6.Command Specification
WRITE BUFFER
SONY AIT-3Ex drive SDX-800V series Ver.1.0
6-108
6.31.
WRITE BUFFER 3Bh
Bit
Byte
7 6 5 4 3 2 1 0
0
Operation Code (3Bh)
1
Obsolete Reserved
Mode
2
Buffer ID
3
(MSB)
Buffer Offset
5
(LSB)
6
(MSB)
Parameter List Length
8
(LSB)
9
Control
WRITE BUFFER is used in conjunction with the READ BUFFER command as a diagnostic function.
WRITE BUFFER command is valid only when there is no tape inserted in the drive, or when the tape is positioned at
BOT. An attempt to issue the Write Buffer command when the tape is not at BOT will result in a CHECK CONDITION
status with a Request Sense Key of ILLEGAL REQUEST.
Note:
The drive will write any buffered data to tape prior to executing this command. Any data that is then transferred
by the WRITE BUFFER is not written to tape.
Mode:
The drive supports the following values within the Mode field. If any other value is set, the drive will terminate
the command with a CHECK CONDITION status and an ILLEGAL REQUEST sense key set.
Any Write Data, file-marks or set-marks in buffer will be transfer to tape before this command is executed.
Table 6-103: WRITE BUFFER Mode Field
Mode
Description
0000b
0010b
1010b
Write combined header and data
Write data
Echo Buffer
Combined Header and Data Mode
- in this mode, the test data to be transferred must be preceded by a four-byte
header. The four-byte header consists of all reserved bytes. The Parameters List Length specifies the maximum
number of bytes that will be transferred during the DATA OUT phase. This number includes four bytes of header, so
the data length to be stored in the buffer is transfer length minus four. The initiator should ensure that the transfer
length is not greater than four plus the available length that is returned in the header of the READ BUFFER
command.
Data Mode
- in this mode, the DATA OUT phase contains only buffer test data.
Table 6-104: WRITE BUFFER Mode Field
Buffer ID:
The supported values are:
Buffer ID
Description
Offset
0
80
81
82
83
Write Group Buffer
Write Group Buffer
Write Group Buffer
Write Group Buffer
Write Group Buffer
0 - 0x01000000
0 - 0x01000000
0x01000000 - 0x02000000
0x02000000 - 0x03000000
0x03000000 - 0x04000000
If an unsupported Buffer ID code is requested, the drive returns a CHECK CONDITION status with an ILLEGAL
REQUEST sense key.
Buffer Offset:
The buffer offset field contains the byte offset within the specified buffer from which data shall be
transferred to. The initiator should conform to the offset boundary requirements returned in the WRITE BUFFER
descriptor. If the target is unable to accept the specified buffer offset, it shall return CHECK CONDITION status, shall
set the Sense Key to ILLEGAL REQUEST, and set the Additional Sense Code to ILLEGAL FIELD IN CDB.
