Avago Technologies LSI53C825AE User Manual
Page 202
5-18
SCSI SCRIPTS Instruction Set
Initiator Mode
Select Instruction
1. The LSI53C825A 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.
2. If the LSI53C825A wins arbitration, it attempts to
select the SCSI device whose ID is defined in the
destination ID field of the instruction. Once the
LSI53C825A 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.
3. If the LSI53C825A 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 LSI53C825A to Initiator mode if it is
reselected, or to Target mode if it is selected.
4. If the Select with SATN/ field is set, the SATN/ signal
is asserted during the selection phase.
Wait Disconnect Instruction
The LSI53C825A 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
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