Subject: VS2K questions, SCSI floppy info
From: Roger Ivie <>
List: port-vax
Date: 06/25/1998 21:09:45

I'm finally getting back to playing with NetBSD/VAX. I fiddled with it
on a MicroVAX II a few years ago, but failed to bring it up on a 2000.
Now I've got a bit of spare hardware and a little spare enthusiasm to try

What I'd like to do is make a MV2000 containing a floppy and a SCSI hard
disk. Boot the loader from the floppy, and tell it to load the kernel from
the SCSI disk. Reasonable?

For convenience, it would be nice if I could use a 3.5" floppy drive on 
the 2000. I understand that the 2000 doesn't know about anything newer than
RX33s, so I've hacked over rawrite from the i386 distribution to only write
15 sectors/track; the theory being that a diskette image laid out this way
will look the same as if it were written on an RX33 (the MV2000 will ignore
the extra sectors on the track). I'm not having much success booting the
boot floppy image. Does it boot on a MV2000? Should I give up on the 3.5"
floppy and install an RX33 in the beast (and, consequently, install a
5.25" floppy in a PC to build diskette images)?

I see in the archives recent questions about Digital's SCSI floppy controller;
I wrote about half the firmware for the thing and therefore should be able
to answer just about any question you have. I have a copy of the technical
reference for it sitting on my shelf.

The controller uses the drive selects to determine the type of drive attached.
If the drive responds as drive 0, it assumes the drive is an RX23 and
reports itself to be an RX23 drive. If the drive responds to drive 1, it
assumes the drive is an RX33 and reports itself to be an RX33 drive. Newer
models can handle 2.88MB drives on drive select 2, which cause it to assume
it's an RX26. The important thing here is to make certain the drive you are
using can be jumpered; many new drives are fixed as drive select 1, so the
controller will always assume they're RX33s.

Yes, the drive appears to be a generic removable device. I attached one to
an Amiga while debugging the firmware and used it as a hard disk. Worked
great, but 1.44MB isn't a large hard disk.

Roger Ivie