
1-6
Introduction
consists of an inquiry command to detect gross problems. The enhanced
check sends a known data pattern using the Read and Write Buffer
commands to detect additional problems. Margined check verifies that
the physical parameters have some degree of margin. By varying LVD
drive strength and REQ/ACK timing characteristics level 3 verifies that no
errors occur on the transfers. These altered signals are only used during
the diagnostic check and not during normal system operation. Should
errors occur with any of these checks, the system can drop back to a
lower transmission speed on a per target basis to ensure robust system
operation.
1.4 Benefits of LVD Link
The SYM53C1010 supports LVD through LVD Link. This signaling
technology increases the reliability of SCSI data transfers over longer
distances than are supported by SE SCSI. The low current output of LVD
allows the I/O transceivers to be integrated directly onto the chip. LVD
provides the reliability of High Voltage Differential (HVD) SCSI without
the added cost of external differential transceivers. Ultra3 SCSI with LVD
allows a longer SCSI cable and more devices on the bus, with the same
cables defined in the SCSI-3 Parallel Interface standard for Ultra SCSI.
LVD provides a long-term migration path to even faster SCSI transfer
rates without compromising signal integrity, cable length, or connectivity.
For backward compatibility to existing SE devices, the SYM53C1010
features universal LVD Link transceivers that support LVD SCSI and SE
SCSI. This allows use of the SYM53C1010 in both legacy and Ultra3
SCSI applications.
1.5 Benefits of TolerANT
Technology
The SYM53C1010 features TolerANT technology, which includes active
negation on the SCSI drivers and input signal filtering on the SCSI
receivers. Active negation causes the SCSI Request, Acknowledge,
Data, and Parity signals to be actively driven high rather than passively
pulled up by terminators.
TolerANT receiver technology improves data integrity in unreliable
cabling environments where other devices would be subject to data