Avago Technologies LSI53C1010R - Manual (Page 156)

4-38 Registers
Version 2.2 Copyright © 2000–2003 by LSI Logic Corporation. All rights reserved.
The SCSI First Byte Received (SFBR) register 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 LSI53C1010R 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 indeterminate 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
LSI53C1010R 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
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