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32- or 64-bit Kernel Startup Mode Selector for Mac

By Markus Winter Free

Developer's Description

MacOS X 10.6 Snow Leopard is 64-bit - or is it?. Well, actually MacOS X 10.6 Snow Leopard is both 32-bit and 64-bit, and what that means for you depends on both your hardware and your settings.

I put up an accompanying 0 website which should answer most of your questions at

What does this app do?

  • it shows whether you have a 32-bit or a 64-bit processor
  • it shows whether you have a 32-bit or a 64-bit EFI
  • it shows whether the MacOS X Kernel is set to boot in 32-bit or in 64-bit mode
  • it shows whether the MacOS X Kernel is running in 32-bit or in 64-bit mode
  • it shows whether Apple officially supports booting a 64-bit kernel on your Mac
  • it allows you to select whether you want to start the MacOS X Kernel in 32-bit or in 64-bit mode (the setting might be ignored on MacBooks, depending on how Apple implements the restriction)
  • accompanying webpage explains what the whole commotion about 32-bit and 64-bit in MacOS X Snow Leopard is about

Full Specifications

What's new in version 1.6

  • New: added info for the new Mac Models.
  • New: added bug report in case it throws an error (haven't had it happen or heard of any but as I was adding this to all my apps ...).

Thanks for all the feedback - but PLEASE read the website before asking questions. About 500 people must have asked why their Mac is still in 32bit KERNEL mode after applying the settings - and it is explained in detail on the website (I think I got rather grumpy after answering the first 300 mails)


Date Added March 4, 2010
Version 1.6

Operating Systems

Additional Requirements
  • Mac OS X 10.5 - 10.6
  • Intel processor
  • Popularity

    Total Downloads 9,530
    Downloads Last Week 2
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