> However, I'm falling down on the
> first part.  When I try to mount a partition as /dev/sd1g, it seems to mount
> but my disk subsequently comes up fried.

Eww...  Double-check the partition sizes and extents in the output from
'disklabel sd1'.  I know that I've gotten burned by one MacOS partition
tool that put in the wrong size for a partition...
Are you using sd1 for anything else?  I.e., is it a drive that's known
to work with the driver that you're using (SBC or non-SBC if you have
the 53c80 or esp if you have a 53c9x).

> Er, "g" isn't the whole-disk partition, is it?  I thought that was "d".

'c', actually.  On the i386, it's 'd' for hyster^H^H^H^H^Historical
reasons.

> especially since at this point I have no idea where to start looking.

Start with 'disklabel sd1'.  That gives you output something like:
# /dev/rsd1c:
type: SCSI
disk: SCSI disk
label: fictitious
flags:
bytes/sector: 512
sectors/track: 139
tracks/cylinder: 4
sectors/cylinder: 556
cylinders: 3835
total sectors: 2134305
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0		# milliseconds
track-to-track seek: 0	# milliseconds
drivedata: 0 

5 partitions:
#        size   offset    fstype   [fsize bsize   cpg]
  a:  2003137   131168    4.2BSD        0     0     0 	# (Cyl.  235*- 3838*)
  b:    65536       96      swap                    	# (Cyl.    0*- 118*)
  c:  2134305        0    unused        0     0       	# (Cyl.    0 - 3838*)
  d:    65536    65632       HFS                    	# (Cyl.  118*- 235*)
  e:       32       64   unknown                    	# (Cyl.    0*- 0*)
disklabel: boot block size 0
disklabel: super block size 0

On this disk, 'a' is the root partition, 'b' is swap, 'c' is the whole
disk, 'd' is a small MacOS partition (32MB), and 'e' is the SCSI Manager
4.3 driver partition (which will disappear after my latest disksubr
changes show up).

Does this help?

-allen

-- 
              Allen Briggs - end killing - briggs@macbsd.com