Avago Technologies LSI53C825AE - Manual (Page 18)

1-4 Introduction
TolerANT receiver technology improves data integrity in unreliable
cabling environments where other devices would be subject to data
corruption. TolerANT receivers filter the SCSI bus signals to eliminate
unwanted transitions, without the long signal delay associated with
RC-type input filters. This improved driver and receiver technology helps
eliminate double clocking of data, the single biggest reliability issue with
SCSI operations. TolerANT input signal filtering is a built-in feature of the
LSI53C825A and all LSI Logic fast SCSI devices. On the LSI53C825A,
the user may select a filtering period of 30 or 60 ns, with bit 1 in the
SCSI
Test Two (STEST2) register.
The benefits of TolerANT technology include increased immunity to noise
when the signal is going HIGH, better performance due to balanced duty
cycles, and improved fast SCSI transfer rates. In addition, TolerANT SCSI
devices do not cause glitches on the SCSI bus at power-up or
power-down, so other devices on the bus are also protected from data
corruption. TolerANT technology is compatible with both the Alternative
One and Alternative Two termination schemes proposed by the American
National Standards Institute.
1.4 LSI53C825A Benefits Summary
This section provides an overview of the LSI53C825A features and
benefits. It contains information on
SCSI Performance , PCI Performance ,
Integration , Ease of Use , Flexibility , Reliability, and Testability .
1.4.1 SCSI Performance
To improve SCSI performance, the LSI53C825A:
•
Includes 4 Kbyte internal RAM for SCRIPTS instruction storage
•
SCSI synchronous offset increased from 8 to 16 levels
•
Supports variable block size and scatter/gather data transfers
•
Performs sustained memory-to-memory DMA transfers faster than
47 Mbytes/s (@ 33 MHz)
•
Minimizes SCSI I/O start latency
•
Performs complex bus sequences without interrupts, including
restore data pointers