The PowerBook G3 Series 1999 computer is different from previous PowerBook computers in that it has no single, large ROM that contains many components of the Mac OS software, along with the 68K emulator, hardware initialization, and the nanokernel. Instead, a small ROM provides hardware initialization functions and provides a mechanism to load the Mac OS ROM image into RAM. The new software architecture that is centered around ROM-in-RAM and its ramifications is called the NewWorld architecture.