Figure 6.1 SCRIPTS Overview

System Processor

System Memory

SCSI Initiator Write Example

×Select ATN 0, alt_addr

×Move from identify_msg_buf, when MSG_OUT

×Move from cmd_buf, when CMD

×Move from data_buf when DATA_OUT

×Move from stat_in_buf, when STATUS

×Move from msg_in_buf, when MSG_IN

×Move SCNTL2 & 7F to SCNTL2

×Clear ACK

×Wail disconnect alt2

×Int 10

Data Structure

Message Buffer

Command Buffer

Data Buffer

Status Buffer

S Y S T E M

B

U

S

Write DSP

Fetch

SCRIPTS LSI53C810A SCSI Bus

Data

6.3 Block Move Instructions

The Block Move SCRIPTS instruction is used to move data between the SCSI bus and memory. For a 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.

Block Move Instructions

6-5

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LSI 53C810A technical manual Block Move Instructions, Scripts Overview