Having difficulty getting miniroot-12.fs.sun4 to work on an slc:

dd if=miniroot-12.fs.sun4 of=/dev/rsd0b bs=20b conv=sync

appears to work, but when I boot(,,1)netbsd -s I get a 'not executable'
err msg.

Config:
*	Slc
*	External 450mb sd(0,1,0) with sunOS 4.1.4
*	External 1g with nothing on sd(0,0,0) (id3 natch)
*	Partitioning the 1g with type11; partition standard so I have
a,b,g parts for /, /swap, and /usr
*	I have newfs'ed a and g not b (swap)
*	When I boot back to sunOS sd0 has back magic number and I have
to reformat

What am I missing, and could I simply dd netbsd or netbsd.generic to
sd0a?

mike