Mac OS

Macintosh Operating System which is a short form Mac OS is a branded name for a series of graphical user interface based operating systems. These Operating systems have been developed by Apple Inc. Mac OS came on the face of the world in 1984 with the original Macintosh 128k.

It was an Operating System whose main purpose was to facilitate the ordinary people who do not have the technical knowledge required for working with MS-DOS. Before the mid of 1990s the term “Mac OS” did not really exist. Many versions of Mac OS were only compatible with Motorola 68000-based Macintoshes. The versions which came after these earlier versions were compatible with the PowerPC(PPC) architecture.

We can divide Mac OS into two familiar operating systems:

• Classic Mac OS
• Mac OS X

Classic Mac OS (1984-2001)

This Operating system was totally different from the DOS operating system as it was a graphical operating system from top to bottom.

Features:

• Singletasking in the earlier versions
• Cooperative multitasking for the later versions.
• Limited memory management
• Protected memory lack.
• Time consuming Troubleshooting.

Classic Mac OS originally used the Macintosh File System (MFS). MFS is basically a flat file system having only a single level of folders. It was substituted by the Hierarchical File System (HFS). HFS had a true directory tree. MFS and HFS both are compatible anyhow.

Many of the file systems used with DOS, Linux or any other operating system handle a file as a sequence of bytes, requiring the program to know the purpose of the particular bytes. On the other hand, MFS and HFS gave different “forks” to the files.

• Data Fork: This contained the information similar to other file systems, e.g bitmaps of an image file or text of a document.
• Resource Fork: This fork contained other structured data, e.g graphics, sounds, menu definitions or code chunks.

A file can only consist of resources having an empty data fork or the vice versa. For a text file it could contain its data in the data fork and indentation information in the resources fork. This is done to ensure that the text data could still be recognized if the styling information is not recognized by a particular application. These forks create some problems while interoperating with other operating systems, i-e copying to a non-Mac system from a Mac system would shred it of its resource fork.

Mac OS X (2000-present):

It brought Unix-style pre-emptive multitasking and memory management to the Mac platform. Mac OS X is based on the Mach kernel and the BSD implementation of UNIX.

Features:

• Improved memory management system, which allowed more programs to execute at the same time.
• It included command line.
• It supports PowerPC G3 and newer processors

Mac OS X is backward compatible for running the older Mac applications. User must install PowerPC based Macs ship with OS 9.2 and also OS X, as it is not installed by default.

Though many of the original Mac OS users have been upgraded to Mac OS X, but a few people criticize that Mac OS X is much more difficult and less user friendly than its predecessor. Also many of the features present in Mac OS were not re-implemented in Mac OS X.