Sun3 machines usually need little or no preparation before installing
OpenBSD, other than the usual, well advised precaution of BACKING UP
ALL DATA on any attached storage devices.

You will need to know the SCSI target ID of the drive on which you
will install OpenBSD.

It might be a good time to run the diagnostics on your Sun3.  First,
attach a terminal to the "ttya" serial port, then set the "Diag/Norm"
switch to the Diagnostic position, and power-on the machine.  The
Diag. switch setting forces console interaction to occur on ttya.

The console location (ttya, ttyb, or keyboard/display) is controlled
by address 0x1f in the EEPROM, which you can examine and change in
the PROM monitor by entering "q 1f", then a numeric value (or just a
'.' if you don't want to change it, and "q" again to return to the prom).
Console values are:
	00: monochrome framebuffer (on-board or VME)
	10: tty a (9600-N-8-1)
	11: tty b (1200-N-8-1)
	12: color framebuffer
	20: color option board on P4 (model 3/60 only)

OpenBSD will use the EEPROM setting to determine which device to
use as the console, so you should make sure it is correct.

Please note that while OpenBSD and SunOS have a reasonable degree of
compatibility between disk labels and filesystems there are some problems
to watch out for during initial installation or when trying to maintain
both OpenBSD and SunOS environments on the same system.

    If the OpenBSD fsck(8) utility is used on a SunOS filesystem, it will
    set OpenBSD "clean flags" and BSD4.4 summary fields in the superblock.
    SunOS does *not* like this and you will have to do a "fsck -b 32" under
    SunOS to access an alternate superblock to repair the filesystem.  You
    should always specify SunOS filesystem with a "pass number" of 0 in
    their /etc/fstab entry to prevent this, and preferably mount them "RO".

    If SunOS fsck is used on an OpenBSD filesystem in the default OpenBSD
    (4.4BSD) format, it will first complain about the superblock and then
    about missing . and .. entries.  Do *not* try to "correct" these
    problems, as attempting to do so will completely trash the filesystem.

    You should avoid using softupdates (option softdep in /etc/fstab)
    on your shared filesystems.
    Although untested, it is likely that SunOS would be confused by a 
    filesystem with soft update flags enabled.

The OpenBSD "Sun Compatible" disklabel have been extended to support 16
partitions, however the old SunOS format(8) utility only sees the first
8 partitions and may "lose" information about the extended partitions.

Use SunOS format(8) only with *extreme* caution on drives that contain
OpenBSD partitions.

OpenBSD and Sun BSD bootblocks are similar in concept, though implemented
differently.  The OpenBSD bootblocks are architecture independent and also
understand the extended disklabels with 16 partitions.  You can use SunOS
bootblocks, but remember that OpenBSD bootblocks must be installed with
OpenBSD installboot and SunOS bootblocks with SunOS installboot.