New World ROM

New World ROM computers are Macintosh models that do not use a Macintosh Toolbox ROM on the logic board. Due to 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. A facility for loading the Toolbox from the startup device was, however, made available, allowing the use of Mac OS 8 and Mac OS 9 on New World machines.

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.

All PowerPC Macs from the iMac, the iBook, the Blue and White Power Mac G3 and the Bronze Keyboard PowerBook G3 forward are New World ROM machines, while all previous models (including the Beige Power Mac G3 and all other beige and platinum Macs) are Old World ROM machines. Intel based Macs are incapable of running Mac OS 9, and on these machines EFI is used instead of Open Firmware, which both New World and Old World machines are based on.