AT INTERFACE and ATA COMMANDS
WA31273A / WA32543A / WA33203A / WA32163A / WA31083A / WA32162A 6-21
Some parameters are defines as 32 bit value (e.g., words 57 and 58). Such fields are
transferred using two word transfers. The device shall first transfer the least significant
bits, bits 15 through 0 of the value, on bits DD15 through DD0 respectively. After the
least significant bits have been transferred, the most significant bits, bits 31 through 16
of the value, shall be transferred on DD15 through DD0 respectively.
Some parameters are defined as a string of ASCII characters. For the string “Copyright”,
the character ‘C’ is the first byte, ‘0’ is the 2nd byte, etc. When such fields are transferred,
the order of transmission is:
the 1st character (‘C’) is on bits DD15 through DD8 of the first word
the 2nd character (‘o’) is on bits DD7 through DD0 of the first word
the 3rd character (‘p’) is on bits DD15 through DD8 of the second word
the 4th character (‘y’) is on bits DD7 through DD0 of the second word
etc.
6-4-4-1 Word 1 : Number of cylinders
The number of user-addressable logical cylinders in the default translation mode.
6-4-4-2 Word 3 : Number of logical heads
The number of user-addressable logical heads in the default translation mode.
6-4-4-3 Word 6 : Number of logical sectors per logical track
The number of user-addressable sectors per logical track in the default translation mode.
6-4-4-4 Word 10-19 : Serial Number
If word 10 of this field is 0000h, then the serial number is not specified and the definition
of the remaining words of this field are vendor specific.
If word 10 of this field is net equal to 0000h, then this field contains the serial number of
the device. The contents of this field is an ASCII character string of twenty bytes. The
device shall pad the character string with spaces (20h), if necessary, to ensure that the
string is the proper length.
6-4-4-5 Word 22 : Number of vendor specific bytes on Read/Write Long
commands
The contents of this field specifies the number of vendor specific bytes that are
appropriate for the device. If the contents of this field are set to a value other than 4, the
SET FEATURES command should be used to switch the length of READ LONG and
WRITE LONG commands from 512 plus 4 to 512 plus the value specified in this word.
