Implementation Requirements
Julyl 2017 Command Set 27
Control Byte
The control byte is the last byte of every Command Descriptor Block and has the
following structure:
• Vendor Specific
Provides additional information about the device or a command.
• NACA
The normal auto contingent allegiance bit controls the rules for handling an auto
contingent condition caused by a command. This bit is set to 0 to indicate that if a
contingent allegiance condition occurs, the command will return a check
condition.
• Flag (not supported)
This bit causes an interrupt in the initiator allowing a device to respond with
intermediate status. This bit is not supported and should be 0.
• Link (not supported)
Allows devices that support command linking to continue the I/O process. This
bit is not supported and should be 0.
TABLE 4-4 Control Byte
Byte
Bit
76543210
5, 9, or 11 Vendor Specific Reserved NACA
(0)
Flag
(0)
Link
(0)
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