Hitachi ULTRASTAR 15K450 HUS154530VLF400 - Manual (Page 231)

Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
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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.
The function of this command and the meaning of fields within the command descriptor block depend on the contents of the
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 LINK