Table 1.3 scsi bus length limits, 3 benefits of ultra320 scsi, Benefits of ultra320 scsi – Avago Technologies LSI53C320 User Manual

Page 15: Scsi bus length limits

Benefits of Ultra320 SCSI

1-5

Version 2.2

1.3 Benefits of Ultra320 SCSI

The LSI53C320 SCSI Bus Expander supports Ultra320 SCSI. This
interface expands the bandwidth of the SCSI bus to allow faster
synchronous data transfers of up to 320 Mbytes/s. Ultra320 SCSI
provides double the data transfer rate of the Ultra160 SCSI interface.

The LSI53C320 performs 16-bit, Ultra320 SCSI synchronous data
transfers as fast as 320 Mbytes/s on the side of the device. This
advantage is most noticeable in heavily loaded systems or large block
size applications, such as video on-demand and image processing.

Ultra320 SCSI doubles both the data and clock frequencies from
Ultra160 SCSI. Due to the increased data and clock speeds, Ultra320
SCSI introduces skew compensation and intersymbol interference (ISI)
compensation. These new features simplify system design by resolving
timing issues at the chip level. Skew compensation adjusts for timing
differences between data and clock signals caused by cabling, board
traces, and so on. ISI compensation enhances the first pulse after a
change in state to ensure data integrity. The LSI53C320 performs skew
compensation on the receiver side of the device and ISI compensation
on the driver side of the device.

Ultra320 SCSI supports Cyclic Redundancy Check (CRC), which
provides error checking code to detect the validity of data. CRC
increases the reliability of data transfers by transferring four bytes of
code along with data. CRC detects all single bit errors, two bits in error,
or other error types within a single 32-bit range.

Table 1.3

SCSI Bus Length Limits

Segment

Mode

Length Limit

A, D

LVD (Ultra320 SCSI)

Up to 12 meters

SE (Ultra SCSI)

Up to 1.5 meters

B, C

LVD (Ultra320 SCSI)

Up to 12 meters

SE (Ultra SCSI)

Up to 1.5 meters

A + B + C + D

Ultra320 SCSI (only)

Less than 25 meters

1. Refer to

Section 2.2.3, “Maximum Cable Lengths,”

for more information on

cable length limits in an Ultra320 SCSI environment.