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	TD_RAWWRITE/ETD_RAWWRITE -- write raw data to the disk.

	This command writes a track of raw data from the provided buffer to
	the specified track on disk. The data is copied straight to the disk
	with no processing done on it. It will appear exactly on the disk as
	it is in the memory buffer, hopefully in a legal MFM format.

	This interface is intended for sophisticated programmers only.
	Amiga reserves the right to make enhancements to the disk
	format in the future. We will provide compatibility via the
	CMD_WRITE and ETD_WRITE commands, anyone using TD_RAWWRITE is
	bypassing this upwards compatibility, and may thus stop working.

	io_Device	preset by the call to OpenDevice()
	io_Unit		preset by the call to OpenDevice()
	io_Command      TD_RAWWRITE or ETD_RAWWRITE.
	io_Flags	if the IOTDB_INDEXSYNC bit is set then the driver
			will make a best effort attempt to start writing
			from the index mark.  Note that there will be at
			least some delay, and perhaps a great deal of delay
			(for example if interrupts have been disabled).
	io_Length	Length of buffer in bytes, with a maximum of 32768
	io_Data		Pointer to CHIP memory buffer where raw track data is
			to be taken.
	io_Offset	The number of the track to write to.
	iotd_Count	(ETD_RAWWRITE only) maximum allowable change counter

	io_Error - 0 for success, or an error code as defined in

	The track buffer provided MUST be in CHIP memory

	There is a delay between the index pulse and the start of bits
	going out to the driver (e.g. write gate enabled). This delay
	is in the range of 135-200 microseconds. This delay breaks
	down as follows: 55 microsecs is software interrupt overhead
	(this is the time from interrupt to the write of the DSKLEN
	register). 66 microsecs is one horizontal line delay (remember
	that disk IO is synchronized with agnus' display fetches).
	The last variable (0-65 microsecs) is an additional scan line
	since DSKLEN is poked anywhere in the horizontal line. This leaves
	15 microsecs unaccounted for...  Sigh.

	In short, You will almost never get bits within the first 135
	microseconds of the index pulse, and may not get it until 200
	microseconds. At 4 microsecs/bit, this works out to be between
	4 and 7 bytes of user data of delay.

	This command does not work reliably under versions of Kickstart
	earlier than V36, especially on systems with 1 floppy drive.


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