IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive, Specifications

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Byte Value Description
ÄÄÄÄ ÄÄÄÄÄ ÄÄÄÄÄÄÄÄÄÄÄ
0 23H Ignore Wide Residue message
1 01H Ignore
Figure 135. Ignore Wide Residue Message Format
The Ignore Wide Residue Message is sent from the target to indicate that the number of valid bytes sent
during the last R E Q / A C K handshake of a DATA IN phase is less than the negotiated transfer width. The
ignore field (always = 01h) indicates that one byte (data bits 8-15) should be ignored. This message is sent
immediately following the DATA IN phase and prior to any other messages. Even though a byte is invalid,
it's corresponding parity bit is valid for the value transferred.
9.1.19 IDENTIFY (80 - FF)
This message is set by either the initiator or the file to establish the logical path connection between the two
devices.
The I D E N T I F Y message is defined as follows:
Bit 7 This bit is always set to one to distinguish the I D E N T I F Y message from other messages.
Bit 6 This bit is only set to one by the initiator to grant the file the privilege of disconnecting. If this
bit is zero, the file will not disconnect, unless the initiator instructs the file to disconnect by
sending a DISCONNECT Message to the file.
This bit is set to zero when the file sends an
I D E N T I F Y message to the initiator.
Bits 5-3 These bits are reserved and must be zero for an I D E N T I F Y message.
Note: If an invalid Identify message is received with these bits not equal to zero, then the file
sends a MESSAGE R E J E C T message to the initiator and goes to the Bus Free phase to signal a
catastrophic error condition.
Bits 2-0 These bits specify the logical unit number (LUN).
Only one L U N may be identified for any one selection sequence. If the file receives an IDEN-
TIFY message with a new L U N after the L U N had previously been identified, the file will go to
the BUS F R E E phase to signal a catastrophic error.
The initiator may send more than one
Identify message during a selection sequence in order to toggle disconnect/reconnect permission if
the specified L U N remains the same.
When the I D E N T I F Y message is sent from the file to the initiator during reconnection, an implied
R E S T O R E P O I N T E R S message must be performed by the initiator.
9.2 Supported Message Functions
The implementation of the supported messages will also include the following functions.
Retry SCSI Command or STATUS phase
The retry will be caused by the following error condition.
−
The file detected SCSI bus parity error(Command phase)
−
The file receives I N I T I A T O R D E T E C T E D E R R O R MESSAGE during or at the conclusion of an
information transfer phase (Command Data Out or Status Phase)
SCSI MESSAGE SYSTEM
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