Reformulation of earlier post (9/13):

I've got a Vaxstation 3500, with KDA50 controller, that had no disks
in it when I found it.  Since then, I found a box of 4 RA73's (I've
learned from looking at old posts on Info-Vax that this is called a
SABB) and have been successful at installing them one at a time
in the 3500 cabinet.  The operator control panel on the front of
the box has buttons for two drives, 0 and 1.  The KDA50 has 4
"licorice" black strap cables, with 8-pin connectors at the
end.  When I found the machine, two of these were plugged into
the back of an external outlet on the cabinet, which accepts
cables from the SABB.  (The DEC number on this box is
7025405-01, I am guessing this is standard on 3500's.)
I am trying to use cables 0 and 1 to
install two disks into the cabinet.

I have black cable 0 and 1 plugged into the "A" ports on
each disk (they have ports "A" and "B").  The operator control
panel has two 20-pin cables that are connected to each disk.
The operator control panel has the following layout:

Run      Fault       Ready   Write Protect    A       B
-------------------------------------------------------------
light  |  light   |  light  |  button     | button | button |  1
-------------------------------------------------------------
light  |  light   |  light  |  button     | button | button |  0
-------------------------------------------------------------

I have two disks now in the box, and have installed bootable
NetBSD 1.4.1 on each of them.  I can press in button A for
drive 0, and it's bootable as DUA0.  Or I can press in button
A for drive 1, and it's bootable as DUA0.  But if I press in
both buttons, the lights are all on when I first fire up the
machine, but as soon as I try to boot, the lights switch off,
and I then get a DEVOFFLINE message.  I suspect there is
some issue about conflicting unit numbers, but it seems as
if the operator control panel is supposed to set the unit
numbers to 0 and 1.

I have gathered by reading around that this computer often
shipped with two RA70's in it.  Is it also possible to
put in two RA73's?

Doug