FDC37C78-HT View Datasheet(PDF) - Microchip Technology
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Description
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FDC37C78-HT Datasheet PDF : 82 Pages
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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.
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 25) 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
26 and Table 27 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 25 - Verify Command Result Phase Table
MT
EC
SC/EOT VALUE
TERMINATION RESULT
0
0
SC = DTL
Success Termination
EOT ≤ # Sectors Per Side
Result Phase Valid
0
0
SC = DTL
Unsuccessful Termination
EOT > # Sectors Per Side
Result Phase Invalid
0
1
SC ≤ # Sectors Remaining AND
Successful Termination
EOT ≤ # Sectors Per Side
Result Phase Valid
0
1
SC > # Sectors Remaining OR
Unsuccessful Termination
EOT > # Sectors Per Side
Result Phase Invalid
1
0
SC = DTL
Successful Termination
EOT ≤ # Sectors Per Side
Result Phase Valid
1
0
SC = DTL
Unsuccessful Termination
EOT > # Sectors Per Side
Result Phase Invalid
1
1
SC ≤ # Sectors Remaining AND
Successful Termination
EOT ≤ # Sectors Per Side
Result Phase Valid
1
1
SC > # Sectors Remaining OR
Unsuccessful Termination
EOT > # Sectors Per Side
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.
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