User guide

Figure 2–7 Alpha VME 4 Primary Breakout Module
1
3
5
2
4
6
MLO-013263
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Part Number: 54-24663-01
Part Number: 54-22605-01
7. Set the SCSI termination jumper on the breakout module (refer to
Figure 2–8).
The SCSI bus must be terminated at each end. In most installations, the
breakout module is one end of the SCSI bus and the far end of the SCSI
ribbon cable is the other end of the SCSI bus. In this case, enable the SCSI
termination by placing the jumper across pins 1 and 3 (default).
If the breakout module is not at the end of the SCSI bus, disable the SCSI
termination by placing the jumper across pins 3 and 5.
8. Set the watchdog signal jumper on the breakout module (refer to Figure 2–8).
The Digital Alpha VME 4 module supplies an external watchdog reset signal
that you can connect to a monitoring device. If you make no connection to
this external signal, the setting of the jumper makes no difference.
Setting the jumper across pins 4 and 6 (default) provides an internal 2 kOhm
to +5 V pullup for this signal. Setting the jumper across pins 2 and 4 provides
no pullup. This allows you to attach a monitoring device that operates at a
different voltage level. The monitoring device must provide voltage and
a pullup resistor that do not exceed the output specifications of a 74LS05
2–16 Installation Procedures