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1. Introduction
The SCSI Interface
The SCSI functionality for the LSI integrated SCSI is contained within the LSI
integrated PCI-SCSI I/O Processor chip. The LSI integrated SCSI connects
directly to the two SCSI buses for SE or LVD SCSI applications and generates
timing and protocol in compliance with the SCSI standard. Each SCSI inter-
face operates at a burst transfer rate of up to 40 Mbyte per second for wide
single-ended transfers, and up to 80 Mbyte per second for wide LVD SCSI
transfers.
The SCSI interfaces on the LSI integrated SCSI operates as two 16-bit, syn-
chronous or asynchronous, single-ended or LVD, and supports Ultra2 SCSI
protocols and 16-bit arbitration. The LSI integrated SCSI provides autosensing,
dual mode SE/LVD SCSI termination. Termination is normally enabled. When
a SCSI device is sensed to be connected to both connectors, LSI integrated
SCSI termination is automatically disabled. The LSI integrated SCSI supplies
SCSI bus TERMPWR (termination power) through a blocking diode and self-
resetting 1.5 A short circuit protection device. A 40 MHz oscillator is installed
with the LSI integrated SCSI to provide the clock frequency to the LSI inte-
grated SCSI that is necessary to support Wide Ultra2 SCSI transfers of up to 80
Mbytes/s.
Wide Ultra2 SCSI
The LSI integrated SCSI has full support for Wide Ultra2 SCSI. This interface is
an extension of the SCSI-3 family of standards that expands the bandwidth of the
SCSI bus to allow faster synchronous data transfers, up to 80 Mbytes/s. Wide
Ultra2 SCSI provides a doubling of the data rate over the Ultra2 SCSI interface,
while it increases cable lengths and allows a larger number of devices on the
cable than Ultra2 SCSI interfaces. Special SCSI cables are specified for opera-
tion with Wide Ultra and Ultra2 SCSI devices, and you must consider the total
number of devices and the length of your SCSI bus when setting up your system.
The cable provided is matched for a Fast/Ultra/Ultra2 SE or LVD operation.
This cable also has built-in LVD termination since most Ultra2 hard disk drives
are not made with onboard LVD termination.
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ASUS LSI SCSI User's Manual
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