Datasheet

Command Processing
2-18 C141-C008
In the case of an ORDERED QUEUE, the IDD executes commands in the order
in which they are received.
All the commands received with a SIMPLE QUEUE before commands received
with an ORDERED QUEUE are executed before the commands received with an
ORDERED QUEUE, without relation to the INIT.
Commands received with a HEAD OF QUEUE are registered at the top of the
queue for waiting execution. The IDD does not interrupt the current command
execution and executes them after completion of current command execution.
When commands with the HEAD OF QUEUE are received continuously, the IDD
first executes the command which was received last.
All commands received with a SIMPLE QUEUE after commands received with
an ORDERED QUEUE are executed after the commands received with an
ORDERED QUEUE.
A command received with a HEAD OF QUEUE is registered at the head of the
execution queue and is executed when execution of the current command is
completed. Processing of the command currently being executed is not
interrupted.
When commands with a HEAD OF QUEUE are received continuously, the IDD
executes the latest command to be received first.
The RESERVE, RELEASE, RESERVE EXTENDED and RELEASE
EXTENDED commands should be issued together with an ORDERED QUEUE.
If HEAD OF QUEUE is used with these commands, it may result in duplication
of the previously issued command and the Reserve state.
The TEST UNIT READY and INQUIRY commands do not exert an influence on
the IDD's state, so they can be issued together with a HEAD OF QUEUE.
The INIT can specify two recovery options by the QErr bit of the control mode
parameter (Page A) of the Mode Select parameters, but this IDD does not support
the QErr bit.
Reporting of commands for which deferred errors were previously terminated is
done. Therefore, the queue tag values assigned to those commands are not
reported.
Use ABORT TASK SET, ABTS, TARGET RESET or CLEAR TASK SET to
clear some or all of the queued commands.
If “0001” is specified by the Queue algorithm modifier in the control mode page,
the IDD performs reordering processing of commands with respect to commands
issued together with the SIMPLE QUEUE. Reordering processing is performed
with the purpose of reducing the total processing time in command processing.