LSI U80ALVD - Manual (Page 18)

1-6 Using the LSIU80ALVD
1.3.4.1 Benefits of LVDlink
The LSI53C895A supports LVD for SCSI, which is a signaling technology
that increases the reliability of SCSI data transfers over longer distances
than supported by SE SCSI. The low current output of LVD allows the
I/O transceivers to be integrated directly into the chip. LVD provides the
reliability of HVD SCSI without the added cost of external differential
transceivers. Ultra2 SCSI with LVD allows a longer SCSI cable and more
devices on the bus, using the same cables defined in the SCSI-3 parallel
Interface (SPI-2) standard for Ultra SCSI.
Important: To utilize Ultra2 SCSI performance, the user must only
have LVD devices on the bus. Do not mix any SE devices
with LVD devices as the entire bus will drop to SE with
maximum Ultra SCSI performance.
1.3.5 On-Board LED
On-board LEDs are used to indicate the status of the SCSI bus.
The SCSI Activity LED lights when the SCSI bus is transferring
information.