Interface Descriptions; The Pci Interface; The Scsi Interface - Asus PCI-SC896 User Manual

2ch. ultra2 pci scsi card

Table of Contents

1. Introduction

1.3 Interface Descriptions

This section provides a more detailed explanation about the PCI Interface, the

SCSI Interface, the SCSI Activity LED Interface, and Wide Ultra2 SCSI.

PCI is a high-speed standard local bus for interfacing a number of I/O compo-

nents to a PC processor and memory subsystem. The PCI functionality for the

PCI-SC896 is contained within the ASUS PCI-SC896 PCI-SCSI I/O Processor

chip. The PCI-SC896 connects directly to the PCI bus and generates timing

protocol in compliance with the PCI specification. The PCI interface operates as

a 32-bit DMA bus master. The connection is made through the edge connector

J1. The signal definitions and pin numbers conform to the PCI Local Bus Speci-

fication Revision 2.1 standard. The PCI-SC896 conforms to the PCI universal

signaling environment for a 5 V or 3.3 V PCI bus.

The SCSI functionality for the PCI-SC896 is contained within the ASUS PCI-

SC896 PCI-SCSI I/O Processor chip. The PCI-SC896 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 interface 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 PCI-SC896 operates as two 16-bit, synchronous or

asynchronous, single-ended or LVD, and supports Ultra2 SCSI protocols and

16-bit arbitration. The PCI-SC896 board provides autosensing, dual mode SE/

LVD SCSI termination. Termination is normally enabled. When a SCSI device

is sensed to be connected to both internal and external connectors, termination

for that channel is automatically disabled. The PCI-SC896 supplies SCSI bus

TERMPWR (termination power) through a blocking diode and self-resetting

1.5 A short circuit protection device. An on-board LED lights up when

TERMPWR is shorted and turns off. A 40 MHz oscillator is installed on the

PCI-SC896 board to provide the clock frequency to the PCI-SC896 that is

necessary to support Wide Ultra2 SCSI transfers of up to 80 Mbytes/s.

ASUS PCI-SC896 User's Manual

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