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

I/O Instruction

6-13

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LSI 53C810A technical manual IT10 Instruction Type I/O Instruction 3130 OPC20 OpCode 2927