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Tweak List: Carbon

"Carbon, " as Steve Jobs exclaimed, "is the basis for all life."

When Apple announced the Rhapsody project, they realized that they needed some way to ensure backward compatibility with the MacOS. Not all that many Mac users were going to migrate to this new NeXT-based platform just because Apple said so. So, Apple devised the Blue Box and many were placated.

But the entire Rhapsody project just never quite clicked for developers. Apple's plan for Rhapsody only allowed for a single programming option - Rhapsody's Yellow Box. Developers who didn't want to learn Objective-C and/or the Yellow Box decided not to become Rhapsody developers.

Instead, many developers chose to continue to develop for the current MacOS which would continue on in Rhapsody's Blue Box.

With so few legacy Mac developers committed to proper Rhapsody development, and without any backing from major Mac software creators such as Microsoft and Adobe, Apple succumbed to popular criticism and shifted its focus to a new OS paradigm: MacOS X. MacOS X adds the legacy Mac developer support in a new set of APIs known as Carbon.

In an effort to encourage MacOS developers to continue developing for the platform, Apple engineers came up with the idea of Carbon.

Carbon is really just a re-implementation of a good amount of the Macintosh Toolbox. Somewhere between 75-90% of the current Macintosh Toolbox will remain in Carbon in one form or another. Other functions will be added to complete the set of APIs for the transition to EQD and other MacOS X technologies. Carbon provides Mac developers considerable backwards compatibility with their code - though networking code may be made useless under Carbon. And with the addition of Quartz, there are plenty of other little areas which may need tweaked.

It is being specifically crafted so that all pure-Carbon applications can effortlessly utilize such "modern" OS features as preemptive multitasking, symmetric multiprocessing, powerful thread management, and more on MacOS X. Due to software limitations, there features will not be available to Carbon applications running on MacOS 8.x because there are no features like these in MacOS 8.x.

While there has been no official or definitive word as of yet, Apple will most likely add the full Carbon implementation to the next MacOS 8.x release in addition to their publicly and widely-known plans to include it in MacOS X.

Oh, yes, and Carbon is for PowerPC development only. The reason for this is that MacOS X will not ship with a 68k emulator, and therefore will not be able to execute 68k code. While Mixed Mode Switches will be supported by Carbon, they are there for programmer convenience and nothing else. All developers are urged to purge their apps of 68k MM calls as soon as possible.

It is this PowerPC requirement that means that even though Carbon applications can run on MacOS 8.1 (which is the last MacOS release which supported old 68k based machines), you cannot run Carbon applications on 68k-based Macintoshes.

For more Carbon information, check out our Carbon resources in our links page.