[Geoman]

Yes, the "Field Service Handbook for SGI Crimson" states on page 2-9:

4. As a general guideline, populate the VME slots from slot 1 to slot 4.
5. Jumpers located between VME slots (1-4) are bus grant (BG) and interrupt acknowledge (IACK) jumpers. Use the following rules when jumpering the
VME slots:
o If any VME slot is empty, BG and IACK jumpers located to the left of the empty slot must be installed
o If a board is installed in a VME slot, the jumpers for that slot must be removed
6. If the GENLOCK board is installed in a VME slot, it must reside in slot 4 and the GENLOCK jumpers (located to the left of bottom connector for slot 4) must be removed

and on page 2-14:

3. Configure VME controller boards in slots 1-4
o install VME boards beginning with Slot 1.
o there must be either a board installed in a slot or jumpers installed between the beginning of the VME backplane and the last VME board (see page 2-8
for jumper locations).
o Slot 4 may contain either a VME board or a CG2 genlock video board.

So since Vigra has to be installed in Slot 1, I did not set any jumpers (ie the Backplane is 'jumper free'), because it is the only VME-Board installed. Did I got that right?

On the other hand, if I read the excellent sgistuff.net :

General rules regarding VME setup:

o populate slots from slot #1 to slot #4
o remove BG/IACK jumper for every slot that cards are installed in
o if one slot is empty the BG/IACK jumpers must be set

The exception to this rule is the Genlock board which always goes in slot #4. If that is installed the genlock jumpers located to left of bottom connector of slot #4 must be in place.

I would have to install jumpers on BG/IACK-Positions on VME-Slots #2-3 and leave #1 (Vigra) and #4 (empty Genlock-Position) both open.
That's a bit contradictory to the field service handbook.