Sony SDX-1100V Write Buffer 3Bh, Reserved Mode Buffer ID, Write Buffer Mode Field Description

6.Command Specification WRITE BUFFER

6.31.WRITE BUFFER 3Bh

Bit	7	6		5	4		3	2		1	0
Byte
0					Operation		Code (3Bh)
1			Reserved						Mode
2						Buffer ID
3	(MSB)				Buffer Offset
5											(LSB)
6	(MSB)				Parameter List Length
8											(LSB)
9						Control

The WRITE BUFFER command is used in conjunction with the READ BUFFER command as a diagnostic function.

The WRITE BUFFER command except Echo buffer is executed only when there is no tape inserted in the drive or when the tape is positioned at BOT. Otherwise, the drive will return a CHECK CONDITION status with an ILLEGAL Request Sense Key.

Note: The drive will write any buffered data to tape prior to executing the WRITE BUFFER command except Echo buffer. 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 with an ILLEGAL REQUEST sense key.

Table 6-104: WRITE BUFFER Mode Field

Mode	Description
0000b	Combined header and data
0010b	Data
1010b	Echo Buffer

Combined Header and Data Mode (0000b) - 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 will 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 (0010b)- In this mode, the DATA-OUT phase contains only buffer test data.

Echo Buffer (1010b) - In this mode the data will be stored in an echo buffer. Data will be sent aligned on four-byte boundaries. The BUFFER ID and BUFFER OFFSET fields are ignored in this mode. The drive assigns echo buffer on a per initiator basis. The initiator will attempt to ensure that the parameter list length does not exceed the capacity of the echo buffer. The BUFFER CAPACITY field in the READ BUFFER echo buffer descriptor determines the capacity of the echo buffer. If the PARAMETER LIST LENGTH field exceeds the buffer capacity, the drive will return a CHECK CONDITION status with a Request Sense Key of ILLEGAL REQUEST.

Table 6-105: WRITE BUFFER Mode Field

Buffer ID: The supported values are:

Buffer ID	Description		Offset
0	Write Group Buffer	0	- 0x01000000
80	Write Group Buffer	0	- 0x01000000
81	Write Group Buffer	0x01000000 - 0x02000000
82	Write Group Buffer	0x02000000 - 0x03000000
83	Write Group Buffer	0x03000000 - 0x03700000

If an unsupported Buffer ID code is requested, the drive returns a CHECK CONDITION status with an ILLEGAL REQUEST sense key.

6-106 SONY AIT-5 drive SDX-1100V series Ver.1.0