Avago Technologies LSI53C1010 - Manual (Page 43)

Overview of SCRIPTS Instructions 3-3
bit, and may enable interrupt on the fly, so that the interrupt instruction
does not halt the SCRIPTS processor.
3.1.4 Read/Write Instructions
The Read/Write Instruction type is selected when the two high order bits
of the DCMD register are 0b01, with the opcode bit values from
0b101–0b111. Read/Write instructions perform the following register
operations, depending on the value of the operator bits in the Move
Register instructions.
Table 3.2 describes these instructions.
3.1.5 Block Move Instructions
The Block Move instruction type is selected when the two high order bits
of the DCMD register are 0b00. Block Moves transfer data (user data or
SCSI information) between user memory and the SCSI bus. Data comes
from any memory address, so scatter/gather operations for user data are
transparent to the chip and the external processor. A separate Block
Move instruction is written for each piece of data being moved. This
instruction allows indirect and table indirect addressing.
3.1.6 Load and Store Instructions
The Load/Store instruction type is selected when the three high order
bits of the DCMD register are 0b111. Load and Store instructions are a
more efficient way to move data directly between memory and an internal
register than the Memory Move instruction. This is due to the fact that
they utilize two Dwords instead of three and require one PCI bus
ownership instead of two. Load and Store instructions move a maximum
Table 3.2 Read/Write Instructions
Instruction Type Definition
Move from SFBR Moves the SCSI First Byte Received (SFBR)
register (0x08) to a specified register address.
Move to SFBR Moves a specified register value to the SFBR
register.
Read/Modify/Write Reads a specified register, modifies it, and writes
the result back into the same register.