Trying to attach a Sony Optical disk to a DECstation 3100, help!

[Michel Fingerhut]

We are trying to install a Sony "Magneto Optical Disk Drive Subsystem
SMO-5501-11" to a DECstation 3100 under Ultrix 3.0 (soon 4.1).

1..  In console mode, ">> test -c" sees the disk and correctly displays
     vendor and other info.

2..  At boot time, autoconfig identifies it as "rz3 ( UNKNOWN ) ..."
     which is right insofar as the SCSI unit number, and gives hope that
     the driver will know what to do next.  But...

3..  When attempting to format it (with /etc/rzdisk) or newfs, it reports
		rz3: mode select failed
     and I'm stuck.

Can anyone please help?  Preference to email (I'll post summaries) since
our news feed is often broken.  Thanks in advance,

Michael Fingerhut
mf at ircam.fr