Operating system

Prior to the Macintosh OS X operating system the Macs used an operating system based upon a single processor (computer CPU) which processed data and ran applications using what was called cooperative multitasking. Cooperative multitasking allowed programs to sometimes take control of the central processing unit. Now with the newer Macintosh operating system, OS 10.2.x (Jaguar) and later versions there is a UNIX-like kernel in the operating system, two processors and the central processing unit processes data with symmetric multiprocessing (uses both CPU's or "chips" to process data) and it uses preemptive multitasking, not allowing any application to take control of the central processing units.
 
If users want to run older software, the PowerMac G4 is a dual-booting machine meaning you can either boot into the older OS 9.2 or a version of OS X. (This is called "dual bootable".) Software written for the OS X (pronounced OS ten) will not run in the OS 9 environment but older legacy software is capable of being run while booted into the newer OS X, just that the newer features of the OS X will not be available when running applications designed for the OS 9 or older operating systems.