Seagate ST373455LC - Cheetah 73.4 GB Hard Drive Installation Manual page 49

Barracuda 18LP Installation Guide, Rev. B 47
LC drives
Single-ended/low-voltage-differential selection
The SE jumper, when installed on J2, forces the drive I/O circuits
and all other devices on the SCSI bus to operate in the single-
ended (SE) mode. When the SE jumper is not on, the SCSI I/O
can operate in either single-ended or low-voltage differential
(LVD) mode, depending on which mode the host device has
selected using the "DIFFSNS" I/O line. The SE jumper should
not be installed unless the system documentation specifically
states that it should be installed. The I/O bus can transfer data at
a much higher data rate in the LVD mode, but the system must
be designed to accommodate a higher data rate.