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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 BIOS PNP AND PCI SETUP. For
Double-ended configurations, the Termination for that particular channel must be
set to Disabled in BIOS PNP AND PCI SETUP. Each channel may have up to 15
Ultra2 or Ultra-Wide 68-pin devices (ID#0-15, with #7 reserved for the chipset).
Channel B may have up to 7 Ultra-Fast 50-pin devices (ID#0-6, with #7 reserved for
the chipset), but channel B's 68-pin devices must be deducted by the number of 50-
pin devices because each channel can only have up to 15 SCSI devices.
IMPORTANT: SCSI devices of different speeds mixed on the same channel will
bring all the other devices on that channel down to the slowest speed. Because the
50-pin Ultra-Fast connector is shared on Channel B, the fastest that can be attained
on the Channel B 68-pin Ultra2 connector is equal to the slowest device between the
two connectors. Basically, if you want to use both Ultra2 devices and Ultra-Fast
devices, use the 68 pins on Channel A and the 50 pins on Channel B. Do not use the
68 pins on Channel B in this case.
NOTE: Ultra2 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
Disable Termination in BIOS
68pin or 50pin Connector
Double-Ended Configuration
Enable Termination in BIOS
68pin or 50pin Connector
Single-Ended Configuration
30
III. INSTALLATION
Chassis
ASUS XG-DLS User's Manual
(External Cable)
External SCSI
SCSI Deivice
Cable Conn.
(no termination)
SCSI Deivice
Internal to
(no termination)
External Conn.
(Internal Cable)
SCSI Deivice
SCSI Deivice
(no termination)
(no termination)
(Internal or External)
SCSI Deivice
(Terminated)
Termination
Block
Termination
Block
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