Seagate Ultra 320 User Manual
Page 149
Parallel SCSI Interface Product Manual, Rev. A
135
See notes following Table 61.
Table 61:
Typical variable length CDB
Notes for Tables 57, 58, 59, 60, and 61.
[1] The Operation Code field of the Command Descriptor Block contains the code value indentifying the oper-
ation being requested by the CDB. The Operation Code provides for a possible 256 command operation
codes. Details of the various commands with their operation codes are defined in Section 8.0 of this man-
ual.
[2] Service Action. All typical CDB formats except the typical 6-byte format provide for a Service Action field
containing a coded value identifying a function to be performed under the more general command func-
tion specified in the Operation Code field. While the Service Action field is defined for typical CDB formats,
it is used as described in this clause only in those CDB formats that explicitly contain a Service Action
field. When the specific field Service Action is not defined in a CDB format, the bits identified as the Ser-
vice Action field in a typical CDB may be used for other purposes. More details appear on this in Section
10
(MSB)
TRANSFER LENGTH (If required) [4]
PARAMETER LIST LENGTH (if required) [5]
ALLOCATION LENGTH (if required) [6]
11
12
13
(LSB)
14
Reserved
15
CONTROL [7]
Bit
Byte
7
6
5
4
3
2
1
0
0
OPERATION CODE (7Fh) [1]
1
CONTROL [7]
2
Reserved
3
Reserved
4
Reserved
5
ENCRYPTION IDENTIFICATION [8]
6
Reserved
7
ADDITIONAL CDB LENGTH (n–7) [9]
8
(MSB)
SERVICE ACTION [2]
9
(LSB)
10
:
n
SERVICE ACTION SPECIFIC FIELDS [10]
Bit
Byte
7
6
5
4
3
2
1
0