User's Guide

Page 22 DDS-4 SCSI Interface Manual, Rev. B
State or Phase Description
Message Out
Phase
If the host is in the Message Out Phase and sends a
message bytes and the drive detects a parity error, the
drive:
• attempts one retry then goes to Bus Free.
An Initiator that accommodates disconnect/reconnect can indicate this capability to
the DAT drive during the Selection phase by asserting both its own Initiator SCSI ID
bit as well as the DAT SCSI ID bit (allows the DAT drive to know with which Initiator
to reconnect). The Initiator must also assert ATN before exiting the Selection phase
(prior to releasing SEL) and send an Identify message out of C0h to the DAT drive.
This sequence causes the drive to enter the Message-Out phase when the
Selection phase completes.
The first message sent by the host after the Selection phase is an Identify message.
Under normal conditions, the first message sent by the DAT drive after a
Reselection phase is also Identify. Under certain exceptional conditions, the host
may send the Abort message or the Bus Device Reset message instead of Identify
as the first message.