System

System is the original system resource file used in classic Mac OS. It began at Apple Computer as a very basic, graphical operating system which was only available in black and white for the first Macintosh.

Versions
There were many versions of the System available, growing incrementally with each release.

System 1, 2, 3 and 4
System 1 is the original version of the file in Mac OS, which first used the primitive Macintosh File System. Versions 2, 3 and 4 are relatively similar, adding new features with each release. It was stored in the System Folder and its icon looked like that of the Finder. The Font/DA Mover utility was necessary to add resources to the System file, such as fonts and desk accessories


 * System 1 was the base release in 1984.
 * System 2 updated the Finder and added the Hierarchical File System in version 2.1.
 * System 3 was introduced with the Macintosh Plus.
 * System 4 introduced AppleShare.

System 5
There is no System file version 5, but "System 5" was sold as a marketing name which packaged System 4.2 with an optional new cooperative multitasking system called MultiFinder.

System 6
System 6 unified the disparate and confusing version numbers of the system software components and improved the stability of MultiFinder. System 6.0.4 was the first to introduce battery-driven features, such as Sleep, for the Macintosh Portable.

System 7
System 7 was a major update with a more colorful graphical user interface, support for virtual memory, and cooperative multitasking permanently enabled. The System file took on the appearance of an openable suitcase to allow the user to add resources more easily, rendering the Font/DA Mover obsolete. System 7.1.2 introduced the transition to PowerPC processors and Mac OS 7.5.1 introduced the official name change to Mac OS.

Mac OS 8
The System file in Mac OS 8 was developed under the direction of co-founder Steve Jobs, who had returned to Apple. It featured the Platinum appearance salvaged from the cancelled Copland project, but stll retained the cooperative multitasking of earlier versions. Mac OS 8.1 introduced support for very large drives with HFS Plus as well as DVD-ROMs. Mac OS 8.6 introduced a rewritten PowerPC-native nanokernel for improved performance and stability.

Mac OS 9
The System file in Mac OS 9 improved networking and was the last major iteration in classic Mac OS. It continued to be used through the Classic environment until it was phased out completely in Mac OS X 10.5.

Mac OS X
Starting with Mac OS X, which was derived from NeXTSTEP, system resources are stored in a System folder instead of a singular suitcase file. Additional resources are stored in the Library folder.