Message System
Message Sequencing and Handling
During the selection phase, the Identify message must be the first message out
from the initiator to the library. This message initiates the message system. The
library must receive an Identify message during the selection phase to enable it to
respond to the attention line during subsequent phases. When the message system
has been initiated by the Identify message during the selection phase, the library
accepts messages from the initiator when the attention line is active.
Synchronous Negotiations
The library will accept negotiations for synchronous communication but will
always negotiate to asynchronous communication.
Wide Negotiations
The library will accept negotiations for wide transfers but will always negotiate to
narrow, 8-bit transfers.
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Chapter 3 SCSI Bus Operations 27