Avago Technologies LSI8751D User Manual
Page 204
6-8
Instruction Set of the I/O Processor
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:
•
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.
Opcode
27
This 1-bit field defines the instruction to be executed as
a block move (MOVE).
Target Mode
These instructions perform the following steps:
1. The LSI53C875 verifies that it is connected to the
SCSI bus as a Target before executing this
instruction.
2. The LSI53C875 asserts the SCSI phase signals
(SMSG/, SC_D/, and SI_O/) as defined by the Phase
Field bits in the instruction.
3. If the instruction is for the command phase, the
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 (
bit 1) is clear, then the LSI53C875
00
Byte Count
Physical Data Address
OPC
Instruction Defined
0
MOVE
1
CHMOV