Tandberg Data
Hardware Interface
___________________________________________________________________________
Tandberg SLR Reference Manual
8-15
8.4.10. Message Out Phase
The Message Out Phase is used in the following way:
When an Initiator signals that disconnection is allowed.
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When an Initiator has detected a parity error.
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When it aborts a command.
When it resets a Target without resetting the whole bus.
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When the Initiator and the Drive negotiates synchronous transfer parameters.
The Message Out Phase has the following sequence:
The Initiator starts by
asserting the ATN line.
The handshake protocol
for the Identify Message
is like the one described
in Section 8.5.3, Selec-
tion Phase.
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The assertion of ATN
enables the Target to
know which transfer the
message refers to.
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When the Drive detects
that ATN is asserted, it
enters the Message Out
Phase by asserting
MSG and C/D while de-
asserting I/O.
After a bus settling de-
lay of at least 400 ns,
the Target asserts REQ.
-ATN
-MSG
-C/D
-I/O
-REQ
-ACK
Info Byte
Mess. Out Byte
Message Out Phase
min. 400 ns
min. 55
ns
min. 0 ns
min. 0
ns
-DB(0-7, P)
DB(8-15, P1)
Figure 8.9 Attention Interlock and Message Out Transfer
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The Initiator places the mes-
sage byte on the bus and as-
serts ACK.
+
The Target then deassert REQ,
and the Initiator can deassert
ACK.
The Message Out Phase ter-
minates when the Target deas-
serts MSG.