Avago Technologies LSI53C896 - Manual (Page 151)

SCSI Registers 4-39
Version 3.3 Copyright © 1998–2003 by LSI Logic Corporation. All rights reserved.
The SCSI First Byte Received (SFBR) is not writable using the CPU, and
therefore not by a Memory Move. However, it can be loaded using
SCRIPTS Read/Write operations. To load the SFBR with a byte stored
in system memory, the byte must first be moved to an intermediate
LSI53C896 SCSI function register (such as the SCRATCH register), and
then to the SFBR.
This register also contains the state of the lower eight bits of the SCSI data
bus during the Selection phase if the COM bit in the
DMA Control (DCNTL)
register is clear.
If the COM bit is cleared, do not access this register using SCRIPTS
operations, because nondeterminate operations may occur. (This
includes SCRIPTS Read/Write operations and conditional transfer control
instructions that initialize the
SCSI First Byte Received (SFBR) register.)
Register: 0x09
SCSI Output Control Latch (SOCL)
Read/Write
This register is used primarily for diagnostic testing or programmed I/O
operation. It is controlled by the SCRIPTS processor when executing
SCSI SCRIPTS.
SCSI Output Control Latch (SOCL) is used only when
transferring data using programmed I/O. Some bits are set or cleared
when executing SCSI SCRIPTS. Do not write to the register when the
LSI53C896 SCSI function starts executing normal SCSI SCRIPTS.
REQ Assert SCSI REQ/ Signal 7
ACK Assert SCSI ACK/ Signal 6
BSY Assert SCSI BSY/ Signal 5
SEL Assert SCSI SEL/ Signal 4
ATN Assert SCSI ATN/ Signal 3
MSG Assert SCSI MSG/ Signal 2
C_D Assert SCSI C_D/ Signal 1
I/O Assert SCSI I_O/ Signal 0
7 6 5 4 3 2 1 0
REQ ACK BSY SEL ATN MSG C_D I/O
0 0 0 0 0 0 0 0