K6602637
Rev.3
02.27.01
- 47 -
Multiple Mode command, which must be executed prior to the Write Multiple command, sets the block count
of sectors to be transferred. When the Write Multiple command is issued, the Sector count Register contains
the number of sectors (not the number of blocks or the block count) requested. If the number of requested
sector is not evenly divisible by the block count, as many full blocks as possible are transferred, followed by
a final, partial block transfer. The Partial block transfer shall be for n sectors, where n = residue of {Sector
Count/(Sector Count per Block)} Disk errors encountered during Write Multiple commands are posted after
the attempted disk write of the block or partial block transferred. The write operation ends with the sector in
error, regardless of the position in the block. Subsequent blocks are not transferred in the event of an error.
Interrupts are generated when DRQ is set at the beginning of transfer of each block, except first block.
6.3.2.4.5 Format Track [50h]
This command provides a means to mark a sector as bad or to reassign it logically. The logical 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 device sets the DRQ bit and waits for the
host fill the sector buffer. When the sector buffer is filled with 512 bytes of data, the device clears DRQ, sets
BSY, and begins the command execution. One 16-bit word of format table data represents each formatting
method of sectors. The words are contiguous from the start of a sector. If the format table data remains
below 512 bytes after words of the last sector are entered, the buffer should be filled with "0" DD15-8
contains the sector number, and DD7-0 contains one of the descriptor values defined as follows.
Code
Formatting method
00h
Formats a sector as good
This command is used only in the Physical mode, but the Physical mode is not released. If the device is not
in the Physical mode, the device executes a vendor specific operation.
6.3.2.5 Non-Data Commands
Execution of these commands does not involve any data transfer.
1) The host writes any required parameters to the registers.
2) The host writes the command code to the Command Registers.
3) The device sets BSY.
4) When the device has completed processing, it clears BSY and asserts INTRQ.
5) The host reads the Status Register.
6) The device negates INTRQ.
6.3.2.5.1 Initialize Device Parameters [91h]
These parameters allow the host to set the number of sectors per track and the number of heads per
cylinder. Upon receipt of the command, the device sets BSY, saves the specified parameters, clears BSY,
and generates an interrupt. The only two register values that this command uses are the Sector Count
Register that specifies the number of sectors per track, and the Device/Head Register that specifies the
number of heads minus 1. The DRV bit is used for selecting a device. The sector count and head values are
not checked for validity by this command. If they are invalid, no error will be posted until an illegal access is
made by some other command.
