Western Digital T13/2132-D ATA string byte swapping Word Byte Character in string, Byte Value

June 23, 2010 T13/2132-D Revision 3

Each pair of bytes in an ATA string is swapped as shown in table 4.

Table 4 — ATA string byte swapping

Word Byte Character in string

00 Second character

1First character

12 Fourth character

3Third character

...	...	...
n	2n	Last character
	2n+1	Second-to-last character

If the field contains the string “abcdefg ”, including one padding space character at the end, then the word and byte representations for the field are shown in table 5.

	Table 5 — ATA firmware revision example
Word	Value	Byte	Value
23	6162h (i.e., “ba”)	36	62h	(i.e., ‘b’)
		37	61h	(i.e., ‘a’)
24	6364h (i.e., “dc”)	38	64h	(i.e., ‘d’)
		39	63h	(i.e., ‘c’)
25	6566h (i.e., “fe”)	40	66h	(i.e., ‘f’)
		41	65h	(i.e., ‘e’)
26	6720h (i.e., “ g”)	42	20h	(i.e., ‘ ’, the space character)
		43	67h	(i.e., ‘g’)

Working Draft Enhanced Disk Drive - 4 (EDD-4) 11