Whither the Mac OS?

In the coming months Apple plans to revolutionize its elderly operating system by publishing the beta version of a totally new OS based upon Unix and the NextStep Mach kernel, called "Mac OS X." So why is O'Reilly publishing a book about Mac OS 9? Because Mac OS 9 is the foundation of the graphical user interface for all future Mac OS versions. Mac OS 9 is both today and tomorrow and you have to understand and use it to get the most out of Mac OS X. Mac OS 9 is not going away anytime soon.

Some History
Why is Apple moving away from its proprietary software to open source software? Why is Apple creating such a radical change and what does it mean for basic consumers?

One of the problems with the "classic" Macintosh operating system is that it is old. The core software that comprises the Mac OS is based upon code written in the late 1970 and early 1980s. On top of this antiquated code, Apple has piled many patches, so-called System Extensions, that add capabilities and APIs that do the same; to maintain compatibility with software that is dependant on first-generation integrated circuitry while building in modern tools such as multitasking, drag and drop copy and pasting, file sharing over the Internet, and so forth. Apple knows that the Macintosh operating system has become stretched to its limits by all of these additions and corrections and has been working for about four or five years on a replacement OS.

At the 1998 World Wide Developer's Conference, Apple announced that it was streamlining the Mac operating system replacing a prior announced major OS transformation to NextStep (code-named Rhapsody) with an easier transition model. The new OS, now called Mac OS X would still be based on NextStep's Mach kernel, but new layers of compatibility software would allow legacy Macintosh software an easier road to compatibility. This intermediary layer of software is called Carbon.

Interested in other Mac OS books? Check out David Pogue's Mac OS 9: The Missing Manual.

Carbon is a new Toolbox manager containing those APIs that run successfully with Mac OS X's kernel. The method for this modernization is the removal of antiquated code more than 2,000 APIs and the adding of replacement APIs to support modern operating system features such as a new 2D display system called Quartz, OpenGL for 3D rendering, Unix programming APIs such as pre-emptive multitasking and protected memory, a new networking scheme based on BSD 4.4 Sockets, a new Finder, and so forth. All of this rewritten programming interface support is called Carbon.

Mac OS X provides three user environments:

• "Classic" that allows old, non-recompiled Macintosh programs to run safely on Mac OS X but without the advanced bells and whistles of the new operating system.
• "Carbon" that lets Carbon-compliant applications gain access to all of the features of Mac OS X.
• "Cocoa" an environment to support programs written in Java or C++ to gain full access to the Mac OS X operating system.

Mac OS 9 contains Carbon and Core Foundation, and will probably be the foundation for future GUIs in Mac OS X. Mac OS 9 already sports many modern OS features, such as a pre-emptive multitasking Finder, File Sharing over TCP/IP, the ability to set up multiple user accounts, and many others. Mac OS 9 provides over 50 updates and new features to the venerable Mac OS.

To summarize, Mac OS 9 is not a dead-end, but the beginning of a new era for Apple software. One that takes getting used to. Mac OS 9 provides you with the tools to learn new ways of Mac working before making the jump to Mac OS X.