Avago Technologies LSI53C1000R User Manual
Page 259
I/O Instructions
5-17
Version 2.2
Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
Initiator Mode
Select Instruction
The LSI53C1000R arbitrates for the SCSI bus by
asserting the SCSI ID stored in the
register. If it loses arbitration, it tries again during the next
available arbitration cycle without reporting any lost
arbitration status.
If the LSI53C1000R wins arbitration, it attempts to select
the SCSI device whose ID is defined in the destination ID
field of the instruction. When the LSI53C1000R wins
arbitration, it fetches the next instruction from the address
pointed to by the
register.
This way the SCRIPTS can move to the next instruction
before the selection completes. It continues executing
SCRIPTS until a SCRIPT that requires a response from
the target is encountered.
If the LSI53C1000R is selected or reselected before
winning arbitration, it fetches the next instruction from the
address pointed to by the 32-bit jump address field stored
in the
register. Manually set
the LSI53C1000R to the initiator mode if it is reselected,
or to the target mode if it is selected.
If the Select with SATN/ field is set, the SATN/ signal is
asserted during the selection phase.
Wait Disconnect Instruction
The LSI53C1000R waits for the target to perform a “legal”
disconnect from the SCSI bus. A “legal” disconnect
occurs when SBSY/ and SSEL/ are inactive for a
minimum of one Bus Free delay (400 ns), after the
LSI53C1000R receives a Disconnect Message or a
Command Complete Message.
OPC2
OPC1
OPC0 Instruction Defined
0
0
0
Select
0
0
1
Wait Disconnect
0
1
0
Wait Reselect
0
1
1
Set
1
0
0
Clear