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WRITE BUFFER 3Bh
Commands
183
WRITE BUFFER 3Bh
Write Buffer is used to transfer data into memory on the drive for the purposes of diagnostics, tests
or firmware upgrade. The data is placed into one of the drive buffers depending on the Mode and
Buffer ID fields of the command.
CAUTION: Do not attempt to use the buffer modifying functions of this command unless you
really know what you are doing. The buffer modifying functions are intended as a diagnostic
aid to be used in conjunction with the
Read Buffer command. It is not possible to modify data in
the buffer so that it subsequently written to media because all host data is flushed before
executing the command.
The firmware download functions are intended for use by manufacturing and by customers using
upgrade utilities supplied by HP.
Pre-execution checks:
Command descriptor block:
CDB fields:
Illegal Field Reservation Deferred Error Unit Attention
7 6 5 4 3 2 1 0
0 Operation Code (3Bh)
1 Reserved (0) Mode
2 Buffer ID
3 (MSB)
Buffer Offset
5 (LSB)
6 (MSB)
Parameter List Length
8 (LSB)
9 Control
Mode This field can be set to one of the following values:
00h The drive transfers a 4-byte header from the host (which should be set to zeros),
followed by (allocation length
− 4) bytes of data. The data is written into the
buffer identified by the Buffer ID, starting from offset zero in the buffer.
The Buffer ID and Buffer Offset must both be zero. Allocation Length must not
exceed (buffer size + 4).
02h The drive transfers allocation length bytes of data from the host, bytes of data
which is placed in the buffer indicated by Buffer ID, starting from Buffer Offset
from the start of the buffer. No header is sent.
The Buffer Offset and Allocation Length must be kept within the buffer size, and
the Buffer ID must to set to one of the valid values.