Maxtor 10K V manual 213WRITE Buffer Command-Field Descriptions

	Table 5-213WRITE BUFFER Command-Field Descriptions
Field	Description
Mode	Five modes are supported by the drive; Combined Header and Data, Data Only, Download Microcode and
	Save, and Write Data from Echo Buffer. The permissible values for Buffer ID, Buffer Offset are as fol-
	lows:
	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	Buffer ID must be 0
	Buffer Offset must be 0
	Parameter List Length must be set to between 0 and 516 (4 bytes of header and up to 512 bytes of data).
	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.
	Buffer ID. When non-zero, the value specifies a specific track line in the controller’s cache. If Buffer ID
0010b	of zero is specified, the buffer referenced is the same as if Buffer ID of one were specified.
	Buffer Offset. When non-zero, the value can range from 0 to one less than the number of sectors/track
	multiplied by 512. This value must be either a zero or a multiple of 512.
	Parameter List Length. 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.
	Download Microcode and Save. 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	The controller does a hard reset on command completion. In Download Microcode and Save mode, the
	other Command Descriptor Blocks are supported as follows:
	Buffer ID – Undefined and ignored.
	Buffer Offset – The offset of the buffer being transferred. For example: for 512 byte transfers use 0, 512,
	1024, 1536,.... For 1K byte transfers use 0, 1024, 2048, 3072...

Parameter List Length – Must be the size of the buffer being transferred.

7Download Microcode and Save with Offset. This mode acts the same as mode 0101b but is restricted to

(0111b) sending the bytes in sequential order.

Write Data from Echo Buffer

	In this mode, the host transfers data and stores it in an echo buffer. The data will be preserved in the echo
1010b	buffer unless there is an intervening command.
	Buffer ID Ignored.
	Buffer Offset Ignored.

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