Avago Technologies LSI8751D User Manual
Page 209
I/O Instruction
6-13
Target Mode
Reselect Instruction
The LSI53C875 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 LSI53C875 wins arbitration, it attempts to reselect
the SCSI device whose ID is defined in the destination ID
field of the instruction. Once the LSI53C875 wins
arbitration, it fetches the next instruction from the address
pointed to by the
register.
This way the SCRIPTS can move on to the next
instruction before the reselection completes. It continues
executing SCRIPTS until a SCRIPT that requires a
response from the Initiator is encountered.
If the LSI53C875 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
LSI53C875 to Initiator mode if it is reselected, or to Tar-
get mode if it is selected.
Disconnect Instruction
The LSI53C875 disconnects from the SCSI bus by
deasserting all SCSI signal outputs.
Wait Select Instruction
If the LSI53C875 is selected, it fetches the next
instruction from the address pointed to by the
register.
OPC2 OPC1 OPC0
Instruction Defined
0
0
0
Reselect
0
0
1
Disconnect
0
1
0
Wait Select
0
1
1
Set
1
0
0
Clear