IBM HANDBOOK 260 - Manual (Page 134)

116 RS/6000 43P 7043 Models 150 and 260 Handbook
Y-cable to the adapters 68-pin external connector. The remaining two legs of
the Y-cable are used to attach other systems and devices to the SCSI bus.
If the PCI Differential Ultra SCSI adapter is at the end of the SCSI bus, the
shorter leg of the Y-cable must be terminated with the appropriate terminator.
Note: The high-availability configuration (Y-cable with a terminator on the
shorter leg) allows disconnection of the adapter from a
live SCSI bus by
removal of the external bus connection (the middle leg of the Y-cable).
Although termination and SCSI bus continuity is maintained during removal of
the adapter, the noise generated may create undetected data errors if the bus
is in use during the time of removal. To maintain data integrity, the SCSI bus
should be inactive during the removal of adapters, cables, or terminators.
Table 26 provides a list of required terminators.
Table 26. Terminator For Description-Ended Installations
Cabling Examples for the PCI Differential Ultra SCSI Adapter
Figure 32 and Figure 33 shows how to cable the PCI Differential Ultra SCSI
Adapter.
Figure 32. Differential External Narrow Bus
M/T FC Part
Number Connector Terminator Description
DE External
Devices Part of cable
FC 87G1356 50-pin low
density 8-bit external bus
terminator
DE External
Devices Part of cable
FC 61G8324 68-pin high
density 16-bit external bus
terminator
1
3
5