Identify 80H-Ffh; Table 1-6 Head Of Queue Tag; Table 1-7 Ordered Queue Tag - HP 2600fx - Optical Disk Drive Command Reference Manual

Table 1-6 Head of Queue Tag
The Head of Queue Tag message specifies that the I/O process be placed
first in the logical unit's command queue. When the drive receives a
subsequent I/O process received with a Head of Queue Tag message, the
I/O process that has been already done is not interrupted.
Table 1-7 Ordered Queue Tag
The Ordered Queue Tag message specifies that the I/O process be placed
in the logical unit's command queue for execution in the order received.
All queued I/O processes for the logical unit received prior to this I/O
process are executed before this I/O process is executed. All queued I/O
processes received after this I/O process are executed after this I/O
process, except for I/O processes received with a Head of Queue Tag
message.

Identify 80H-FFH

These messages are sent by either the initiator or the target to establish
the physical path connection between initiator and target for a particular
logical unit.
Bit 7
Bit 6
Bit 5-3
Chapter 1
Byte 7 6
0
1
Byte 7 6
0
1
This bit is always set to 1.
This bit is set to 1 by the initiator to indicate that the
initiator has the ability to accommodate the disconnec-
tion and reconnection.
Reserved.
5 4 3
Message Code (21H)
Queue Tag (00H-FFH)
5 4 3
Message Code (22H)
Queue Tag (00H-FFH)
SCSI Command Overview
Drive Control Commands
2 1 0
2 1 0
1-13