
Instruction Set of the I/O Processor
Memory Move Instructions
SYM53C810A Data Manual
6-21
Bits 15-8 Data Compare Mask
T he Data Compare Mask allows a SCRIPT S
instruction to test certain bits within a data
byte. During the data compare, any mask bits
that are set cause the corresponding bit in the
SFBR data byte to be ignored. For instance, a
mask of 01111111b and data compare value of
1X X X X X X X b allows the SCRIPT S proces-
sor to determine whether or not the high order
bit is set while ignoring the remaining bits.
Bits 7-0
Data Compare Value
T his 8-bit field is the data to be compared
against the SCSI First Byte Received (SFBR)
register. T hese bits are used in conjunction
with the Data Compare Mask Field to test for
a particular data value.
Second Dword
Bits 31-0 Jump Address
T his 32-bit field contains the address of the
next instruction to fetch when a jump is taken.
Once the SYM53C810A has fetched the
instruction from the address pointed to by
these 32 bits, this address is incremented by 4,
loaded into the DSP register and becomes the
current instruction pointer.
Memory Move Instructions
T his SCRIPT S Instruction allows the
SYM53C810A to execute high performance block
moves of 32-bit data from one part of main mem-
ory to another. In this mode, the SYM53C810A is
an independent, high performance DMA control-
ler irrespective of SCSI operations. Since the regis-
ters of the SYM53C810A can be mapped into
system memory, this SCRIPT S instruction also
moves an SYM53C810A register to or from mem-
ory or another SYM53C810A register. Figure 6-6
illustrates the register bit values that represent a
Memory Move instruction.
For Memory Move instructions, bits 5 and 4
(SIOM and DIOM) in the DMODE register
determine whether the source or destination
addresses reside in memory or I/O space. By set-
ting these bits appropriately, data may be moved
within memory space, within I/O space, or
between the two address spaces.
T he Memory Move instruction is used to copy the
specified number of bytes from the source address
to the destination address.
Allowing the SYM53C810A 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 MB may
be transferred with one instruction. T here are two
restrictions:
1. Both the source and destination addresses
must start with the same address alignment
(A(1-0) must be the same). If source and
destination are not aligned, then an illegal
instruction interrupt will occur.
2. Indirect addresses are not allowed. A burst of
data is fetched from the source address, put
into the DMA FIFO and then written out to
the destination address. T he move continues
until the byte count decrements to zero, then
another SCRIPT S instruction is fetched from
system memory.