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How To Disable Rosetta on Your Mac

written by: CompuDav•edited by: Rebecca Scudder•updated: 11/15/2009

Rosetta was a technology created by Apple in order to run old PowerPC applications on new Intel hardware. However, with the vast majority of applications being Universal or Intel-only, Rosetta is becoming obsolete. If you want to disable Rosetta without uninstalling it, we'll show you how.

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    Rosetta Explained

    Way back in the ancient days of 2005 (and for technology, this is like the dinosaur era of real life), Apple shocked the whole world by announcing that they would be switching their processors to the Intel line instead of the venerable PowerPC processors that they had been using for the decade prior. The problem with this switch was that applications written for the PowerPC could not be run on the Intel platform, so the brilliant developers at Apple created a little software program that could dynamically translate the PowerPC instructions into those that any x86 processor could understand. This program was called Rosetta.

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    Disable This Technology

    But now, since the vast majority of software is either Universal or Intel, Rosetta feels much like an antiquated technology that might no longer be needed by the average user. Indeed, if you're a stickler for making sure that everything you run is Intel-only, there's a nifty little command line trick that you can do to disable Rosetta "on-the-fly" so to speak. Simply open up the Terminal and type in the following command:

    sudo sysctl -w kern.exec.archhandler.powerpc=/usr/libexec/oah/RosettaNonGrata

    This will disable Rosetta on your machine by sending the PowerPC code to an executable that does not interpret it. So, if you try to open a PowerPC application, you'll be prompted to install Rosetta. If you'd like to re-enable Rosetta, you can do so via the following command:

    sudo sysctl -w kern.exec.archhandler.powerpc=/usr/libexec/oah/translate

    Upon entering this, Rosetta will be reactivated on your Mac.

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    Why?

    Some astute readers might be wondering what's the point of this trick - that is, why would anyone want to disable something that is only on-demand anyways? One reason might be to immediately know if something you download is PowerPC only or maybe you just want to be 100% sure that any universal binary is running Intel code. Another reason might be that you find that all of your applications are presently Intel-only and thus it seems kind of pointless to run anything PowerPC and you'd like to be made aware of it.

    Regardless of the reasons, this is a great trick because you don't have to completely uninstall Rosetta. Rather, you can simply turn off its translating abilities and re-enable them if you find that you really need to run that legacy PowerPC application. With the vast majority of recent Mac software being Intel or Universal, you might find that you never even need Rosetta at all!