American Megatrends MegaDual, User Manual

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Chapter 1 Hardware Installation 51
Step 11 Connect SCSI I/O,
Continued
SCSI Termination The SCSI channels on the MegaDual motherboard use active termination for each SCSI
channel. You must terminate the SCSI bus properly. The SCSI bus on each SCSI channel
is an electrical transmission line and it must be terminated properly at both ends to
minimize reflections and losses. You complete the SCSI bus by setting termination at both
ends.
Do not add terminators in the middle of the SCSI bus. The end devices must be located as
close as possible to the terminators. A simple rule is to place SCSI terminator after the last
SCSI device on each of the SCSI connectors. MegaDual automatically terminates the
onboard SCSI connectors.
Stub length The stub length shall not exceed 0.1 meter. The spacing of devices on the SCSI bus
should be at least three times the stub length to avoid stub clustering.
SCSI Cables Teflon flat ribbon cables give the best performance in the Ultra-SCSI environment. These
cables should be used for all internal cabling. To minimize discontinuities and signal
reflections, the use of cables with different impedances on the same bus should be
minimized.
Cont’d