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Chapter 4 SCSI Commands
READ BUFFER Command (3Ch)
DLT-S4 Interface Reference Guide
269
Echo Buffer Descriptor
Mode (0Bh)
4
In this mode, the drive returns a maximum of 4 bytes of
READ BUFFER
descriptor information. The drive returns the descriptor information for
the Echo Buffer. The Buffer Offset field is reserved in this mode. The
allocation length should be set to 4 or greater. The drive transfers the
lesser of the allocation length or 4 bytes of the
READ BUFFER
descriptor.
Figure 132 ECHO BUFFER
Descriptor — Data Format
Figure 133 ECHO BUFFER
Descriptor
—
Field
Descriptions
Bit
7
6
5
4
3
2
1
0
Byte
0
Reserved
EBOS
1
Reserved
2
Reserved
Buffer Capacity
3
Buffer Capacity
Field
Description
EBOS
Echo Buffer Overwritten Supported. Set to 1 to
indicate that the drive returns the Additional Sense
Code
ECHO BUFFER OVERWRITTEN
if the data being
read from the Echo Buffer is not the data previously
written by the same initiator.
Buffer
Capacity
Always returns 252, indicating the size of the Echo
Buffer.