Fujitsu M2488, Руководство по эксплуатации продукта

Страница: 222 / 528

TAPE UNIT SCSI COMMANDS M2488 PRODUCT GUIDE
4-140 CG00000-011503 REV. A April 1997
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.
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
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
Transfer Length 3
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.