IBM IC35L018UCDY10, Specifications

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transfer width agreement is reinstated if the drive successfully retransmits the WIDE DATA TRANSFER
REQUEST message to the Initiator. For any other message the drive completes negotiation and goes to
the negotiated data transfer width.
10.1.3.2 Transfer Width Negotiation started by the drive
If the drive recognizes that negotiation is required, it sends a WIDE DATA TRANSFER REQUEST mes-
sage to the Initiator with the transfer width exponent equal to 1 (E = 01h). The Initiator must respond by
asserting the ATN signal prior to its release of ACK for the REQ/ACK handshake of the last byte of the
WIDE DATA TRANSFER REQUEST message. This provides an interlock during the wide data transfer
negotiation. If the Initiator does not assert the ATN signal, the drive goes to 8 bit mode. If the Initiator
asserts the ATN signal, the drive changes to the MESSAGE OUT phase and receives a message from the
initiator.
If the first message received is a WIDE DATA TRANSFER REQUEST message, the Target establishes
the new data transfer mode. The Target interprets the Initiator corresponding transfer width exponent as
shown in the following table.
(8 Bit) Ei > 01h
16 Bit Ei = 01h
8 Bit Ei = 00h
Target Data Transfer Width Initiator Request
Figure 185. Target Request to Initiator
If the first message received from the Initiator is either a MESSAGE PARITY ERROR or a MESSAGE
REJECT message, the drive goes to 8 bit data transfer mode. In the case of a MESSAGE PARITY
ERROR, the wide data transfer negotiation is restarted if the drive successfully retransmits the
WIDE DATA TRANSFER REQUEST message to the Initiator.
If the first message received from the Initiator is any other message, the Target goes to 8 bit data transfer
mode. The Target assumes that the Initiator does not support wide data transfer and does not attempt to
renegotiate with this Initiator.
The implied agreement for wide data transfer operation is not considered to exist by the Target until the
Target leaves the MESSAGE OUT phase, implying that no parity error was detected. If the Target detects
a parity error while attempting to receive the message from the Initiator, the Target goes to 8 bit data
transfer mode. The Target will attempt to resume the wide data transfer negotiation by retrying the
MESSAGE OUT phase.
Note: If during the MESSAGE IN phase of negotiations (either Target or Initiator started) ATN is asserted
prior to transmission of the last byte of the message and the message is not MESSAGE PARITY ERROR
or MESSAGE REJECT, the drive goes to 8-bit data transfer mode.
Ultrastar 146Z10 hard disk drive specifications
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