Read Data Buffer Command; Read Combined Descriptor Header And Data Mode - Seagate ST11200 Product Manual

106
_____________________________________________________________________________________
5.1.2.4 Read Data Buffer command (3Ch)
Bit 7
Byte(s)
0 0
1 Logical Unit No [1]
0
2
3 (MSB)
4
5
6 (MSB)
7
8
9 0
The Read Buffer command is used in conjunction with the Write Buffer command as a diagnostic function for
testing disc drive memory and the SCSI bus integrity. This command shall not alter the medium. Command
format is shown in Table 5.1.2-3.
Notes.
[1] LUN must be zero.
[2] Read Buffer Mode Field. The interpretation of data bits 0-2 is given in the following table and in para-
graphs following the table.
DB2 DB1
0 0
0 1
0 1
5.1.2.4.1 Read Combined Descriptor Header and Data mode (000b) (see Table 5.1.2-4)
In this mode, a four byte Read Buffer header followed by the data bytes are returned to the initiator during the
Data In phase. The buffer ID and the buffer offset fields are not used by drives supported by this manual, and
must be zero.
Bit 7
Byte(s)
0 0
1 (MSB)
2
3
Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
Table 5.1.2-3. Read Buffer
6 5
0 1
RSVD
0 0
Buffer ID [5]
Buffer Offset
Allocation Length [2]
0 0
DB0
0 Read combined descriptor header and data (section 5.1.2.4.1)
0 Read data (section 5.1.2.4.2)
1 Read descriptor (section 5.1.2.4.3)
Table 5.1.2-4. Read Buffer Header (Mode 000b)
6 5
0 0
Buffer Capacity
4 3
1 1
Mode [2]
0 0
0 0
4 3
0 0
2 1
1 0
0 0
[6]
[6]
[6](LSB)
(LSB)
0 Flag [4] Link
2 1
0 0
(LSB)
0
0
0
0
0