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Information technology - AT Attachment Interface for Disk Drives

WORKING DRAFT X3T10 791D Revision 4c

9.8 Format track <-- command code 50h, mandatory command

The implementation of the Format Track command is vendor specific. The
actions may be a physical reformatting of a track, initializing the data field
contents to some value, or doing nothing.

The Sector Count Register contains the number of sectors per track.

The track address is specified in the Cylinder High and Cylinder Low
Registers, and the number of sectors is specified in the Sector Count
Register. When the command is accepted, the drive sets the DRQ bit and waits
for the host to fill the sector buffer. When the sector buffer is full, the
drive clears DRQ, sets BSY and begins command execution.

The contents of the sector buffer shall not be written to the media, and may
be either ignored or interpreted as follows:



One 16-bit word represents each sector, the words being contiguous from the
start of a sector. Any words remaining in the buffer after the representation
of the last sector are filled with zeros. DD15-8 contain the sector number.
If an interleave is specified, the words appear in the same sequence as they
appear on the track. DD7-0 contain a descriptor value defined as follows:

00h - Format sector as good;
20h - Unassign the alternate location for this sector;
40h - Assign this sector to an alternate location;
80h - Format sector as bad.

NOTES

9 - Some users of the ATA drive expect the operating system partition table to
be erased on a Format command. It is recommended that a drive which does not
perform a physical format of the track, write a data pattern of all zeros to the
sectors which have been specified by the Format Track command.

10 - It is recommended that implementors resassign data blocks which show
repeated errors.

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