Benefits Of Ultra160 Scsi - LSI LSI53C1000 Technical Manual

1.2 Benefits of Ultra160 SCSI
1-4
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Supports enhanced protection on nondata asynchronous phases
through AIP
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Supports CRC checking and generation in DT phases
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Supports Domain Validation
– Basic (level 1) with Inquiry Command (Inquiry Check)
– Enhanced (level 2) with Read/Write Buffer
– Margined (level 3) with margining of LVD drivers and
programmable skew test
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All cycles to SCRIPTS RAM stay internal to the device, not
generating PCI cycles
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SCRIPTS engine with improved instruction fetch performance
Ultra160 SCSI delivers data up to two times faster than Ultra2 SCSI.
Ultra160 SCSI is an extension of the SPI-3 draft standard that allows
faster synchronous SCSI data transfer rates than Ultra2 SCSI. When
enabled, Ultra160 SCSI performs 80 megatransfers per second
(megatransfers/s) resulting in approximately double the synchronous
data transfer rates of Ultra2 SCSI. The LSI53C1000 performs 16-bit,
Ultra160 SCSI synchronous data transfers as fast as 160 Mbytes/s. This
advantage is most noticeable in heavily loaded systems, or large block
size applications such as video on-demand and image processing.
The Ultra160 data transfer speed is accomplished using DT clocking.
DT clocking refers to transferring data on both polarity edges of the
request or acknowledge signals. Data is clocked on both rising and falling
edges of the request and acknowledge signals. Double-edge clocking
doubles data transfer speeds without increasing the clock rate.
Ultra160 SCSI also includes CRC, which offers higher levels of data
reliability by ensuring complete integrity of transferred data. CRC is a
32-bit scheme, referred to as CRC-32. CRC is guaranteed to detect all
single bit errors, any two bits in error, or any combination of errors within
a single 32-bit range.
Introduction