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3. HARDWARE SETUP
SCSI Connection and Termination Information
Each SCSI channel is like a water hose where the inside must be opened and the
ends must be closed. Each connector, whether 68 pins or 50 pins may have single or
double-ended configurations. For Single-Ended configurations, the Termination for
that particular channel must be set to Enabled in 4.4.3 PCI Configuration. For
Double-ended configurations, the Termination for that particular channel must be
set to Disabled in 4.4.3 PCI Configuration. Each channel may have up to 15 de-
vices (ID#0-15, with #7 reserved for the chipset).
The onboard Adaptec AIC-7892B chipset (optional) incorporates an advanced
multimode I/O cell that supports both single-ended (SE) and low voltage differential
(LVD) devices. With Ultra160 devices, the SCSI bus platform performs at full Ul-
tra160 speeds (up to 80 MB/sec in 8-bit mode and up to 160 MB/sec in 16-bit mode)
and extended cabling 12m (or 25m in a point-to-point configuration). When an SE
device is attached, the bus defaults to an SE speed and cable length.
In mixed environments of LVD and SE devices, the onboard host adapter can be coupled
with the Adaptec AIC-3860Q transceiver chipset (optional) to bridge the compatibility
gap. By dividing the SCSI bus into independent SE and low voltage differential (LVD)
segments, the transceiver chipset supports legacy devices without limiting performance
and cable length on the LVD segment.
NOTE: Ultra160 devices do not have termination jumpers so a terminator block on
the SCSI cable is needed. If your end devices have its own termination, you may use
it instead.
SCSI Connection Examples
P3C-LS / L / S
Adaptec
AIC-7892B
Chipset
PCI-to-Ultra3 (LVD)
P3C-LS/L/S Mixed LVD
and Single-Ended Device Configurations
ASUS P3C-L / P3C-S / P3C-LS User's Manual
Ultra160 SCSI
Connector
Wide SCSI Connector
CD-ROM
L
S
SE Mode
LVD Mode
Adaptec
AIC-3860Q
Chipset
LVD Devices
Disk 1
Disk 2
Single-Ended Devices
Scanner
Disk 3
Tape
51
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