7DQGEHUJ'DWD 0HVVDJHV
7DQGEHUJ'/73URGXFW0DQXDO 
 ',6&211(&70HVVDJHK
The DISCONNECT message is sent from the drive to inform the initiator that the
present connection is going to be broken (the drive plans to disconnect by releasing
the BSY signal) and a later reconnect will be required to complete the current I/O
process. The message does not cause the initiator to save the data pointer. After
sending the message, the drive goes to the BUS FREE phase by releasing the BSY
signal.
The DISCONNECT message can also be sent by the initiator to tell the drive to
suspend the current phase and disconnect from the bus. The drive’s response to
and its handling of a DISCONNECT message are based on when, in the I/O
process, the initiator introduces the DISCONNECT message. Table 4–4
summarizes the drive’s response.
%863KDVH 'ULYH5HVSRQVH
SELECTION The drive discards the DISCONNECT message and goes to BUS
FREE.
COMMAND The drive discards the DISCONNECT message and goes to BUS
FREE. The ATTENTION request is ignored while the Command
Descriptor Block is fetched. The drive does not switch to
MESSAGE OUT until the current DMA completes.
DATA The ATTENTION request is ignored while the current data
transfer completes; that is, the drive does not switch to
MESSAGE OUT until after the current DMA completes. The drive
returns a MESSAGE REJECT message and responds with
CHECK CONDITION status, indicating the command aborted
because of an invalid message.
STATUS The drive sends a MESSAGE REJECT message, then sends
COMMAND COMPLETE.
MESSAGE IN The drive sends a MESSAGE REJECT message and switches to
the BUS FREE phase.
7DEOH±'ULYH5HVSRQVHWR',6&211(&70HVVDJH