> Somebody please correct me,
  ^^^^^^^^^^^^^^^^^^^^^^^^^^  you asked for it :)

> but none of the drives must be configured to provide termination.
> The BUS is only terminated by the SCSI card and the external
> terminator on the Multifunction IO card.

Close but no cigar. Any SCSI bus should be terminated at both ends.
On the 928 in question the MFIO's SCSI bus should be terminated at
the external connection (at the board IF that is where the bus ends)
and at the end of the ribbon cable in the internal I/O bay - typically
where ldev 1 resides. Most SCSI discs are capable of providing
termination - most SCSI DDS drives are not capable of providing
termination.
 Hint - the address jumpers are located on the DDS drives backside.
Each device on the bus must have a unique address. Normally ID=7
(SCSI Single Ended as with the 928's MFIO card)
is used by the interface leaving ID0 thru 6 for peripherals.
Typically discs would populate from high numbered addresses and
downward (ldev1 ID=6, ldev2 ID=5 ...) and DDS drives from low
numbered addresses and upward (ldev7 ID=0, ldev8 ID=1 ...) and
of course must match the addresses in sysgen to work with MPE but
this is not a requirement for recognition by MAPPER.

                         Hope this helps.

                         Bob J. -- Ideal Computer Services
                         http://www.icsgroup.com