Hitachi HUS154530VLF400 User Manual
Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
215
19.20 READ BUFFER (3C)
Table 180: READ BUFFER (3C)
The READ BUFFER command is used in conjunction with the WRITE BUFFER command as a diagnostic function for test-
ing the memory of the drive and the SCSI bus integrity. This command does not alter the medium.
ing the memory of the drive and the SCSI bus integrity. This command does not alter the medium.
The function of this command and the meaning of fields within the command descriptor block depend on the contents of the
mode field.
mode field.
MODE Description
00000
Read Combined Header and Data
00010
Read Data
00011
Descriptor
01010
Read Data from Echo Buffer
01011
Echo Buffer Descriptor
11010
Enable Expander Communications Protocol and Echo Buffer
All others
Not supported
Byte
Bit
7
6
5
4
3
2
1
0
0
Command Code = 3Ch
1
Reserved = 0
Mode
2
Buffer ID = 0
3-5
(MSB)
Buffer Offset
(LSB)
6-8
(MSB) Allocation Length
(LSB)
9
VU = 0
Reserved = 0
FLAG
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