Avago Technologies LSI53C876E - Manual (Page 133)

SCSI Registers 4-39
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 operation, as 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
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
This register is used primarily for diagnostic testing or programmed I/O
operation. It is controlled by the SCRIPTS processor when executing
SCSI SCRIPTS. SOCL is used only when transferring data using
programmed I/O. Some bits are set (1) or reset (0) when executing SCSI
SCRIPTS. Do not write to the register once the LSI53C876 SCSI function
starts executing normal SCSI SCRIPTS.
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