EC versus SC and EOT value.
Definitions:
# Sectors Per Side = Number of formatted
sectors per each side of the disk.
# Sectors Remaining = Number of formatted
sectors left which can be read, including side 1
of the disk if MT is set to "1".
Table 24 - Verify Command Result Phase Table
MT
EC
SC/EOT VALUE
TERMINATION RESULT
0
SC = DTL
EOT
≤ # Sectors Per Side
Success Termination
Result Phase Valid
0
SC = DTL
EOT > # Sectors Per Side
Unsuccessful Termination
Result Phase Invalid
0
1
SC
≤ # Sectors Remaining AND
EOT
≤ # Sectors Per Side
Successful Termination
Result Phase Valid
0
1
SC > # Sectors Remaining OR
EOT > # Sectors Per Side
Unsuccessful Termination
Result Phase Invalid
1
0
SC = DTL
EOT
≤ # Sectors Per Side
Successful Termination
Result Phase Valid
1
0
SC = DTL
EOT > # Sectors Per Side
Unsuccessful Termination
Result Phase Invalid
1
SC
≤ # Sectors Remaining AND
EOT
≤ # Sectors Per Side
Successful Termination
Result Phase Valid
1
SC > # Sectors Remaining OR
EOT > # Sectors Per Side
Unsuccessful Termination
Result Phase Invalid
Note: If MT is set to "1" and the SC value is greater than the number of remaining formatted sectors
on Side 0, verifying will continue on Side 1 of the disk.