Motorola CPV5000 Installation And Reference Manual page 69

Ultra SCSI controller
Figure 4-1 shows the termination scheme. When a CPV5000 board is installed
into a system with no rear I/O, the terminators next to J4 are active. This
provides termination at the end of the SCSI bus right at J4. If a non-wide device
is plugged into the CPV5000's 68-pin connector, pin 50 will become
grounded. This will cause the terminators for the CTRL and SCD0-7 signals to
be turned off. The last device on the cable provides termination for these
4
signals.
If a wide device is plugged into the CPV5000's 68-pin connector, pin 1 will be
grounded, and all three terminators will be turned off. In this case, a wide
device must be connected at the end of the cable.
If a rear I/O transition module is plugged in, pin E5 will be grounded. This will
disable the CPV5000's terminators next to J4 since the end of the SCSI bus will
be at the 68-pin connector on the rear I/O board. If a non-wide device is
plugged into the rear I/O's 68-pin connector, pin 50 will become grounded.
This will cause the terminators for the CTRL and SCD0-7 signals to be turned
off. The last device on the cable provides termination for these signals.
If a wide device is plugged into the rear I/O's 68-pin connector, pin 1 will be
grounded, and all three terminators will be turned off. In this case, a wide
device must be connected at the end of the cable. If a 68-pin to 50-pin SCSI
adapter is used it must have straight through connections with no pins hooked
together.
4-13