Fujitsu M2488 manual Write command 0Ah, Write CDB Description, Write Field Description

TAPE UNIT SCSI COMMANDS M2488 PRODUCT GUIDE

4-3.31 WRITE command 0Ah

The WRITE command transfers one or more blocks from the initiator to the current position on the logical unit.

4-3.31.1 WRITE CDB Description

WRITE is a six-byte command. The bytes are as shown below and described in Table 4-128. Common fields are described in paragraph 4-3.1 on page 4-4.

								BITS
BYTES	7		6	5		4			3		2	1		0
0	0		0	0		0			1		0	1		0
1
			LUN							Reserved					Fixed
2
		MSB
3
							Transfer Length
4															LSB
5
					Reserved								Flag		Link

Note: Changeable fields in the CDB are shaded.

Table 4-128. WRITE Field Description

BYTE	BIT	VALUE	DESCRIPTION
0	0-7	0Ah	Operation code.
1	0		The Fixed bit specifies both the meaning of the transfer length field and
			whether fixed-length or variable-length blocks are to be transferred.
			If the Fixed bit is zero, a single block is transferred with the bytes trans-
			ferred being the lesser of the actual block length or the requested transfer
			length.
			If the Fixed bit is one, the transfer length specifies the number of blocks to
			be transferred to the initiator.
2-4			The Transfer Length indicates the number of bytes or blocks to transfer.
			The block length used is the current block length specified in the mode
			parameters block descriptor (refer to the Mode Select Block Descriptor in
			Table 4-47 on page 4- 53.)
			When the transfer length is zero, no data is transferred and the current
			position on the logical unit is not changed. This condition is not considered
			an error.

4-3.31.2 WRITE CHECK CONDITION Status

This control unit implements both fixed-block and variable-block modes. Reference the Read Block Limits and Mode Select (mode parameters block descriptor) commands for more informa- tion about fixed and variable block modes. If the Fixed bit is one and the current mode is variable (as set by MODE SELECT command or default power on condition) the command is rejected with

4-140 CG00000-011503 REV. A April 1997