2 second dword, 4 i/o instruction, Second dword – LSI 53C875A User Manual
Page 213: I/o instruction
I/O Instruction
5-13
5.3.2 Second Dword
Start Address
[31:0]
This 32-bit field specifies the starting address of the data
to move to/from memory. This field is copied to the
register. When the LSI53C875A
transfers data to or from memory, the DNAD register is
incremented by the number of bytes transferred.
When bit 29 is set, indicating indirect addressing, this
address is a pointer to an address in memory that points
to the data location. When bit 28 is set, indicating table
indirect addressing, the value in this field is an offset into
a table pointed to by the
The table entry contains byte count and address
information.
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.
31
0
DMA SCRIPTS Pointer Save (DSPS)
Register
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
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