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AltiVec and other limitations
While Rosetta will work to translate many Mac programs, it does have some important limitations.
"Many, but not all, applications can run translated," Apple said in a paper for developers. "Applications that run translated will never run as fast as they run as a native binary because the translation process itself incurs a processing cost."
Apple said that Rosetta is "designed to translate currently shipping applications that run on a PowerPC with a G3 processor and that are built for Mac OS X."
However, Apple said Rosetta can't run several types of code: that written specifically to use the PowerPC's AltiVec instructions; that which requires a G4 or G5 chip;
programs written for Mac OS 9, which today can run with Mac OS X's "classic" environment; kernel extensions; applications that depend on kernel extensions; and code that inserts preferences in the System Preferences pane.
"How compatible your application is with Rosetta depends on the type of application it is," Apple said. "Applications that have a lot of user interaction and low computational needs, such as a word processor, are quite compatible. Those that have a moderate amount of user interaction and some high computational needs or that use OpenGL are, in most cases, also quite compatible. Those that have intense computing needs aren't compatible."
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