LSI 53C810A - Manual (Page 153)

I/O Instruction 6-13
indirect addressing, the value in this field is an offset into
a table pointed to by the
Data Structure Address (DSA) .
The table entry contains byte count and address
information.
6.4 I/O Instruction
The I/O SCRIPTS instruction causes the LSI53C810A to trigger common
SCSI hardware sequences such as Set/Clear ACK, Set/Clear ATN,
Set/Clear Target Mode, Select With ATN, or Wait for Reselect.
6.4.1 First Dword
IT[1:0] Instruction Type - I/O Instruction [31:30]
OPC[2:0] OpCode [29:27]
The following OpCode bits have different meanings,
depending on whether the LSI53C810A is operating in
initiator or target mode.
Note: OpCode selections 101–111 are considered Read/Write
instructions, and are described
Section 6.5, “Read/Write
Instructions.”
Target Mode
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