Quantum ATL SuperLoader ATL, User Manual

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Quantum ATL SuperLoader Software Interface Guide 9
Chapter 2
2
Messages
The SCSI message system allows communication between an
initiator and the SuperLoader for interface management and
command qualification. Messages can be originated by either the
initiator or the SuperLoader. This section contains a detailed
description of the messages supported by the SuperLoader.
Message Format
2
A message can be one or more bytes in length. One or more
messages can be sent during a single MESSAGE phase, but a
message cannot be split over MESSAGE phases. The initiator is
required to end the MESSAGE OUT phase (by negating ATN)
when it sends certain messages that are identified in table 1 .
When a connection to the SuperLoader is established, for example
the SuperLoader is selected with ATN asserted, the first message
byte passed by the initiator must be either an IDENTIFY, ABORT,
or BUS DEVICE RESET message. If not, the SuperLoader discards
the message, saves no status information, and goes to the BUS
FREE phase.