System 3.0 (Finder 5.1) was introduced with the Macintosh Plus, officially implementing HFS, 800K startup drives, support for several new technologies including SCSI and AppleShare, and Trash 'bulging' (i.e., when the Trash contains files, it gains a bulged appearance).This version was specifically to support the Hard Disk 20 and only implements HFS in RAM startup and most floppy disks remain MFS 400 K volumes. System 2.1 (Finder 5.0) introduced the Hierarchical File System (HFS) which has real directories.System 2.0 added support for AppleTalk and the newly introduced LaserWriter to use it.The Finder provides virtual folders that could be used to organize files, but these folders are not visible from any other application and do not actually exist on the disk. System 1.0, 1.1, and 2.0 use a flat file system named Macintosh File System (MFS).Version numbers of the operating system are based on the version numbers of these two files. The two files are contained in a folder directory labeled 'System Folder', which contains other resource files, like a printer driver, needed to interact with the System.

The software consists of two user-visible files: the System file, and the Finder, an application used for file management that also displays the Desktop.

Because of this, early versions of the operating system do not have a distinct name.

Mac clones Īs part of Apple's goal of creating a computer with appliance-like simplicity, there is no explicit distinction made between the operating system software and the hardware it runs on. To provide such niceties at a low level, early Mac OS depends on core system software in ROM on the motherboard, which also ensure that only Apple computers or licensed clones (with the copyright-protected ROMs from Apple) can run Mac OS. This is in contrast to MS-DOS and CP/M computers of the time, which display such messages in a mono-spaced font on a black background, and require the use of the keyboard rather than a mouse, for input. This architecture also allows for a completely graphical OS interface at the lowest level without the need for a text-only console or command-line mode: boot time errors, such as finding no functioning disk drives, are communicated to the user graphically, usually with an icon or the distinctive Chicago bitmap font and a Chime of Death or a series of beeps. The initial purpose of this is to avoid using up the limited storage of floppy disks on system support, given that the early Macs have no hard disk (only one model of Mac was ever actually bootable using the ROM alone, the 1991 Mac Classic model). In systems prior to PowerPC G3-based systems, significant parts of the system are stored in physical ROM on the motherboard.

Mac os 9