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User’s Guide 21020285 D
Chapter 5 Initiator Mode Pass-through Commands
Initiator Pass-through Parameter Block Format Page 5 - 9
Flags-2
The bits of this field are used to select SCSI-2 and additional command control
features implemented by the RF3880 adapter. The meanings of the bits are as
follows:
TAG OPTS - These two bits let you choose the tagged queuing method you
wish used with the current command. You can choose one of three types of
messages for the RF3880 adapter to use when issuing the command.
Note
Depending on the SCSI-
2 device you are using,
you may also need to
enable tagged queuing
with a MODE SELECT
page 0AH, Common
Device-Type Control
Parameters command to
the device. See your
vendor-supplied
peripheral
documentation for more
information.
In order for these bits to apply to the current operation you must have already
enabled tagged queuing with either the Unit Options or Extended Unit Options
command. These commands are covered in detail in Chapter 7, Board-control
Commands. If you do not enable tagged queuing with the Unit Options or
Extended Unit Options command, the TAG OPTS bits are ignored.
For more information about the use of tagged queuing, see the usage discussion
in Chapter 8.
E4H 1 0 Ciprico defined
E5H
thru
EFH
0 0 not defined
F0H 0 0 Ciprico defined
F1H 0 0 not defined
F2H 0 0 not defined
F3H 0 0 not defined
F4H 0 0 Ciprico defined
F5H
thru
FFH
0 0 not defined
BITS
76543210
0 0 0 0 JSM IAD TAG OPTS
Table 31: Bit-meanings of Flag-2 Field
Opcode DAT DIR Description
Table 30: DAT and DIR Automatic Settings
TAG OPT
Value
Meaning:
00
SIMPLE QUEUE TAG MESSAGE: The command may be processed
by the SCSI-2 device out of sequence for efficiency. Example: device
may sort commands by logical block address.
01
ORDERED QUEUE TAG MESSAGE: The command must be
executed by the SCSI-2 device in the order sent by the adapter (in
order with respect to other commands sent with the ORDERED
QUEUE TAG MESSAGE).
10
HEAD OF QUEUE TAG MESSAGE: The command is executed by
the SCSI-2 device before all other commands previously sent,
including other Head of Queue Tag commands but excluding
command currently in process.
11 Reserved
Table 32: Meaning of TAG OPTS Bits