Dell Dimension XPS 50 Reference Manual page 64

3-18 Dell Dimension XPS Txxx and Txxxr Systems Reference and Troubleshooting Guide
The SCSI standard requires termination at two end points. If only internal devices are
connected, the SCSI host adapter card is terminated at one end. The device end of
the cable must then be terminated in one of two ways: either the cable contains a ter-
minator, or the device attached to the end connector must be terminated. However, if
you have both internal and external devices attached to the SCSI host adapter card,
the card should have termination disabled. External SCSI cables do not have termina-
tors, so termination must be enabled on the external SCSI device itself. Any devices
attached to inner connectors on the SCSI cable should have termination disabled.
Refer to the documentation for each device for instructions on enabling and disabling
termination.
The type of cabling you receive with a SCSI device depends on the type of device you
are installing:
If you are installing an internal narrow SCSI device (such as a CD-ROM drive, a
Zip drive, or tape drive), you have a 50-pin internal SCSI cable as shown in
Figure 3-14. One end of this cable attaches to the SCSI host adapter card. The
three connectors on the other end of the cable are used for attaching up to three
narrow SCSI devices installed in the externally accessible drive bays.
68-pin SCSI cable
(to hard-disk drive)
If you are installing an internal wide SCSI device (such as a wide SCSI hard-disk
drive), you have a 68-pin internal SCSI cable as shown in Figure 3-14. One end of
this cable attaches to the SCSI host adapter card and the two connectors on the
other end of the cable are used for attaching up to two SCSI hard-disk drives.
If you are installing an external SCSI device, you have a shielded external cable
that connects to the external SCSI connector on the SCSI host adapter card. You
have a separate power cable to connect the SCSI device to an AC power source.
50-pin SCSI cable
(to device in
externally accessible
drive bay)