> "The file just loaded is intended for a different CPU type."

This is the PROM saying that it did not find an acceptable magic
number in the boot program it has loaded. The most likely cause
used to be forgetting to tweak the NetBSD boot program on the
TFTP server when net-booting (the NetBSD a.out magic number
must be replaced with SunOS a.out magic).  See the installation
notes and the `/usr/mdec/binstall' script for inspiration.

-pk