Is it possible to run 32-bit only screen savers in Mountain Lion?

Just opening /System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app in 32-bit mode doesn't run 32-bit only screen savers.

  • I just tried it on 10.8 on my iMac. It works well. Jan 15, 2013 at 14:12
  • @MatthieuRiegler, what exactly did you try? A 64-bit screen saver open with ScreenSaverEngine.app in 32-bit mode or a 32-bit one?
    – 1.61803
    Jan 15, 2013 at 14:21
  • My Bad I just ran ScreenSaverEngine.app. I thought you just tried to run this. Jan 15, 2013 at 14:27

1 Answer 1


I don't think you can do this. I believe that Mountain Lion is 64-bit only, since my old Mac Pro, which is technically 64-bit capable, but won't run Mountain Lion. Lion could be booted into 32-bit mode, but I don't think Mountain Lion can.

  • Single apps can run in 32-bit mode in ML. Regarding your Mac Pro arstechnica.com/apple/2012/07/…
    – 1.61803
    Jan 15, 2013 at 17:25
  • There were other issues with screen savers. The 32-bit ness may be a red herring. In either 10.6 or 10.7 Apple required that screen savers were compiled with the "Garbage Collection Compatible" bit on. Once they did this screen savers had to be recompiled to work. The Screen Saver system preference view would put up a message telling you to contact the developer for an update. I had to do this for a couple screen savers I wrote. The chances of getting an old screen saver working on Mountain Lion are slim, unless you have the source code.
    – Ɱark Ƭ
    Jan 15, 2013 at 18:04
  • Just curious @MarkThalman but what screen savers did you write? I 'collect' them - currently 159 in my ~/Library/SS.
    – da4
    Oct 15, 2013 at 15:40
  • @da4 Nothing that I've ever released. Mostly clocks that bounce around the screen. One with the currently playing iTunes track and album artwork. You may be interested in RedPill <github.com/lpar/RedPill.git> It came up on SO a while ago. I changed the color of the glyphs to purple.
    – Ɱark Ƭ
    Oct 15, 2013 at 16:37

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