OK, I've gotten further into why there are problems. I've traced back to
src/distrib/common/Makefile.makedev, line 30:

_MAKEDEVOBJDIR!=cd ${NETBSDSRCDIR}/etc && ${PRINTOBJDIR}
MAKEDEVSCRIPT=  ${_MAKEDEVOBJDIR}/MAKEDEV

I traced PRINTOBJDIR back to
/usr/share/mk/bsd.own.mk

.if empty(.MAKEFLAGS:M-V*)
PRINTOBJDIR=    ${MAKE} -V .OBJDIR
.else
PRINTOBJDIR=    echo # prevent infinite recursion
.endif

So it would appear that the MAKEDEVSCRIPT should be in the .OBJDIR

Net7300# make -V .OBJDIR
/usr/src/distrib/macppc/floppies/ramdisk
Net7300#

but there is no MAKEDEV file present. Apparently a step or two is
missing, that of an architectural specific MAKEDEV file. Does anyone
have any suggestions?

thanks,
tim