Table of Contents
Advertisement
CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
NO OPERATION
08h.
This message is sent from an initiator in response to a
the controller's request for a message when the initiator does not currently
have any other valid message to send.
MESSAGE PARITY ERROR 09h.
This message is sent from the initiator to the
controller to indicate that one or more bytes in the last message it received
had a parity error.
In order to indicate its intentions of sending this message, the initiator
shall assert the ATN signal prior to its release of ACK for the REQ/ACK
handshake of the message that has the pari ty error.
This provides an
interlock so that the controller can determine which message has the parity
error.
If the controller receives this message under any other circumstance,
it will signal a catastrophic error condition by releasing the BSY signal
without any further information transfer attempt.
LINKED COMMAND COMPLETE OAb.
the initiator to indicate that
and that status has been sent.
the initial state for the next
This message is sent from the controller to an
the execution of a linked command has completed
The initiator shall then set the pointers to
linked command.
LINKED COMMAND COMPLETE (WITH FLAG) OBh.
This message is sent from the
controller
to an initiator to indicate that the execution of a linked command
(with the flag bit set to one) has completed and that status has been sent.
The initiator shall then set the pointers to the initial state of the next
linked command.
Typically this message would be used to cause an interrupt in
the initiator between two linked commands.
BUS DEVICE RESET 0Ch.
This message is sent from an initiator to direct the
controller to clear all current commands on that SCSI device.
This message
forces the SCSI device to an initial state with no operations pending for any
initiator.
Upon recognizing this message, the controller will go to the BUS
FREE phase.
IDENTIFY BOh to FFh.
These messages are sent by either the initiator or the
controller to establish the physical path connection between an initiator and
controller for a particular logical unit.
The logical unit number addresses
one physical drive attached to the controller.
Bit
7.
This bit shall be set to one to distinguish these messages from
the other messages.
Bit
6.
This bit is only set to one by the initiator to grant the the
privilege of disconnecting.
If this bit is zero, the controller will not
disconnect.
This bit is set to zero when the identify message is sent by the
controller.
Bits
5-3.
Reserved.
Bits 2-0.
These bits specify the
logical unit number in the controller.
4-9
Advertisement
Table of Contents
