New World ROM Macintosh computers are the Macintosh models that do not use a Macintosh Toolbox ROM on the logic board, but instead use an Open Firmware boot ROM. All Macs from the iMac forward are New World ROM machines, while all previous models (including all beige and platinum Macs) are Old World ROM machines. Intel based Mac computers 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.