Second Dword; I/O Instruction - LSI LSI53C875A Technical Manual

5.3.2 Second Dword

31
x x x x x x x

5.4 I/O Instruction

DMA SCRIPTS Pointer Save (DSPS)
x x x x x x x
Start Address
This 32-bit field specifies the starting address of the data
to move to/from memory. This field is copied to the
Next Address (DNAD)
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.
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 DMA Command (DCMD)
OPC2 OPC1
0 0
0 0
0 1
0 1
1 0
This section describes these I/O operations.
I/O Instruction
Register
x x x x x x x
register. When the LSI53C875A
Data Structure Address
register.
OPC0 Target Mode
0 Reselect
1 Disconnect
0 Wait Select
1 Set
0 Clear
x x x x x x x
Initiator Mode
Select
Wait Disconnect
Wait Reselect
Set
Clear
0
x x x x
[31:0]
DMA
(DSA).
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