37C957FR datasheet(76/328 Pages) SMSC

76 / 328 page

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.

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 30 and Table

31 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".

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