4 i/o instruction, 1 first dword, I/o instruction – Avago Technologies LSI53C895A User Manual
Page 235: First dword
I/O Instruction
5-13
5.4 I/O Instruction
I/O Instructions perform the following SCSI operations in Target and
Initiator mode. These I/O operations are chosen with the opcode bits in
the
register.
This section describes these I/O operations.
5.4.1 First Dword
IT[1:0]
Instruction Type - I/O Instruction
[31:30]
The IT bit configuration (01) defines an I/O Instruction
Type.
OPC[2:0]
OpCode
[29:27]
The OpCode bit configurations define the I/O operation
performed but the OpCode bit meanings change in Target
mode compared to Initiator mode. OpCode bit
configurations (101, 110, and 111) are considered
Read/Write instructions, and are described in
Section 5.5, “Read/Write Instructions.”
This section
describes Target mode operations.
OPC2
OPC1
OPC0
Target Mode
Initiator Mode
0
0
0
Reselect
Select
0
0
1
Disconnect
Wait Disconnect
0
1
0
Wait Select
Wait Reselect
0
1
1
Set
Set
1
0
0
Clear
Clear
31 30 29
27 26 25 24 23
20 19
16 15
11 10
9
8
7
6
5
4
3
2
0
Register
Register
IT[1:0] OPC[2:0] RA TI Sel
R
ENDID[3:0]
R
CC TM
R
ACK
R
ATN
R
0
1
x
x
x
x
x
x
0
0
0
0
x
x
x
x
0
0
0
0
0
x
x
0
0
x
0
0
x
0
0
0