3Interface Cards SCSI Adapter Cards

Additional SCSI Card Features

The Adaptec® SCSI card provides double transition clocking, cyclical redundancy check, and domain validation.

Feature

 

Description

 

 

Double Transition

Changes the digital protocol to use both edges of

Clocking

the SCSI request/acknowledge signal clock. It

 

allows designers to use Ultra2 cables. The signal

 

in an Ultra2 SCSI runs a 40 MHz, while data runs

 

at only 20 MHz or 80 MB/second on a 16-bit wide

 

bus.

 

Using both edges of the same signal at 40 MHz the

 

data rate can be increased to 40 MB/second or 160

 

MB/second on a 16-bit wide bus.

 

 

Cyclical Redundancy

Provides extra data protection for marginal cables

Check

that are connected to external devices. The Ultra3

 

SCSI cyclical redundancy check detects all:

 

•

Single error bits

 

•

Double bit errors

 

• Odd number of errors

 

• Burst errors up to 32-bits long

 

 

Domain Validation

Tests networks, cables, backplanes, terminators,

 

and hard disk drives to ensure that the

 

environment is operating at required specification.

 

If reliability is at risk the speed of transfer is

 

lowered.

 

 

 

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