There are 3 types of programs in Mac OS X: Cocoa, Carbon and Classic.
Cocoa programs are written just for Mac OS X to take full advantage of the new OS such as the advanced memory protection, preemptive multitasking and the improved memory management. This type of program will not run on Mac OS 9.2.2 or any other older version of Mac OS. Mac OS X comes with some Cocoa applications such as Mail, Stickies and iPhoto.
Carbon programs are written with less effort compare to rewrite the whole program in Cocoa. Carbon program does not offer full features available in Mac OS X. This type of program runs on both Mac OS X and Mac OS 9. Example of Carbonized programs are Acrobat Reader 5.0, Interarchy and the Finder itself. We shall see more and more Carbonized programs being release by the developers.
Classic programs are written for OS from System 7 to Mac OS 9.2.2. Those programs will not run on Mac OS X. It will take a long time for developers to rewrite the program for Mac OS X. According to ‘Mac OS X: The missing manual’ by David Pague. There are about 18,000 Mac program in the market. NOT ALL programs are Cocoa programs or Carbonized programs. Most of it are still Classic programs.
Mac OS X allows you to run classic programs by launching Mac OS 9 (or better known as Classic) on top of Mac OS X. During the boot up, you will see a window with Mac OS 9.x booting. You still see the extensions and control panels marching out from the bottom left of the window. Bugs in extensions and control panels can still CRASH and SLOW DOWN the classic (You know that). According to Apple, some extensions and control panels are no longer function under classic when booting on top of Mac OS X. We strongly advice you to disable as much extensions and control panels as possible to make the classic environment faster, stable and take up less RAM. This technique also greatly speeds up loading (or booting) of Classic in Mac OS X.
We did a simple test on one PowerMac with 192MB of RAM. A copy of Mac OS X with classic booted up with all extensions and control panels ENABLED, the remaining free RAM is 86.7MB. Same test on same copy of Mac OS X with classic booted up with unnecessay extensions and control panels DISABLED, the remaining free RAM is 114MB. The different is 27.3MB!!!
Some classic programs do not run well in classic environment running on top of Mac OS X especially for classic program that need direct access to the hardware such as the digital camera connected to USB port. You need to run those programs on a Mac booting from Mac OS 9 (Not classic booting on top of Mac OS X).
It is very obvious that there is still a need for Extension Overload in Mac OS X to manage extensions, control panels and other items in Mac OS. We are committed to continue develop Extension Overload. We are currently working on a carbonized version of Extension Overload. Newer version of Extension Overload will be out very soon.
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We also welcome feedback. Looking forward to hear from you.
