Maxtor ATLAS 10K III - Manual (Page 173)

SCSI Description
Maxtor Atlas 10K III 5-109
Table 5-130 READ BUFFER Command-Field Descriptions
(KGNF &GUETKRVKQP
Mode
Four modes are supported by the drive; Combined Header and Data, Data Only, Descrip-
tor Only, and Read Data from Echo Buffer. The permissible values for Buffer ID, Buffer
Offset, are as follows:
0000b
Combined Header and Data – In this mode, data to be transferred is preceded by a 4-
byte header that contains the buffer capacity. The resulting descriptor and data are trans-
ferred to the initiator during the command’s data-in buffer transfer.
$WHHGT +& must be 0
$WHHGT 1HHUGV must be 0
Allocation length must be set to between 0 and 516 (4 bytes of header and up to 512
bytes of data).
0010b
Data Only– In this mode, the data-in buffer transfer contains data from the controller’s
memory.
$WHHGT +&. 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 a Buffer ID
of one were specified.
$WHHGT 1HHUGV. When non-zero, the value of Buffer Offset 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.
#NNQECVKQP .GPIVJ Must be between zero and the maximum number of sectors/track mul-
tiplied by 512.
0011b
Descriptor Only
When requesting a descriptor (a description of the buffer referenced in the Buffer IDfield),
the resulting data is the offset boundary requirements and the length of each buffer.
$WHHGT +& When non-zero, the value specifies a specific track line within the controller’s
cache. If Buffer ID of 0 is specified, the buffer referenced is the same as if a Buffer ID of
1 were specified.
$WHHGT 1HHUGV Must be zero
#NNQECVKQP .GPIVJ Must be between 4 (header) and the maximum number of sectors/
track multiplied by 512 + header size.
1010b Read Data from Echo Buffer
In this mode, the drive transfers data to the host from the echo buffer. The echo buffer
will transfer the same data as when the WRITE BUFFER command with the mode field
set to echo buffer was issued.
$WHHGT +& Ignored.
$WHHGT 1HHUGV Ignored.