NCR S26 - Manual (Page 150)

SCSI Channel Configurations
D-10 Hot Plug Backplane
Connect the second set pins for both jumpers J3 and J4 as shown in the figure
below.
Figure D-6. J3 and J4 Jumper Settings
J3 J4
The table below lists the terminator settings for the dual-channel
configuration.
Table D-2. Terminator Settings for Dual-Channel Configuration
Terminator Setting
With External Device
RA1, RA2, RA3
RA4, RA5, RA6 Removed
Installed
Without External Device
RA1, RA2, RA3
RA4, RA5, RA6 Installed
Installed
Note: Be sure the terminator switches are set to the right (split) position when
installing a dual-channel configuration.