LSI53C875 LSI Logic, LSI53C875 Datasheet - Page 204

• Manufacturer Part Number: LSI53C875
• Description: PCI to Ultra SCSI I/O Processor
• Manufacturer: LSI Logic

6-8
Instruction Set of the I/O Processor
1. The LSI53C875 verifies that it is connected to the
2. The LSI53C875 asserts the SCSI phase signals
3. If the instruction is for the command phase, the
SCRIPTS can directly execute operating system I/O data
structures, saving time at the beginning of an I/O
operation. The I/O data structure can begin on any
longword boundary and may cross system segment
boundaries.
There are two restrictions on the placement of pointer
data in system memory:
Opcode
This 1-bit field defines the instruction to be executed as
a block move (MOVE).
Target Mode
OPC
0
1
These instructions perform the following steps:
The eight bytes of data in the MOVE instruction must
be contiguous, as shown below, and
Indirect data fetches are not available during
execution of a Memory-to-Memory DMA operation.
SCSI bus as a Target before executing this
instruction.
(SMSG/, SC_D/, and SI_O/) as defined by the Phase
Field bits in the instruction.
LSI53C875 receives the first command byte and
decodes its SCSI Group Code.
– If the SCSI Group Code is either Group 0, Group 1,
Group 2, or Group 5, and if the Vendor Unique
Enhancement 1 (VUE1) bit
(SCNTL2),
00
Instruction Defined
MOVE
CHMOV
bit 1) is clear, then the LSI53C875
Physical Data Address
Byte Count
(SCSI Control Two
27