The introduction of the AWS 95 has led to questions with regard to the SCSI
termination requirements for the internal Processor Direct Slot Card and
the SCSI busses that it supports. The internal and external SCSI buses on
the AWS 95 are two separate electrical buses that are logically treated as
one via software. This means external cabling and termination issues do
not affect the internal bus and vice-versa. Both buses are terminated at
the main board. The second termination point for the internal SCSI bus is
built-in to the end of the internal SCSI cable, and the second termination
point for the external SCSI bus is provided via a terminator connected to
the last device on the external SCSI chain.
The AWS 95 retains the same termination scheme on the main board and on
the PDS card for a total of four electrically separated SCSI buses. The
two buses attached to the PDS card are terminated at the PDS card. The
second termination point for the internal PDS SCSI bus is built-in to the
end of the internal SCSI cable, and the second termination point for the
external PDS SCSI bus is provided via a terminator connected to the last
device on the external PDS SCSI chain.