LSI LSI53C895A, Technical Manual

Page: 227 / 364

Block Move Instruction 5-5
Figure 5.1 SCRIPTS Overview
5.3 Block Move Instruction
Performing a Block Move instruction, bit 5, Source I/O - Memory Enable
(SIOM) and bit 4, Destination I/O - Memory Enable (DIOM) in the
DMA
Mode (DMODE) register determines whether the source/destination
address resides in memory or I/O space. When data is being moved onto
the SCSI bus, SIOM controls whether that data comes from I/O or
memory space. When data is being moved off of the SCSI bus, DIOM
controls whether that data goes to I/O or memory space.
System Processor
System Memory
SCSI Initiator Write Example
×
Select ATN 0, alt_addr
×
Move from identify_msg_buf,
when MSG_OUT
×
Move from data_buf when DATA_OUT
×
Move from stat_in_buf, when STATUS
×
Move SCNTL2 & 7F to SCNTL2
×
Clear ACK
×
Wail disconnect alt2
×
Int 10
Table
byte count
address
byte count
address
byte count
address
byte count
address
Data Structure
Message Buffer
Command Buffer
Data Buffer
Status Buffer
B
U
S
S
Y
S
T
E
M
Write DSA
Write
DSP
Fetch
SCRIPTS
Data
LSI53C895A
SCSI Bus
see block
diagram in
Chapter 2
For details,
P
C
I