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3.4.4
READ BUFFER (3C)
Bit
Byte
0
1
2
3
4
5
6
7
8
9
This command is used in combination with the WRITE BUFFER command to diagnose the
normalcy of the IDD's data buffer memory and the SCSI bus.
The IDD have a 7680 K byte size data buffer.. In this command, each data byte position in the data
buffer must be specified in 4-byte units using buffer addresses within the range X'000000' to
X'77FFFF'.
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 below can be selected.
"Mode" Bit
(1)
Mode = 0, 0, 0, 0: Header + data, without address specification
When this mode is specified, the data stored in the IDD's data buffer are transferred to the INIT after
the 4-byte header. Zero must be specified in the "Buffer offset" field in the CDB.
C141-E167
7
6
LUN
X'00' (Buffer ID)
Buffer Offset (MSB)
Buffer Offset
Buffer Offset (LSB)
Transfer Byte Length (MSB)
Transfer Byte Length
Transfer Byte Length (LSB)
0
0
3
2
1
0
0
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
1
0
1
0
1
0
1
1
3.4 Maintenance, Diagnostic Commands
5
4
3
X'3C'
0
0
0
0
Transfer Mode
Header + Data, without Address Specification
Header + Data, with Address Specification
Data Only, with Address Specification
Buffer Descriptor
Echo buffer
Echo buffer descriptor
2
1
0
Mode
0
0
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3 - 107
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