HP C737990900 - Manual (Page 111)

Commands 111
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READ BUFFER 3Ch
R EAD BUFFER reads data from the memory on the drive and sends it to the
initiator. The value of the Mode field determines whether only the 4-byte
descriptor is returned, only the data is returned, or whether both are returned.
Pre-Execution Checks:
If any of the following rules are broken then CHECK CONDITION status is
reported. Sense data will be as described in Illegal Field Checks.
Command Descriptor Block:
CDB Fields:
Illegal Field Reservation Deferred Error Unit Attention
7 6 5 4 3 2 1 0
0 Operation Code (3Ch)
1 Reserved(0) Mode
2 Buffer ID
3 (MSB)
Buffer Offset
5 (LSB)
6 (MSB)
Allocation Length
8 (LSB)
9 Control
Mode 00000b A 4-byte descriptor is returned, followed by (Allocation Length - 4) bytes of data.The
data is read from the buffer identified by the Buffer ID, starting from offset zero in the
buffer.
The Buffer ID and Buffer Offset must both be 00h.
00010b The drive returns Allocation Length bytes of data which is read from the buffer identified
by the Buffer ID, starting from Buffer Offset bytes from the start of the buffer.
There are no restrictions on the value of Buffer ID and Buffer Offset, except that the Buffer
Offset must be kept within the buffer size.