NetBSD for RS6000 7011-250 (or -220)?

Hi, 

I have access to a RS6000/250 (this is printed on the front) or
Type: 7011 Model: 220 (printed on the back). It has a blank SCSI disk
(no AIX), floppy drive, GXT150 video card (with 13W3 socket), a
Token-Ring card in a slot, on-board AUI port and all the RAM slots are
used. On the board there is a sticker "80 Mhz". so I _think_ it is a
MCA-based 7011-250 with a PPC601 @80 Mhz.

Unfortunately I know nothing about RS6000 machines :-/. If I switch the
machine on, the floppy gets accessed twice, the SCSI disk is powered up
and some numbers flash on the front display. Using a 13W3-to-VGA adapter
for SUN machines the monitor does not get a signal.

Is there some kind of BIOS/OpenBootProm or serial console? Should the
13W3-to-VGA adapter work?

Help.

ciao
     Klaus