Avago Technologies LSI53C1020 - Manual (Page 48)

2-22 Functional Description
Version 2.4 Copyright © 2001–2004 by LSI Logic Corporation. All rights reserved.
2.4.1.8 SureLINK Domain Validation
SureLINK Domain Validation establishes the integrity of a SCSI bus
connection between an initiator and a target. Under the SureLINK
Domain Validation procedure, a host queries a device to determine its
ability to communicate at the negotiated data transfer rate.
SureLINK Domain Validation provides three levels of integrity checking:
Basic (Level 1) with inquiry command; Enhanced (Level 2) with
read/write buffer; and Margined (Level 3) with drive strength margining
and slew rate control. The basic check consists of an inquiry command
to detect gross problems. The enhanced check sends a known data
pattern using the read and write buffer commands to detect additional
problems. The margined check verifies that the physical parameters have
a reasonable operating margin. Use SureLINK Domain Validation only
during the diagnostic system checks and not during normal system
operation. If transmission errors occur during any of these checks, the
system can reduce the transmission rate on a per-target basis to ensure
robust system operation.
2.4.2 SCSI Bus Interface
This section describes the SCSI bus modes that the LSI53C1020
supports and the SCSI bus termination methods necessary to operate a
high speed SCSI bus.
2.4.2.1 SCSI Bus Modes
The LSI53C1020 supports SE and LVD transfers. To increase device
connectivity and SCSI cable length, the LSI53C1020 features LVDlink
technology, which is the LSI Logic implementation of LVD SCSI. LVDlink
transceivers provide the inherent reliability of differential SCSI and a
long-term migration path for faster SCSI transfer rates.
The DIFFSENS signal detects the different input voltages for HVD, LVD,
and SE. The LSI53C1020 drivers are tolerant of HVD signal strengths,
but do not support the HVD bus mode. The LSI53C1020 SCSI device
3-states its SCSI drivers when it detects an HVD signal level.