Fujitsu M2488 manual Read command 08h, Read CDB Description, Read Field Description, Sili

M2488 PRODUCT GUIDE TAPE UNIT SCSI COMMANDS

4-3.14 READ command 08h

The READ command transfers one or more blocks to the initiator beginning with the next block on the logical unit.

Upon termination of the READ command, the logical position is located after the last block trans- ferred (EOM side).

4-3.14.1 READ CDB Description

READ is a six-byte command. The bytes are as shown below and described in Table 4-60. Com- mon 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	0		0
1
			LUN						Reserved			SILI		Fixed
2
		MSB
3
							Transfer Length
4														LSB
5
					Reserved							Flag		Link

Note: Changeable fields in the CDB are shaded.

			Table 4-60. READ Field Description
BYTE	BIT	VALUE		DESCRIPTION
0	0-7	08h		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.
		0		If the Fixed bit is zero, a single block is transferred with the bytes transferred
				being the lesser of the actual block length or the requested transfer length.
		1		If the Fixed bit is one, the transfer length specifies the number of blocks to be
				transferred to the initiator.
1	1			Suppress Incorrect Length Indication (SILI) flag.
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 7-53.)
		0		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.

April 1997 CG00000-011503 REV. A 4-63