The iBook™s PowerPC G4 processor works hand in hand with Mac OS X to give you a one-two performance punch. Mac OS X features preemptive multitasking that allocates processor cycles on an as-needed basis and protected memory that keeps you up and running even if an application happens to crash. Enhancing the performance of the PowerPC G4 is its aptly named Velocity Engine. The Velocity Engine processes data in huge 128-bit chunks, instead of the smaller 32-bit or 64-bit chunks, and can perform complex calculations two to four times faster than run-of-the-mill PCs.