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Command Specifications
270 C141-C013
4.4.4 READ BUFFER (3C)
Bit
Byte
7 6 5 4 3 2 1 0
0 X'3C'
1 0 0 0 0 Mode
2 X'00' (Buffer ID)
3 Buffer Offset (MSB)
4 Buffer Offset
5 Buffer Offset (LSB)
6 Transfer Byte Length (MSB)
7 Transfer Byte Length
8 Transfer Byte Length (LSB)
9 0 0 0 0 0 0 0 0
This command is used in combination with the WRITE BUFFER command to
diagnose the normalcy of the HDD's data buffer memory and the SAS interface.
In this command, each data byte position in the data buffer must be specified in
4-byte units using buffer addresses.
The functions of this command and the contents of the data transferred to the
INIT are specified by the "Mode" field in the CDB and one of the transfer modes
shown in Table 4.62 can be selected.
Table 4.62 READ BUFFER transfer mode
"Mode" Bit 3 2 1 0 Transfer Mode
0 0 0 0 Header + Data, without Address Specification
0 0 0 1 Header + Data, with Address Specification
0 0 1 0 Data Only, with Address Specification
0 0 1 1 Buffer Descriptor
1 0 1 0 Echo buffer
1 0 1 1 Echo buffer descriptor