Block Move Instructions 6-5
Figure 6.1 SCRIPTS Overview
6.3 Block Move Instructions
The Block MoveSCRIPTS instr uction is used to movedata between the
SCSI bus and memory. Fora Block Move instruction, the LSI53C810A
operates much like a chaining DMA device with a SCSI controller
attached. Figure 6.2 illustrates the register bit values that represent a
Block Move instruction. In Block Move instructions, bits 5 and 4 (SIOM
and DIOM) in the DMA Mode (DMODE) register determine 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
×SelectATN 0, alt_addr
×Movefrom identify_msg_buf, when MSG_OUT
×Movefrom cmd_buf, when CMD
×Movefrom data_buf when DATA_OUT
×Movefrom stat_in_buf, when STATUS
×Movefrom msg_in_buf, when MSG_IN
×MoveSCNTL2 & 7F to SCNTL2
×ClearACK
×Waildisconnect alt2
×Int10
S
Y
S
T
E
M
Write DSP
Fetch
SCRIPTS
Data
LSI53C810A SCSI Bus

B

U
S
Data Structure
Message Buffer
Command Buffer
Data Buffer
Status Buffer