1.3.3Ultra2 SCSI Technology

The LSIU80ALVD fully supports Ultra2 SCSI. Ultra2 SCSI is an extension of the SCSI Parallel Interface 2 and 3 (SPI-2 and SPI-3) family of standards that expands the bandwidth of the SCSI bus, allowing faster synchronous data transfers.

For the internal bus, special impedance SCSI ribbon cables are specified for operation with Ultra and Ultra2 SCSI devices. You must consider the total length of the bus cables and the number of devices on the SCSI bus when setting up your system.

Use SCSI cables that have been rated for standard SCSI (Fast, Ultra, and Ultra2) environments.

See Chapter 2, “Installing the LSIU80ALVD,”for a detailed explanation of SCSI bus connections.

1.3.4LVDlink Technology

To support greater device connectivity and a longer SCSI cable, the LSIU80ALVD features LVDlink technology, the LSI Logic implementation of Universal LVD SCSI. LVDlink transceivers provide the inherent reliability of differential SCSI, and a long-term migration path to faster SCSI transfer rates.

The LVDlink transceivers reduce the power needed to drive the SCSI bus, so that the I/O drivers can be integrated directly into the chip. LVDlink technology lowers the amplitude of noise reflections and allows higher transmission frequencies.

The LVDlink transceivers operate in LVD and SE modes. They also allow the chip to detect a High Voltage Differential (HVD) signal when the chip is mistakenly connected to external HVD transceivers. The LSI53C895A automatically detects which type of signal is connected, based on the voltage detected, and automatically switches as needed to the SE or LVD mode. All bus devices must be LVD or SE. If a HVD device is detected, the board puts the SCSI bus in the high impedance state and shuts down.

Interface Descriptions

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