Maxtor 10K III manual Write Buffer Command-Field Descriptions

SCSI Description

									WRITE BUFFER Command-Field Descriptions
		Four modes are supported by the drive; Combined Header and Data, Data Only, Download
	Mode(KGNF	Microcode and Save, and Write Data from&GUETKRVKQPEcho Buffer. The permissible values for Buffer
		ID, Buffer Offset are as follows:
		Combined Header and Data – In this mode, the data to be transferred is preceded by a 4-
		byte header that contains reserved bytes that must be set to 0. The resulting descriptor and
		data are fetched from the initiator during the command's data-out buffer transfer and, after
		the descriptor has been validated, only the data is written to the controller's memory.
	0000b		must be 0
							must be 0
		bytes of data).							must be set to between 0 and 516 (4 bytes of header and up to 512
		Data Only– In this mode, the data-out buffer transfer contains buffer data. Data is written
		to the drive's buffer starting at the location specified by the Buffer ID and Buffer Offset.
			. When non-zero, the value specifies a specific track line in the controller’s cache.
		If Buffer ID of zero is specified, the buffer referenced is the same as if Buffer ID of one were
	0010b	specified$WHHGT￿.
						. When non-zero, the value can range from 0 to one less than the number of
		sectors/trackTablemultiplied5-219								by 512. This value must be either a zero or a multiple of 512.
								. This value must be a multiple of 512. The maximum value for this
		field is one more than the number of sectors/track times 512. The minimum value is 0.
										In this mode, a microcode image is transferred to the drive,
		and if valid, is saved in the controller's non-volatile memory. This image must be transferred
		with all buffers of the same size (the last buffer of the transfer cannot be of a different size)
		and the buffer size must be a multiple of 512. Most images are multiples of 512 and 1K. In
		that case, it is safe to have 512 byte transfers or 1K transfers. For example, if the image
		size is 369K, then 738 512-byte buffers can be transferred or 369 1K byte buffers can be
		transferred					It is also possible to transfer the image in one large buffer.
	0101b	&QYPNQCF/KETQEQFG￿CPF￿5CXG￿
		The controller does a hard reset on command completion. In Download Microcode and Save
		mode,	1HHUGVthe other￿					Command Descriptor Blocks are supported as follows:
		2CTCOGVGT–￿.KUVUndefined￿.GPIVJ￿and ignored.
		$WHHGT￿					– The offset of the buffer being transferred. For example: for 512 byte trans-
		fers use 0, 512, 1024, 1536,.... For 1K byte transfers use 0, 1024, 2048, 3072...
		+&￿							– Must be the size of the buffer being transferred.
	7									This mode acts the same as mode 0101b but
	(0111b)	is&QYPNQCF/KETQEQFGrestricted to sending￿CPFthe￿5CXGbytes￿YKVJin ￿sequential1HHUGV￿￿order.
		Write Data from Echo Buffer
		1HHUGV
		In this mode, the host transfers data and stores it in an echo buffer. The data will be pre-
	1010b	served in the echo buffer unless there is an intervening command.
					.KUV￿.GPIVJ
			Ignored.
		2CTCOGVGT+&		￿			Ignored.
5-174		Maxtor Atlas 10K I
			1HHUGV
		2CTCOGVGT1HHUGV+&￿￿.KUV￿.GPIVJ