Is MacOS an open source system? No.
Classic Mac OS is closed source. Mac OS X is closed source as well, but many libraries and applications within it are open source, e.g. XNU the kernel is open source, and Darwin the underlying UNIX operating system was open source.
The oldest mac OS is System 1
Go to system preferences. Open the Classic system preference, and you should see the option to start up in classic mode.
Mac OS X is a preemptive multitasking system.
No. Mac OS is an operating system.
Mac-OS=Disk operating system==Linux OS==Windows OS==Unix OS=
The Mac OS was designed by Apple as the operating system for their Macintosh range of computers. The first Mac OS, originally known as System Software, was introduced with the first Macintosh in 1984. Over the years the original Mac OS was developed, improved and expanded until Mac OS 9 in 2001. For version 10 Apple reworked the Mac OS around a UNIX core and this is known as Mac OS X.
OS stands for operating system. It is basically what runs your computer. Examples of operating systems are Windows XP, Windows Vista, Windows 7, Mac OS X Tiger, Mac OS X Leopard, and Mac OS X Snow Leopard (there are many more).
The Mac's operating system was originally known as the System Software. It later became known as Mac OS followed by a version number - Mac OS 7, Mac OS 8 etc. The current 10th version is known as Mac OS X.
After Mac OS. Mac OS was based on the earlier Xerox Alto system.
no
Mac OS X is the operating system used by G5 Macs. The latest version of Mac OS X that will work on a G5 is Mac OS X 10.5 (also known as Leopard).