Ignore Wide Residue (23H); Identify (80 - Ff) - IBM Ultrastar 36LZX Specifications

10.1.19 IGNORE WIDE RESIDUE (23h)

Byte Value Description
0 23H Ignore Wide Residue message
1 01H Ignore
Figure 178. 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 REQ/ACK 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 after the DATA IN phase and prior to any other messages. Even though a byte is in-
valid, it's corresponding parity bit is valid for the value transferred.

10.1.20 IDENTIFY (80 - FF)

This message is set by either the initiator or the drive to establish the logical path connection between
the two devices.
The IDENTIFY message is defined as follows:
Bit 7 This bit is always set to one to distinguish the IDENTIFY message from other messages.
Bit 6 This bit is only set to one by the initiator to grant the drive the privilege of disconnecting. If
this bit is zero, the drive will not disconnect unless the initiator instructs the drive to
disconnect by sending a DISCONNECT Message to the drive. This bit is set to zero when the
drive sends an IDENTIFY message to the initiator.
Bits 5-0 These bits specify the logical unit number (LUN).
Only one LUN may be identified for any one selection sequence. If the drive receives an
IDENTIFY message with a new LUN after the LUN had previously been identified, the drive
will go to the BUS FREE 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 LUN remains the same.
When the IDENTIFY message is sent from the drive to the initiator during reconnection, an implied
RESTORE POINTERS message must be performed by the initiator.
Ultrastar 36LZX hard disk drive specifications
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