[1] Due to Mac OS X not requiring the availability of the Toolbox, this allowed ROM sizes to shrink dramatically (typically from 4 MB to 1 MB), and facilitated the use of flash memory for system firmware instead of the now more expensive and less flexible Mask ROM that most previous Macs used.
The New World architecture was developed for the Macintosh Network Computer, an unrealized project that eventually contributed several key technologies to the first-generation iMac.
Because of this, versions 1.0.5 and 2.x had several serious bugs, as well as missing functionality (such as being able to load files from a HFS partition or a TFTP server).
Apple also set the default input and output devices to ttya (the modem port on beige Macs), which made it difficult for normal users to get to Open Firmware; to do so it was necessary to either hook up a terminal, or change the Open Firmware settings from inside Mac OS using a tool such as Boot Variables or Apple's System Disk.
The Toolbox ROM was embedded inside a CHRP script in the System Folder called "Mac OS ROM", along with a short loader stub and a copy of the Happy Mac icon suitable for display from Open Firmware.