Quantum 10K II - Manual (Page 75)

SCSI Description
5–8 Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives
Bit 7 6 5 4 3 2 1 0
Byte
5 Vendor Specific Reserved NACA Flag Link
Figure 5–2 Command Descriptor Block Control Field — Data Format
Table 5–3 Command Descriptor Block Control Field — Field Descriptions
Field Description
Vendor Specific Bits These bits must be 0.
NACA Normal Auto-Contingent Allegiance - This bit must be zero to indicate
that SCSI-2 Contingent Allegiance rules apply.
Link Bit A Link bit set to one signals that the initiator requests continuation of a
task (I/O Process) across two or more SCSI commands. If the Link bit is
one and the flag bit is zero, and the command completes successfully,
the drive will continue the task and return a status of INTERMEDIATE and
a service response of Linked Command Complete.
If the Link bit and the Flag bit of the Control word are both set to one,
and the drive completes a command with a status of INTERMEDIATE, the
drive shall return a service response of Linked Command Complete (with
Flag). Refer to Section 5.6 for Linked Commands description.
Flag Bit The Flag bit is used in conjunction with the Link Bit to notify the initiator
in an expedient manner that a command has been completed. Aflag bit
set to 1 is valid only when the Link Bit is set to 1.