Sun OpenBoot Firmware (IEEE 1275) is pretty smart. It is basically a 
Forth interpreter with some standard program code and a device tree 
database already loaded. It tells us what devices are present and 
therefore what devices to attach device drivers to, and loads up our 
primary boot block.

The boot path is interpreted by that, in addition to the NetBSD boot 
code, and the NetBSD kernel.

 Erik <fair@netbsd.org>