Avago Technologies LSI53C876E - Manual (Page 224)

5-34 SCSI SCRIPTS Instruction Set
0b1XXXXXXX allows the SCRIPTS processor to
determine whether or not the high order bit is set while
ignoring the remaining bits.
DCV Data Compare Value [7:0]
This 8-bit field is the data compared against the SCSI
First Byte Received (SFBR) register. These bits are used
in conjunction with the Data Compare Mask Field to test
for a particular data value. If the COM bit (
DMA Control
(DCNTL) , bit 0) is cleared, the value in the SFBR register
may not be stable. In this case, do not use instructions
using this data compare value.
5.6.2 Second Dword
Jump Address [31:0]
This 32-bit field contains the address of the next
instruction to fetch when a jump is taken. Once the
LSI53C876 fetches the instruction from the address
pointed to by these 32 bits, this address is incremented
by 4, loaded into the
DMA SCRIPTS Pointer (DSP)
register and becomes the current instruction pointer.
5.7 Memory Move Instructions
For Memory Move instructions, bits 5 and 4 (SIOM and DIOM) in the
DMA Mode (DMODE) register determine whether the source or
destination addresses reside in memory or I/O space. By setting these
bits appropriately, data may be moved within memory space, within I/O
space, or between the two address spaces.
The Memory Move instruction is used to copy the specified number of
bytes from the source address to the destination address.
Allowing the LSI53C876 to perform memory moves frees the system
processor for other tasks and moves data at higher speeds than available
from current DMA controllers. Up to 16 Mbytes may be transferred with
one instruction. There are two restrictions: